The role of auditory and kinaesthetic feedback mechanisms on phonatory stability in children.

PubMed

Rathna Kumar, S B; Azeem, Suhail; Choudhary, Abhishek Kumar; Prakash, S G R

2013-12-01

Auditory feedback plays an important role in phonatory control. When auditory feedback is disrupted, various changes are observed in vocal motor control. Vocal intensity and fundamental frequency (F0) levels tend to increase in response to auditory masking. Because of the close reflexive links between the auditory and phonatory systems, it is likely that phonatory stability may be disrupted when auditory feedback is disrupted or altered. However, studies on phonatory stability under auditory masking condition in adult subjects showed that most of the subjects maintained normal levels of phonatory stability. The authors in the earlier investigations suggested that auditory feedback is not the sole contributor to vocal motor control and phonatory stability, a complex neuromuscular reflex system known as kinaesthetic feedback may play a role in controlling phonatory stability when auditory feedback is disrupted or lacking. This proposes the need to further investigate this phenomenon as to whether children show similar patterns of phonatory stability under auditory masking since their neuromotor systems are still at developmental stage, less mature and are less resistant to altered auditory feedback than adults. A total of 40 normal hearing and speaking children (20 male and 20 female) between the age group of 6 and 8 years participated as subjects. The acoustic parameters such as shimmer, jitter and harmonic-to-noise ratio (HNR) were measures and compared between no masking condition (0 dB ML) and masking condition (90 dB ML). Despite the neuromotor systems being less mature in children and less resistant than adults to altered auditory feedback, most of the children in the study demonstrated increased phonatory stability which was reflected by reduced shimmer, jitter and increased HNR values. This study implicates that most of the children demonstrate well established patterns of kinaesthetic feedback, which might have allowed them to maintain normal levels of vocal motor control even in the presence of disturbed auditory feedback. Hence, it can be concluded that children also exhibit kinaesthetic feedback mechanism to control phonatory stability when auditory feedback is disrupted which in turn highlights the importance of kinaesthetic feedback to be included in the therapeutic/intervention approaches for children with hearing and neurogenic speech deficits.

Direct laser additive fabrication system with image feedback control

DOEpatents

Griffith, Michelle L.; Hofmeister, William H.; Knorovsky, Gerald A.; MacCallum, Danny O.; Schlienger, M. Eric; Smugeresky, John E.

2002-01-01

A closed-loop, feedback-controlled direct laser fabrication system is disclosed. The feedback refers to the actual growth conditions obtained by real-time analysis of thermal radiation images. The resulting system can fabricate components with severalfold improvement in dimensional tolerances and surface finish.

Identification of neural structures involved in stuttering using vibrotactile feedback.

PubMed

Cheadle, Oliver; Sorger, Clarissa; Howell, Peter

Feedback delivered over auditory and vibratory afferent pathways has different effects on the fluency of people who stutter (PWS). These features were exploited to investigate the neural structures involved in stuttering. The speech signal vibrated locations on the body (vibrotactile feedback, VTF). Eleven PWS read passages under VTF and control (no-VTF) conditions. All combinations of vibration amplitude, synchronous or delayed VTF and vibrator position (hand, sternum or forehead) were presented. Control conditions were performed at the beginning, middle and end of test sessions. Stuttering rate, but not speaking rate, differed between the control and VTF conditions. Notably, speaking rate did not change between when VTF was delayed versus when it was synchronous in contrast with what happens with auditory feedback. This showed that cerebellar mechanisms, which are affected when auditory feedback is delayed, were not implicated in the fluency-enhancing effects of VTF, suggesting that there is a second fluency-enhancing mechanism. Copyright © 2018 Elsevier Inc. All rights reserved.

Auditory-Motor Control of Vocal Production during Divided Attention: Behavioral and ERP Correlates.

PubMed

Liu, Ying; Fan, Hao; Li, Jingting; Jones, Jeffery A; Liu, Peng; Zhang, Baofeng; Liu, Hanjun

2018-01-01

When people hear unexpected perturbations in auditory feedback, they produce rapid compensatory adjustments of their vocal behavior. Recent evidence has shown enhanced vocal compensations and cortical event-related potentials (ERPs) in response to attended pitch feedback perturbations, suggesting that this reflex-like behavior is influenced by selective attention. Less is known, however, about auditory-motor integration for voice control during divided attention. The present cross-modal study investigated the behavioral and ERP correlates of auditory feedback control of vocal pitch production during divided attention. During the production of sustained vowels, 32 young adults were instructed to simultaneously attend to both pitch feedback perturbations they heard and flashing red lights they saw. The presentation rate of the visual stimuli was varied to produce a low, intermediate, and high attentional load. The behavioral results showed that the low-load condition elicited significantly smaller vocal compensations for pitch perturbations than the intermediate-load and high-load conditions. As well, the cortical processing of vocal pitch feedback was also modulated as a function of divided attention. When compared to the low-load and intermediate-load conditions, the high-load condition elicited significantly larger N1 responses and smaller P2 responses to pitch perturbations. These findings provide the first neurobehavioral evidence that divided attention can modulate auditory feedback control of vocal pitch production.

Effective components of feedback from Routine Outcome Monitoring (ROM) in youth mental health care: study protocol of a three-arm parallel-group randomized controlled trial

PubMed Central

2014-01-01

Background Routine Outcome Monitoring refers to regular measurements of clients’ progress in clinical practice, aiming to evaluate and, if necessary, adapt treatment. Clients fill out questionnaires and clinicians receive feedback about the results. Studies concerning feedback in youth mental health care are rare. The effects of feedback, the importance of specific aspects of feedback, and the mechanisms underlying the effects of feedback are unknown. In the present study, several potentially effective components of feedback from Routine Outcome Monitoring in youth mental health care in the Netherlands are investigated. Methods/Design We will examine three different forms of feedback through a three-arm parallel-group randomized controlled trial. 432 children and adolescents (aged 4 to 17 years) and their parents, who have been referred to mental health care institution Pro Persona, will be randomly assigned to one of three feedback conditions (144 participants per condition). Randomization will be stratified by age of the child or adolescent and by department. All participants fill out questionnaires at the start of treatment, one and a half months after the start of treatment, every three months during treatment, and at the end of treatment. Participants in the second and third feedback conditions fill out an additional questionnaire. In condition 1, clinicians receive basic feedback regarding clients’ symptoms and quality of life. In condition 2, the feedback of condition 1 is extended with feedback regarding possible obstacles to a good outcome and with practical suggestions. In condition 3, the feedback of condition 2 is discussed with a colleague while following a standardized format for case consultation. The primary outcome measure is symptom severity and secondary outcome measures are quality of life, satisfaction with treatment, number of sessions, length of treatment, and rates of dropout. We will also examine the role of being not on track (not responding to treatment). Discussion This study contributes to the identification of effective components of feedback and a better understanding of how feedback functions in real-world clinical practice. If the different feedback components prove to be effective, this can help to support and improve the care for youth. Trial registration Dutch Trial Register NTR4234 PMID:24393491

Treatment of Childhood Migraine Using Autogenic Feedback Training.

ERIC Educational Resources Information Center

Labbe, Elise L.

1984-01-01

Compared autogenic feedback training with a waiting-list control group as a treatment for children (N=28) with migraine headaches. Children in the treatment condition were significantly improved at the end of treatment and at one-month and six-month follow-up. No improvement was found for the children in the control condition. (BH)

Examining the Minimal Required Elements of a Computer-Tailored Intervention Aimed at Dietary Fat Reduction: Results of a Randomized Controlled Dismantling Study

ERIC Educational Resources Information Center

Kroeze, Willemieke; Oenema, Anke; Dagnelie, Pieter C.; Brug, Johannes

2008-01-01

This study investigated the minimally required feedback elements of a computer-tailored dietary fat reduction intervention to be effective in improving fat intake. In all 588 Healthy Dutch adults were randomly allocated to one of four conditions in an randomized controlled trial: (i) feedback on dietary fat intake [personal feedback (P feedback)],…

Operating wind turbines in strong wind conditions by using feedforward-feedback control

NASA Astrophysics Data System (ADS)

Feng, Ju; Sheng, Wen Zhong

2014-12-01

Due to the increasing penetration of wind energy into power systems, it becomes critical to reduce the impact of wind energy on the stability and reliability of the overall power system. In precedent works, Shen and his co-workers developed a re-designed operation schema to run wind turbines in strong wind conditions based on optimization method and standard PI feedback control, which can prevent the typical shutdowns of wind turbines when reaching the cut-out wind speed. In this paper, a new control strategy combing the standard PI feedback control with feedforward controls using the optimization results is investigated for the operation of variable-speed pitch-regulated wind turbines in strong wind conditions. It is shown that the developed control strategy is capable of smoothening the power output of wind turbine and avoiding its sudden showdown at high wind speeds without worsening the loads on rotor and blades.

Design of robust adaptive controller and feedback error learning for rehabilitation in Parkinson's disease: a simulation study.

PubMed

Rouhollahi, Korosh; Emadi Andani, Mehran; Karbassi, Seyed Mahdi; Izadi, Iman

2017-02-01

Deep brain stimulation (DBS) is an efficient therapy to control movement disorders of Parkinson's tremor. Stimulation of one area of basal ganglia (BG) by DBS with no feedback is the prevalent opinion. Reduction of additional stimulatory signal delivered to the brain is the advantage of using feedback. This results in reduction of side effects caused by the excessive stimulation intensity. In fact, the stimulatory intensity of controllers is decreased proportional to reduction of hand tremor. The objective of this study is to design a new controller structure to decrease three indicators: (i) the hand tremor; (ii) the level of delivered stimulation in disease condition; and (iii) the ratio of the level of delivered stimulation in health condition to disease condition. For this purpose, the authors offer a new closed-loop control structure to stimulate two areas of BG simultaneously. One area (STN: subthalamic nucleus) is stimulated by an adaptive controller with feedback error learning. The other area (GPi: globus pallidus internal) is stimulated by a partial state feedback (PSF) controller. Considering the three indicators, the results show that, stimulating two areas simultaneously leads to better performance compared with stimulating one area only. It is shown that both PSF and adaptive controllers are robust regarding system parameter uncertainties. In addition, a method is proposed to update the parameters of the BG model in real time. As a result, the parameters of the controllers can be updated based on the new parameters of the BG model.

Decentralised output feedback control of Markovian jump interconnected systems with unknown interconnections

NASA Astrophysics Data System (ADS)

Li, Li-Wei; Yang, Guang-Hong

2017-07-01

The problem of decentralised output feedback control is addressed for Markovian jump interconnected systems with unknown interconnections and general transition rates (TRs) allowed to be unknown or known with uncertainties. A class of decentralised dynamic output feedback controllers are constructed, and a cyclic-small-gain condition is exploited to dispose the unknown interconnections so that the resultant closed-loop system is stochastically stable and satisfies an H∞ performance. With slack matrices to cope with the nonlinearities incurred by unknown and uncertain TRs in control synthesis, a novel controller design condition is developed in linear matrix inequality formalism. Compared with the existing works, the proposed approach leads to less conservatism. Finally, two examples are used to illustrate the effectiveness of the new results.

Reduced-order dynamic output feedback control of uncertain discrete-time Markov jump linear systems

NASA Astrophysics Data System (ADS)

Morais, Cecília F.; Braga, Márcio F.; Oliveira, Ricardo C. L. F.; Peres, Pedro L. D.

2017-11-01

This paper deals with the problem of designing reduced-order robust dynamic output feedback controllers for discrete-time Markov jump linear systems (MJLS) with polytopic state space matrices and uncertain transition probabilities. Starting from a full order, mode-dependent and polynomially parameter-dependent dynamic output feedback controller, sufficient linear matrix inequality based conditions are provided for the existence of a robust reduced-order dynamic output feedback stabilising controller with complete, partial or none mode dependency assuring an upper bound to the ? or the ? norm of the closed-loop system. The main advantage of the proposed method when compared to the existing approaches is the fact that the dynamic controllers are exclusively expressed in terms of the decision variables of the problem. In other words, the matrices that define the controller realisation do not depend explicitly on the state space matrices associated with the modes of the MJLS. As a consequence, the method is specially suitable to handle order reduction or cluster availability constraints in the context of ? or ? dynamic output feedback control of discrete-time MJLS. Additionally, as illustrated by means of numerical examples, the proposed approach can provide less conservative results than other conditions in the literature.

Multiple feedback control apparatus for power conditioning equipment

NASA Technical Reports Server (NTRS)

Biess, John (Inventor); Yu, Yuan (Inventor)

1977-01-01

An improved feedback control system to govern the cyclic operation of the power switch of a non-dissipative power conditioning equipment. The apparatus includes two or three control loops working in unison. The first causes the output DC level to be compared with a reference, and the error amplified for control purposes. The second utilizes the AC component of the voltage across the output filter inductor or the current through the output filter capacitor, and the third loop senses the output transients.

Feedback is the breakfast of champions: the significance of self-controlled formal feedback for autonomous task engagement.

PubMed

Meng, Liang; Yang, Zijing

2018-01-03

With the aim of examining the positive effect of the formal feedback mechanism itself beyond its informational aspect, we engaged participants in the stopwatch task and recorded their electroencephalogram throughout the experiment. This task requires a button press to stop the watch within a given time interval, the completion of which is simultaneously accompanied by adequate information on task performance. In the self-controlled feedback mode, participants could freely choose whether to request formal feedback after completing the task. In another mode, additional feedback was not provided. The 'non-choice' cue was found to elicit a more negative cue-elicited feedback negativity compared with 'choice', suggesting that the opportunity to solicit formal feedback was perceived as more desirable. In addition, a more enhanced stimulus-preceding negativity was observed prior to the task initiation cue in the self-controlled feedback condition, indicating that participants paid more sustained anticipatory attention during task preparation. Taken together, these electrophysiological results suggested an inherent reward within the formal feedback mechanism itself and the significance of self-controlled formal feedback for autonomous task engagement.

The effect of feedback-assisted reduction in heart rate reactivity on videogame performance.

PubMed

Larkin, K T; Manuck, S B; Kasprowicz, A L

1990-12-01

In 67 male volunteers, we examined the reduction of cardiovascular responsivity to a psychomotor challenge (videogame) achieved by use of heart rate (HR) feedback and effects of these procedures on concomitant behavioral performance. Each subject participated in a pretraining assessment of his cardiovascular responses to the videogame, a training condition, and a posttraining assessment identical to the initial evaluation. During training, subjects were assigned to one of four conditions: (a) a habituation control group receiving no instructions to alter HR (HC); (b) an instructions-only control group receiving instructions to maintain a low or unchanged HR during videogame presentations (IC); (c) a feedback group receiving instructions to reduce HR using ongoing HR feedback (FB-); or (d) a feedback group receiving instructions to lower HR and given HR feedback plus a score contingency in which total game score was jointly determined by subjects' game performance and success at HR control (FB+). Subjects receiving feedback (FB+, FB-) exhibited greater reductions in HR response to the videogame in the posttraining assessment than control (HC, IC) subjects; FB+ subjects showed greater HR reductions than subjects in any other group. FB+ and FB- subjects showed a lower SBP at posttraining relative to the two control groups, but no reduction in task-induced blood pressure reactivity. There were no group differences in videogame performance, either before or following training.

Counterintuitive Effects of Online Feedback in Middle School Math: Results from a Randomized Controlled Trial in ASSISTments

ERIC Educational Resources Information Center

McGuire, Patrick; Tu, Shihfen; Logue, Mary Ellin; Mason, Craig A.; Ostrow, Korinn

2017-01-01

This study compared the effects of three different feedback formats provided to sixth grade mathematics students within a web-based online learning platform, ASSISTments. A sample of 196 students were randomly assigned to one of three conditions: (1) text-based feedback; (2) image-based feedback; and (3) correctness only feedback. Regardless of…

Motivation in vigilance - Effects of self-evaluation and experimenter-controlled feedback.

NASA Technical Reports Server (NTRS)

Warm, J. S.; Kanfer, F. H.; Kuwada, S.; Clark, J. L.

1972-01-01

Vigilance experiments have been performed to study the relative efficiency of feedback operations in enhancing vigilance performance. Two feedback operations were compared - i.e., experimenter-controlled feedback in the form of knowledge of results (KR) regarding response times to signal detections, and subject-controlled feedback in the form of self-evaluation (SE) of response times to signal detections. The subjects responded to the aperiodic offset of a visual signal during a 1-hr vigil. Both feedback operations were found to enhance performance efficiency: subjects in the KR and SE conditions had faster response times than controls receiving no evaluative feedback. Moreover, the data of the KR and SE groups did not differ significantly from each other. The results are discussed in terms of the hypothesis that self-evaluation is a critical factor underlying the incentive value of KR in vigilance tasks.

ASDTIC: A feedback control innovation

NASA Technical Reports Server (NTRS)

Lalli, V. R.; Schoenfeld, A. D.

1972-01-01

The ASDTIC (Analog Signal to Discrete Time Interval Converter) control subsystem provides precise output control of high performance aerospace power supplies. The key to ASDTIC operation is that it stably controls output by sensing output energy change as well as output magnitude. The ASDTIC control subsystem and control module were developed to improve power supply performance during static and dynamic input voltage and output load variations, to reduce output voltage or current regulation due to component variations or aging, to maintain a stable feedback control with variations in the loop gain or loop time constants, and to standardize the feedback control subsystem for power conditioning equipment.

ASDTIC - A feedback control innovation.

NASA Technical Reports Server (NTRS)

Lalli, V. R.; Schoenfeld, A. D.

1972-01-01

The ASDTIC (analog signal to discrete time interval converter) control subsystem provides precise output control of high performance aerospace power supplies. The key to ASDTIC operation is that it stably controls output by sensing output energy change as well as output magnitude. The ASDTIC control subsystem and control module were developed to improve power supply performance during static and dynamic input voltage and output load variations, to reduce output voltage or current regulation due to component variations or aging, to maintain a stable feedback control with variations in the loop gain or loop time constants, and to standardize the feedback control subsystem for power conditioning equipment.

Strength of German accent under altered auditory feedback

PubMed Central

HOWELL, PETER; DWORZYNSKI, KATHARINA

2007-01-01

Borden’s (1979, 1980) hypothesis that speakers with vulnerable speech systems rely more heavily on feedback monitoring than do speakers with less vulnerable systems was investigated. The second language (L2) of a speaker is vulnerable, in comparison with the native language, so alteration to feedback should have a detrimental effect on it, according to this hypothesis. Here, we specifically examined whether altered auditory feedback has an effect on accent strength when speakers speak L2. There were three stages in the experiment. First, 6 German speakers who were fluent in English (their L2) were recorded under six conditions—normal listening, amplified voice level, voice shifted in frequency, delayed auditory feedback, and slowed and accelerated speech rate conditions. Second, judges were trained to rate accent strength. Training was assessed by whether it was successful in separating German speakers speaking English from native English speakers, also speaking English. In the final stage, the judges ranked recordings of each speaker from the first stage as to increasing strength of German accent. The results show that accents were more pronounced under frequency-shifted and delayed auditory feedback conditions than under normal or amplified feedback conditions. Control tests were done to ensure that listeners were judging accent, rather than fluency changes caused by altered auditory feedback. The findings are discussed in terms of Borden’s hypothesis and other accounts about why altered auditory feedback disrupts speech control. PMID:11414137

Personalized Mailed Feedback for College Drinking Prevention: A Randomized Clinical Trial

ERIC Educational Resources Information Center

Larimer, Mary E.; Lee, Christine M.; Kilmer, Jason R.; Fabiano, Patricia M.; Stark, Christopher B.; Geisner, Irene M.; Mallett, Kimberly A.; Lostutter, Ty W.; Cronce, Jessica M.; Feeney, Maggie; Neighbors, Clayton

2007-01-01

The current study was designed to evaluate the efficacy of a mailed feedback and tips intervention as a universal prevention strategy for college drinking. Participants (N = 1,488) were randomly assigned to feedback or assessment-only control conditions. Results indicated that the mailed feedback intervention had a preventive effect on drinking…

Feedback-controlled heat transport in quantum devices: theory and solid-state experimental proposal

NASA Astrophysics Data System (ADS)

Campisi, Michele; Pekola, Jukka; Fazio, Rosario

2017-05-01

A theory of feedback-controlled heat transport in quantum systems is presented. It is based on modelling heat engines as driven multipartite systems subject to projective quantum measurements and measurement-conditioned unitary evolutions. The theory unifies various results presented previously in the literature. Feedback control breaks time reversal invariance. This in turn results in the fluctuation relation not being obeyed. Its restoration occurs through appropriate accounting of the gain and use of information via measurements and feedback. We further illustrate an experimental proposal for the realisation of a Maxwell demon using superconducting circuits and single-photon on-chip calorimetry. A two-level qubit acts as a trap-door, which, conditioned on its state, is coupled to either a hot resistor or a cold one. The feedback mechanism alters the temperatures felt by the qubit and can result in an effective inversion of temperature gradient, where heat flows from cold to hot thanks to the gain and use of information.

Robust design of feedback feed-forward iterative learning control based on 2D system theory for linear uncertain systems

NASA Astrophysics Data System (ADS)

Li, Zhifu; Hu, Yueming; Li, Di

2016-08-01

For a class of linear discrete-time uncertain systems, a feedback feed-forward iterative learning control (ILC) scheme is proposed, which is comprised of an iterative learning controller and two current iteration feedback controllers. The iterative learning controller is used to improve the performance along the iteration direction and the feedback controllers are used to improve the performance along the time direction. First of all, the uncertain feedback feed-forward ILC system is presented by an uncertain two-dimensional Roesser model system. Then, two robust control schemes are proposed. One can ensure that the feedback feed-forward ILC system is bounded-input bounded-output stable along time direction, and the other can ensure that the feedback feed-forward ILC system is asymptotically stable along time direction. Both schemes can guarantee the system is robust monotonically convergent along the iteration direction. Third, the robust convergent sufficient conditions are given, which contains a linear matrix inequality (LMI). Moreover, the LMI can be used to determine the gain matrix of the feedback feed-forward iterative learning controller. Finally, the simulation results are presented to demonstrate the effectiveness of the proposed schemes.

Structured output-feedback controller synthesis with design specifications

NASA Astrophysics Data System (ADS)

Hao, Yuqing; Duan, Zhisheng

2017-03-01

This paper considers the problem of structured output-feedback controller synthesis with finite frequency specifications. Based on the orthogonal space information of input matrix, an improved parameter-dependent Lyapunov function method is first proposed. Then, a two-stage construction method is designed, which depends on an initial centralised controller. Corresponding design conditions for three types of output-feedback controllers are presented in terms of unified representations. Moreover, heuristic algorithms are provided to explore the desirable controllers. Finally, the effectiveness of these proposed methods is illustrated via some practical examples.

Neural correlates of anticipation and processing of performance feedback in social anxiety.

PubMed

Heitmann, Carina Y; Peterburs, Jutta; Mothes-Lasch, Martin; Hallfarth, Marlit C; Böhme, Stephanie; Miltner, Wolfgang H R; Straube, Thomas

2014-12-01

Fear of negative evaluation, such as negative social performance feedback, is the core symptom of social anxiety. The present study investigated the neural correlates of anticipation and perception of social performance feedback in social anxiety. High (HSA) and low (LSA) socially anxious individuals were asked to give a speech on a personally relevant topic and received standardized but appropriate expert performance feedback in a succeeding experimental session in which neural activity was measured during anticipation and presentation of negative and positive performance feedback concerning the speech performance, or a neutral feedback-unrelated control condition. HSA compared to LSA subjects reported greater anxiety during anticipation of negative feedback. Functional magnetic resonance imaging results showed deactivation of medial prefrontal brain areas during anticipation of negative feedback relative to the control and the positive condition, and medial prefrontal and insular hyperactivation during presentation of negative as well as positive feedback in HSA compared to LSA subjects. The results indicate distinct processes underlying feedback processing during anticipation and presentation of feedback in HSA as compared to LSA individuals. In line with the role of the medial prefrontal cortex in self-referential information processing and the insula in interoception, social anxiety seems to be associated with lower self-monitoring during feedback anticipation, and an increased self-focus and interoception during feedback presentation, regardless of feedback valence. © 2014 Wiley Periodicals, Inc.

The damaging effect of confirming feedback on the relation between eyewitness certainty and identification accuracy.

PubMed

Bradfield, Amy L; Wells, Gary L; Olson, Elizabeth A

2002-02-01

The authors investigated eyewitnesses' retrospective certainty (see G. L. Wells & A. L. Bradfield, 1999). The authors hypothesized that extemal influence from the lineup administrator would damage the certainty-accuracy relation by inflating the retrospective certainty of inaccurate eyewitnesses more than that of accurate eyewitnesses (N = 245). Two variables were manipulated: eyewitness accuracy (through the presence or absence of the culprit in the lineup) and feedback (confirming vs. control). Confirming feedback inflated retrospective certainty more for inaccurate eyewitnesses than for accurate eyewitnesses, significantly reducing the certainty-accuracy relation (from r = .58 in the control condition to r = .37 in the confirming feedback condition). Double-blind testing is recommended for lineups to prevent these external influences on eyewitnesses.

Robust consensus control with guaranteed rate of convergence using second-order Hurwitz polynomials

NASA Astrophysics Data System (ADS)

Fruhnert, Michael; Corless, Martin

2017-10-01

This paper considers homogeneous networks of general, linear time-invariant, second-order systems. We consider linear feedback controllers and require that the directed graph associated with the network contains a spanning tree and systems are stabilisable. We show that consensus with a guaranteed rate of convergence can always be achieved using linear state feedback. To achieve this, we provide a new and simple derivation of the conditions for a second-order polynomial with complex coefficients to be Hurwitz. We apply this result to obtain necessary and sufficient conditions to achieve consensus with networks whose graph Laplacian matrix may have complex eigenvalues. Based on the conditions found, methods to compute feedback gains are proposed. We show that gains can be chosen such that consensus is achieved robustly over a variety of communication structures and system dynamics. We also consider the use of static output feedback.

On the Stability of Collocated Controllers in the Presence or Uncertain Nonlinearities and Other Perils

NASA Technical Reports Server (NTRS)

Joshi, S. M.

1985-01-01

Robustness properties are investigated for two types of controllers for large flexible space structures, which use collocated sensors and actuators. The first type is an attitude controller which uses negative definite feedback of measured attitude and rate, while the second type is a damping enhancement controller which uses only velocity (rate) feedback. It is proved that collocated attitude controllers preserve closed loop global asymptotic stability when linear actuator/sensor dynamics satisfying certain phase conditions are present, or monotonic increasing nonlinearities are present. For velocity feedback controllers, the global asymptotic stability is proved under much weaker conditions. In particular, they have 90 phase margin and can tolerate nonlinearities belonging to the (0,infinity) sector in the actuator/sensor characteristics. The results significantly enhance the viability of both types of collocated controllers, especially when the available information about the large space structure (LSS) parameters is inadequate or inaccurate.

Modeling trial by trial and block feedback in perceptual learning

PubMed Central

Liu, Jiajuan; Dosher, Barbara; Lu, Zhong-Lin

2014-01-01

Feedback has been shown to play a complex role in visual perceptual learning. It is necessary for performance improvement in some conditions while not others. Different forms of feedback, such as trial-by-trial feedback or block feedback, may both facilitate learning, but with different mechanisms. False feedback can abolish learning. We account for all these results with the Augmented Hebbian Reweight Model (AHRM). Specifically, three major factors in the model advance performance improvement: the external trial-by-trial feedback when available, the self-generated output as an internal feedback when no external feedback is available, and the adaptive criterion control based on the block feedback. Through simulating a comprehensive feedback study (Herzog & Fahle 1997, Vision Research, 37 (15), 2133–2141), we show that the model predictions account for the pattern of learning in seven major feedback conditions. The AHRM can fully explain the complex empirical results on the role of feedback in visual perceptual learning. PMID:24423783

The Effects of Fluency Enhancing Conditions on Sensorimotor Control of Speech in Typically Fluent Speakers: An EEG Mu Rhythm Study

PubMed Central

Kittilstved, Tiffani; Reilly, Kevin J.; Harkrider, Ashley W.; Casenhiser, Devin; Thornton, David; Jenson, David E.; Hedinger, Tricia; Bowers, Andrew L.; Saltuklaroglu, Tim

2018-01-01

Objective: To determine whether changes in sensorimotor control resulting from speaking conditions that induce fluency in people who stutter (PWS) can be measured using electroencephalographic (EEG) mu rhythms in neurotypical speakers. Methods: Non-stuttering (NS) adults spoke in one control condition (solo speaking) and four experimental conditions (choral speech, delayed auditory feedback (DAF), prolonged speech and pseudostuttering). Independent component analysis (ICA) was used to identify sensorimotor μ components from EEG recordings. Time-frequency analyses measured μ-alpha (8–13 Hz) and μ-beta (15–25 Hz) event-related synchronization (ERS) and desynchronization (ERD) during each speech condition. Results: 19/24 participants contributed μ components. Relative to the control condition, the choral and DAF conditions elicited increases in μ-alpha ERD in the right hemisphere. In the pseudostuttering condition, increases in μ-beta ERD were observed in the left hemisphere. No differences were present between the prolonged speech and control conditions. Conclusions: Differences observed in the experimental conditions are thought to reflect sensorimotor control changes. Increases in right hemisphere μ-alpha ERD likely reflect increased reliance on auditory information, including auditory feedback, during the choral and DAF conditions. In the left hemisphere, increases in μ-beta ERD during pseudostuttering may have resulted from the different movement characteristics of this task compared with the solo speaking task. Relationships to findings in stuttering are discussed. Significance: Changes in sensorimotor control related feedforward and feedback control in fluency-enhancing speech manipulations can be measured using time-frequency decompositions of EEG μ rhythms in neurotypical speakers. This quiet, non-invasive, and temporally sensitive technique may be applied to learn more about normal sensorimotor control and fluency enhancement in PWS. PMID:29670516

Generation of synthetic surface electromyography signals under fatigue conditions for varying force inputs using feedback control algorithm.

PubMed

Venugopal, G; Deepak, P; Ghosh, Diptasree M; Ramakrishnan, S

2017-11-01

Surface electromyography is a non-invasive technique used for recording the electrical activity of neuromuscular systems. These signals are random, complex and multi-component. There are several techniques to extract information about the force exerted by muscles during any activity. This work attempts to generate surface electromyography signals for various magnitudes of force under isometric non-fatigue and fatigue conditions using a feedback model. The model is based on existing current distribution, volume conductor relations, the feedback control algorithm for rate coding and generation of firing pattern. The result shows that synthetic surface electromyography signals are highly complex in both non-fatigue and fatigue conditions. Furthermore, surface electromyography signals have higher amplitude and lower frequency under fatigue condition. This model can be used to study the influence of various signal parameters under fatigue and non-fatigue conditions.

Stimulus-dependent modulation of visual neglect in a touch-screen cancellation task.

PubMed

Keller, Ingo; Volkening, Katharina; Garbacenkaite, Ruta

2015-05-01

Patients with left-sided neglect frequently show omissions and repetitive behavior on cancellation tests. Using a touch-screen-based cancellation task, we tested how visual feedback and distracters influence the number of omissions and perseverations. Eighteen patients with left-sided visual neglect and 18 healthy controls performed four different cancellation tasks on an iPad touch screen: no feedback (the display did not change during the task), visual feedback (touched targets changed their color from black to green), visual feedback with distracters (20 distracters were evenly embedded in the display; detected targets changed their color from black to green), vanishing targets (touched targets disappeared from the screen). Except for the condition with vanishing targets, neglect patients had significantly more omissions and perseverations than healthy controls in the remaining three subtests. Both conditions providing feedback by changing the target color showed the highest number of omissions. Erasure of targets nearly diminished omissions completely. The highest rate of perseverations was observed in the no-feedback condition. The implementation of distracters led to a moderate number of perseverations. Visual feedback without distracters and vanishing targets abolished perseverations nearly completely. Visual feedback and the presence of distracters aggravated hemispatial neglect. This finding is compatible with impaired disengagement from the ipsilesional side as an important factor of visual neglect. Improvement of cancellation behavior with vanishing targets could have therapeutic implications. (c) 2015 APA, all rights reserved).

Stability analysis of dynamic collaboration model with control signals on two lanes

NASA Astrophysics Data System (ADS)

Li, Zhipeng; Zhang, Run; Xu, Shangzhi; Qian, Yeqing; Xu, Juan

2014-12-01

In this paper, the influence of control signals on the stability of two-lane traffic flow is mainly studied by applying control theory with lane changing behaviors. We present the two-lane dynamic collaboration model with lateral friction and the expressions of feedback control signals. What is more, utilizing the delayed feedback control theory to the two-lane dynamic collaboration model with control signals, we investigate the stability of traffic flow theoretically and the stability conditions for both lanes are derived with finding that the forward and lateral feedback signals can improve the stability of traffic flow while the backward feedback signals cannot achieve it. Besides, direct simulations are conducted to verify the results of theoretical analysis, which shows that the feedback signals have a significant effect on the running state of two vehicle groups, and the results are same with the theoretical analysis.

Evaluating the Impact of Feedback on Elementary Aged Students’ Fluency Growth in Written Expression: A Randomized Controlled Trial

PubMed Central

Truckenmiller, Adrea J.; Eckert, Tanya L.; Codding, Robin S.; Petscher, Yaacov

2016-01-01

The purpose of this randomized controlled trial was to evaluate elementary-aged students’ writing fluency growth in response to (a) instructional practices, (b) sex differences, and (c) student’s initial level of writing fluency. Third-grade students (n=133) in three urban elementary schools were randomly assigned to either an individualized performance feedback condition (n=46), a practice-only condition (i.e., weekly writing practice; n = 39), or an instructional control condition (n = 48) for 8 weeks. Findings included support for use of performance feedback as an instructional component in general education classrooms (Hedges’ g = 0.66), whereas simple practice with curriculum-based measurement in written expression did not produce growth significantly greater than standard instructional practices. The hypothesis that girls write significantly more than boys was supported. However, girls and boys did not differ in their rate of growth. Finally, students’ initial risk status in writing fluency did not differentially predict growth in writing fluency over the course of the study. Implications for incorporating feedback as a basic component of intervention in writing are discussed. PMID:25432270

Integrated Flight/Structural Mode Control for Very Flexible Aircraft Using L1 Adaptive Output Feedback Controller

NASA Technical Reports Server (NTRS)

Che, Jiaxing; Cao, Chengyu; Gregory, Irene M.

2012-01-01

This paper explores application of adaptive control architecture to a light, high-aspect ratio, flexible aircraft configuration that exhibits strong rigid body/flexible mode coupling. Specifically, an L(sub 1) adaptive output feedback controller is developed for a semi-span wind tunnel model capable of motion. The wind tunnel mount allows the semi-span model to translate vertically and pitch at the wing root, resulting in better simulation of an aircraft s rigid body motion. The control objective is to design a pitch control with altitude hold while suppressing body freedom flutter. The controller is an output feedback nominal controller (LQG) augmented by an L(sub 1) adaptive loop. A modification to the L(sub 1) output feedback is proposed to make it more suitable for flexible structures. The new control law relaxes the required bounds on the unmatched uncertainty and allows dependence on the state as well as time, i.e. a more general unmatched nonlinearity. The paper presents controller development and simulated performance responses. Simulation is conducted by using full state flexible wing models derived from test data at 10 different dynamic pressure conditions. An L(sub 1) adaptive output feedback controller is designed for a single test point and is then applied to all the test cases. The simulation results show that the L(sub 1) augmented controller can stabilize and meet the performance requirements for all 10 test conditions ranging from 30 psf to 130 psf dynamic pressure.

Motor Controller System For Large Dynamic Range of Motor Operation

NASA Technical Reports Server (NTRS)

Howard, David E. (Inventor); Alhorn, Dean C. (Inventor); Smith, Dennis A. (Inventor); Dutton, Kenneth R. (Inventor); Paulson, Mitchell Scott (Inventor)

2006-01-01

A motor controller system uses a rotary sensor with a plurality of signal conditioning units, coupled to the rotary sensor. Each of these units, which is associated with a particular range of motor output shaft rotation rates, generate a feedback signal indicative of the position of the motor s output shaft. A controller (i) converts a selected motor output shaft rotation rate to a corresponding incremental amount of rotational movement for a selected fixed time period, (ii) selects, at periodic completions of the selected fixed time period, the feedback signal from one of the signal conditioning units for which the particular range of motor output shaft rotation rates associated therewith encompasses the selected motor output shaft rotation rate, and (iii) generates a motor drive signal based on a difference between the incremental amount of rotational movement and the feedback signal from the selected one of the signal conditioning Units.

Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems

PubMed Central

Xia, Feng; Ma, Longhua; Peng, Chen; Sun, Youxian; Dong, Jinxiang

2008-01-01

There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting cross-layer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An event-driven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN. PMID:27879934

Binocular and Monocular Depth Cues in Online Feedback Control of 3-D Pointing Movement

PubMed Central

Hu, Bo; Knill, David C.

2012-01-01

Previous work has shown that humans continuously use visual feedback of the hand to control goal-directed movements online. In most studies, visual error signals were predominantly in the image plane and thus were available in an observer’s retinal image. We investigate how humans use visual feedback about finger depth provided by binocular and monocular depth cues to control pointing movements. When binocularly viewing a scene in which the hand movement was made in free space, subjects were about 60 ms slower in responding to perturbations in depth than in the image plane. When monocularly viewing a scene designed to maximize the available monocular cues to finger depth (motion, changing size and cast shadows), subjects showed no response to perturbations in depth. Thus, binocular cues from the finger are critical to effective online control of hand movements in depth. An optimal feedback controller that takes into account of the low peripheral stereoacuity and inherent ambiguity in cast shadows can explain the difference in response time in the binocular conditions and lack of response in monocular conditions. PMID:21724567

Monitoring and control of amygdala neurofeedback involves distributed information processing in the human brain.

PubMed

Paret, Christian; Zähringer, Jenny; Ruf, Matthias; Gerchen, Martin Fungisai; Mall, Stephanie; Hendler, Talma; Schmahl, Christian; Ende, Gabriele

2018-03-30

Brain-computer interfaces provide conscious access to neural activity by means of brain-derived feedback ("neurofeedback"). An individual's abilities to monitor and control feedback are two necessary processes for effective neurofeedback therapy, yet their underlying functional neuroanatomy is still being debated. In this study, healthy subjects received visual feedback from their amygdala response to negative pictures. Activation and functional connectivity were analyzed to disentangle the role of brain regions in different processes. Feedback monitoring was mapped to the thalamus, ventromedial prefrontal cortex (vmPFC), ventral striatum (VS), and rostral PFC. The VS responded to feedback corresponding to instructions while rPFC activity differentiated between conditions and predicted amygdala regulation. Control involved the lateral PFC, anterior cingulate, and insula. Monitoring and control activity overlapped in the VS and thalamus. Extending current neural models of neurofeedback, this study introduces monitoring and control of feedback as anatomically dissociated processes, and suggests their important role in voluntary neuromodulation. © 2018 Wiley Periodicals, Inc.

Linear Matrix Inequality Method for a Quadratic Performance Index Minimization Problem with a class of Bilinear Matrix Inequality Conditions

NASA Astrophysics Data System (ADS)

Tanemura, M.; Chida, Y.

2016-09-01

There are a lot of design problems of control system which are expressed as a performance index minimization under BMI conditions. However, a minimization problem expressed as LMIs can be easily solved because of the convex property of LMIs. Therefore, many researchers have been studying transforming a variety of control design problems into convex minimization problems expressed as LMIs. This paper proposes an LMI method for a quadratic performance index minimization problem with a class of BMI conditions. The minimization problem treated in this paper includes design problems of state-feedback gain for switched system and so on. The effectiveness of the proposed method is verified through a state-feedback gain design for switched systems and a numerical simulation using the designed feedback gains.

Feedback Controller Design for the Synchronization of Boolean Control Networks.

PubMed

Liu, Yang; Sun, Liangjie; Lu, Jianquan; Liang, Jinling

2016-09-01

This brief investigates the partial and complete synchronization of two Boolean control networks (BCNs). Necessary and sufficient conditions for partial and complete synchronization are established by the algebraic representations of logical dynamics. An algorithm is obtained to construct the feedback controller that guarantees the synchronization of master and slave BCNs. Two biological examples are provided to illustrate the effectiveness of the obtained results.

Feedback to semi-professional counselors in treating child aggression.

PubMed

Shechtman, Zipora; Tutian, Rony

2017-05-01

To investigate the impact of outcome feedback provided to semi-professional counselors of children and adolescents at risk for aggressive behavior, following group treatment. Participants included 230 aggressive children and adolescents and 64 educators in a quasi-experimental design of 3 conditions: experimental group with feedback, experimental group without feedback, and control group (no treatment). The current study employed a feedback system based on self-report aggression scores measured after each session, provided to teachers, including an alert system and weekly follow-up group support. Outcomes were more favorable for the treatment children than the control group, but feedback had no impact on the results. Outcome feedback provided to group therapists does not have an effect on children and adolescents' reduction of aggression. Further research is needed to identify possible reasons for failure to show feedback effect.

Letter to the editor concerning the article "Effects of acoustic feedback training in elite-standard Para-Rowing" by Schaffert and Mattes (2015).

PubMed

Hill, Holger

2015-01-01

In a case study, Schaffert and Mattes reported the application of acoustic feedback (sonification) to optimise the time course of boat acceleration. The authors attributed an increased boat speed in the feedback condition to an optimised boat acceleration (mainly during the recovery phase). However, in rowing it is biomechanically impossible to increase the boat speed significantly by reducing the fluctuations in boat acceleration during the rowing cycle. To assess such a, potentially small, optimising effect experimentally, the confounding variables must be controlled very accurately (that is especially the propulsive forces must be kept constant between experimental conditions or the differences in propulsive forces between conditions must be much smaller than the effects on boat speed resulting from an optimised movement pattern). However, this was not controlled adequately by the authors. Instead, the presented boat acceleration data show that the increased boat speed under acoustic feedback was due to increased propulsive forces.

Robust non-fragile finite-frequency H∞ static output-feedback control for active suspension systems

NASA Astrophysics Data System (ADS)

Wang, Gang; Chen, Changzheng; Yu, Shenbo

2017-07-01

This paper deals with the problem of non-fragile H∞ static output-feedback control of vehicle active suspension systems with finite-frequency constraint. The control objective is to improve ride comfort within the given frequency range and ensure the hard constraints in the time-domain. Moreover, in order to enhance the robustness of the controller, the control gain perturbation is also considered in controller synthesis. Firstly, a new non-fragile H∞ finite-frequency control condition is established by using generalized Kalman-Yakubovich-Popov (GKYP) lemma. Secondly, the static output-feedback control gain is directly derived by using a non-iteration algorithm. Different from the existing iteration LMI results, the static output-feedback design is simple and less conservative. Finally, the proposed control algorithm is applied to a quarter-car active suspension model with actuator dynamics, numerical results are made to show the effectiveness and merits of the proposed method.

Identification of optimal feedback control rules from micro-quadrotor and insect flight trajectories.

PubMed

Faruque, Imraan A; Muijres, Florian T; Macfarlane, Kenneth M; Kehlenbeck, Andrew; Humbert, J Sean

2018-06-01

This paper presents "optimal identification," a framework for using experimental data to identify the optimality conditions associated with the feedback control law implemented in the measurements. The technique compares closed loop trajectory measurements against a reduced order model of the open loop dynamics, and uses linear matrix inequalities to solve an inverse optimal control problem as a convex optimization that estimates the controller optimality conditions. In this study, the optimal identification technique is applied to two examples, that of a millimeter-scale micro-quadrotor with an engineered controller on board, and the example of a population of freely flying Drosophila hydei maneuvering about forward flight. The micro-quadrotor results show that the performance indices used to design an optimal flight control law for a micro-quadrotor may be recovered from the closed loop simulated flight trajectories, and the Drosophila results indicate that the combined effect of the insect longitudinal flight control sensing and feedback acts principally to regulate pitch rate.

Grip force control during virtual object interaction: effect of force feedback,accuracy demands, and training.

PubMed

Gibo, Tricia L; Bastian, Amy J; Okamura, Allison M

2014-03-01

When grasping and manipulating objects, people are able to efficiently modulate their grip force according to the experienced load force. Effective grip force control involves providing enough grip force to prevent the object from slipping, while avoiding excessive force to avoid damage and fatigue. During indirect object manipulation via teleoperation systems or in virtual environments, users often receive limited somatosensory feedback about objects with which they interact. This study examines the effects of force feedback, accuracy demands, and training on grip force control during object interaction in a virtual environment. The task required subjects to grasp and move a virtual object while tracking a target. When force feedback was not provided, subjects failed to couple grip and load force, a capability fundamental to direct object interaction. Subjects also exerted larger grip force without force feedback and when accuracy demands of the tracking task were high. In addition, the presence or absence of force feedback during training affected subsequent performance, even when the feedback condition was switched. Subjects' grip force control remained reminiscent of their employed grip during the initial training. These results motivate the use of force feedback during telemanipulation and highlight the effect of force feedback during training.

Auditory Masking Effects on Speech Fluency in Apraxia of Speech and Aphasia: Comparison to Altered Auditory Feedback

PubMed Central

Haley, Katarina L.

2015-01-01

Purpose To study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not expected to improve speech fluency. Method Ten participants with APH/AOS and 10 neurologically healthy (NH) participants were studied under both feedback conditions. To allow examination of individual responses, we used an ABACA design. Effects were examined on syllable rate, disfluency duration, and vocal intensity. Results Seven of 10 APH/AOS participants increased fluency with masking by increasing rate, decreasing disfluency duration, or both. In contrast, none of the NH participants increased speaking rate with MAF. In the AAF condition, only 1 APH/AOS participant increased fluency. Four APH/AOS participants and 8 NH participants slowed their rate with AAF. Conclusions Speaking with MAF appears to increase fluency in a subset of individuals with APH/AOS, indicating that overreliance on auditory feedback monitoring may contribute to their disorder presentation. The distinction between responders and nonresponders was not linked to AOS diagnosis, so additional work is needed to develop hypotheses for candidacy and underlying control mechanisms. PMID:26363508

Consensus Algorithms for Networks of Systems with Second- and Higher-Order Dynamics

NASA Astrophysics Data System (ADS)

Fruhnert, Michael

This thesis considers homogeneous networks of linear systems. We consider linear feedback controllers and require that the directed graph associated with the network contains a spanning tree and systems are stabilizable. We show that, in continuous-time, consensus with a guaranteed rate of convergence can always be achieved using linear state feedback. For networks of continuous-time second-order systems, we provide a new and simple derivation of the conditions for a second-order polynomials with complex coefficients to be Hurwitz. We apply this result to obtain necessary and sufficient conditions to achieve consensus with networks whose graph Laplacian matrix may have complex eigenvalues. Based on the conditions found, methods to compute feedback gains are proposed. We show that gains can be chosen such that consensus is achieved robustly over a variety of communication structures and system dynamics. We also consider the use of static output feedback. For networks of discrete-time second-order systems, we provide a new and simple derivation of the conditions for a second-order polynomials with complex coefficients to be Schur. We apply this result to obtain necessary and sufficient conditions to achieve consensus with networks whose graph Laplacian matrix may have complex eigenvalues. We show that consensus can always be achieved for marginally stable systems and discretized systems. Simple conditions for consensus achieving controllers are obtained when the Laplacian eigenvalues are all real. For networks of continuous-time time-variant higher-order systems, we show that uniform consensus can always be achieved if systems are quadratically stabilizable. In this case, we provide a simple condition to obtain a linear feedback control. For networks of discrete-time higher-order systems, we show that constant gains can be chosen such that consensus is achieved for a variety of network topologies. First, we develop simple results for networks of time-invariant systems and networks of time-variant systems that are given in controllable canonical form. Second, we formulate the problem in terms of Linear Matrix Inequalities (LMIs). The condition found simplifies the design process and avoids the parallel solution of multiple LMIs. The result yields a modified Algebraic Riccati Equation (ARE) for which we present an equivalent LMI condition.

Combined feedforward and feedback control of a redundant, nonlinear, dynamic musculoskeletal system.

PubMed

Blana, Dimitra; Kirsch, Robert F; Chadwick, Edward K

2009-05-01

A functional electrical stimulation controller is presented that uses a combination of feedforward and feedback for arm control in high-level injury. The feedforward controller generates the muscle activations nominally required for desired movements, and the feedback controller corrects for errors caused by muscle fatigue and external disturbances. The feedforward controller is an artificial neural network (ANN) which approximates the inverse dynamics of the arm. The feedback loop includes a PID controller in series with a second ANN representing the nonlinear properties and biomechanical interactions of muscles and joints. The controller was designed and tested using a two-joint musculoskeletal model of the arm that includes four mono-articular and two bi-articular muscles. Its performance during goal-oriented movements of varying amplitudes and durations showed a tracking error of less than 4 degrees in ideal conditions, and less than 10 degrees even in the case of considerable fatigue and external disturbances.

Speech Compensation for Time-Scale-Modified Auditory Feedback

ERIC Educational Resources Information Center

Ogane, Rintaro; Honda, Masaaki

2014-01-01

Purpose: The purpose of this study was to examine speech compensation in response to time-scale-modified auditory feedback during the transition of the semivowel for a target utterance of /ija/. Method: Each utterance session consisted of 10 control trials in the normal feedback condition followed by 20 perturbed trials in the modified auditory…

Combined Audience and Video Feedback With Cognitive Review Improves State Anxiety and Self-Perceptions During Speech Tasks in Socially Anxious Individuals.

PubMed

Chen, Junwen; McLean, Jordan E; Kemps, Eva

2018-03-01

This study investigated the effects of combined audience feedback with video feedback plus cognitive preparation, and cognitive review (enabling deeper processing of feedback) on state anxiety and self-perceptions including perception of performance and perceived probability of negative evaluation in socially anxious individuals during a speech performance. One hundred and forty socially anxious students were randomly assigned to four conditions: Cognitive Preparation + Video Feedback + Audience Feedback + Cognitive Review (CP+VF+AF+CR), Cognitive Preparation + Video Feedback + Cognitive Review (CP+VF+CR), Cognitive Preparation + Video Feedback only (CP+VF), and Control. They were asked to deliver two impromptu speeches that were evaluated by confederates. Participants' levels of anxiety and self-perceptions pertaining to the speech task were assessed before and after feedback, and after the second speech. Compared to participants in the other conditions, participants in the CP+VF+AF+CR condition reported a significant decrease in their state anxiety and perceived probability of negative evaluation scores, and a significant increase in their positive perception of speech performance from before to after the feedback. These effects generalized to the second speech. Our results suggest that adding audience feedback to video feedback plus cognitive preparation and cognitive review may improve the effects of existing video feedback procedures in reducing anxiety symptoms and distorted self-representations in socially anxious individuals. Copyright © 2017. Published by Elsevier Ltd.

Mode Selection Rules for a Two-Delay System with Positive and Negative Feedback Loops

NASA Astrophysics Data System (ADS)

Takahashi, Kin'ya; Kobayashi, Taizo

2018-04-01

The mode selection rules for a two-delay system, which has negative feedback with a short delay time t1 and positive feedback with a long delay time t2, are studied numerically and theoretically. We find two types of mode selection rules depending on the strength of the negative feedback. When the strength of the negative feedback |α1| (α1 < 0) is sufficiently small compared with that of the positive feedback α2 (> 0), 2m + 1-th harmonic oscillation is well sustained in a neighborhood of t1/t2 = even/odd, i.e., relevant condition. In a neighborhood of the irrelevant condition given by t1/t2 = odd/even or t1/t2 = odd/odd, higher harmonic oscillations are observed. However, if |α1| is slightly less than α2, a different mode selection rule works, where the condition t1/t2 = odd/even is relevant and the conditions t1/t2 = odd/odd and t1/t2 = even/odd are irrelevant. These mode selection rules are different from the mode selection rule of the normal two-delay system with two positive feedback loops, where t1/t2 = odd/odd is relevant and the others are irrelevant. The two types of mode selection rules are induced by individually different mechanisms controlling the Hopf bifurcation, i.e., the Hopf bifurcation controlled by the "boosted bifurcation process" and by the "anomalous bifurcation process", which occur for |α1| below and above the threshold value αth, respectively.

Neural mechanisms underlying auditory feedback control of speech

PubMed Central

Reilly, Kevin J.; Guenther, Frank H.

2013-01-01

The neural substrates underlying auditory feedback control of speech were investigated using a combination of functional magnetic resonance imaging (fMRI) and computational modeling. Neural responses were measured while subjects spoke monosyllabic words under two conditions: (i) normal auditory feedback of their speech, and (ii) auditory feedback in which the first formant frequency of their speech was unexpectedly shifted in real time. Acoustic measurements showed compensation to the shift within approximately 135 ms of onset. Neuroimaging revealed increased activity in bilateral superior temporal cortex during shifted feedback, indicative of neurons coding mismatches between expected and actual auditory signals, as well as right prefrontal and Rolandic cortical activity. Structural equation modeling revealed increased influence of bilateral auditory cortical areas on right frontal areas during shifted speech, indicating that projections from auditory error cells in posterior superior temporal cortex to motor correction cells in right frontal cortex mediate auditory feedback control of speech. PMID:18035557

Improvements in force variability and structure from vision- to memory-guided submaximal isometric knee extension in subacute stroke.

PubMed

Chow, John W; Stokic, Dobrivoje S

2018-03-01

We examined changes in variability, accuracy, frequency composition, and temporal regularity of force signal from vision-guided to memory-guided force-matching tasks in 17 subacute stroke and 17 age-matched healthy subjects. Subjects performed a unilateral isometric knee extension at 10, 30, and 50% of peak torque [maximum voluntary contraction (MVC)] for 10 s (3 trials each). Visual feedback was removed at the 5-s mark in the first two trials (feedback withdrawal), and 30 s after the second trial the subjects were asked to produce the target force without visual feedback (force recall). The coefficient of variation and constant error were used to quantify force variability and accuracy. Force structure was assessed by the median frequency, relative spectral power in the 0-3-Hz band, and sample entropy of the force signal. At 10% MVC, the force signal in subacute stroke subjects became steadier, more broadband, and temporally more irregular after the withdrawal of visual feedback, with progressively larger error at higher contraction levels. Also, the lack of modulation in the spectral frequency at higher force levels with visual feedback persisted in both the withdrawal and recall conditions. In terms of changes from the visual feedback condition, the feedback withdrawal produced a greater difference between the paretic, nonparetic, and control legs than the force recall. The overall results suggest improvements in force variability and structure from vision- to memory-guided force control in subacute stroke despite decreased accuracy. Different sensory-motor memory retrieval mechanisms seem to be involved in the feedback withdrawal and force recall conditions, which deserves further study. NEW & NOTEWORTHY We demonstrate that in the subacute phase of stroke, force signals during a low-level isometric knee extension become steadier, more broadband in spectral power, and more complex after removal of visual feedback. Larger force errors are produced when recalling target forces than immediately after withdrawing visual feedback. Although visual feedback offers better accuracy, it worsens force variability and structure in subacute stroke. The feedback withdrawal and force recall conditions seem to involve different memory retrieval mechanisms.

Feedback Blunting: Total Sleep Deprivation Impairs Decision Making that Requires Updating Based on Feedback.

PubMed

Whitney, Paul; Hinson, John M; Jackson, Melinda L; Van Dongen, Hans P A

2015-05-01

To better understand the sometimes catastrophic effects of sleep loss on naturalistic decision making, we investigated effects of sleep deprivation on decision making in a reversal learning paradigm requiring acquisition and updating of information based on outcome feedback. Subjects were randomized to a sleep deprivation or control condition, with performance testing at baseline, after 2 nights of total sleep deprivation (or rested control), and following 2 nights of recovery sleep. Subjects performed a decision task involving initial learning of go and no go response sets followed by unannounced reversal of contingencies, requiring use of outcome feedback for decisions. A working memory scanning task and psychomotor vigilance test were also administered. Six consecutive days and nights in a controlled laboratory environment with continuous behavioral monitoring. Twenty-six subjects (22-40 y of age; 10 women). Thirteen subjects were randomized to a 62-h total sleep deprivation condition; the others were controls. Unlike controls, sleep deprived subjects had difficulty with initial learning of go and no go stimuli sets and had profound impairment adapting to reversal. Skin conductance responses to outcome feedback were diminished, indicating blunted affective reactions to feedback accompanying sleep deprivation. Working memory scanning performance was not significantly affected by sleep deprivation. And although sleep deprived subjects showed expected attentional lapses, these could not account for impairments in reversal learning decision making. Sleep deprivation is particularly problematic for decision making involving uncertainty and unexpected change. Blunted reactions to feedback while sleep deprived underlie failures to adapt to uncertainty and changing contingencies. Thus, an error may register, but with diminished effect because of reduced affective valence of the feedback or because the feedback is not cognitively bound with the choice. This has important implications for understanding and managing sleep loss-induced cognitive impairment in emergency response, disaster management, military operations, and other dynamic real-world settings with uncertain outcomes and imperfect information. © 2015 Associated Professional Sleep Societies, LLC.

Feedback Blunting: Total Sleep Deprivation Impairs Decision Making that Requires Updating Based on Feedback

PubMed Central

Whitney, Paul; Hinson, John M.; Jackson, Melinda L.; Van Dongen, Hans P.A.

2015-01-01

Study Objectives: To better understand the sometimes catastrophic effects of sleep loss on naturalistic decision making, we investigated effects of sleep deprivation on decision making in a reversal learning paradigm requiring acquisition and updating of information based on outcome feedback. Design: Subjects were randomized to a sleep deprivation or control condition, with performance testing at baseline, after 2 nights of total sleep deprivation (or rested control), and following 2 nights of recovery sleep. Subjects performed a decision task involving initial learning of go and no go response sets followed by unannounced reversal of contingencies, requiring use of outcome feedback for decisions. A working memory scanning task and psychomotor vigilance test were also administered. Setting: Six consecutive days and nights in a controlled laboratory environment with continuous behavioral monitoring. Subjects: Twenty-six subjects (22–40 y of age; 10 women). Interventions: Thirteen subjects were randomized to a 62-h total sleep deprivation condition; the others were controls. Results: Unlike controls, sleep deprived subjects had difficulty with initial learning of go and no go stimuli sets and had profound impairment adapting to reversal. Skin conductance responses to outcome feedback were diminished, indicating blunted affective reactions to feedback accompanying sleep deprivation. Working memory scanning performance was not significantly affected by sleep deprivation. And although sleep deprived subjects showed expected attentional lapses, these could not account for impairments in reversal learning decision making. Conclusions: Sleep deprivation is particularly problematic for decision making involving uncertainty and unexpected change. Blunted reactions to feedback while sleep deprived underlie failures to adapt to uncertainty and changing contingencies. Thus, an error may register, but with diminished effect because of reduced affective valence of the feedback or because the feedback is not cognitively bound with the choice. This has important implications for understanding and managing sleep loss-induced cognitive impairment in emergency response, disaster management, military operations, and other dynamic real-world settings with uncertain outcomes and imperfect information. Citation: Whitney P, Hinson JM, Jackson ML, Van Dongen HPA. Feedback blunting: total sleep deprivation impairs decision making that requires updating based on feedback. SLEEP 2015;38(5):745–754. PMID:25515105

Comparing the effects of positive and negative feedback in information-integration category learning.

PubMed

Freedberg, Michael; Glass, Brian; Filoteo, J Vincent; Hazeltine, Eliot; Maddox, W Todd

2017-01-01

Categorical learning is dependent on feedback. Here, we compare how positive and negative feedback affect information-integration (II) category learning. Ashby and O'Brien (2007) demonstrated that both positive and negative feedback are required to solve II category problems when feedback was not guaranteed on each trial, and reported no differences between positive-only and negative-only feedback in terms of their effectiveness. We followed up on these findings and conducted 3 experiments in which participants completed 2,400 II categorization trials across three days under 1 of 3 conditions: positive feedback only (PFB), negative feedback only (NFB), or both types of feedback (CP; control partial). An adaptive algorithm controlled the amount of feedback given to each group so that feedback was nearly equated. Using different feedback control procedures, Experiments 1 and 2 demonstrated that participants in the NFB and CP group were able to engage II learning strategies, whereas the PFB group was not. Additionally, the NFB group was able to achieve significantly higher accuracy than the PFB group by Day 3. Experiment 3 revealed that these differences remained even when we equated the information received on feedback trials. Thus, negative feedback appears significantly more effective for learning II category structures. This suggests that the human implicit learning system may be capable of learning in the absence of positive feedback.

System analysis of force feedback microscopy

NASA Astrophysics Data System (ADS)

Rodrigues, Mario S.; Costa, Luca; Chevrier, Joël; Comin, Fabio

2014-02-01

It was shown recently that the Force Feedback Microscope (FFM) can avoid the jump-to-contact in Atomic force Microscopy even when the cantilevers used are very soft, thus increasing force resolution. In this letter, we explore theoretical aspects of the associated real time control of the tip position. We take into account lever parameters such as the lever characteristics in its environment, spring constant, mass, dissipation coefficient, and the operating conditions such as controller gains and interaction force. We show how the controller parameters are determined so that the FFM functions at its best and estimate the bandwidth of the system under these conditions.

Neural Substrates of Visual Spatial Coding and Visual Feedback Control for Hand Movements in Allocentric and Target-Directed Tasks

PubMed Central

Thaler, Lore; Goodale, Melvyn A.

2011-01-01

Neuropsychological evidence suggests that different brain areas may be involved in movements that are directed at visual targets (e.g., pointing or reaching), and movements that are based on allocentric visual information (e.g., drawing or copying). Here we used fMRI to investigate the neural correlates of these two types of movements in healthy volunteers. Subjects (n = 14) performed right hand movements in either a target-directed task (moving a cursor to a target dot) or an allocentric task (moving a cursor to reproduce the distance and direction between two distal target dots) with or without visual feedback about their hand movement. Movements were monitored with an MR compatible touch panel. A whole brain analysis revealed that movements in allocentric conditions led to an increase in activity in the fundus of the left intra-parietal sulcus (IPS), in posterior IPS, in bilateral dorsal premotor cortex (PMd), and in the lateral occipital complex (LOC). Visual feedback in both target-directed and allocentric conditions led to an increase in activity in area MT+, superior parietal–occipital cortex (SPOC), and posterior IPS (all bilateral). In addition, we found that visual feedback affected brain activity differently in target-directed as compared to allocentric conditions, particularly in the pre-supplementary motor area, PMd, IPS, and parieto-occipital cortex. Our results, in combination with previous findings, suggest that the LOC is essential for allocentric visual coding and that SPOC is involved in visual feedback control. The differences in brain activity between target-directed and allocentric visual feedback conditions may be related to behavioral differences in visual feedback control. Our results advance the understanding of the visual coordinate frame used by the LOC. In addition, because of the nature of the allocentric task, our results have relevance for the understanding of neural substrates of magnitude estimation and vector coding of movements. PMID:21941474

Significance of auditory and kinesthetic feedback to singers' pitch control.

PubMed

Mürbe, Dirk; Pabst, Friedemann; Hofmann, Gert; Sundberg, Johan

2002-03-01

An accurate control of fundamental frequency (F0) is required from singers. This control relies on auditory and kinesthetic feedback. However, a loud accompaniment may mask the auditory feedback, leaving the singers to rely on kinesthetic feedback. The object of the present study was to estimate the significance of auditory and kinesthetic feedback to pitch control in 28 students beginning a professional solo singing education. The singers sang an ascending and descending triad pattern covering their entire pitch range with and without masking noise in legato and staccato and in a slow and a fast tempo. F0 was measured by means of a computer program. The interval sizes between adjacent tones were determined and their departures from equally tempered tuning were calculated. The deviations from this tuning were used as a measure of the accuracy of intonation. Statistical analysis showed a significant effect of masking that amounted to a mean impairment of pitch accuracy by 14 cent across all subjects. Furthermore, significant effects were found of tempo as well as of the staccato/legato conditions. The results indicate that auditory feedback contributes significantly to singers' control of pitch.

Coherent feedback control of a single qubit in diamond

NASA Astrophysics Data System (ADS)

Hirose, Masashi; Cappellaro, Paola

2016-04-01

Engineering desired operations on qubits subjected to the deleterious effects of their environment is a critical task in quantum information processing, quantum simulation and sensing. The most common approach relies on open-loop quantum control techniques, including optimal-control algorithms based on analytical or numerical solutions, Lyapunov design and Hamiltonian engineering. An alternative strategy, inspired by the success of classical control, is feedback control. Because of the complications introduced by quantum measurement, closed-loop control is less pervasive in the quantum setting and, with exceptions, its experimental implementations have been mainly limited to quantum optics experiments. Here we implement a feedback-control algorithm using a solid-state spin qubit system associated with the nitrogen vacancy centre in diamond, using coherent feedback to overcome the limitations of measurement-based feedback, and show that it can protect the qubit against intrinsic dephasing noise for milliseconds. In coherent feedback, the quantum system is connected to an auxiliary quantum controller (ancilla) that acquires information about the output state of the system (by an entangling operation) and performs an appropriate feedback action (by a conditional gate). In contrast to open-loop dynamical decoupling techniques, feedback control can protect the qubit even against Markovian noise and for an arbitrary period of time (limited only by the coherence time of the ancilla), while allowing gate operations. It is thus more closely related to quantum error-correction schemes, although these require larger and increasing qubit overheads. Increasing the number of fresh ancillas enables protection beyond their coherence time. We further evaluate the robustness of the feedback protocol, which could be applied to quantum computation and sensing, by exploring a trade-off between information gain and decoherence protection, as measurement of the ancilla-qubit correlation after the feedback algorithm voids the protection, even if the rest of the dynamics is unchanged.

Augmented feedback of COM and COP modulates the regulation of quiet human standing relative to the stability boundary.

PubMed

Kilby, Melissa C; Slobounov, Semyon M; Newell, Karl M

2016-06-01

The experiment manipulated real-time kinematic feedback of the motion of the whole body center of mass (COM) and center of pressure (COP) in anterior-posterior (AP) and medial-lateral (ML) directions to investigate the variables actively controlled in quiet standing of young adults. The feedback reflected the current 2D postural positions within the 2D functional stability boundary that was scaled to 75%, 30% and 12% of its original size. The findings showed that the distance of both COP and COM to the respective stability boundary was greater during the feedback trials compared to a no feedback condition. However, the temporal safety margin of the COP, that is, the virtual time-to-contact (VTC), was higher without feedback. The coupling relation of COP-COM showed stable in-phase synchronization over all of the feedback conditions for frequencies below 1Hz. For higher frequencies (up to 5Hz), there was progressive reduction of COP-COM synchronization and local adaptation under the presence of augmented feedback. The findings show that the augmented feedback of COM and COP motion differentially and adaptively influences spatial and temporal properties of postural motion relative to the stability boundary while preserving the organization of the COM-COP coupling in postural control. Copyright © 2016. Published by Elsevier B.V.

Comparative study of flare control laws. [optimal control of b-737 aircraft approach and landing

NASA Technical Reports Server (NTRS)

Nadkarni, A. A.; Breedlove, W. J., Jr.

1979-01-01

A digital 3-D automatic control law was developed to achieve an optimal transition of a B-737 aircraft between various initial glid slope conditions and the desired final touchdown condition. A discrete, time-invariant, optimal, closed-loop control law presented for a linear regulator problem, was extended to include a system being acted upon by a constant disturbance. Two forms of control laws were derived to solve this problem. One method utilized the feedback of integral states defined appropriately and augmented with the original system equations. The second method formulated the problem as a control variable constraint, and the control variables were augmented with the original system. The control variable constraint control law yielded a better performance compared to feedback control law for the integral states chosen.

A study of helicopter stability and control including blade dynamics

NASA Technical Reports Server (NTRS)

Zhao, Xin; Curtiss, H. C., Jr.

1988-01-01

A linearized model of rotorcraft dynamics has been developed through the use of symbolic automatic equation generating techniques. The dynamic model has been formulated in a unique way such that it can be used to analyze a variety of rotor/body coupling problems including a rotor mounted on a flexible shaft with a number of modes as well as free-flight stability and control characteristics. Direct comparison of the time response to longitudinal, lateral and directional control inputs at various trim conditions shows that the linear model yields good to very good correlation with flight test. In particular it is shown that a dynamic inflow model is essential to obtain good time response correlation, especially for the hover trim condition. It also is shown that the main rotor wake interaction with the tail rotor and fixed tail surfaces is a significant contributor to the response at translational flight trim conditions. A relatively simple model for the downwash and sidewash at the tail surfaces based on flat vortex wake theory is shown to produce good agreement. Then, the influence of rotor flap and lag dynamics on automatic control systems feedback gain limitations is investigated with the model. It is shown that the blade dynamics, especially lagging dynamics, can severly limit the useable values of the feedback gain for simple feedback control and that multivariable optimal control theory is a powerful tool to design high gain augmentation control system. The frequency-shaped optimal control design can offer much better flight dynamic characteristics and a stable margin for the feedback system without need to model the lagging dynamics.

Control of Uncertain Systems under Constraints: Switching Horizon Predictive Control of Persistently Disturbed Input-Saturated Plants

DTIC Science & Technology

2006-12-01

on at any time from a family of candidate feedback-gains so as to control a discrete- time input-saturated LTI system possibly subject to persistent... times robustness Mosca, E. (2006) Control of Uncertain Systems under Constraints: Switching Horizon Predictive Control of Persistently Disturbed...feedback controls u = f(x̂) (3) so as to ensure, under suitable conditions, stability in the noiseless case as well as finite l∞-induced gain of the

Self-tuning pressure-feedback control by pole placement for vibration reduction of excavator with independent metering fluid power system

NASA Astrophysics Data System (ADS)

Ding, Ruqi; Xu, Bing; Zhang, Junhui; Cheng, Min

2017-08-01

Independent metering control systems are promising fluid power technologies compared with traditional valve controlled systems. By breaking the mechanical coupling between the inlet and outlet, the meter-out valve can open as large as possible to reduce energy consumptions. However, the lack of damping in outlet causes stronger vibrations. To address the problem, the paper designs a hybrid control method combining dynamic pressure-feedback and active damping control. The innovation resides in the optimization of damping by introducing pressure feedback to make trade-offs between high stability and fast response. To achieve this goal, the dynamic response pertaining to the control parameters consisting of feedback gain and cut-off frequency, are analyzed via pole-zero locations. Accordingly, these parameters are tuned online in terms of guaranteed dominant pole placement such that the optimal damping can be accurately captured under a considerable variation of operating conditions. The experiment is deployed in a mini-excavator. The results pertaining to different control parameters confirm the theoretical expectations via pole-zero locations. By using proposed self-tuning controller, the vibrations are almost eliminated after only one overshoot for different operation conditions. The overshoots are also reduced with less decrease of the response time. In addition, the energy-saving capability of independent metering system is still not affected by the improvement of controllability.

Attentional bias to pain and social threat in pediatric patients with functional abdominal pain and pain-free youth before and after performance evaluation.

PubMed

Beck, Joy E; Lipani, Tricia A; Baber, Kari F; Dufton, Lynette; Garber, Judy; Smith, Craig A; Walker, Lynn S

2011-05-01

This study investigated attentional biases for pain and social threat versus neutral stimuli in 54 youth with functional abdominal pain (FAP) and 53 healthy control subjects (ages 10 to 16 years). We assessed attentional bias using a visual probe detection task (PDT) that presented pain and social threat words in comparison to neutral words at conscious (1250 ms) and preconscious (20 ms) presentation rates. We administered the PDT before and after random assignment of participants to a laboratory stressor--failure versus success feedback regarding their performance on a challenging computer game. All analyses controlled for trait anxiety. At the conscious rate of stimulus presentation, FAP patients exhibited preferential attention toward pain compared with neutral stimuli and compared with the control group. FAP patients maintained preferential attention toward conscious pain stimuli after performance feedback in both failure and success conditions. At the preconscious rate of stimulus presentation, FAP patients' attention was neutral at baseline but increased significantly toward pain stimuli after performance feedback in both failure and success conditions. FAP patients' somatic symptoms increased in both failure and success conditions; control youth's somatic symptoms only increased after failure. Regarding social threat, neither FAP nor control youth exhibited attentional bias toward social threat compared with neutral stimuli at baseline, but both FAP and control youth in the failure condition significantly increased attention away from social threat after failure feedback. Results suggest that FAP patients preferentially attend to pain stimuli in conscious awareness. Moreover, performance evaluation may activate their preconscious attention to pain stimuli. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Dynamics of nonlinear feedback control.

PubMed

Snippe, H P; van Hateren, J H

2007-05-01

Feedback control in neural systems is ubiquitous. Here we study the mathematics of nonlinear feedback control. We compare models in which the input is multiplied by a dynamic gain (multiplicative control) with models in which the input is divided by a dynamic attenuation (divisive control). The gain signal (resp. the attenuation signal) is obtained through a concatenation of an instantaneous nonlinearity and a linear low-pass filter operating on the output of the feedback loop. For input steps, the dynamics of gain and attenuation can be very different, depending on the mathematical form of the nonlinearity and the ordering of the nonlinearity and the filtering in the feedback loop. Further, the dynamics of feedback control can be strongly asymmetrical for increment versus decrement steps of the input. Nevertheless, for each of the models studied, the nonlinearity in the feedback loop can be chosen such that immediately after an input step, the dynamics of feedback control is symmetric with respect to increments versus decrements. Finally, we study the dynamics of the output of the control loops and find conditions under which overshoots and undershoots of the output relative to the steady-state output occur when the models are stimulated with low-pass filtered steps. For small steps at the input, overshoots and undershoots of the output do not occur when the filtering in the control path is faster than the low-pass filtering at the input. For large steps at the input, however, results depend on the model, and for some of the models, multiple overshoots and undershoots can occur even with a fast control path.

Shape memory alloy wire for self-sensing servo actuation

NASA Astrophysics Data System (ADS)

Josephine Selvarani Ruth, D.; Dhanalakshmi, K.

2017-01-01

This paper reports on the development of a straightforward approach to realise self-sensing shape memory alloy (SMA) wire actuated control. A differential electrical resistance measurement circuit (the sensorless signal conditioning (SSC) circuit) is designed; this sensing signal is directly used as the feedback for control. Antagonistic SMA wire actuators designed for servo actuation is realized in self-sensing actuation (SSA) mode for direct control with the differential electrical resistance feedback. The self-sensing scheme is established on a 1-DOF manipulator with the discrete time sliding mode controls which demonstrates good control performance, whatever be the disturbance and loading conditions. The uniqueness of this work is the design of the generic electronic SSC circuit for SMA actuated system, for measurement and control. With a concern to the implementation of self-sensing technique in SMA, this scheme retains the systematic control architecture by using the sensing signal (self-sensed, electrical resistance corresponding to the system position) for feedback, without requiring any processing as that of the methods adopted and reported previously for SSA techniques of SMA.

Entry flight control system downmoding evaluation

NASA Technical Reports Server (NTRS)

Barnes, H. A.

1978-01-01

A method to desensitize the entry flight control system to structural vibration feedback which might induce an oscillatory instability is described. Trends in vehicle response and handling characteristics as a function of gain combinations in the FCS forward and rate feedback loops were described as observed in a man-in-the-loop simulation. Among the flight conditions considered are the effects of downmoding with APU failures, off-nominal trajectory conditions, sensed angle of attack errors, the impact on RCS fuel consumption, performance in the presence of aero variations, recovery from large FCS upsets, and default gains.

Output Containment Control of Linear Heterogeneous Multi-Agent Systems Using Internal Model Principle.

PubMed

Zuo, Shan; Song, Yongduan; Lewis, Frank L; Davoudi, Ali

2017-01-04

This paper studies the output containment control of linear heterogeneous multi-agent systems, where the system dynamics and even the state dimensions can generally be different. Since the states can have different dimensions, standard results from state containment control do not apply. Therefore, the control objective is to guarantee the convergence of the output of each follower to the dynamic convex hull spanned by the outputs of leaders. This can be achieved by making certain output containment errors go to zero asymptotically. Based on this formulation, two different control protocols, namely, full-state feedback and static output-feedback, are designed based on internal model principles. Sufficient local conditions for the existence of the proposed control protocols are developed in terms of stabilizing the local followers' dynamics and satisfying a certain H∞ criterion. Unified design procedures to solve the proposed two control protocols are presented by formulation and solution of certain local state-feedback and static output-feedback problems, respectively. Numerical simulations are given to validate the proposed control protocols.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2016-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking*

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:27990059

Gap-metric-based robustness analysis of nonlinear systems with full and partial feedback linearisation

NASA Astrophysics Data System (ADS)

Al-Gburi, A.; Freeman, C. T.; French, M. C.

2018-06-01

This paper uses gap metric analysis to derive robustness and performance margins for feedback linearising controllers. Distinct from previous robustness analysis, it incorporates the case of output unstructured uncertainties, and is shown to yield general stability conditions which can be applied to both stable and unstable plants. It then expands on existing feedback linearising control schemes by introducing a more general robust feedback linearising control design which classifies the system nonlinearity into stable and unstable components and cancels only the unstable plant nonlinearities. This is done in order to preserve the stabilising action of the inherently stabilising nonlinearities. Robustness and performance margins are derived for this control scheme, and are expressed in terms of bounds on the plant nonlinearities and the accuracy of the cancellation of the unstable plant nonlinearity by the controller. Case studies then confirm reduced conservatism compared with standard methods.

Monetary Reward and Punishment to Response Inhibition Modulate Activation and Synchronization Within the Inhibitory Brain Network.

PubMed

Chikara, Rupesh K; Chang, Erik C; Lu, Yi-Chen; Lin, Dar-Shong; Lin, Chin-Teng; Ko, Li-Wei

2018-01-01

A reward or punishment can modulate motivation and emotions, which in turn affect cognitive processing. The present simultaneous functional magnetic resonance imaging-electroencephalography study examines neural mechanisms of response inhibition under the influence of a monetary reward or punishment by implementing a modified stop-signal task in a virtual battlefield scenario. The participants were instructed to play as snipers who open fire at a terrorist target but withhold shooting in the presence of a hostage. The participants performed the task under three different feedback conditions in counterbalanced order: a reward condition where each successfully withheld response added a bonus (i.e., positive feedback) to the startup credit, a punishment condition where each failure in stopping deduced a penalty (i.e., negative feedback), and a no-feedback condition where response outcome had no consequences and served as a control setting. Behaviorally both reward and punishment conditions led to significantly down-regulated inhibitory function in terms of the critical stop-signal delay. As for the neuroimaging results, increased activities were found for the no-feedback condition in regions previously reported to be associated with response inhibition, including the right inferior frontal gyrus and the pre-supplementary motor area. Moreover, higher activation of the lingual gyrus, posterior cingulate gyrus (PCG) and inferior parietal lobule were found in the reward condition, while stronger activation of the precuneus gyrus was found in the punishment condition. The positive feedback was also associated with stronger changes of delta, theta, and alpha synchronization in the PCG than were the negative or no-feedback conditions. These findings depicted the intertwining relationship between response inhibition and motivation networks.

Stability and chaotification of vibration isolation floating raft systems with time-delayed feedback control.

PubMed

Li, Y L; Xu, D L; Fu, Y M; Zhou, J X

2011-09-01

This paper presents a systematic study on the stability of a two-dimensional vibration isolation floating raft system with a time-delayed feedback control. Based on the generalized Sturm criterion, the critical control gain for the delay-independent stability region and critical time delays for the stability switches are derived. The critical conditions can provide a theoretical guidance of chaotification design for line spectra reduction. Numerical simulations verify the correctness of the approach. Bifurcation analyses reveal that chaotification is more likely to occur in unstable region defined by these critical conditions, and the stiffness of the floating raft and mass ratio are the sensitive parameters to reduce critical control gain.

Fabrication and test of digital output interface devices for gas turbine electronic controls

NASA Technical Reports Server (NTRS)

Newirth, D. M.; Koenig, E. W.

1978-01-01

A program was conducted to develop an innovative digital output interface device, a digital effector with optical feedback of the fuel metering valve position, for future electronic controls for gas turbine engines. A digital effector (on-off solenoids driven directly by on-off signals from a digital electronic controller) with optical position feedback was fabricated, coupled with the fuel metering valve, and tested under simulated engine operating conditions. The testing indicated that a digital effector with optical position feedback is a suitable candidate, with proper development for future digital electronic gas turbine controls. The testing also identified several problem areas which would have to be overcome in a final production configuration.

Can corrective feedback improve recognition memory?

PubMed

Kantner, Justin; Lindsay, D Stephen

2010-06-01

An understanding of the effects of corrective feedback on recognition memory can inform both recognition theory and memory training programs, but few published studies have investigated the issue. Although the evidence to date suggests that feedback does not improve recognition accuracy, few studies have directly examined its effect on sensitivity, and fewer have created conditions that facilitate a feedback advantage by encouraging controlled processing at test. In Experiment 1, null effects of feedback were observed following both deep and shallow encoding of categorized study lists. In Experiment 2, feedback robustly influenced response bias by allowing participants to discern highly uneven base rates of old and new items, but sensitivity remained unaffected. In Experiment 3, a false-memory procedure, feedback failed to attenuate false recognition of critical lures. In Experiment 4, participants were unable to use feedback to learn a simple category rule separating old items from new items, despite the fact that feedback was of substantial benefit in a nearly identical categorization task. The recognition system, despite a documented ability to utilize controlled strategic or inferential decision-making processes, appears largely impenetrable to a benefit of corrective feedback.

The absence or temporal offset of visual feedback does not influence adaptation to novel movement dynamics.

PubMed

McKenna, Erin; Bray, Laurence C Jayet; Zhou, Weiwei; Joiner, Wilsaan M

2017-10-01

Delays in transmitting and processing sensory information require correctly associating delayed feedback to issued motor commands for accurate error compensation. The flexibility of this alignment between motor signals and feedback has been demonstrated for movement recalibration to visual manipulations, but the alignment dependence for adapting movement dynamics is largely unknown. Here we examined the effect of visual feedback manipulations on force-field adaptation. Three subject groups used a manipulandum while experiencing a lag in the corresponding cursor motion (0, 75, or 150 ms). When the offset was applied at the start of the session (continuous condition), adaptation was not significantly different between groups. However, these similarities may be due to acclimation to the offset before motor adaptation. We tested additional subjects who experienced the same delays concurrent with the introduction of the perturbation (abrupt condition). In this case adaptation was statistically indistinguishable from the continuous condition, indicating that acclimation to feedback delay was not a factor. In addition, end-point errors were not significantly different across the delay or onset conditions, but end-point correction (e.g., deceleration duration) was influenced by the temporal offset. As an additional control, we tested a group of subjects who performed without visual feedback and found comparable movement adaptation results. These results suggest that visual feedback manipulation (absence or temporal misalignment) does not affect adaptation to novel dynamics, independent of both acclimation and perceptual awareness. These findings could have implications for modeling how the motor system adjusts to errors despite concurrent delays in sensory feedback information. NEW & NOTEWORTHY A temporal offset between movement and distorted visual feedback (e.g., visuomotor rotation) influences the subsequent motor recalibration, but the effects of this offset for altered movement dynamics are largely unknown. Here we examined the influence of 1 ) delayed and 2 ) removed visual feedback on the adaptation to novel movement dynamics. These results contribute to understanding of the control strategies that compensate for movement errors when there is a temporal separation between motion state and sensory information. Copyright © 2017 the American Physiological Society.

Control systems for platform landings cushioned by air bags

NASA Astrophysics Data System (ADS)

Ross, Edward W.

1987-07-01

This report presents an exploratory mathematical study of control systems for airdrop platform landings cushioned by airbags. The basic theory of airbags is reviewed and solutions to special cases are noted. A computer program is presented, which calculates the time-dependence of the principal variables during a landing under the action of various control systems. Two existing control systems of open-loop type are compared with a conceptual feedback (closed-loop) system for a fairly typical set of landing conditions. The feedback controller is shown to have performance much superior to the other systems. The feedback system undergoes an interesting oscillation not present in the other systems, the source of which is investigated. Recommendations for future work are included.

Adaptive output-feedback control for switched stochastic uncertain nonlinear systems with time-varying delay.

PubMed

Song, Zhibao; Zhai, Junyong

2018-04-01

This paper addresses the problem of adaptive output-feedback control for a class of switched stochastic time-delay nonlinear systems with uncertain output function, where both the control coefficients and time-varying delay are unknown. The drift and diffusion terms are subject to unknown homogeneous growth condition. By virtue of adding a power integrator technique, an adaptive output-feedback controller is designed to render that the closed-loop system is bounded in probability, and the state of switched stochastic nonlinear system can be globally regulated to the origin almost surely. A numerical example is provided to demonstrate the validity of the proposed control method. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Further Results on Sufficient LMI Conditions for H∞ Static Output Feedback Control of Discrete-Time Systems

NASA Astrophysics Data System (ADS)

Feng, Zhi-Yong; Xu, Li; Matsushita, Shin-Ya; Wu, Min

Further results on sufficient LMI conditions for H∞ static output feedback (SOF) control of discrete-time systems are presented in this paper, which provide some new insights into this issue. First, by introducing a slack variable with block-triangular structure and choosing the coordinate transformation matrix properly, the conservativeness of one kind of existing sufficient LMI condition is further reduced. Then, by introducing a slack variable with linear matrix equality constraint, another kind of sufficient LMI condition is proposed. Furthermore, the relation of these two kinds of LMI conditions are revealed for the first time through analyzing the effect of different choices of coordinate transformation matrices. Finally, a numerical example is provided to demonstrate the effectiveness and merits of the proposed methods.

Model-Based Adaptive Event-Triggered Control of Strict-Feedback Nonlinear Systems.

PubMed

Li, Yuan-Xin; Yang, Guang-Hong

2018-04-01

This paper is concerned with the adaptive event-triggered control problem of nonlinear continuous-time systems in strict-feedback form. By using the event-sampled neural network (NN) to approximate the unknown nonlinear function, an adaptive model and an associated event-triggered controller are designed by exploiting the backstepping method. In the proposed method, the feedback signals and the NN weights are aperiodically updated only when the event-triggered condition is violated. A positive lower bound on the minimum intersample time is guaranteed to avoid accumulation point. The closed-loop stability of the resulting nonlinear impulsive dynamical system is rigorously proved via Lyapunov analysis under an adaptive event sampling condition. In comparing with the traditional adaptive backstepping design with a fixed sample period, the event-triggered method samples the state and updates the NN weights only when it is necessary. Therefore, the number of transmissions can be significantly reduced. Finally, two simulation examples are presented to show the effectiveness of the proposed control method.

Self-controlled concurrent feedback facilitates the learning of the final approach phase in a fixed-base flight simulator.

PubMed

Huet, Michaël; Jacobs, David M; Camachon, Cyril; Goulon, Cedric; Montagne, Gilles

2009-12-01

This study (a) compares the effectiveness of different types of feedback for novices who learn to land a virtual aircraft in a fixed-base flight simulator and (b) analyzes the informational variables that learners come to use after practice. An extensive body of research exists concerning the informational variables that allow successful landing. In contrast, few studies have examined how the attention of pilots can be directed toward these sources of information. In this study, 15 participants were asked to land a virtual Cessna 172 on 245 trials while trying to follow the glide-slope area as accurately as possible. Three groups of participants practiced under different feedback conditions: with self-controlled concurrent feedback (the self-controlled group), with imposed concurrent feedback (the yoked group), or without concurrent feedback (the control group). The self-controlled group outperformed the yoked group, which in turn outperformed the control group. Removing or manipulating specific sources of information during transfer tests had different effects for different individuals. However, removing the cockpit from the visual scene had a detrimental effect on the performance of the majority of the participants. Self-controlled concurrent feedback helps learners to more quickly attune to the informational variables that allow them to control the aircraft during the approach phase. Knowledge concerning feedback schedules can be used for the design of optimal practice methods for student pilots, and knowledge about the informational variables used by expert performers has implications for the design of cockpits and runways that facilitate the detection of these variables.

Attention training through gaze-contingent feedback: Effects on reappraisal and negative emotions.

PubMed

Sanchez, Alvaro; Everaert, Jonas; Koster, Ernst H W

2016-10-01

Reappraisal is central to emotion regulation but its mechanisms are unclear. This study tested the theoretical prediction that emotional attention bias is linked to reappraisal of negative emotion-eliciting stimuli and subsequent emotional responding using a novel attentional control training. Thirty-six undergraduates were randomly assigned to either the control or the attention training condition and were provided with different task instructions while they performed an interpretation task. Whereas control participants freely created interpretations, participants in the training condition were instructed to allocate attention toward positive words to efficiently create positive interpretations (i.e., recruiting attentional control) while they were provided with gaze-contingent feedback on their viewing behavior. Transfer to attention bias and reappraisal success was evaluated using a dot-probe task and an emotion regulation task which were administered before and after the training. The training condition was effective at increasing attentional control and resulted in beneficial effects on the transfer tasks. Analyses supported a serial indirect effect with larger attentional control acquisition in the training condition leading to negative attention bias reduction, in turn predicting greater reappraisal success which reduced negative emotions. Our results indicate that attentional mechanisms influence the use of reappraisal strategies and its impact on negative emotions. The novel attention training highlights the importance of tailored feedback to train attentional control. The findings provide an important step toward personalized delivery of attention training. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Response of microchip solid-state laser to external frequency-shifted feedback and its applications

PubMed Central

Tan, Yidong; Zhang, Shulian; Zhang, Song; Zhang, Yongqing; Liu, Ning

2013-01-01

The response of the microchip solid-state Nd:YAG laser, which is subjected to external frequency-shifted feedback, is experimentally and theoretically analysed. The continuous weak response of the laser to the phase and amplitude of the feedback light is achieved by controlling the feedback power level, and this system can be used to achieve contact-free measurement of displacement, vibration, liquid evaporation and thermal expansion with nanometre accuracy in common room conditions without precise environmental control. Furthermore, a strong response, including chaotic harmonic and parametric oscillation, is observed, and the spectrum of this response, as examined by a frequency-stabilised Nd:YAG laser, indicates laser spectral linewidth broadening. PMID:24105389

Response of microchip solid-state laser to external frequency-shifted feedback and its applications.

PubMed

Tan, Yidong; Zhang, Shulian; Zhang, Song; Zhang, Yongqing; Liu, Ning

2013-10-09

The response of the microchip solid-state Nd:YAG laser, which is subjected to external frequency-shifted feedback, is experimentally and theoretically analysed. The continuous weak response of the laser to the phase and amplitude of the feedback light is achieved by controlling the feedback power level, and this system can be used to achieve contact-free measurement of displacement, vibration, liquid evaporation and thermal expansion with nanometre accuracy in common room conditions without precise environmental control. Furthermore, a strong response, including chaotic harmonic and parametric oscillation, is observed, and the spectrum of this response, as examined by a frequency-stabilised Nd:YAG laser, indicates laser spectral linewidth broadening.

Stabilization of nonlinear systems using sampled-data output-feedback fuzzy controller based on polynomial-fuzzy-model-based control approach.

PubMed

Lam, H K

2012-02-01

This paper investigates the stability of sampled-data output-feedback (SDOF) polynomial-fuzzy-model-based control systems. Representing the nonlinear plant using a polynomial fuzzy model, an SDOF fuzzy controller is proposed to perform the control process using the system output information. As only the system output is available for feedback compensation, it is more challenging for the controller design and system analysis compared to the full-state-feedback case. Furthermore, because of the sampling activity, the control signal is kept constant by the zero-order hold during the sampling period, which complicates the system dynamics and makes the stability analysis more difficult. In this paper, two cases of SDOF fuzzy controllers, which either share the same number of fuzzy rules or not, are considered. The system stability is investigated based on the Lyapunov stability theory using the sum-of-squares (SOS) approach. SOS-based stability conditions are obtained to guarantee the system stability and synthesize the SDOF fuzzy controller. Simulation examples are given to demonstrate the merits of the proposed SDOF fuzzy control approach.

Kinematic and neurophysiological consequences of an assisted-force-feedback brain-machine interface training: a case study.

PubMed

Silvoni, Stefano; Cavinato, Marianna; Volpato, Chiara; Cisotto, Giulia; Genna, Clara; Agostini, Michela; Turolla, Andrea; Ramos-Murguialday, Ander; Piccione, Francesco

2013-01-01

In a proof-of-principle prototypical demonstration we describe a new type of brain-machine interface (BMI) paradigm for upper limb motor-training. The proposed technique allows a fast contingent and proportionally modulated stimulation of afferent proprioceptive and motor output neural pathways using operant learning. Continuous and immediate assisted-feedback of force proportional to rolandic rhythm oscillations during actual movements was employed and illustrated with a single case experiment. One hemiplegic patient was trained for 2 weeks coupling somatosensory brain oscillations with force-field control during a robot-mediated center-out motor-task whose execution approaches movements of everyday life. The robot facilitated actual movements adding a modulated force directed to the target, thus providing a non-delayed proprioceptive feedback. Neuro-electric, kinematic, and motor-behavioral measures were recorded in pre- and post-assessments without force assistance. Patient's healthy arm was used as control since neither a placebo control was possible nor other control conditions. We observed a generalized and significant kinematic improvement in the affected arm and a spatial accuracy improvement in both arms, together with an increase and focalization of the somatosensory rhythm changes used to provide assisted-force-feedback. The interpretation of the neurophysiological and kinematic evidences reported here is strictly related to the repetition of the motor-task and the presence of the assisted-force-feedback. Results are described as systematic observations only, without firm conclusions about the effectiveness of the methodology. In this prototypical view, the design of appropriate control conditions is discussed. This study presents a novel operant-learning-based BMI-application for motor-training coupling brain oscillations and force feedback during an actual movement.

Goals-feedback conditions and episodic memory: Mechanisms for memory gains in older and younger adults.

PubMed

West, Robin L; Dark-Freudeman, Alissa; Bagwell, Dana K

2009-02-01

Research has established that challenging memory goals always lead to score increases for younger adults, and can increase older adults' scores under supportive conditions. This study examined beliefs and on-task effort as potential mechanisms for these self-regulatory gains, in particular to learn whether episodic memory gains across multiple trials of shopping list recall are controlled by the same factors for young and old people. Goals with feedback led to higher recall and strategic categorisation than a control condition. Strategy usage was the strongest predictor of gains over trials for both age groups. Age, goal condition, and effort also predicted scores across the entire sample. Older adults' gains, but not younger adults' gains, were affected significantly by the interaction of self-efficacy beliefs and goal condition, and condition interacted with locus of control to predict younger adult gains. These results emphasise the importance of self-regulatory effort and positive beliefs for facilitating goal-related memory gains.

Event-related potentials in response to cheating and cooperation in a social dilemma game.

PubMed

Bell, Raoul; Sasse, Julia; Möller, Malte; Czernochowski, Daniela; Mayr, Susanne; Buchner, Axel

2016-02-01

A sequential prisoner's dilemma game was combined with psychophysiological measures to examine the cognitive underpinnings of reciprocal exchange. Participants played four rounds of the game with partners who either cooperated or cheated. In a control condition, the partners' faces were shown, but no interaction took place. The partners' behaviors were consistent in the first three rounds of the game, but in the last round some of the partners unexpectedly changed strategies. In the first round of the game, the feedback about a partner's decision elicited a feedback P300, which was more pronounced for cooperation and cheating in comparison to the control condition, but did not vary as a function of feedback valence. In the last round, both the feedback negativity and the feedback P300 were sensitive to expectancy violations. There was no consistent evidence for a negativity bias, that is, enhanced allocation of attention to feedback about another person's cheating in comparison to feedback about another person's cooperation. Instead, participants focused on both positive and negative information, and flexibly adjusted their processing biases to the diagnosticity of the information. This conclusion was corroborated by the ERP correlates of memory retrieval. Successful retrieval of a partner's reputation was associated with an anterior positivity between 400 and 600 ms after face onset. This anterior positivity was more pronounced for both cooperator and cheater faces in comparison to control faces. The results suggest that it is not the negativity of social information, but rather its motivational and behavioral relevance that determines its processing. © 2015 Society for Psychophysiological Research.

Midterm peer feedback in problem-based learning groups: the effect on individual contributions and achievement.

PubMed

Kamp, Rachelle J A; van Berkel, Henk J M; Popeijus, Herman E; Leppink, Jimmie; Schmidt, Henk G; Dolmans, Diana H J M

2014-03-01

Even though peer process feedback is an often used tool to enhance the effectiveness of collaborative learning environments like PBL, the conditions under which it is best facilitated still need to be investigated. Therefore, this study investigated the effects of individual versus shared reflection and goal setting on students' individual contributions to the group and their academic achievement. In addition, the influence of prior knowledge on the effectiveness of peer feedback was studied. In this pretest-intervention-posttest study 242 first year students were divided into three conditions: condition 1 (individual reflection and goal setting), condition 2 (individual and shared reflection and goal setting), and condition 3 (control group). Results indicated that the quality of individual contributions to the tutorial group did not improve after receiving the peer feedback, nor did it differ between the three conditions. With regard to academic achievement, only males in conditions 1 and 2 showed better academic achievement compared with condition 3. However, there was no difference between both ways of reflection and goal setting with regard to achievement, indicating that both ways are equally effective. Nevertheless, it is still too early to conclude that peer feedback combined with reflection and goal setting is not effective in enhancing students' individual contributions. Students only had a limited number of opportunities to improve their contributions. Therefore, future research should investigate whether an increase in number of tutorial group meetings can enhance the effectiveness of peer feedback. In addition, the effect of quality of reflection and goal setting could be taken into consideration in future research.

Closed-loop control of grasping with a myoelectric hand prosthesis: which are the relevant feedback variables for force control?

PubMed

Ninu, Andrei; Dosen, Strahinja; Muceli, Silvia; Rattay, Frank; Dietl, Hans; Farina, Dario

2014-09-01

In closed-loop control of grasping by hand prostheses, the feedback information sent to the user is usually the actual controlled variable, i.e., the grasp force. Although this choice is intuitive and logical, the force production is only the last step in the process of grasping. Therefore, this study evaluated the performance in controlling grasp strength using a hand prosthesis operated through a complete grasping sequence while varying the feedback variables (e.g., closing velocity, grasping force), which were provided to the user visually or through vibrotactile stimulation. The experiments were conducted on 13 volunteers who controlled the Otto Bock Sensor Hand Speed prosthesis. Results showed that vibrotactile patterns were able to replace the visual feedback. Interestingly, the experiments demonstrated that direct force feedback was not essential for the control of grasping force. The subjects were indeed able to control the grip strength, predictively, by estimating the grasping force from the prosthesis velocity of closing. Therefore, grasping without explicit force feedback is not completely blind, contrary to what is usually assumed. In our study we analyzed grasping with a specific prosthetic device, but the outcomes are also applicable for other devices, with one or more degrees-of-freedom. The necessary condition is that the electromyography (EMG) signal directly and proportionally controls the velocity/grasp force of the hand, which is a common approach among EMG controlled prosthetic devices. The results provide important indications on the design of closed-loop EMG controlled prosthetic systems.

Active control of multiple resistive wall modes

NASA Astrophysics Data System (ADS)

Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Bolzonella, T.; Cecconello, M.; Drake, J. R.; Kuldkepp, M.; Manduchi, G.; Marchiori, G.; Marrelli, L.; Martin, P.; Menmuir, S.; Ortolani, S.; Rachlew, E.; Spizzo, G.; Zanca, P.

2005-12-01

A two-dimensional array of saddle coils at Mc poloidal and Nc toroidal positions is used on the EXTRAP T2R reversed-field pinch (Brunsell P R et al 2001 Plasma Phys. Control. Fusion 43 1457) to study active control of resistive wall modes (RWMs). Spontaneous growth of several RWMs with poloidal mode number m = 1 and different toroidal mode number n is observed experimentally, in agreement with linear MHD modelling. The measured plasma response to a controlled coil field and the plasma response computed using the linear circular cylinder MHD model are in quantitive agreement. Feedback control introduces a linear coupling of modes with toroidal mode numbers n, n' that fulfil the condition |n - n'| = Nc. Pairs of coupled unstable RWMs are present in feedback experiments with an array of Mc × Nc = 4 × 16 coils. Using intelligent shell feedback, the coupled modes are generally not controlled even though the field is suppressed at the active coils. A better suppression of coupled modes may be achieved in the case of rotating modes by using the mode control feedback scheme with individually set complex gains. In feedback with a larger array of Mc × Nc = 4 × 32 coils, the coupling effect largely disappears, and with this array, the main internal RWMs n = -11, -10, +5, +6 are all simultaneously suppressed throughout the discharge (7 8 wall times). With feedback there is a two-fold extension of the pulse length, compared to discharges without feedback.

Development of electrical feedback controlled heat pipes and the advanced thermal control flight experiment

NASA Technical Reports Server (NTRS)

Bienert, W. B.

1974-01-01

The development and characteristics of electrical feedback controlled heat pipes (FCHP) are discussed. An analytical model was produced to describe the performance of the FCHP under steady state and transient conditions. An advanced thermal control flight experiment was designed to demonstrate the performance of the thermal control component in a space environment. The thermal control equipment was evaluated on the ATS-F satellite to provide performance data for the components and to act as a thermal control system which can be used to provide temperature stability of spacecraft components in future applications.

Robust H(infinity) tracking control of boiler-turbine systems.

PubMed

Wu, J; Nguang, S K; Shen, J; Liu, G; Li, Y G

2010-07-01

In this paper, the problem of designing a fuzzy H(infinity) state feedback tracking control of a boiler-turbine is solved. First, the Takagi and Sugeno fuzzy model is used to model a boiler-turbine system. Next, based on the Takagi and Sugeno fuzzy model, sufficient conditions for the existence of a fuzzy H(infinity) nonlinear state feedback tracking control are derived in terms of linear matrix inequalities. The advantage of the proposed tracking control design is that it does not involve feedback linearization technique and complicated adaptive scheme. An industrial boiler-turbine system is used to illustrate the effectiveness of the proposed design as compared with a linearized approach. 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Mixed H2/Hinfinity output-feedback control of second-order neutral systems with time-varying state and input delays.

PubMed

Karimi, Hamid Reza; Gao, Huijun

2008-07-01

A mixed H2/Hinfinity output-feedback control design methodology is presented in this paper for second-order neutral linear systems with time-varying state and input delays. Delay-dependent sufficient conditions for the design of a desired control are given in terms of linear matrix inequalities (LMIs). A controller, which guarantees asymptotic stability and a mixed H2/Hinfinity performance for the closed-loop system of the second-order neutral linear system, is then developed directly instead of coupling the model to a first-order neutral system. A Lyapunov-Krasovskii method underlies the LMI-based mixed H2/Hinfinity output-feedback control design using some free weighting matrices. The simulation results illustrate the effectiveness of the proposed methodology.

Visual and somatic sensory feedback of brain activity for intuitive surgical robot manipulation.

PubMed

Miura, Satoshi; Matsumoto, Yuya; Kobayashi, Yo; Kawamura, Kazuya; Nakashima, Yasutaka; Fujie, Masakatsu G

2015-01-01

This paper presents a method to evaluate the hand-eye coordination of the master-slave surgical robot by measuring the activation of the intraparietal sulcus in users brain activity during controlling virtual manipulation. The objective is to examine the changes in activity of the intraparietal sulcus when the user's visual or somatic feedback is passed through or intercepted. The hypothesis is that the intraparietal sulcus activates significantly when both the visual and somatic sense pass feedback, but deactivates when either visual or somatic is intercepted. The brain activity of three subjects was measured by the functional near-infrared spectroscopic-topography brain imaging while they used a hand controller to move a virtual arm of a surgical simulator. The experiment was performed several times with three conditions: (i) the user controlled the virtual arm naturally under both visual and somatic feedback passed, (ii) the user moved with closed eyes under only somatic feedback passed, (iii) the user only gazed at the screen under only visual feedback passed. Brain activity showed significantly better control of the virtual arm naturally (p<;0.05) when compared with moving with closed eyes or only gazing among all participants. In conclusion, the brain can activate according to visual and somatic sensory feedback agreement.

ALL-ELECTRONIC DROPLET GENERATION ON-CHIP WITH REAL-TIME FEEDBACK CONTROL FOR EWOD DIGITIAL MICROFLUIDICS

PubMed Central

Gong, Jian; Kim, Chang-Jin “CJ”

2009-01-01

Electrowetting-on-dielectric (EWOD) actuation enables digital (or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabricaion and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1:x (x < 1) mixing, in comparison to the previously considered n:m mixing (i.e., n and m unit droplets). PMID:18497909

All-electronic droplet generation on-chip with real-time feedback control for EWOD digital microfluidics.

PubMed

Gong, Jian; Kim, Chang-Jin C J

2008-06-01

Electrowetting-on-dielectric (EWOD) actuation enables digital (or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabrication and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1 : x (x < 1) mixing, in comparison to the previously considered n : m mixing (i.e., n and m unit droplets).

A new lattice hydrodynamic model based on control method considering the flux change rate and delay feedback signal

NASA Astrophysics Data System (ADS)

Qin, Shunda; Ge, Hongxia; Cheng, Rongjun

2018-02-01

In this paper, a new lattice hydrodynamic model is proposed by taking delay feedback and flux change rate effect into account in a single lane. The linear stability condition of the new model is derived by control theory. By using the nonlinear analysis method, the mKDV equation near the critical point is deduced to describe the traffic congestion. Numerical simulations are carried out to demonstrate the advantage of the new model in suppressing traffic jam with the consideration of flux change rate effect in delay feedback model.

System identification from closed-loop data with known output feedback dynamics

NASA Technical Reports Server (NTRS)

Phan, Minh; Juang, Jer-Nan; Horta, Lucas G.; Longman, Richard W.

1992-01-01

This paper presents a procedure to identify the open loop systems when it is operating under closed loop conditions. First, closed loop excitation data are used to compute the system open loop and closed loop Markov parameters. The Markov parameters, which are the pulse response samples, are then used to compute a state space representation of the open loop system. Two closed loop configurations are considered in this paper. The closed loop system can have either a linear output feedback controller or a dynamic output feedback controller. Numerical examples are provided to illustrate the proposed closed loop identification method.

Static inverter with synchronous output waveform synthesized by time-optimal-response feedback

NASA Technical Reports Server (NTRS)

Kernick, A.; Stechschulte, D. L.; Shireman, D. W.

1976-01-01

Time-optimal-response 'bang-bang' or 'bang-hang' technique, using four feedback control loops, synthesizes static-inverter sinusoidal output waveform by self-oscillatory but yet synchronous pulse-frequency-modulation (SPFM). A single modular power stage per phase of ac output entails the minimum of circuit complexity while providing by feedback synthesis individual phase voltage regulation, phase position control and inherent compensation simultaneously for line and load disturbances. Clipped sinewave performance is described under off-limit load or input voltage conditions. Also, approaches to high power levels, 3-phase arraying and parallel modular connection are given.

Optimal feedback control infinite dimensional parabolic evolution systems: Approximation techniques

NASA Technical Reports Server (NTRS)

Banks, H. T.; Wang, C.

1989-01-01

A general approximation framework is discussed for computation of optimal feedback controls in linear quadratic regular problems for nonautonomous parabolic distributed parameter systems. This is done in the context of a theoretical framework using general evolution systems in infinite dimensional Hilbert spaces. Conditions are discussed for preservation under approximation of stabilizability and detectability hypotheses on the infinite dimensional system. The special case of periodic systems is also treated.

Effectiveness of patient feedback as an educational intervention to improve medical student consultation (PTA Feedback Study): study protocol for a randomized controlled trial.

PubMed

Lai, Michelle Mei Yee; Roberts, Noel; Martin, Jenepher

2014-09-17

Oral feedback from clinical educators is the traditional teaching method for improving clinical consultation skills in medical students. New approaches are needed to enhance this teaching model. Multisource feedback is a commonly used assessment method for learning among practising clinicians, but this assessment has not been explored rigorously in medical student education. This study seeks to evaluate if additional feedback on patient satisfaction improves medical student performance. The Patient Teaching Associate (PTA) Feedback Study is a single site randomized controlled, double-blinded trial with two parallel groups.An after-hours general practitioner clinic in Victoria, Australia, is adapted as a teaching clinic during the day. Medical students from two universities in their first clinical year participate in six simulated clinical consultations with ambulatory patient volunteers living with chronic illness. Eligible students will be randomized in equal proportions to receive patient satisfaction score feedback with the usual multisource feedback and the usual multisource feedback alone as control. Block randomization will be performed. We will assess patient satisfaction and consultation performance outcomes at baseline and after one semester and will compare any change in mean scores at the last session from that at baseline. We will model data using regression analysis to determine any differences between intervention and control groups. Full ethical approval has been obtained for the study. This trial will comply with CONSORT guidelines and we will disseminate data at conferences and in peer-reviewed journals. This is the first proposed trial to determine whether consumer feedback enhances the use of multisource feedback in medical student education, and to assess the value of multisource feedback in teaching and learning about the management of ambulatory patients living with chronic conditions. Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12613001055796.

The Influence of Restricted Visual Feedback on Dribbling Performance in Youth Soccer Players.

PubMed

Fransen, Job; Lovell, Thomas W J; Bennett, Kyle J M; Deprez, Dieter; Deconinck, Frederik J A; Lenoir, Matthieu; Coutts, Aaron J

2017-04-01

The aim of the current study was to examine the influence of restricted visual feedback using stroboscopic eyewear on the dribbling performance of youth soccer players. Three dribble test conditions were used in a within-subjects design to measure the effect of restricted visual feedback on soccer dribbling performance in 189 youth soccer players (age: 10-18 y) classified as fast, average or slow dribblers. The results showed that limiting visual feedback increased dribble test times across all abilities. Furthermore, the largest performance decrement between stroboscopic and full vision conditions was in fast dribblers, showing that fast dribblers were most affected by reduced visual information. This may be due to a greater dependency on visual feedback at increased speeds, which may limit the ability to maintain continuous control of the ball. These findings may have important implications for the development of soccer dribbling ability.

Augmented kinematic feedback from haptic virtual reality for dental skill acquisition.

PubMed

Suebnukarn, Siriwan; Haddawy, Peter; Rhienmora, Phattanapon; Jittimanee, Pannapa; Viratket, Piyanuch

2010-12-01

We have developed a haptic virtual reality system for dental skill training. In this study we examined several kinds of kinematic information about the movement provided by the system supplement knowledge of results (KR) in dental skill acquisition. The kinematic variables examined involved force utilization (F) and mirror view (M). This created three experimental conditions that received augmented kinematic feedback (F, M, FM) and one control condition that did not (KR-only). Thirty-two dental students were randomly assigned to four groups. Their task was to perform access opening on the upper first molar with the haptic virtual reality system. An acquisition session consisted of two days of ten trials of practice in which augmented kinematic feedback was provided for the appropriate experimental conditions after each trial. One week after, a retention test consisting of two trials without augmented feedback was completed. The results showed that the augmented kinematic feedback groups had larger mean performance scores than the KR-only group in Day 1 of the acquisition and retention sessions (ANOVA, p<0.05). The apparent differences among feedback groups were not significant in Day 2 of the acquisition session (ANOVA, p>0.05). The trends in acquisition and retention sessions suggest that the augmented kinematic feedback can enhance the performance earlier in the skill acquisition and retention sessions.

Framing of feedback impacts student's satisfaction, self-efficacy and performance.

PubMed

van de Ridder, J M Monica; Peters, Claudia M M; Stokking, Karel M; de Ru, J Alexander; Ten Cate, Olle Th J

2015-08-01

Feedback is considered important to acquire clinical skills. Research evidence shows that feedback does not always improve learning and its effects may be small. In many studies, a variety of variables involved in feedback provision may mask either one of their effects. E.g., there is reason to believe that the way oral feedback is framed may affect its effect if other variables are held constant. In a randomised controlled trial we investigated the effect of positively and negatively framed feedback messages on satisfaction, self-efficacy, and performance. A single blind randomised controlled between-subject design was used, with framing of the feedback message (positively-negatively) as independent variable and examination of hearing abilities as the task. First year medical students' (n = 59) satisfaction, self-efficacy, and performance were the dependent variables and were measured both directly after the intervention and after a 2 weeks delay. Students in the positively framed feedback condition were significantly more satisfied and showed significantly higher self-efficacy measured directly after the performance. Effect sizes found were large, i.e., partial η (2) = 0.43 and η (2) = 0.32 respectively. They showed a better performance throughout the whole study. Significant performance differences were found both at the initial performance and when measured 2 weeks after the intervention: effects were of medium size, respectively r = -.31 and r = -.32. Over time in both conditions performance and self-efficacy decreased. Framing the feedback message in either a positive or negative manner affects students' satisfaction and self-efficacy directly after the intervention be it that these effects seem to fade out over time. Performance may be enhanced by positive framing, but additional studies need to confirm this. We recommend using a positive frame when giving feedback on clinical skills.

A theory of circular organization and negative feedback: defining life in a cybernetic context.

PubMed

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

A Theory of Circular Organization and Negative Feedback: Defining Life in a Cybernetic Context

NASA Astrophysics Data System (ADS)

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

Evaluation of a Worksite-Controlled Smoking Program.

ERIC Educational Resources Information Center

Glasgow, Russell E.; And Others

1984-01-01

Evaluated the relative effectiveness of three versions of a controlled smoking program conducted in the worksite: abrupt reduction, gradual reduction, or gradual reduction plus feedback on nicotine consumption. All conditions were effective. There was some indication that the gradual reduction condition was more effective than the abrupt…

Processing of Continuously Provided Punishment and Reward in Children with ADHD and the Modulating Effects of Stimulant Medication: An ERP Study

PubMed Central

Groen, Yvonne; Tucha, Oliver; Wijers, Albertus A.; Althaus, Monika

2013-01-01

Objectives Current models of ADHD suggest abnormal reward and punishment sensitivity, but the exact mechanisms are unclear. This study aims to investigate effects of continuous reward and punishment on the processing of performance feedback in children with ADHD and the modulating effects of stimulant medication. Methods 15 Methylphenidate (Mph)-treated and 15 Mph-free children of the ADHD-combined type and 17 control children performed a selective attention task with three feedback conditions: no-feedback, gain and loss. Event Related Potentials (ERPs) time-locked to feedback and errors were computed. Results All groups performed more accurately with gain and loss than without feedback. Feedback-related ERPs demonstrated no group differences in the feedback P2, but an enhanced late positive potential (LPP) to feedback stimuli (both gains and losses) for Mph-free children with ADHD compared to controls. Feedback-related ERPs in Mph-treated children with ADHD were similar to controls. Correlational analyses in the ADHD groups revealed that the severity of inattention problems correlated negatively with the feedback P2 amplitude and positively with the LPP to losses and omitted gains. Conclusions The early selective attention for rewarding and punishing feedback was relatively intact in children with ADHD, but the late feedback processing was deviant (increased feedback LPP). This may explain the often observed positive effects of continuous reinforcement on performance and behaviour in children with ADHD. However, these group findings cannot be generalised to all individuals with the ADHD, because the feedback-related ERPs were associated with the severity of the inattention problems. Children with ADHD-combined type with more inattention problems showed both deviant early attentional selection of feedback stimuli, and deviant late processing of non-reward and punishment. PMID:23555639

Processing of continuously provided punishment and reward in children with ADHD and the modulating effects of stimulant medication: an ERP study.

PubMed

Groen, Yvonne; Tucha, Oliver; Wijers, Albertus A; Althaus, Monika

2013-01-01

Current models of ADHD suggest abnormal reward and punishment sensitivity, but the exact mechanisms are unclear. This study aims to investigate effects of continuous reward and punishment on the processing of performance feedback in children with ADHD and the modulating effects of stimulant medication. 15 Methylphenidate (Mph)-treated and 15 Mph-free children of the ADHD-combined type and 17 control children performed a selective attention task with three feedback conditions: no-feedback, gain and loss. Event Related Potentials (ERPs) time-locked to feedback and errors were computed. All groups performed more accurately with gain and loss than without feedback. Feedback-related ERPs demonstrated no group differences in the feedback P2, but an enhanced late positive potential (LPP) to feedback stimuli (both gains and losses) for Mph-free children with ADHD compared to controls. Feedback-related ERPs in Mph-treated children with ADHD were similar to controls. Correlational analyses in the ADHD groups revealed that the severity of inattention problems correlated negatively with the feedback P2 amplitude and positively with the LPP to losses and omitted gains. The early selective attention for rewarding and punishing feedback was relatively intact in children with ADHD, but the late feedback processing was deviant (increased feedback LPP). This may explain the often observed positive effects of continuous reinforcement on performance and behaviour in children with ADHD. However, these group findings cannot be generalised to all individuals with the ADHD, because the feedback-related ERPs were associated with the severity of the inattention problems. Children with ADHD-combined type with more inattention problems showed both deviant early attentional selection of feedback stimuli, and deviant late processing of non-reward and punishment.

Output control using feedforward and cascade controllers

NASA Technical Reports Server (NTRS)

Seraji, H.

1987-01-01

An open-loop solution to the output control problem in SISO (single-input, single-output) systems by means of feedforward and cascade controllers is investigated. A simple characterization of feedforward controllers, which achieve steady-state disturbance rejection, is given in a transfer-function setting. Cascade controllers which cause steady-state command tracking are characterized. Disturbance decoupling and command matching controllers are identified. Conditions for existence of feedforward and cascade controllers are given. For unstable systems, it is shown that a stabilizing feedback controller can be used without affecting the feedforward and cascade controllers used for output control; hence, the three controllers can be designed independently. Output control by a combination of feedforward and feedback is discussed.

The effects of self-controlled feedback on learning of a "relaxed phonation task".

PubMed

Ma, Estella P-M; Yiu, Gigi K-Y; Yiu, Edwin M-L

2013-11-01

This study examined the effects of self-controlled feedback paradigm on motor learning of a relaxed phonation task. It investigated whether providing the learner with more control over practice condition has positive influences on the performance and learning of "relaxed phonation" skill. Vocally healthy individuals were randomly assigned into either self-controlled feedback group (SELF) or clinician-controlled feedback group (YOKED). All participants were engaged in a reading aloud task. Throughout the task, their perilaryngeal muscle activities were measured at thyrohyoid (TH) and orofacial (OF) sites using surface electromyography (EMG). The EMG values measured at the TH site were provided to participants as terminal biofeedback. Participants were required to minimize the EMG values. The SELF group received EMG biofeedback whenever they requested it, whereas the YOKED group received the same feedback schedule as chosen by their self-controlled counterparts. The pooled data for all participants revealed that there was a significant reduction of muscle tension across baseline, training, and retention phases. Generalization was shown to reading of untrained passage. Interestingly, significant reduction of muscle tension across training and retention tests was found in the control OF site but not in the target TH site. The results failed to demonstrate significant differences between SELF and YOKED groups. It provided no clear evidence to conclude that self-controlled feedback paradigm was beneficial to learning of relaxed phonation. Copyright © 2013 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Comparative cost-effectiveness of two interventions to promote work functioning by targeting mental health complaints among nurses: pragmatic cluster randomised trial.

PubMed

Noben, Cindy; Smit, Filip; Nieuwenhuijsen, Karen; Ketelaar, Sarah; Gärtner, Fania; Boon, Brigitte; Sluiter, Judith; Evers, Silvia

2014-10-01

The specific job demands of working in a hospital may place nurses at elevated risk for developing distress, anxiety and depression. Screening followed by referral to early interventions may reduce the incidence of these health problems and promote work functioning. To evaluate the comparative cost-effectiveness of two strategies to promote work functioning among nurses by reducing symptoms of mental health complaints. Three conditions were compared: the control condition consisted of online screening for mental health problems without feedback about the screening results. The occupational physician condition consisted of screening, feedback and referral to the occupational physician for screen-positive nurses. The third condition included screening, feedback, and referral to e-mental health. The study was designed as an economic evaluation alongside a pragmatic cluster randomised controlled trial with randomisation at hospital-ward level. The study included 617 nurses in one academic medical centre in the Netherlands. Treatment response was defined as an improvement on the Nurses Work Functioning Questionnaire of at least 40% between baseline and follow-up. Total per-participant costs encompassed intervention costs, direct medical and non-medical costs, and indirect costs stemming from lost productivity due to absenteeism and presenteeism. All costs were indexed for the year 2011. At 6 months follow-up, significant improvement in work functioning occurred in 20%, 24% and 16% of the participating nurses in the control condition, the occupational physician condition and the e-mental health condition, respectively. In these conditions the total average annualised costs were €1752, €1266 and €1375 per nurse. The median incremental cost-effectiveness ratio for the occupational physician condition versus the control condition was dominant, suggesting cost savings of €5049 per treatment responder. The incremental cost-effectiveness ratio for the e-mental health condition versus the control condition was estimated at €4054 (added costs) per treatment responder. Sensitivity analyses attested to the robustness of these findings. The occupational physician condition resulted in greater treatment responses for less costs relative to the control condition and can therefore be recommended. The e-mental health condition produced less treatment response than the control condition and cannot be recommended as an intervention to improve work functioning among nurses. Copyright © 2014 Elsevier Ltd. All rights reserved.

A stochastic optimal feedforward and feedback control methodology for superagility

NASA Technical Reports Server (NTRS)

Halyo, Nesim; Direskeneli, Haldun; Taylor, Deborah B.

1992-01-01

A new control design methodology is developed: Stochastic Optimal Feedforward and Feedback Technology (SOFFT). Traditional design techniques optimize a single cost function (which expresses the design objectives) to obtain both the feedforward and feedback control laws. This approach places conflicting demands on the control law such as fast tracking versus noise atttenuation/disturbance rejection. In the SOFFT approach, two cost functions are defined. The feedforward control law is designed to optimize one cost function, the feedback optimizes the other. By separating the design objectives and decoupling the feedforward and feedback design processes, both objectives can be achieved fully. A new measure of command tracking performance, Z-plots, is also developed. By analyzing these plots at off-nominal conditions, the sensitivity or robustness of the system in tracking commands can be predicted. Z-plots provide an important tool for designing robust control systems. The Variable-Gain SOFFT methodology was used to design a flight control system for the F/A-18 aircraft. It is shown that SOFFT can be used to expand the operating regime and provide greater performance (flying/handling qualities) throughout the extended flight regime. This work was performed under the NASA SBIR program. ICS plans to market the software developed as a new module in its commercial CACSD software package: ACET.

Learned control over spinal nociception in patients with chronic back pain.

PubMed

Krafft, S; Göhmann, H-D; Sommer, J; Straube, A; Ruscheweyh, R

2017-10-01

Descending pain inhibition suppresses spinal nociception, reducing nociceptive input to the brain. It is modulated by cognitive and emotional processes. In subjects with chronic pain, it is impaired, possibly contributing to pain persistence. A previously developed feedback method trains subjects to activate their descending inhibition. Participants are trained to use cognitive-emotional strategies to reduce their spinal nociception, as quantified by the nociceptive flexor reflex (RIII reflex), under visual feedback about their RIII reflex size. The aim of the present study was to test whether also subjects with chronic back pain can achieve a modulation of their descending pain inhibition under RIII feedback. In total, 33 subjects with chronic back pain received either true (n = 18) or sham RIII feedback (n = 15), 15 healthy control subjects received true RIII feedback. All three groups achieved significant RIII suppression, largest in controls (to 76 ± 26% of baseline), intermediate in chronic back pain subjects receiving true feedback (to 82 ± 13%) and smallest in chronic back pain subjects receiving sham feedback (to 89 ± 14%, all p < 0.05). However, only chronic pain subjects receiving true feedback significantly improved their descending inhibition over the feedback training, quantified by the conditioned pain modulation effect (test pain reduction of baseline before training: to 98 ± 26%, after: to 80 ± 21%, p < 0.01). Our results show that subjects with chronic back pain can achieve a reduction of their spinal nociception and improve their descending pain inhibition under RIII feedback training. Subjects with chronic back pain can learn to control their spinal nociception, quantified by the RIII reflex, when they receive feedback about the RIII reflex. © 2017 European Pain Federation - EFIC®.

Observer-based output feedback control of networked control systems with non-uniform sampling and time-varying delay

NASA Astrophysics Data System (ADS)

Meng, Su; Chen, Jie; Sun, Jian

2017-10-01

This paper investigates the problem of observer-based output feedback control for networked control systems with non-uniform sampling and time-varying transmission delay. The sampling intervals are assumed to vary within a given interval. The transmission delay belongs to a known interval. A discrete-time model is first established, which contains time-varying delay and norm-bounded uncertainties coming from non-uniform sampling intervals. It is then converted to an interconnection of two subsystems in which the forward channel is delay-free. The scaled small gain theorem is used to derive the stability condition for the closed-loop system. Moreover, the observer-based output feedback controller design method is proposed by utilising a modified cone complementary linearisation algorithm. Finally, numerical examples illustrate the validity and superiority of the proposed method.

Facial Feedback and Social Input: Effects on Laughter and Enjoyment in Children with Autism Spectrum Disorders.

PubMed

Helt, Molly S; Fein, Deborah A

2016-01-01

Both social input and facial feedback appear to be processed differently by individuals with autism spectrum disorder (ASD). We tested the effects of both of these types of input on laughter in children with ASD. Sensitivity to facial feedback was tested in 43 children with ASD, aged 8-14 years, and 43 typically developing children matched for mental age (6-14), in order to examine whether children with ASD use bodily feedback as an implicit source of information. Specifically, children were asked to view cartoons as they normally would (control condition), and while holding a pencil in their mouth forcing their smiling muscles into activation (feedback condition) while rating their enjoyment of the cartoons. The authors also explored the effects of social input in children with ASD by investigating whether the presence of a caregiver or friend (companion condition), or the presence of a laugh track superimposed upon the cartoon (laugh track condition) increased the children's self-rated enjoyment of cartoons or the amount of positive affect they displayed. Results showed that the group with ASD was less affected by all three experimental conditions, but also that group differences seemed to have been driven by one specific symptom of ASD: restricted range of affect. The strong relationship between restricted affect and insensitivity to facial feedback found in this study sheds light on the implications of restricted affect for social development in ASD.

State feedback control design for Boolean networks.

PubMed

Liu, Rongjie; Qian, Chunjiang; Liu, Shuqian; Jin, Yu-Fang

2016-08-26

Driving Boolean networks to desired states is of paramount significance toward our ultimate goal of controlling the progression of biological pathways and regulatory networks. Despite recent computational development of controllability of general complex networks and structural controllability of Boolean networks, there is still a lack of bridging the mathematical condition on controllability to real boolean operations in a network. Further, no realtime control strategy has been proposed to drive a Boolean network. In this study, we applied semi-tensor product to represent boolean functions in a network and explored controllability of a boolean network based on the transition matrix and time transition diagram. We determined the necessary and sufficient condition for a controllable Boolean network and mapped this requirement in transition matrix to real boolean functions and structure property of a network. An efficient tool is offered to assess controllability of an arbitrary Boolean network and to determine all reachable and non-reachable states. We found six simplest forms of controllable 2-node Boolean networks and explored the consistency of transition matrices while extending these six forms to controllable networks with more nodes. Importantly, we proposed the first state feedback control strategy to drive the network based on the status of all nodes in the network. Finally, we applied our reachability condition to the major switch of P53 pathway to predict the progression of the pathway and validate the prediction with published experimental results. This control strategy allowed us to apply realtime control to drive Boolean networks, which could not be achieved by the current control strategy for Boolean networks. Our results enabled a more comprehensive understanding of the evolution of Boolean networks and might be extended to output feedback control design.

A wearable skin stretch haptic feedback device: Towards improving balance control in lower limb amputees.

PubMed

Husman, M A B; Maqbool, H F; Awad, M I; Abouhossein, A; Dehghani-Sanij, A A

2016-08-01

Haptic feedback to lower limb amputees is essential to maximize the functionality of a prosthetic device by providing information to the user about the interaction with the environment and the position of the prostheses in space. Severed sensory pathway and the absence of connection between the prosthesis and the Central Nervous System (CNS) after lower limb amputation reduces balance control, increases visual dependency and increases risk of falls among amputees. This work describes the design of a wearable haptic feedback device for lower limb amputees using lateral skin-stretch modality intended to serve as a feedback cue during ambulation. A feedback scheme was proposed based on gait event detection for possible real-time postural adjustment. Preliminary perceptual test with healthy subjects in static condition was carried out and the results indicated over 98% accuracy in determining stimuli location around the upper leg region, suggesting good perceptibility of the delivered stimuli.

Corrective Feedback, Spoken Accuracy and Fluency, and the Trade-Off Hypothesis

ERIC Educational Resources Information Center

Chehr Azad, Mohammad Hassan; Farrokhi, Farahman; Zohrabi, Mohammad

2018-01-01

The current study was an attempt to investigate the effects of different corrective feedback (CF) conditions on Iranian EFL learners' spoken accuracy and fluency (AF) and the trade-off between them. Consequently, four pre-intermediate intact classes were randomly selected as the control, delayed explicit metalinguistic CF, extensive recast, and…

Effect of Training and Level of External Auditory Feedback on the Singing Voice: Pitch Inaccuracy

PubMed Central

Bottalico, Pasquale; Graetzer, Simone; Hunter, Eric J.

2016-01-01

Background One of the aspects of major relevance to singing is the control of fundamental frequency. Objectives The effects on pitch inaccuracy, defined as the distance in cents in equally tempered tuning between the reference note and the sung note, of the following conditions were evaluated: (1) level of external feedback, (2) tempo (slow or fast), (3) articulation (legato or staccato), (4) tessitura (low, medium or high) and (5) semi-phrase direction (ascending or descending). Methods The subjects were 10 non-professional singers, and 10 classically-trained professional or semi-professional singers (10 males and 10 females). Subjects sang one octave and a fifth arpeggi with three different levels of external auditory feedback, two tempi and two articulations (legato or staccato). Results It was observed that inaccuracy was greatest in the descending semi-phrase arpeggi produced at a fast tempo and with a staccato articulation, especially for non-professional singers. The magnitude of inaccuracy was also relatively large in the high tessitura relative to the low and medium tessitura for such singers. Counter to predictions, when external auditory feedback was strongly attenuated by the hearing protectors, non-professional singers showed greater pitch accuracy than in the other external feedback conditions. This finding indicates the importance of internal auditory feedback in pitch control. Conclusions With an increase in training, the singer’s pitch inaccuracy decreases. PMID:26948385

"I Forgot I Wasn't Saving the World": the Use of Formative and Summative Assessment in Instructional Video Games for Undergraduate Biology

NASA Astrophysics Data System (ADS)

Lookadoo, Kathryn L.; Bostwick, Eryn N.; Ralston, Ryan; Elizondo, Francisco Javier; Wilson, Scott; Shaw, Tarren J.; Jensen, Matthew L.

2017-12-01

This study examined the role of formative and summative assessment in instructional video games on student learning and engagement. A 2 (formative feedback: present vs absent) × 2 (summative feedback: present vs absent) factorial design with an offset control (recorded lecture) was conducted to explore the impacts of assessment in video games. A total of 172 undergraduates were randomly assigned to one of four instructional video game conditions or the control. Results found that knowledge significantly increased from the pretest for players in all game conditions. Participants in summative assessment conditions learned more than players without summative assessment. In terms of engagement outcomes, formative assessment conditions did not significantly produce better learning engagement outcomes than conditions without formative assessment. However, summative assessment conditions were associated with higher temporal disassociation than non-summative conditions. Implications for future instructional video game development and testing are discussed in the paper.

Effects of blindness on production-perception relationships: Compensation strategies for a lip-tube perturbation of the French [u].

PubMed

Ménard, Lucie; Turgeon, Christine; Trudeau-Fisette, Paméla; Bellavance-Courtemanche, Marie

2016-01-01

The impact of congenital visual deprivation on speech production in adults was examined in an ultrasound study of compensation strategies for lip-tube perturbation. Acoustic and articulatory analyses of the rounded vowel /u/ produced by 12 congenitally blind adult French speakers and 11 sighted adult French speakers were conducted under two conditions: normal and perturbed (with a 25-mm diameter tube inserted between the lips). Vowels were produced with auditory feedback and without auditory feedback (masked noise) to evaluate the extent to which both groups relied on this type of feedback to control speech movements. The acoustic analyses revealed that all participants mainly altered F2 and F0 and, to a lesser extent, F1 in the perturbed condition - only when auditory feedback was available. There were group differences in the articulatory strategies recruited to compensate; while all speakers moved their tongues more backward in the perturbed condition, blind speakers modified tongue-shape parameters to a greater extent than sighted speakers.

Synergistic Effects on the Elderly People's Motor Control by Wearable Skin-Stretch Device Combined with Haptic Joystick

PubMed Central

Yoon, Han U.; Anil Kumar, Namita; Hur, Pilwon

2017-01-01

Cutaneous sensory feedback can be used to provide additional sensory cues to a person performing a motor task where vision is a dominant feedback signal. A haptic joystick has been widely used to guide a user by providing force feedback. However, the benefit of providing force feedback is still debatable due to performance dependency on factors such as the user's skill-level, task difficulty. Meanwhile, recent studies have shown the feasibility of improving a motor task performance by providing skin-stretch feedback. Therefore, a combination of two aforementioned feedback types is deemed to be promising to promote synergistic effects to consistently improve the person's motor performance. In this study, we aimed at identifying the effect of the combined haptic and skin-stretch feedbacks on the aged person's driving motor performance. For the experiment, 15 healthy elderly subjects (age 72.8 ± 6.6 years) were recruited and were instructed to drive a virtual power-wheelchair through four different courses with obstacles. Four augmented sensory feedback conditions were tested: no feedback, force feedback, skin-stretch feedback, and a combination of both force and skin-stretch feedbacks. While the haptic force was provided to the hand by the joystick, the skin-stretch was provided to the steering forearm by a custom-designed wearable skin-stretch device. We tested two hypotheses: (i) an elderly individual's motor control would benefit from receiving information about a desired trajectory from multiple sensory feedback sources, and (ii) the benefit does not depend on task difficulty. Various metrics related to skills and safety were used to evaluate the control performance. Repeated measure ANOVA was performed for those metrics with two factors: task scenario and the type of the augmented sensory feedback. The results revealed that elderly subjects' control performance significantly improved when the combined feedback of both haptic force and skin-stretch feedback was applied. The proposed approach suggest the feasibility to improve people's task performance by the synergistic effects of multiple augmented sensory feedback modalities. PMID:28690514

A model of neuro-musculo-skeletal system for human locomotion under position constraint condition.

PubMed

Ni, Jiangsheng; Hiramatsu, Seiji; Kato, Atsuo

2003-08-01

The human locomotion was studied on the basis of the interaction of the musculo-skeletal system, the neural system and the environment. A mathematical model of human locomotion under position constraint condition was established. Besides the neural rhythm generator, the posture controller and the sensory system, the environment feedback controller and the stability controller were taken into account in the model. The environment feedback controller was proposed for two purposes, obstacle avoidance and target position control of the swing foot. The stability controller was proposed to imitate the self-balancing ability of a human body and improve the stability of the model. In the stability controller, the ankle torque was used to control the velocity of the body gravity center. A prediction control algorithm was applied to calculate the torque magnitude of the stability controller. As an example, human stairs climbing movement was simulated and the results were given. The simulation result proved that the mathematical modeling of the task was successful.

Does visual feedback during walking result in similar improvements in trunk control for young and older healthy adults?

PubMed

Anson, Eric; Rosenberg, Russell; Agada, Peter; Kiemel, Tim; Jeka, John

2013-11-26

Most current applications of visual feedback to improve postural control are limited to a fixed base of support and produce mixed results regarding improved postural control and transfer to functional tasks. Currently there are few options available to provide visual feedback regarding trunk motion while walking. We have developed a low cost platform to provide visual feedback of trunk motion during walking. Here we investigated whether augmented visual position feedback would reduce trunk movement variability in both young and older healthy adults. The subjects who participated were 10 young and 10 older adults. Subjects walked on a treadmill under conditions of visual position feedback and no feedback. The visual feedback consisted of anterior-posterior (AP) and medial-lateral (ML) position of the subject's trunk during treadmill walking. Fourier transforms of the AP and ML trunk kinematics were used to calculate power spectral densities which were integrated as frequency bins "below the gait cycle" and "gait cycle and above" for analysis purposes. Visual feedback reduced movement power at very low frequencies for lumbar and neck translation but not trunk angle in both age groups. At very low frequencies of body movement, older adults had equivalent levels of movement variability with feedback as young adults without feedback. Lower variability was specific to translational (not angular) trunk movement. Visual feedback did not affect any of the measured lower extremity gait pattern characteristics of either group, suggesting that changes were not invoked by a different gait pattern. Reduced translational variability while walking on the treadmill reflects more precise control maintaining a central position on the treadmill. Such feedback may provide an important technique to augment rehabilitation to minimize body translation while walking. Individuals with poor balance during walking may benefit from this type of training to enhance path consistency during over-ground locomotion.

Feedback control methods for drug dosage optimisation. Concepts, classification and clinical application.

PubMed

Vozeh, S; Steimer, J L

1985-01-01

The concept of feedback control methods for drug dosage optimisation is described from the viewpoint of control theory. The control system consists of 5 parts: (a) patient (the controlled process); (b) response (the measured feedback); (c) model (the mathematical description of the process); (d) adaptor (to update the parameters); and (e) controller (to determine optimum dosing strategy). In addition to the conventional distinction between open-loop and closed-loop control systems, a classification is proposed for dosage optimisation techniques which distinguishes between tight-loop and loose-loop methods depending on whether physician's interaction is absent or included as part of the control step. Unlike engineering problems where the process can usually be controlled by fully automated devices, therapeutic situations often require that the physician be included in the decision-making process to determine the 'optimal' dosing strategy. Tight-loop and loose-loop methods can be further divided into adaptive and non-adaptive, depending on the presence of the adaptor. The main application areas of tight-loop feedback control methods are general anaesthesia, control of blood pressure, and insulin delivery devices. Loose-loop feedback methods have been used for oral anticoagulation and in therapeutic drug monitoring. The methodology, advantages and limitations of the different approaches are reviewed. A general feature common to all application areas could be observed: to perform well under routine clinical conditions, which are characterised by large interpatient variability and sometimes also intrapatient changes, control systems should be adaptive. Apart from application in routine drug treatment, feedback control methods represent an important research tool. They can be applied for the investigation of pathophysiological and pharmacodynamic processes. A most promising application is the evaluation of the relationship between an intermediate response (e.g. drug level), which is often used as feedback for dosage adjustment, and the final therapeutic goal.

A lattice hydrodynamic model based on delayed feedback control considering the effect of flow rate difference

NASA Astrophysics Data System (ADS)

Wang, Yunong; Cheng, Rongjun; Ge, Hongxia

2017-08-01

In this paper, a lattice hydrodynamic model is derived considering not only the effect of flow rate difference but also the delayed feedback control signal which including more comprehensive information. The control method is used to analyze the stability of the model. Furthermore, the critical condition for the linear steady traffic flow is deduced and the numerical simulation is carried out to investigate the advantage of the proposed model with and without the effect of flow rate difference and the control signal. The results are consistent with the theoretical analysis correspondingly.

Efficacy of web-based cognitive-behavioural therapy for chronic fatigue syndrome: randomised controlled trial.

PubMed

Janse, A; Worm-Smeitink, M; Bleijenberg, G; Donders, R; Knoop, H

2018-02-01

Face-to-face cognitive-behavioural therapy (CBT) leads to a reduction of fatigue in chronic fatigue syndrome (CFS). Aims To test the efficacy of internet-based CBT (iCBT) for adults with CFS. A total of 240 patients with CFS were randomised to either iCBT with protocol-driven therapist feedback or with therapist feedback on demand, or a waiting list. Primary outcome was fatigue severity assessed with the Checklist Individual Strength (Netherlands Trial Register: NTR4013). Compared with a waiting list, intention-to-treat (ITT) analysis showed a significant reduction of fatigue for both iCBT conditions (protocol-driven feedback: B = -8.3, 97.5% CI -12.7 to -3.9, P < 0.0001; feedback on demand: B = -7.2, 97.5% CI -11.3 to -3.1, P < 0.0001). No significant differences were found between both iCBT conditions on all outcome measures (P = 0.3-0.9). An exploratory analysis revealed that feedback-on-demand iCBT required less therapist time (mean 4 h 37 min) than iCBT with protocol-driven feedback (mean 6 h 9 min, P < 0.001) and also less than face-to-face CBT as reported in the literature. Both iCBT conditions are efficacious and time efficient. Declaration of interest None.

Stabilisation of time-varying linear systems via Lyapunov differential equations

NASA Astrophysics Data System (ADS)

Zhou, Bin; Cai, Guang-Bin; Duan, Guang-Ren

2013-02-01

This article studies stabilisation problem for time-varying linear systems via state feedback. Two types of controllers are designed by utilising solutions to Lyapunov differential equations. The first type of feedback controllers involves the unique positive-definite solution to a parametric Lyapunov differential equation, which can be solved when either the state transition matrix of the open-loop system is exactly known, or the future information of the system matrices are accessible in advance. Different from the first class of controllers which may be difficult to implement in practice, the second type of controllers can be easily implemented by solving a state-dependent Lyapunov differential equation with a given positive-definite initial condition. In both cases, explicit conditions are obtained to guarantee the exponentially asymptotic stability of the associated closed-loop systems. Numerical examples show the effectiveness of the proposed approaches.

Feedforward and feedback control in apraxia of speech: effects of noise masking on vowel production.

PubMed

Maas, Edwin; Mailend, Marja-Liisa; Guenther, Frank H

2015-04-01

This study was designed to test two hypotheses about apraxia of speech (AOS) derived from the Directions Into Velocities of Articulators (DIVA) model (Guenther et al., 2006): the feedforward system deficit hypothesis and the feedback system deficit hypothesis. The authors used noise masking to minimize auditory feedback during speech. Six speakers with AOS and aphasia, 4 with aphasia without AOS, and 2 groups of speakers without impairment (younger and older adults) participated. Acoustic measures of vowel contrast, variability, and duration were analyzed. Younger, but not older, speakers without impairment showed significantly reduced vowel contrast with noise masking. Relative to older controls, the AOS group showed longer vowel durations overall (regardless of masking condition) and a greater reduction in vowel contrast under masking conditions. There were no significant differences in variability. Three of the 6 speakers with AOS demonstrated the group pattern. Speakers with aphasia without AOS did not differ from controls in contrast, duration, or variability. The greater reduction in vowel contrast with masking noise for the AOS group is consistent with the feedforward system deficit hypothesis but not with the feedback system deficit hypothesis; however, effects were small and not present in all individual speakers with AOS. Theoretical implications and alternative interpretations of these findings are discussed.

Feedforward and Feedback Control in Apraxia of Speech: Effects of Noise Masking on Vowel Production

PubMed Central

Mailend, Marja-Liisa; Guenther, Frank H.

2015-01-01

Purpose This study was designed to test two hypotheses about apraxia of speech (AOS) derived from the Directions Into Velocities of Articulators (DIVA) model (Guenther et al., 2006): the feedforward system deficit hypothesis and the feedback system deficit hypothesis. Method The authors used noise masking to minimize auditory feedback during speech. Six speakers with AOS and aphasia, 4 with aphasia without AOS, and 2 groups of speakers without impairment (younger and older adults) participated. Acoustic measures of vowel contrast, variability, and duration were analyzed. Results Younger, but not older, speakers without impairment showed significantly reduced vowel contrast with noise masking. Relative to older controls, the AOS group showed longer vowel durations overall (regardless of masking condition) and a greater reduction in vowel contrast under masking conditions. There were no significant differences in variability. Three of the 6 speakers with AOS demonstrated the group pattern. Speakers with aphasia without AOS did not differ from controls in contrast, duration, or variability. Conclusion The greater reduction in vowel contrast with masking noise for the AOS group is consistent with the feedforward system deficit hypothesis but not with the feedback system deficit hypothesis; however, effects were small and not present in all individual speakers with AOS. Theoretical implications and alternative interpretations of these findings are discussed. PMID:25565143

A web-based computer-tailored smoking prevention programme for primary school children: intervention design and study protocol

PubMed Central

2012-01-01

Background Although the number of smokers has declined in the last decade, smoking is still a major health problem among youngsters and adolescents. For this reason, there is a need for effective smoking prevention programmes targeting primary school children. A web-based computer-tailored feedback programme may be an effective intervention to stimulate youngsters not to start smoking, and increase their knowledge about the adverse effects of smoking and their attitudes and self-efficacy regarding non-smoking. Methods & design This paper describes the development and evaluation protocol of a web-based out-of-school smoking prevention programme for primary school children (age 10-13 years) entitled ‘Fun without Smokes’. It is a transformation of a postal mailed intervention to a web-based intervention. Besides this transformation the effects of prompts will be examined. This web-based intervention will be evaluated in a 2-year cluster randomised controlled trial (c-RCT) with three study arms. An intervention and intervention + prompt condition will be evaluated for effects on smoking behaviour, compared with a no information control condition. Information about pupils’ smoking status and other factors related to smoking will be obtained using a web-based questionnaire. After completing the questionnaire pupils in both intervention conditions will receive three computer-tailored feedback letters in their personal e-mail box. Attitudes, social influences and self-efficacy expectations will be the content of these personalised feedback letters. Pupils in the intervention + prompt condition will - in addition to the personalised feedback letters - receive e-mail and SMS messages prompting them to revisit the ‘Fun without Smokes’ website. The main outcome measures will be ever smoking and the utilisation of the ‘Fun without Smokes’ website. Measurements will be carried out at baseline, 12 months and 24 months of follow-up. Discussion The present study protocol describes the purpose, intervention design and study protocol of ‘Fun without Smokes’. Expectations are that pupils receiving tailored advice will be less likely to smoke after 24 months in contrast to pupils in the control condition. Furthermore, tailored feedback letters and prompting is expected to be more effective than providing tailored feedback letters only. Trial registration Dutch Trial Register NTR3116 PMID:22490110

Reduced sensitivity to neutral feedback versus negative feedback in subjects with mild depression: Evidence from event-related potentials study.

PubMed

Li, Peng; Song, Xinxin; Wang, Jing; Zhou, Xiaoran; Li, Jiayi; Lin, Fengtong; Hu, Zhonghua; Zhang, Xinxin; Cui, Hewei; Wang, Wenmiao; Li, Hong; Cong, Fengyu; Roberson, Debi

2015-11-01

Many previous event-related potential (ERP) studies have linked the feedback related negativity (FRN) component with medial frontal cortex processing and associated this component with depression. Few if any studies have investigated the processing of neutral feedback in mildly depressive subjects in the normal population. Two experiments compared brain responses to neutral feedback with behavioral performance in mildly depressed subjects who scored highly on the Beck Depression Inventory (high BDI) and a control group with lower BDI scores (low BDI). In the first study, the FRN component was recorded when neutral, negative or positive feedback was pseudo-randomly delivered to the two groups in a time estimation task. In the second study, real feedback was provided to the two groups in the same task in order to measure their actual accuracy of performance. The results of experiment one (Exp. 1) revealed that a larger FRN effect was elicited by neutral feedback than by negative feedback in the low BDI group, but no significant difference was found between neutral condition and negative condition in the High BDI group. The present findings demonstrated that depressive tendencies influence the processing of neutral feedback in medial frontal cortex. The FRN effect may work as a helpful index for investigating cognitive bias in depression in future studies. Copyright © 2015 Elsevier Inc. All rights reserved.

Physics-model-based nonlinear actuator trajectory optimization and safety factor profile feedback control for advanced scenario development in DIII-D

DOE PAGES

Barton, Justin E.; Boyer, Mark D.; Shi, Wenyu; ...

2015-07-30

DIII-D experimental results are reported to demonstrate the potential of physics-model-based safety factor profile control for robust and reproducible sustainment of advanced scenarios. In the absence of feedback control, variability in wall conditions and plasma impurities, as well as drifts due to external disturbances, can limit the reproducibility of discharges with simple pre-programmed scenario trajectories. The control architecture utilized is a feedforward + feedback scheme where the feedforward commands are computed off-line and the feedback commands are computed on-line. In this work, firstly a first-principles-driven (FPD), physics-based model of the q profile and normalized beta (β N) dynamics is embeddedmore » into a numerical optimization algorithm to design feedforward actuator trajectories that sheer the plasma through the tokamak operating space to reach a desired stationary target state that is characterized by the achieved q profile and β N. Good agreement between experimental results and simulations demonstrates the accuracy of the models employed for physics-model-based control design. Secondly, a feedback algorithm for q profile control is designed following a FPD approach, and the ability of the controller to achieve and maintain a target q profile evolution is tested in DIII-D high confinement (H-mode) experiments. The controller is shown to be able to effectively control the q profile when β N is relatively close to the target, indicating the need for integrated q profile and β N control to further enhance the ability to achieve robust scenario execution. Furthermore, the ability of an integrated q profile + β N feedback controller to track a desired target is demonstrated through simulation.« less

An exact algebraic solution of the infimum in H-infinity optimization with output feedback

NASA Technical Reports Server (NTRS)

Chen, Ben M.; Saberi, Ali; Ly, Uy-Loi

1991-01-01

This paper presents a simple and noniterative procedure for the computation of the exact value of the infimum in the standard H-infinity-optimal control with output feedback. The problem formulation is general and does not place any restrictions on the direct feedthrough terms between the control input and the controlled output variables, and between the disturbance input and the measurement output variables. The method is applicable to systems that satisfy (1) the transfer function from the control input to the controlled output is right-invertible and has no invariant zeros on the j(w) axis and, (2) the transfer function from the disturbance to the measurement output is left-invertible and has no invariant zeros on the j(w) axis. A set of necessary and sufficient conditions for the solvability of H-infinity-almost disturbance decoupling problem via measurement feedback with internal stability is also given.

Mode-selective control of thermal Brownian vibration of micro-resonator (Generation of a thermal no-equilibrium state by mechanical feedback control)

NASA Astrophysics Data System (ADS)

Kawamura, Y.; Kanegae, R.

2017-09-01

Recently, there have been various attempts to dampen the vibration amplitude of the Brownian motion of a microresonator below the thermal vibration amplitude, with the goal of reaching the quantum ground vibration level. To further develop the approach of reaching the quantum ground state, it is essential to clarify whether or not coupling exists between the different vibration modes of the resonator. In this paper, the mode-selective control of thermal Brownian vibration is shown. The first and the second vibration modes of a micro-cantilever moved by a random Brownian motion are cooled selectively and independently below the thermal vibration amplitude, as determined by the statistical thermodynamic theory, using a mechanical feedback control method. This experimental result shows that the thermal no-equilibrium condition was generated by mechanical feedback control.

Adaptive Fuzzy Tracking Control for a Class of MIMO Nonlinear Systems in Nonstrict-Feedback Form.

PubMed

Chen, Bing; Lin, Chong; Liu, Xiaoping; Liu, Kefu

2015-12-01

This paper focuses on the problem of fuzzy adaptive control for a class of multiinput and multioutput (MIMO) nonlinear systems in nonstrict-feedback form, which contains the strict-feedback form as a special case. By the condition of variable partition, a new fuzzy adaptive backstepping is proposed for such a class of nonlinear MIMO systems. The suggested fuzzy adaptive controller guarantees that the proposed control scheme can guarantee that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded and the tracking errors eventually converge to a small neighborhood around the origin. The main advantage of this paper is that a control approach is systematically derived for nonlinear systems with strong interconnected terms which are the functions of all states of the whole system. Simulation results further illustrate the effectiveness of the suggested approach.

Fuzzy Adaptive Output Feedback Control of Uncertain Nonlinear Systems With Prescribed Performance.

PubMed

Zhang, Jin-Xi; Yang, Guang-Hong

2018-05-01

This paper investigates the tracking control problem for a family of strict-feedback systems in the presence of unknown nonlinearities and immeasurable system states. A low-complexity adaptive fuzzy output feedback control scheme is proposed, based on a backstepping method. In the control design, a fuzzy adaptive state observer is first employed to estimate the unmeasured states. Then, a novel error transformation approach together with a new modification mechanism is introduced to guarantee the finite-time convergence of the output error to a predefined region and ensure the closed-loop stability. Compared with the existing methods, the main advantages of our approach are that: 1) without using extra command filters or auxiliary dynamic surface control techniques, the problem of explosion of complexity can still be addressed and 2) the design procedures are independent of the initial conditions. Finally, two practical examples are performed to further illustrate the above theoretic findings.

Flight investigation of rotor/vehicle state feedback

NASA Technical Reports Server (NTRS)

Briczinski, S. J.; Cooper, D. E.

1975-01-01

The feasibility of using control feedback or rotor tip-path-plane motion or body state as a means of altering rotor and fuselage response in a prescribed manner was investigated to determine the practical limitations of in-flight utilization of a digital computer which conditions and shapes rotor flapping and fuselage state information as feedback signals, before routing these signals to the differential servo actuators. The analysis and test of various feedback schemes are discussed. Test results show that a Kalman estimator routine which is based on only the first harmonic contributions of blade flapping yields tip-path-plane coefficients which are adequate for use in feedback systems, at speeds up to 150 kts.

Two time scale output feedback regulation for ill-conditioned systems

NASA Technical Reports Server (NTRS)

Calise, A. J.; Moerder, D. D.

1986-01-01

Issues pertaining to the well-posedness of a two time scale approach to the output feedback regulator design problem are examined. An approximate quadratic performance index which reflects a two time scale decomposition of the system dynamics is developed. It is shown that, under mild assumptions, minimization of this cost leads to feedback gains providing a second-order approximation of optimal full system performance. A simplified approach to two time scale feedback design is also developed, in which gains are separately calculated to stabilize the slow and fast subsystem models. By exploiting the notion of combined control and observation spillover suppression, conditions are derived assuring that these gains will stabilize the full-order system. A sequential numerical algorithm is described which obtains output feedback gains minimizing a broad class of performance indices, including the standard LQ case. It is shown that the algorithm converges to a local minimum under nonrestrictive assumptions. This procedure is adapted to and demonstrated for the two time scale design formulations.

An optimal output feedback gain variation scheme for the control of plants exhibiting gross parameter changes

NASA Technical Reports Server (NTRS)

Moerder, Daniel D.

1987-01-01

A concept for optimally designing output feedback controllers for plants whose dynamics exhibit gross changes over their operating regimes was developed. This was to formulate the design problem in such a way that the implemented feedback gains vary as the output of a dynamical system whose independent variable is a scalar parameterization of the plant operating point. The results of this effort include derivation of necessary conditions for optimality for the general problem formulation, and for several simplified cases. The question of existence of a solution to the design problem was also examined, and it was shown that the class of gain variation schemes developed are capable of achieving gain variation histories which are arbitrarily close to the unconstrained gain solution for each point in the plant operating range. The theory was implemented in a feedback design algorithm, which was exercised in a numerical example. The results are applicable to the design of practical high-performance feedback controllers for plants whose dynamics vary significanly during operation. Many aerospace systems fall into this category.

Learning in an interactive simulation tool against landslide risks: the role of strength and availability of experiential feedback

NASA Astrophysics Data System (ADS)

Chaturvedi, Pratik; Arora, Akshit; Dutt, Varun

2018-06-01

Feedback via simulation tools is likely to help people improve their decision-making against natural disasters. However, little is known on how differing strengths of experiential feedback and feedback's availability in simulation tools influence people's decisions against landslides. We tested the influence of differing strengths of experiential feedback and feedback's availability on people's decisions against landslides in Mandi, Himachal Pradesh, India. Experiential feedback (high or low) and feedback's availability (present or absent) were varied across four between-subject conditions in a tool called the Interactive Landslide Simulation (ILS): high damage with feedback present, high damage with feedback absent, low damage with feedback present, and low damage with feedback absent. In high-damage conditions, the probabilities of damages to life and property due to landslides were 10 times higher than those in the low-damage conditions. In feedback-present conditions, experiential feedback was provided in numeric, text, and graphical formats in ILS. In feedback-absent conditions, the probabilities of damages were described; however, there was no experiential feedback present. Investments were greater in conditions where experiential feedback was present and damages were high compared to conditions where experiential feedback was absent and damages were low. Furthermore, only high-damage feedback produced learning in ILS. Simulation tools like ILS seem appropriate for landslide risk communication and for performing what-if analyses.

Feedback control laws for highly maneuverable aircraft

NASA Technical Reports Server (NTRS)

Garrard, William L.; Balas, Gary J.

1992-01-01

The results of a study of the application of H infinity and mu synthesis techniques to the design of feedback control laws for the longitudinal dynamics of the High Angle of Attack Research Vehicle (HARV) are presented. The objective of this study is to develop methods for the design of feedback control laws which cause the closed loop longitudinal dynamics of the HARV to meet handling quality specifications over the entire flight envelope. Control law designs are based on models of the HARV linearized at various flight conditions. The control laws are evaluated by both linear and nonlinear simulations of typical maneuvers. The fixed gain control laws resulting from both the H infinity and mu synthesis techniques result in excellent performance even when the aircraft performs maneuvers in which the system states vary significantly from their equilibrium design values. Both the H infinity and mu synthesis control laws result in performance which compares favorably with an existing baseline longitudinal control law.

Closed loop kinesthetic feedback for postural control rehabilitation.

PubMed

Vérité, Fabien; Bachta, Wael; Morel, Guillaume

2014-01-01

Postural control rehabilitation may benefit from the use of smart devices providing biofeedback. This approach consists of increasing the patients perception of their postural state. Namely, postural state is monitored and fed back in real time to the patients through one or more sensory channels. This allows implementing rehabilitation exercises where the patients control their posture with the help of additional sensory inputs. In this paper, a closed loop control of the Center-Of-Pressure (CoP) based on kinesthetic feedback is proposed as a new form of biofeedback. The motion of a one Degree of Freedom (DoF) translational device, lightly touched by the patient's forefinger, is servoed to the patient's CoP position extracted from the measurements of a force plate on which he/she stands. As a result, the patient's CoP can be controllably displaced. A first set of experiments is used to prove the feasibility of this closed-loop control under ideal conditions favoring the perception of the kinesthetic feedback, while the subject is totally unaware of the context. A second set of experiments is then proposed to evaluate the robustness of this approach under experimental conditions that are more realistic with regards to the clinical context of a rehabilitation program involving biofeedback-based exercises.

Robust Feedback Control of Flow Induced Structural Radiation of Sound

NASA Technical Reports Server (NTRS)

Heatwole, Craig M.; Bernhard, Robert J.; Franchek, Matthew A.

1997-01-01

A significant component of the interior noise of aircraft and automobiles is a result of turbulent boundary layer excitation of the vehicular structure. In this work, active robust feedback control of the noise due to this non-predictable excitation is investigated. Both an analytical model and experimental investigations are used to determine the characteristics of the flow induced structural sound radiation problem. The problem is shown to be broadband in nature with large system uncertainties associated with the various operating conditions. Furthermore the delay associated with sound propagation is shown to restrict the use of microphone feedback. The state of the art control methodologies, IL synthesis and adaptive feedback control, are evaluated and shown to have limited success for solving this problem. A robust frequency domain controller design methodology is developed for the problem of sound radiated from turbulent flow driven plates. The control design methodology uses frequency domain sequential loop shaping techniques. System uncertainty, sound pressure level reduction performance, and actuator constraints are included in the design process. Using this design method, phase lag was added using non-minimum phase zeros such that the beneficial plant dynamics could be used. This general control approach has application to lightly damped vibration and sound radiation problems where there are high bandwidth control objectives requiring a low controller DC gain and controller order.

Tactile feedback is an effective instrument for the training of grasping with a prosthesis at low- and medium-force levels.

PubMed

De Nunzio, Alessandro Marco; Dosen, Strahinja; Lemling, Sabrina; Markovic, Marko; Schweisfurth, Meike Annika; Ge, Nan; Graimann, Bernhard; Falla, Deborah; Farina, Dario

2017-08-01

Grasping is a complex task routinely performed in an anticipatory (feedforward) manner, where sensory feedback is responsible for learning and updating the internal model of grasp dynamics. This study aims at evaluating whether providing a proportional tactile force feedback during the myoelectric control of a prosthesis facilitates learning a stable internal model of the prosthesis force control. Ten able-bodied subjects controlled a sensorized myoelectric prosthesis performing four blocks of consecutive grasps at three levels of target force (30, 50, and 70%), repeatedly closing the fully opened hand. In the first and third block, the subjects received tactile and visual feedback, respectively, while during the second and fourth block, the feedback was removed. The subjects also performed an additional block with no feedback 1 day after the training (Retest). The median and interquartile range of the generated forces was computed to assess the accuracy and precision of force control. The results demonstrated that the feedback was indeed an effective instrument for the training of prosthesis control. After the training, the subjects were still able to accurately generate the desired force for the low and medium target (30 and 50% of maximum force available in a prosthesis), despite the feedback being removed within the session and during the retest (low target force). However, the training was substantially less successful for high forces (70% of prosthesis maximum force), where subjects exhibited a substantial loss of accuracy as soon as the feedback was removed. The precision of control decreased with higher forces and it was consistent across conditions, determined by an intrinsic variability of repeated myoelectric grasping. This study demonstrated that the subject could rely on the tactile feedback to adjust the motor command to the prosthesis across trials. The subjects adjusted the mean level of muscle activation (accuracy), whereas the precision could not be modulated as it depends on the intrinsic myoelectric variability. They were also able to maintain the feedforward command even after the feedback was removed, demonstrating thereby a stable learning, but the retention depended on the level of the target force. This is an important insight into the role of feedback as an instrument for learning of anticipatory prosthesis force control.

Three degree-of-freedom force feedback control for robotic mating of umbilical lines

NASA Technical Reports Server (NTRS)

Fullmer, R. Rees

1988-01-01

The use of robotic manipulators for the mating and demating of umbilical fuel lines to the Space Shuttle Vehicle prior to launch is investigated. Force feedback control is necessary to minimize the contact forces which develop during mating. The objective is to develop and demonstrate a working robotic force control system. Initial experimental force control tests with an ASEA IRB-90 industrial robot using the system's Adaptive Control capabilities indicated that control stability would by a primary problem. An investigation of the ASEA system showed a 0.280 second software delay between force input commands and the output of command voltages to the servo system. This computational delay was identified as the primary cause of the instability. Tests on a second path into the ASEA's control computer using the MicroVax II supervisory computer show that time delay would be comparable, offering no stability improvement. An alternative approach was developed where the digital control system of the robot was disconnected and an analog electronic force controller was used to control the robot's servosystem directly, allowing the robot to use force feedback control while in rigid contact with a moving three-degree-of-freedom target. An alternative approach was developed where the digital control system of the robot was disconnected and an analog electronic force controller was used to control the robot's servo system directly. This method allowed the robot to use force feedback control while in rigid contact with moving three degree-of-freedom target. Tests on this approach indicated adequate force feedback control even under worst case conditions. A strategy to digitally-controlled vision system was developed. This requires switching between the digital controller when using vision control and the analog controller when using force control, depending on whether or not the mating plates are in contact.

? and ? nonquadratic stabilisation of discrete-time Takagi-Sugeno systems based on multi-instant fuzzy Lyapunov functions

NASA Astrophysics Data System (ADS)

Tognetti, Eduardo S.; Oliveira, Ricardo C. L. F.; Peres, Pedro L. D.

2015-01-01

The problem of state feedback control design for discrete-time Takagi-Sugeno (TS) (T-S) fuzzy systems is investigated in this paper. A Lyapunov function, which is quadratic in the state and presents a multi-polynomial dependence on the fuzzy weighting functions at the current and past instants of time, is proposed.This function contains, as particular cases, other previous Lyapunov functions already used in the literature, being able to provide less conservative conditions of control design for TS fuzzy systems. The structure of the proposed Lyapunov function also motivates the design of a new stabilising compensator for Takagi-Sugeno fuzzy systems. The main novelty of the proposed state feedback control law is that the gain is composed of matrices with multi-polynomial dependence on the fuzzy weighting functions at a set of past instants of time, including the current one. The conditions for the existence of a stabilising state feedback control law that minimises an upper bound to the ? or ? norms are given in terms of linear matrix inequalities. Numerical examples show that the approach can be less conservative and more efficient than other methods available in the literature.

Zero Power Non-Contact Suspension System with Permanent Magnet Motion Feedback

NASA Astrophysics Data System (ADS)

Sun, Feng; Oka, Koichi

This paper proposes a zero power control method for a permanent magnetic suspension system consisting mainly of a permanent magnet, an actuator, sensors, a suspended iron ball and a spring. A system using this zero power control method will consume quasi-zero power when the levitated object is suspended in an equilibrium state. To realize zero power control, a spring is installed in the magnetic suspension device to counterbalance the gravitational force on the actuator in the equilibrium position. In addition, an integral feedback loop in the controller affords zero actuator current when the device is in a balanced state. In this study, a model was set up for feasibility analysis, a prototype was manufactured for experimental confirmation, numerical simulations of zero power control with nonlinear attractive force were carried out based on the model, and experiments were completed to confirm the practicality of the prototype. The simulations and experiments were performed under varied conditions, such as without springs and without zero power control, with springs and without zero power control, with springs and with zero power control, using different springs and integral feedback gains. Some results are shown and analyzed in this paper. All results indicate that this zero power control method is feasible and effective for use in this suspension system with a permanent magnet motion feedback loop.

Closed-Loop Control of Myoelectric Prostheses With Electrotactile Feedback: Influence of Stimulation Artifact and Blanking.

PubMed

Hartmann, Cornelia; Dosen, Strahinja; Amsuess, Sebastian; Farina, Dario

2015-09-01

Electrocutaneous stimulation is a promising approach to provide sensory feedback to amputees, and thus close the loop in upper limb prosthetic systems. However, the stimulation introduces artifacts in the recorded electromyographic (EMG) signals, which may be detrimental for the control of myoelectric prostheses. In this study, artifact blanking with three data segmentation approaches was investigated as a simple method to restore the performance of pattern recognition in prosthesis control (eight motions) when EMG signals are corrupted by stimulation artifacts. The methods were tested over a range of stimulation conditions and using four feature sets, comprising both time and frequency domain features. The results demonstrated that when stimulation artifacts were present, the classification performance improved with blanking in all tested conditions. In some cases, the classification performance with blanking was at the level of the benchmark (artifact-free data). The greatest pulse duration and frequency that allowed a full performance recovery were 400 μs and 150 Hz, respectively. These results show that artifact blanking can be used as a practical solution to eliminate the negative influence of the stimulation artifact on EMG pattern classification in a broad range of conditions, thus allowing to close the loop in myoelectric prostheses using electrotactile feedback.

Relationships between CO 2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

DOE PAGES

Winnick, Matthew J.; Maher, Kate

2018-01-27

Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO 2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO 2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. Here, we test this theoretical scaling relationship against reactive transport simulations of chemical weathering profilesmore » under open-and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO 2(y =kx n)where nis dependent on reaction stoichiometry and kis dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO 2 at low values and approach open-system scaling at high pCO 2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO 2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence of equilibrium solute concentrations on pCO 2 may represent a direct weathering feedback largely independent of climate and modulated by belowground organic carbon respiration.« less

Relationships between CO 2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winnick, Matthew J.; Maher, Kate

Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO 2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO 2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. Here, we test this theoretical scaling relationship against reactive transport simulations of chemical weathering profilesmore » under open-and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO 2(y =kx n)where nis dependent on reaction stoichiometry and kis dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO 2 at low values and approach open-system scaling at high pCO 2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO 2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence of equilibrium solute concentrations on pCO 2 may represent a direct weathering feedback largely independent of climate and modulated by belowground organic carbon respiration.« less

Relationships between CO2, thermodynamic limits on silicate weathering, and the strength of the silicate weathering feedback

NASA Astrophysics Data System (ADS)

Winnick, Matthew J.; Maher, Kate

2018-03-01

Recent studies have suggested that thermodynamic limitations on chemical weathering rates exert a first-order control on riverine solute fluxes and by extension, global chemical weathering rates. As such, these limitations may play a prominent role in the regulation of carbon dioxide levels (pCO2) over geologic timescales by constraining the maximum global weathering flux. In this study, we develop a theoretical scaling relationship between equilibrium solute concentrations and pCO2 based on equilibrium constants and reaction stoichiometry relating primary mineral dissolution and secondary mineral precipitation. We test this theoretical scaling relationship against reactive transport simulations of chemical weathering profiles under open- and closed-system conditions, representing partially and fully water-saturated regolith, respectively. Under open-system conditions, equilibrium bicarbonate concentrations vary as a power-law function of pCO2 (y = kxn) where n is dependent on reaction stoichiometry and k is dependent on both reaction stoichiometry and the equilibrium constant. Under closed-system conditions, bicarbonate concentrations vary linearly with pCO2 at low values and approach open-system scaling at high pCO2. To describe the potential role of thermodynamic limitations in the global silicate weathering feedback, we develop a new mathematical framework to assess weathering feedback strength in terms of both (1) steady-state atmospheric pCO2 concentrations, and (2) susceptibility to secular changes in degassing rates and transient carbon cycle perturbations, which we term 1st and 2nd order feedback strength, respectively. Finally, we discuss the implications of these results for the effects of vascular land plant evolution on feedback strength, the potential role of vegetation in controlling modern solute fluxes, and the application of these frameworks to a more complete functional description of the silicate weathering feedback. Most notably, the dependence of equilibrium solute concentrations on pCO2 may represent a direct weathering feedback largely independent of climate and modulated by belowground organic carbon respiration.

What would you do? The effect of verbal persuasion on task choice.

PubMed

Lamarche, Larkin; Gionfriddo, Alicia M; Cline, Lindsay E; Gammage, Kimberley L; Adkin, Allan L

2014-01-01

Verbal persuasion has been shown to influence psychological and behavioral outcomes. The present study had two objectives: (1) to examine the effect of verbal persuasion on task choice in a balance setting and (2) to evaluate the use of verbal persuasion as an approach to experimentally induce mismatches between perceived and actual balance. Healthy young adults (N=68) completed an 8-m tandem walk task without vision and then were randomly assigned to a feedback group (good, control, or poor), regardless of actual balance. Following the feedback, participants chose to perform the task in one of three conditions differing in level of challenge and also were required to perform the task under the same pre-feedback conditions. Balance efficacy and perceived stability were rated before and after each pre- and post-feedback task, respectively. Balance performance measures were also collected. Following the feedback, participants in the good group were more likely to choose the most challenging task while those in the poor group were more likely to choose the least challenging task. Following the feedback, all groups showed improved balance performance. However, balance efficacy and perceived stability increased for the good and control groups but balance efficacy decreased and perceived stability was unchanged for the poor group. Thus, these findings demonstrate that verbal persuasion can influence task choice and may be used as an approach to experimentally create mismatches between perceived and actual balance. Copyright © 2013 Elsevier B.V. All rights reserved.

Neural Correlates of the Lombard Effect in Primate Auditory Cortex

PubMed Central

Eliades, Steven J.

2012-01-01

Speaking is a sensory-motor process that involves constant self-monitoring to ensure accurate vocal production. Self-monitoring of vocal feedback allows rapid adjustment to correct perceived differences between intended and produced vocalizations. One important behavior in vocal feedback control is a compensatory increase in vocal intensity in response to noise masking during vocal production, commonly referred to as the Lombard effect. This behavior requires mechanisms for continuously monitoring auditory feedback during speaking. However, the underlying neural mechanisms are poorly understood. Here we show that when marmoset monkeys vocalize in the presence of masking noise that disrupts vocal feedback, the compensatory increase in vocal intensity is accompanied by a shift in auditory cortex activity toward neural response patterns seen during vocalizations under normal feedback condition. Furthermore, we show that neural activity in auditory cortex during a vocalization phrase predicts vocal intensity compensation in subsequent phrases. These observations demonstrate that the auditory cortex participates in self-monitoring during the Lombard effect, and may play a role in the compensation of noise masking during feedback-mediated vocal control. PMID:22855821

Children's feedback preferences in response to an experimentally manipulated peer evaluation outcome: the role of depressive symptoms.

PubMed

Reijntjes, Albert; Dekovic, Maja; Vermande, Marjolijn; Telch, Michael J

2007-06-01

The present study examined the linkage between pre-adolescent children's depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total 'likeability' score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children's self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation.

Feedback stabilization of resistive wall modes in a reversed-field pinch

NASA Astrophysics Data System (ADS)

Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Cecconello, M.; Drake, J. R.; Manduchi, G.; Marchiori, G.

2005-09-01

An array of saddle coils having Nc=16 equally spaced positions along the toroidal direction has been installed for feedback control of resistive wall modes (RWMs) on the EXTRAP T2R reversed-field pinch [P. R. Brunsell, H. Bergsaker, M. Cecconello et al., Plasma Phys. Controlled Fusion 43, 1457 (2001)]. Using feedback, multiple nonresonant RWMs are simultaneously suppressed for three to four wall times. Feedback stabilization of RWMs results in a significant prolongation of the discharge duration. This is linked to a better sustainment of the plasma and tearing mode toroidal rotation with feedback. Due to the limited number of coils in the toroidal direction, pairs of modes with toroidal mode numbers n ,n' that fulfill the condition ∣n-n'∣=Nc are coupled by the feedback action from the discrete coil array. With only one unstable mode in a pair of coupled modes, the suppression of the unstable mode is successful. If two modes are unstable in a coupled pair, two possibilities exist: partial suppression of both modes or, alternatively, complete stabilization of one target mode while the other is left unstable.

Plate with decentralised velocity feedback loops: Power absorption and kinetic energy considerations

NASA Astrophysics Data System (ADS)

Gardonio, P.; Miani, S.; Blanchini, F.; Casagrande, D.; Elliott, S. J.

2012-04-01

This paper is focused on the vibration effects produced by an array of decentralised velocity feedback loops that are evenly distributed over a rectangular thin plate to minimise its flexural response. The velocity feedback loops are formed by collocated ideal velocity sensor and point force actuator pairs, which are unconditionally stable and produce 'sky-hook' damping on the plate. The study compares how the overall flexural vibration of the plate and the local absorption of vibration power by the feedback loops vary with the control gains. The analysis is carried out both considering a typical frequency-domain formulation based on kinetic energy and structural power physical quantities, which is normally used to study vibration and noise problems, and a time-domain formulation also based on kinetic energy and structural power, which is usually implemented to investigate control problems. The time-domain formulation shows to be much more computationally efficient and robust with reference to truncation errors. Thus it has been used to perform a parametric study to assess if, and under which conditions, the minimum of the kinetic energy and the maximum of the absorbed power cost functions match with reference to: (a) the number of feedback control loops, (b) the structural damping in the plate, (c) the mutual distance of a pair of control loops and (d) the mutual gains implemented in a pair of feedback loops.

A global bioheat model with self-tuning optimal regulation of body temperature using Hebbian feedback covariance learning.

PubMed

Ong, M L; Ng, E Y K

2005-12-01

In the lower brain, body temperature is continually being regulated almost flawlessly despite huge fluctuations in ambient and physiological conditions that constantly threaten the well-being of the body. The underlying control problem defining thermal homeostasis is one of great enormity: Many systems and sub-systems are involved in temperature regulation and physiological processes are intrinsically complex and intertwined. Thus the defining control system has to take into account the complications of nonlinearities, system uncertainties, delayed feedback loops as well as internal and external disturbances. In this paper, we propose a self-tuning adaptive thermal controller based upon Hebbian feedback covariance learning where the system is to be regulated continually to best suit its environment. This hypothesis is supported in part by postulations of the presence of adaptive optimization behavior in biological systems of certain organisms which face limited resources vital for survival. We demonstrate the use of Hebbian feedback covariance learning as a possible self-adaptive controller in body temperature regulation. The model postulates an important role of Hebbian covariance adaptation as a means of reinforcement learning in the thermal controller. The passive system is based on a simplified 2-node core and shell representation of the body, where global responses are captured. Model predictions are consistent with observed thermoregulatory responses to conditions of exercise and rest, and heat and cold stress. An important implication of the model is that optimal physiological behaviors arising from self-tuning adaptive regulation in the thermal controller may be responsible for the departure from homeostasis in abnormal states, e.g., fever. This was previously unexplained using the conventional "set-point" control theory.

Control techniques to improve Space Shuttle solid rocket booster separation

NASA Technical Reports Server (NTRS)

Tomlin, D. D.

1983-01-01

The present Space Shuttle's control system does not prevent the Orbiter's main engines from being in gimbal positions that are adverse to solid rocket booster separation. By eliminating the attitude error and attitude rate feedback just prior to solid rocket booster separation, the detrimental effects of the Orbiter's main engines can be reduced. In addition, if angular acceleration feedback is applied, the gimbal torques produced by the Orbiter's engines can reduce the detrimental effects of the aerodynamic torques. This paper develops these control techniques and compares the separation capability of the developed control systems. Currently with the worst case initial conditions and each Shuttle system dispersion aligned in the worst direction (which is more conservative than will be experienced in flight), the solid rocket booster has an interference with the Shuttle's external tank of 30 in. Elimination of the attitude error and attitude rate feedback reduces that interference to 19 in. Substitution of angular acceleration feedback reduces the interference to 6 in. The two latter interferences can be eliminated by atess conservative analysis techniques, that is, by using a root sum square of the system dispersions.

Manipulator control by exact linearization

NASA Technical Reports Server (NTRS)

Kruetz, K.

1987-01-01

Comments on the application to rigid link manipulators of geometric control theory, resolved acceleration control, operational space control, and nonlinear decoupling theory are given, and the essential unity of these techniques for externally linearizing and decoupling end effector dynamics is discussed. Exploiting the fact that the mass matrix of a rigid link manipulator is positive definite, a consequence of rigid link manipulators belonging to the class of natural physical systems, it is shown that a necessary and sufficient condition for a locally externally linearizing and output decoupling feedback law to exist is that the end effector Jacobian matrix be nonsingular. Furthermore, this linearizing feedback is easy to produce.

Information and reward in voluntary heart rate control.

PubMed

Bouchard, M A; Granger, L

1980-10-01

Two studies are reported which examined the relative effects of the pressence and absence of monetary incentives and instructions in a heart rate (HR) regulation task. Twelve male undergraduates were offered seven sessions of feedback assisted voluntary HR control training. In Experiment 1 six S s attempted to increase their HR with the aid of a "success," or positive binary visual signal. In Experiment 2 six S s were instructed to decrease their HR and were assisted by a "failure," or negative binary visual signal. In both studies the presence or absence of E's specific instructions to control HR was systematically varied from sessions 4 to 7. S s were paid on only half of the feedback trials of each session. These variables were thus systematically varied in a within-subject design. The main results suggest that (a) the instructions and monetary incentives significantly facilitated HR acceleration while showing no effects on HR deceleration; (b) in the no-instructions, no-incentive condition, HR control was minimal. The general hypothesis that Estes' interpretation of information and reward apply to human voluntary HR control received some support. It would appear that contrary to a traditional view, the exteroceptive feedback per se does not necessarily act as a reinforcer of the behavior, as witnessed for instance in the no-instructions, no-incentive conditions.

A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation.

PubMed

Huang, Yong; Tao, Gang

2014-09-01

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yong, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn; Tao, Gang, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn

2014-09-01

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

Finite-time H∞ control for a class of discrete-time switched time-delay systems with quantized feedback

NASA Astrophysics Data System (ADS)

Song, Haiyu; Yu, Li; Zhang, Dan; Zhang, Wen-An

2012-12-01

This paper is concerned with the finite-time quantized H∞ control problem for a class of discrete-time switched time-delay systems with time-varying exogenous disturbances. By using the sector bound approach and the average dwell time method, sufficient conditions are derived for the switched system to be finite-time bounded and ensure a prescribed H∞ disturbance attenuation level, and a mode-dependent quantized state feedback controller is designed by solving an optimization problem. Two illustrative examples are provided to demonstrate the effectiveness of the proposed theoretical results.

Dynamic output feedback control of a flexible air-breathing hypersonic vehicle via T-S fuzzy approach

NASA Astrophysics Data System (ADS)

Hu, Xiaoxiang; Wu, Ligang; Hu, Changhua; Wang, Zhaoqiang; Gao, Huijun

2014-08-01

By utilising Takagi-Sugeno (T-S) fuzzy set approach, this paper addresses the robust H∞ dynamic output feedback control for the non-linear longitudinal model of flexible air-breathing hypersonic vehicles (FAHVs). The flight control of FAHVs is highly challenging due to the unique dynamic characteristics, and the intricate couplings between the engine and fight dynamics and external disturbance. Because of the dynamics' enormous complexity, currently, only the longitudinal dynamics models of FAHVs have been used for controller design. In this work, T-S fuzzy modelling technique is utilised to approach the non-linear dynamics of FAHVs, then a fuzzy model is developed for the output tracking problem of FAHVs. The fuzzy model contains parameter uncertainties and disturbance, which can approach the non-linear dynamics of FAHVs more exactly. The flexible models of FAHVs are difficult to measure because of the complex dynamics and the strong couplings, thus a full-order dynamic output feedback controller is designed for the fuzzy model. A robust H∞ controller is designed for the obtained closed-loop system. By utilising the Lyapunov functional approach, sufficient solvability conditions for such controllers are established in terms of linear matrix inequalities. Finally, the effectiveness of the proposed T-S fuzzy dynamic output feedback control method is demonstrated by numerical simulations.

Interface Prostheses With Classifier-Feedback-Based User Training.

PubMed

Fang, Yinfeng; Zhou, Dalin; Li, Kairu; Liu, Honghai

2017-11-01

It is evident that user training significantly affects performance of pattern-recognition-based myoelectric prosthetic device control. Despite plausible classification accuracy on offline datasets, online accuracy usually suffers from the changes in physiological conditions and electrode displacement. The user ability in generating consistent electromyographic (EMG) patterns can be enhanced via proper user training strategies in order to improve online performance. This study proposes a clustering-feedback strategy that provides real-time feedback to users by means of a visualized online EMG signal input as well as the centroids of the training samples, whose dimensionality is reduced to minimal number by dimension reduction. Clustering feedback provides a criterion that guides users to adjust motion gestures and muscle contraction forces intentionally. The experiment results have demonstrated that hand motion recognition accuracy increases steadily along the progress of the clustering-feedback-based user training, while conventional classifier-feedback methods, i.e., label feedback, hardly achieve any improvement. The result concludes that the use of proper classifier feedback can accelerate the process of user training, and implies prosperous future for the amputees with limited or no experience in pattern-recognition-based prosthetic device manipulation.It is evident that user training significantly affects performance of pattern-recognition-based myoelectric prosthetic device control. Despite plausible classification accuracy on offline datasets, online accuracy usually suffers from the changes in physiological conditions and electrode displacement. The user ability in generating consistent electromyographic (EMG) patterns can be enhanced via proper user training strategies in order to improve online performance. This study proposes a clustering-feedback strategy that provides real-time feedback to users by means of a visualized online EMG signal input as well as the centroids of the training samples, whose dimensionality is reduced to minimal number by dimension reduction. Clustering feedback provides a criterion that guides users to adjust motion gestures and muscle contraction forces intentionally. The experiment results have demonstrated that hand motion recognition accuracy increases steadily along the progress of the clustering-feedback-based user training, while conventional classifier-feedback methods, i.e., label feedback, hardly achieve any improvement. The result concludes that the use of proper classifier feedback can accelerate the process of user training, and implies prosperous future for the amputees with limited or no experience in pattern-recognition-based prosthetic device manipulation.

Effects of head movement and proprioceptive feedback in training of sound localization

PubMed Central

Honda, Akio; Shibata, Hiroshi; Hidaka, Souta; Gyoba, Jiro; Iwaya, Yukio; Suzuki, Yôiti

2013-01-01

We investigated the effects of listeners' head movements and proprioceptive feedback during sound localization practice on the subsequent accuracy of sound localization performance. The effects were examined under both restricted and unrestricted head movement conditions in the practice stage. In both cases, the participants were divided into two groups: a feedback group performed a sound localization drill with accurate proprioceptive feedback; a control group conducted it without the feedback. Results showed that (1) sound localization practice, while allowing for free head movement, led to improvement in sound localization performance and decreased actual angular errors along the horizontal plane, and that (2) proprioceptive feedback during practice decreased actual angular errors in the vertical plane. Our findings suggest that unrestricted head movement and proprioceptive feedback during sound localization training enhance perceptual motor learning by enabling listeners to use variable auditory cues and proprioceptive information. PMID:24349686

Brief online interventions targeting risk and protective factors for increased and problematic alcohol use among American college students studying abroad

PubMed Central

Pedersen, Eric R.; Neighbors, Clayton; Atkins, David C.; Lee, Christine M.; Larimer, Mary E.

2016-01-01

Research documents increased and problematic alcohol use during study abroad experiences for college students yet no research documents effective preventive programs with these students. The present randomized controlled trial was designed to prevent increased and problematic alcohol use abroad by correcting misperceptions of peer drinking norms abroad and by promoting positive and healthy adjustment into the host culture (i.e., sojourner adjustment) through brief online personalized feedback interventions. A sample of 343 study abroad college students was randomly assigned to one of four conditions including a personalized normative feedback intervention (PNF), a sojourner adjustment feedback intervention (SAF), a combined PNF + SAF intervention, and an assessment-only control condition. Generalized estimated equation analyses accounting for baseline drinking and consequences revealed an intervention effect for PNF that was mitigated by baseline drinking level, such that PNF was best for those with lighter baseline drinking, but heavier baseline drinkers receiving PNF alone or PNF + SAF drank comparatively similar or more heavily abroad to those in the control condition. However, PNF + SAF condition participants with greater baseline levels of consequences reported comparatively less consequences abroad than their control participants. Thus, PNF alone may be helpful for lighter drinkers at predeparture and the addition of SAF to PNF may help prevent consequences abroad for those reporting more consequences prior to departure abroad. This research represents an important first step in designing and implementing efficacious interventions with at-risk study abroad college students, for which no current empirically-based programs exist. PMID:28080092

Brief online interventions targeting risk and protective factors for increased and problematic alcohol use among American college students studying abroad.

PubMed

Pedersen, Eric R; Neighbors, Clayton; Atkins, David C; Lee, Christine M; Larimer, Mary E

2017-03-01

Research documents increased and problematic alcohol use during study abroad experiences for college students yet no research documents effective preventive programs with these students. The present randomized controlled trial was designed to prevent increased and problematic alcohol use abroad by correcting misperceptions of peer drinking norms abroad and by promoting positive and healthy adjustment into the host culture (i.e., sojourner adjustment) through brief online personalized feedback interventions. A sample of 343 study abroad college students was randomly assigned to 1 of 4 conditions including a personalized normative feedback intervention (PNF), a sojourner adjustment feedback intervention (SAF), a combined PNF + SAF intervention, and an assessment-only control condition. Generalized estimated equation analyses accounting for baseline drinking and consequences revealed an intervention effect for PNF that was mitigated by baseline drinking level, such that PNF was best for those with lighter baseline drinking, but heavier baseline drinkers receiving PNF alone or PNF + SAF drank comparatively similar or more heavily abroad to those in the control condition. However, PNF + SAF condition participants with greater baseline levels of consequences reported comparatively less consequences abroad than their control participants. Thus, PNF alone may be helpful for lighter drinkers at predeparture and the addition of SAF to PNF may help prevent consequences abroad for those reporting more consequences prior to departure abroad. This research represents an important first step in designing and implementing efficacious interventions with at-risk study abroad college students, for which no current empirically based programs exist. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Randomized Controlled Trial of Motivational Enhancement Therapy with Non-treatment Seeking Adolescent Cannabis Users: A Further Test of the Teen Marijuana Check-Up

PubMed Central

Walker, Denise D.; Stephens, Robert; Roffman, Roger; DeMarce, Josephine; Lozano, Brian; Towe, Sheri; Berg, Belinda

2011-01-01

Aims Cannabis use adversely affects adolescents and interventions that are attractive to adolescents are needed. This trial compared the effects of a brief motivational intervention for cannabis use with a brief educational feedback control and a no-assessment control. Design Participants were randomized into one of three treatment conditions: Motivational Enhancement Therapy (MET), Educational Feedback Control (EFC) or Delayed Feedback Control (DFC). Those assigned to MET and EFC were administered a computerized baseline assessment immediately following randomization and completed assessments at the 3- and 12-month follow-up periods. Participants in the DFC condition were not assessed until the 3-month follow-up. Following the completion of treatment sessions, all participants were offered up to 4 optional individual treatment sessions aimed at cessation of cannabis use. Setting High schools in Seattle, WA, USA. Participants 310 self-referred adolescents who smoked cannabis regularly. Measurements Main outcome measures included days of cannabis use, associated negative consequences, and engagement in additional treatment. Findings At the 3-month follow-up, participants in both the MET and EFC conditions reported significantly fewer days of cannabis use and negative consequences compared to DFC. Frequency of cannabis use was less in MET relative to EFC at 3 months, but did not translate to differences in negative consequences. Reduction in use and problems were sustained at 12-months but there were no differences between MET and EFC interventions. Engagement in additional treatment was minimal and not different by condition. Conclusions Brief interventions can attract and have positive impacts on adolescent cannabis users, but the mechanisms of the effects are yet to be identified. PMID:21688877

Randomized controlled trial of motivational enhancement therapy with nontreatment-seeking adolescent cannabis users: a further test of the teen marijuana check-up.

PubMed

Walker, Denise D; Stephens, Robert; Roffman, Roger; Demarce, Josephine; Lozano, Brian; Towe, Sheri; Berg, Belinda

2011-09-01

Cannabis use adversely affects adolescents and interventions that are attractive to adolescents are needed. This trial compared the effects of a brief motivational intervention for cannabis use with a brief educational feedback control and a no-assessment control. Participants were randomized into one of three treatment conditions: Motivational Enhancement Therapy (MET), Educational Feedback Control (EFC), or Delayed Feedback Control (DFC). Those who were assigned to MET and EFC were administered a computerized baseline assessment immediately following randomization and completed assessments at the 3- and 12-month follow-up periods. Participants in the DFC condition were not assessed until the 3-month follow-up. Following the completion of treatment sessions, all participants were offered up to four optional individual treatment sessions aimed at cessation of cannabis use. The research was conducted in high schools in Seattle, Washington. The participant s included 310 self-referred adolescents who smoked cannabis regularly. The main outcome measures included days of cannabis use, associated negative consequences, and engagement in additional treatment. At the 3-month follow-up, participants in both the MET and EFC conditions reported significantly fewer days of cannabis use and negative consequences compared to those in the DFC. The frequency of cannabis use was less in MET relative to EFC at 3 months, but it did not translate to differences in negative consequences. Reductions in use and problems were sustained at 12 months, but there were no differences between MET and EFC interventions. Engagement in additional treatment was minimal and did not differ by condition. Brief interventions can attract adolescent cannabis users and have positive impacts on them, but the mechanisms of the effects are yet to be identified. (c) 2011 APA, all rights reserved.

A new visual feedback-based magnetorheological haptic master for robot-assisted minimally invasive surgery

NASA Astrophysics Data System (ADS)

Choi, Seung-Hyun; Kim, Soomin; Kim, Pyunghwa; Park, Jinhyuk; Choi, Seung-Bok

2015-06-01

In this study, we developed a novel four-degrees-of-freedom haptic master using controllable magnetorheological (MR) fluid. We also integrated the haptic master with a vision device with image processing for robot-assisted minimally invasive surgery (RMIS). The proposed master can be used in RMIS as a haptic interface to provide the surgeon with a sense of touch by using both kinetic and kinesthetic information. The slave robot, which is manipulated with a proportional-integrative-derivative controller, uses a force sensor to obtain the desired forces from tissue contact, and these desired repulsive forces are then embodied through the MR haptic master. To verify the effectiveness of the haptic master, the desired force and actual force are compared in the time domain. In addition, a visual feedback system is implemented in the RMIS experiment to distinguish between the tumor and organ more clearly and provide better visibility to the operator. The hue-saturation-value color space is adopted for the image processing since it is often more intuitive than other color spaces. The image processing and haptic feedback are realized on surgery performance. In this work, tumor-cutting experiments are conducted under four different operating conditions: haptic feedback on, haptic feedback off, image processing on, and image processing off. The experimental realization shows that the performance index, which is a function of pixels, is different in the four operating conditions.

Failure of feedback as a putative common mechanism of spreading depolarizations in migraine and stroke

NASA Astrophysics Data System (ADS)

Dahlem, Markus A.; Schneider, Felix M.; Schöll, Eckehard

2008-06-01

The stability of cortical function depends critically on proper regulation. Under conditions of migraine and stroke a breakdown of transmembrane chemical gradients can spread through cortical tissue. A concomitant component of this emergent spatio-temporal pattern is a depolarization of cells detected as slow voltage variations. The propagation velocity of ˜3mm/min indicates a contribution of diffusion. We propose a mechanism for spreading depolarizations (SD) that rests upon a nonlocal or noninstantaneous feedback in a reaction-diffusion system. Depending upon the characteristic space and time scales of the feedback, the propagation of cortical SD can be suppressed by shifting the bifurcation line, which separates the parameter regime of pulse propagation from the regime where a local disturbance dies out. The optimization of this feedback is elaborated for different control schemes and ranges of control parameters.

An Optimization Framework for Driver Feedback Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malikopoulos, Andreas; Aguilar, Juan P.

2013-01-01

Modern vehicles have sophisticated electronic control units that can control engine operation with discretion to balance fuel economy, emissions, and power. These control units are designed for specific driving conditions (e.g., different speed profiles for highway and city driving). However, individual driving styles are different and rarely match the specific driving conditions for which the units were designed. In the research reported here, we investigate driving-style factors that have a major impact on fuel economy and construct an optimization framework to optimize individual driving styles with respect to these driving factors. In this context, we construct a set of polynomialmore » metamodels to reflect the responses produced in fuel economy by changing the driving factors. Then, we compare the optimized driving styles to the original driving styles and evaluate the effectiveness of the optimization framework. Finally, we use this proposed framework to develop a real-time feedback system, including visual instructions, to enable drivers to alter their driving styles in response to actual driving conditions to improve fuel efficiency.« less

The effects of driver identity on driving safety in a retrospective feedback system.

PubMed

Zhao, Guozhen; Wu, Changxu

2012-03-01

Retrospective feedback that provides detailed information on a driver's performance in critical driving situations at the end of a trip enhances his/her driving behaviors and safe driving habits. Although this has been demonstrated by a previous study, retrospective feedback can be further improved and applied to non-critical driving situations, which is needed for transportation safety. To propose a new retrospective feedback system that uses driver identity (i.e., a driver's name) and to experimentally study its effects on measures of driving performance and safety in a driving simulator. We conducted a behavioral experimental study with 30 participants. "Feedback type" was a between-subject variable with three conditions: no feedback (control group), feedback without driver identity, and feedback with driver identity. We measured multiple aspects of participants' driving behavior. To control for potential confounds, factors that were significantly correlated with driving behavior (e.g., age and driving experience) were all entered as covariates into a multivariate analysis of variance. To examine the effects of speeding on collision severity in driving simulation studies, we also developed a new index - momentum of potential collision - with a set of equations. Subjects who used a feedback system with driver identity had the fewest speeding violations and central-line crossings, spent the least amount of time speeding and crossing the central line, had the lowest speeding and central-line crossing magnitude, ran the fewest red lights, and had the smallest momentum of potential collision compared to the groups with feedback without driver identity and without feedback (control group). The new retrospective feedback system with driver identity has the potential to enhance a person's driving safety (e.g., speeding, central-line crossing, momentum of potential collision), which is an indication of the valence of one's name in a feedback system design. Copyright © 2011 Elsevier Ltd. All rights reserved.

Consistency of handwriting movements in dementia of the Alzheimer's type: a comparison with Huntington's and Parkinson's diseases.

PubMed

Slavin, M J; Phillips, J G; Bradshaw, J L; Hall, K A; Presnell, I

1999-01-01

Patients with dementia of the Alzheimer's type (DAT) and their matched controls wrote, on a computer graphics tablet, 4 consecutive, cursive letter 'l's, with varying levels of visual feedback: noninking pen and blank paper so that only the hand movements could be seen, noninking pen and lined paper to constrain their writing, goggles to occlude the lower visual field and eliminate all relevant visual feedback, and inking pen with full vision. The kinematic measures of stroke length, duration, and peak velocity were expressed in terms of consistency via a signal-to-noise ratio (M value of each parameter divided by its SD). Irrespective of medication or severity, DAT patients had writing strokes of significantly less consistent lengths than controls', and were disproportionately impaired by reduced visual feedback. Again irrespective of medication or severity, patients' strokes were of significantly less consistent duration, and significantly less consistent peak velocity than controls', independent of feedback conditions. Patients, unlike controls, frequently perseverated, producing more than 4 'l's, or multiple sets of responses, which was not differentially affected by level of visual feedback. The more variable performance of patients supports a degradation of the base motor program, and resembles that of Huntington's rather than Parkinson's disease patients. It may indeed reflect frontal rather than basal ganglia dysfunction.

Design of a feedback-feedforward steering controller for accurate path tracking and stability at the limits of handling

NASA Astrophysics Data System (ADS)

Kapania, Nitin R.; Gerdes, J. Christian

2015-12-01

This paper presents a feedback-feedforward steering controller that simultaneously maintains vehicle stability at the limits of handling while minimising lateral path tracking deviation. The design begins by considering the performance of a baseline controller with a lookahead feedback scheme and a feedforward algorithm based on a nonlinear vehicle handling diagram. While this initial design exhibits desirable stability properties at the limits of handling, the steady-state path deviation increases significantly at highway speeds. Results from both linear and nonlinear analyses indicate that lateral path tracking deviations are minimised when vehicle sideslip is held tangent to the desired path at all times. Analytical results show that directly incorporating this sideslip tangency condition into the steering feedback dramatically improves lateral path tracking, but at the expense of poor closed-loop stability margins. However, incorporating the desired sideslip behaviour into the feedforward loop creates a robust steering controller capable of accurate path tracking and oversteer correction at the physical limits of tyre friction. Experimental data collected from an Audi TTS test vehicle driving at the handling limits on a full length race circuit demonstrates the improved performance of the final controller design.

Overreliance on auditory feedback may lead to sound/syllable repetitions: simulations of stuttering and fluency-inducing conditions with a neural model of speech production

PubMed Central

Civier, Oren; Tasko, Stephen M.; Guenther, Frank H.

2010-01-01

This paper investigates the hypothesis that stuttering may result in part from impaired readout of feedforward control of speech, which forces persons who stutter (PWS) to produce speech with a motor strategy that is weighted too much toward auditory feedback control. Over-reliance on feedback control leads to production errors which, if they grow large enough, can cause the motor system to “reset” and repeat the current syllable. This hypothesis is investigated using computer simulations of a “neurally impaired” version of the DIVA model, a neural network model of speech acquisition and production. The model’s outputs are compared to published acoustic data from PWS’ fluent speech, and to combined acoustic and articulatory movement data collected from the dysfluent speech of one PWS. The simulations mimic the errors observed in the PWS subject’s speech, as well as the repairs of these errors. Additional simulations were able to account for enhancements of fluency gained by slowed/prolonged speech and masking noise. Together these results support the hypothesis that many dysfluencies in stuttering are due to a bias away from feedforward control and toward feedback control. PMID:20831971

Neural dynamic programming and its application to control systems

NASA Astrophysics Data System (ADS)

Seong, Chang-Yun

There are few general practical feedback control methods for nonlinear MIMO (multi-input-multi-output) systems, although such methods exist for their linear counterparts. Neural Dynamic Programming (NDP) is proposed as a practical design method of optimal feedback controllers for nonlinear MIMO systems. NDP is an offspring of both neural networks and optimal control theory. In optimal control theory, the optimal solution to any nonlinear MIMO control problem may be obtained from the Hamilton-Jacobi-Bellman equation (HJB) or the Euler-Lagrange equations (EL). The two sets of equations provide the same solution in different forms: EL leads to a sequence of optimal control vectors, called Feedforward Optimal Control (FOC); HJB yields a nonlinear optimal feedback controller, called Dynamic Programming (DP). DP produces an optimal solution that can reject disturbances and uncertainties as a result of feedback. Unfortunately, computation and storage requirements associated with DP solutions can be problematic, especially for high-order nonlinear systems. This dissertation presents an approximate technique for solving the DP problem based on neural network techniques that provides many of the performance benefits (e.g., optimality and feedback) of DP and benefits from the numerical properties of neural networks. We formulate neural networks to approximate optimal feedback solutions whose existence DP justifies. We show the conditions under which NDP closely approximates the optimal solution. Finally, we introduce the learning operator characterizing the learning process of the neural network in searching the optimal solution. The analysis of the learning operator provides not only a fundamental understanding of the learning process in neural networks but also useful guidelines for selecting the number of weights of the neural network. As a result, NDP finds---with a reasonable amount of computation and storage---the optimal feedback solutions to nonlinear MIMO control problems that would be very difficult to solve with DP. NDP was demonstrated on several applications such as the lateral autopilot logic for a Boeing 747, the minimum fuel control of a double-integrator plant with bounded control, the backward steering of a two-trailer truck, and the set-point control of a two-link robot arm.

Rapid change in articulatory lip movement induced by preceding auditory feedback during production of bilabial plosives.

PubMed

Mochida, Takemi; Gomi, Hiroaki; Kashino, Makio

2010-11-08

There has been plentiful evidence of kinesthetically induced rapid compensation for unanticipated perturbation in speech articulatory movements. However, the role of auditory information in stabilizing articulation has been little studied except for the control of voice fundamental frequency, voice amplitude and vowel formant frequencies. Although the influence of auditory information on the articulatory control process is evident in unintended speech errors caused by delayed auditory feedback, the direct and immediate effect of auditory alteration on the movements of articulators has not been clarified. This work examined whether temporal changes in the auditory feedback of bilabial plosives immediately affects the subsequent lip movement. We conducted experiments with an auditory feedback alteration system that enabled us to replace or block speech sounds in real time. Participants were asked to produce the syllable /pa/ repeatedly at a constant rate. During the repetition, normal auditory feedback was interrupted, and one of three pre-recorded syllables /pa/, /Φa/, or /pi/, spoken by the same participant, was presented once at a different timing from the anticipated production onset, while no feedback was presented for subsequent repetitions. Comparisons of the labial distance trajectories under altered and normal feedback conditions indicated that the movement quickened during the short period immediately after the alteration onset, when /pa/ was presented 50 ms before the expected timing. Such change was not significant under other feedback conditions we tested. The earlier articulation rapidly induced by the progressive auditory input suggests that a compensatory mechanism helps to maintain a constant speech rate by detecting errors between the internally predicted and actually provided auditory information associated with self movement. The timing- and context-dependent effects of feedback alteration suggest that the sensory error detection works in a temporally asymmetric window where acoustic features of the syllable to be produced may be coded.

High frequency inductive lamp and power oscillator

DOEpatents

Kirkpatrick, Douglas A.; Gitsevich, Aleksandr

2005-09-27

An oscillator includes an amplifier having an input and an output, a feedback network connected between the input of the amplifier and the output of the amplifier, the feedback network being configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and a tuning circuit connected to the input of the amplifier, wherein the tuning circuit is continuously variable and consists of solid state electrical components with no mechanically adjustable devices including a pair of diodes connected to each other at their respective cathodes with a control voltage connected at the junction of the diodes. Another oscillator includes an amplifier having an input and an output, a feedback network connected between the input of the amplifier and the output of the amplifier, the feedback network being configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and transmission lines connected to the input of the amplifier with an input pad and a perpendicular transmission line extending from the input pad and forming a leg of a resonant "T", and wherein the feedback network is coupled to the leg of the resonant "T".

Oxytocin selectively facilitates learning with social feedback and increases activity and functional connectivity in emotional memory and reward processing regions.

PubMed

Hu, Jiehui; Qi, Song; Becker, Benjamin; Luo, Lizhu; Gao, Shan; Gong, Qiyong; Hurlemann, René; Kendrick, Keith M

2015-06-01

In male Caucasian subjects, learning is facilitated by receipt of social compared with non-social feedback, and the neuropeptide oxytocin (OXT) facilitates this effect. In this study, we have first shown a cultural difference in that male Chinese subjects actually perform significantly worse in the same reinforcement associated learning task with social (emotional faces) compared with non-social feedback. Nevertheless, in two independent double-blind placebo (PLC) controlled between-subject design experiments we found OXT still selectively facilitated learning with social feedback. Similar to Caucasian subjects this OXT effect was strongest with feedback using female rather than male faces. One experiment performed in conjunction with functional magnetic resonance imaging showed that during the response, but not feedback phase of the task, OXT selectively increased activity in the amygdala, hippocampus, parahippocampal gyrus and putamen during the social feedback condition, and functional connectivity between the amygdala and insula and caudate. Therefore, OXT may be increasing the salience and reward value of anticipated social feedback. In the PLC group, response times and state anxiety scores during social feedback were associated with signal changes in these same regions but not in the OXT group. OXT may therefore have also facilitated learning by reducing anxiety in the social feedback condition. Overall our results provide the first evidence for cultural differences in social facilitation of learning per se, but a similar selective enhancement of learning with social feedback under OXT. This effect of OXT may be associated with enhanced responses and functional connectivity in emotional memory and reward processing regions. © 2015 Wiley Periodicals, Inc.

Combining computer adaptive testing technology with cognitively diagnostic assessment.

PubMed

McGlohen, Meghan; Chang, Hua-Hua

2008-08-01

A major advantage of computerized adaptive testing (CAT) is that it allows the test to home in on an examinee's ability level in an interactive manner. The aim of the new area of cognitive diagnosis is to provide information about specific content areas in which an examinee needs help. The goal of this study was to combine the benefit of specific feedback from cognitively diagnostic assessment with the advantages of CAT. In this study, three approaches to combining these were investigated: (1) item selection based on the traditional ability level estimate (theta), (2) item selection based on the attribute mastery feedback provided by cognitively diagnostic assessment (alpha), and (3) item selection based on both the traditional ability level estimate (theta) and the attribute mastery feedback provided by cognitively diagnostic assessment (alpha). The results from these three approaches were compared for theta estimation accuracy, attribute mastery estimation accuracy, and item exposure control. The theta- and alpha-based condition outperformed the alpha-based condition regarding theta estimation, attribute mastery pattern estimation, and item exposure control. Both the theta-based condition and the theta- and alpha-based condition performed similarly with regard to theta estimation, attribute mastery estimation, and item exposure control, but the theta- and alpha-based condition has an additional advantage in that it uses the shadow test method, which allows the administrator to incorporate additional constraints in the item selection process, such as content balancing, item type constraints, and so forth, and also to select items on the basis of both the current theta and alpha estimates, which can be built on top of existing 3PL testing programs.

Evolutionary game dynamics of controlled and automatic decision-making

NASA Astrophysics Data System (ADS)

Toupo, Danielle F. P.; Strogatz, Steven H.; Cohen, Jonathan D.; Rand, David G.

2015-07-01

We integrate dual-process theories of human cognition with evolutionary game theory to study the evolution of automatic and controlled decision-making processes. We introduce a model in which agents who make decisions using either automatic or controlled processing compete with each other for survival. Agents using automatic processing act quickly and so are more likely to acquire resources, but agents using controlled processing are better planners and so make more effective use of the resources they have. Using the replicator equation, we characterize the conditions under which automatic or controlled agents dominate, when coexistence is possible and when bistability occurs. We then extend the replicator equation to consider feedback between the state of the population and the environment. Under conditions in which having a greater proportion of controlled agents either enriches the environment or enhances the competitive advantage of automatic agents, we find that limit cycles can occur, leading to persistent oscillations in the population dynamics. Critically, however, these limit cycles only emerge when feedback occurs on a sufficiently long time scale. Our results shed light on the connection between evolution and human cognition and suggest necessary conditions for the rise and fall of rationality.

Evolutionary game dynamics of controlled and automatic decision-making.

PubMed

Toupo, Danielle F P; Strogatz, Steven H; Cohen, Jonathan D; Rand, David G

2015-07-01

We integrate dual-process theories of human cognition with evolutionary game theory to study the evolution of automatic and controlled decision-making processes. We introduce a model in which agents who make decisions using either automatic or controlled processing compete with each other for survival. Agents using automatic processing act quickly and so are more likely to acquire resources, but agents using controlled processing are better planners and so make more effective use of the resources they have. Using the replicator equation, we characterize the conditions under which automatic or controlled agents dominate, when coexistence is possible and when bistability occurs. We then extend the replicator equation to consider feedback between the state of the population and the environment. Under conditions in which having a greater proportion of controlled agents either enriches the environment or enhances the competitive advantage of automatic agents, we find that limit cycles can occur, leading to persistent oscillations in the population dynamics. Critically, however, these limit cycles only emerge when feedback occurs on a sufficiently long time scale. Our results shed light on the connection between evolution and human cognition and suggest necessary conditions for the rise and fall of rationality.

The Strength of Cloud Feedbacks and the Structure of Tropical Climate Change - A CESM Sensitivity Study

NASA Astrophysics Data System (ADS)

Erfani, E.; Burls, N.

2017-12-01

The nature of local coupled ocean-atmosphere interactions within the tropics is determined by background conditions such as the depth of the equatorial thermocline, the water vapor content of the tropical atmosphere, and the radiative forcing of tropical clouds. These factors are set not only by the coupled tropical variability itself but also by extra-tropical conditions. For example, the strength of the cold tongue is ultimately controlled by the temperature of waters subducted in the extra-tropics and transported to the equator by the ocean subtropical cells (STCs). Similarly, inter-hemispheric asymmetries in extra-tropical atmospheric heating are communicated to the tropics affecting cross-equatorial heat transport and ITCZ position. Acknowledging from a fully coupled perspective the influence of both tropical and extra-tropical conditions, we are performing a suite of CESM experiments across which we systematically alter the strength of convective and stratus cloud feedbacks. By systematically exploring the sensitivity of the tropical coupled system to imposed changes in the strength of tropical and extra-tropical cloud feedbacks to CO2-induced warming this work aims to formalize our understanding of cloud controls on tropical climate.

Visual-perceptual-kinesthetic inputs on influencing writing performances in children with handwriting difficulties.

PubMed

Tse, Linda F L; Thanapalan, Kannan C; Chan, Chetwyn C H

2014-02-01

This study investigated the role of visual-perceptual input in writing Chinese characters among senior school-aged children who had handwriting difficulties (CHD). The participants were 27 CHD (9-11 years old) and 61 normally developed control. There were three writing conditions: copying, and dictations with or without visual feedback. The motor-free subtests of the Developmental Test of Visual Perception (DTVP-2) were conducted. The CHD group showed significantly slower mean speeds of character production and less legibility of produced characters than the control group in all writing conditions (ps<0.001). There were significant deteriorations in legibility from copying to dictation without visual feedback. Nevertheless, the Group by Condition interaction effect was not statistically significant. Only position in space of DTVP-2 was significantly correlated with the legibility among CHD (r=-0.62, p=0.001). Poor legibility seems to be related to the less-intact spatial representation of the characters in working memory, which can be rectified by viewing the characters during writing. Visual feedback regarding one's own actions in writing can also improve legibility of characters among these children. Copyright © 2013 Elsevier Ltd. All rights reserved.

Visually induced analgesia during massage treatment in chronic back pain patients.

PubMed

Löffler, A; Trojan, J; Zieglgänsberger, W; Diers, M

2017-11-01

Previous findings suggest that watching sites of experimental and chronic pain can exert an analgesic effect. Our present study investigates whether watching one's back during massage increases the analgesic effect of this treatment in chronic back pain patients. Twenty patients with chronic back pain were treated with a conventional massage therapy. During this treatment, patients received a real-time video feedback of their own back. Watching a neutral object, a video of another person of the same sex being massaged, a picture of the own back, and keeping one's eyes closed were used as controls. These conditions were presented in randomized order on five separate days. All conditions yielded significant decreases in habitual pain intensity. The effect of real-time video feedback of the own back on massage treatment was the strongest and differed significantly from the effect of watching a neutral object, but not from the other control conditions, which may have induced slight effects of their own. Repeated real-time video feedback may be useful during massage treatment of chronic pain. This study shows that inducing visual induced analgesia during massage treatment can be helpful in alleviating chronic pain. © 2017 European Pain Federation - EFIC®.

Effect of metrology time delay on overlay APC

NASA Astrophysics Data System (ADS)

Carlson, Alan; DiBiase, Debra

2002-07-01

The run-to-run control strategy of lithography APC is primarily composed of a feedback loop as shown in the diagram below. It is known that the insertion of a time delay in a feedback loop can cause degradation in control performance and could even cause a stable system to become unstable, if the time delay becomes sufficiently large. Many proponents of integrated metrology methods have cited the damage caused by metrology time delays as the primary justification for moving from a stand-alone to integrated metrology. While there is little dispute over the qualitative form of this argument, there has been very light published about the quantitative effects under real fab conditions - precisely how much control is lost due to these time delays. Another issue regarding time delays is that the length of these delays is not typically fixed - they vary from lot to lot and in some cases this variance can be large - from one hour on the short side to over 32 hours on the long side. Concern has been expressed that the variability in metrology time delays can cause undesirable dynamics in feedback loops that make it difficult to optimize feedback filters and gains and at worst could drive a system unstable. By using data from numerous fabs, spanning many sizes and styles of operation, we have conducted a quantitative study of the time delay effect on overlay run- to-run control. Our analysis resulted in the following conclusions: (1) There is a significant and material relationship between metrology time delay and overlay control under a variety of real world production conditions. (2) The run-to-run controller can be configured to minimize sensitivity to time delay variations. (3) The value of moving to integrated metrology can be quantified.

Fault tolerant control laws

NASA Technical Reports Server (NTRS)

Ly, U. L.; Ho, J. K.

1986-01-01

A systematic procedure for the synthesis of fault tolerant control laws to actuator failure has been presented. Two design methods were used to synthesize fault tolerant controllers: the conventional LQ design method and a direct feedback controller design method SANDY. The latter method is used primarily to streamline the full-state Q feedback design into a practical implementable output feedback controller structure. To achieve robustness to control actuator failure, the redundant surfaces are properly balanced according to their control effectiveness. A simple gain schedule based on the landing gear up/down logic involving only three gains was developed to handle three design flight conditions: Mach .25 and Mach .60 at 5000 ft and Mach .90 at 20,000 ft. The fault tolerant control law developed in this study provides good stability augmentation and performance for the relaxed static stability aircraft. The augmented aircraft responses are found to be invariant to the presence of a failure. Furthermore, single-loop stability margins of +6 dB in gain and +30 deg in phase were achieved along with -40 dB/decade rolloff at high frequency.

Aeroassisted orbital maneuvering using Lyapunov optimal feedback control

NASA Technical Reports Server (NTRS)

Grantham, Walter J.; Lee, Byoung-Soo

1987-01-01

A Liapunov optimal feedback controller incorporating a preferred direction of motion at each state of the system which is opposite to the gradient of a specified descent function is developed for aeroassisted orbital transfer from high-earth orbit to LEO. The performances of the Liapunov controller and a calculus-of-variations open-loop minimum-fuel controller, both of which are based on the 1962 U.S. Standard Atmosphere, are simulated using both the 1962 U.S. Standard Atmosphere and an atmosphere corresponding to the STS-6 Space Shuttle flight. In the STS-6 atmosphere, the calculus-of-variations open-loop controller fails to exit the atmosphere, while the Liapunov controller achieves the optimal minimum-fuel conditions, despite the + or - 40 percent fluctuations in the STS-6 atmosphere.

Output Feedback Distributed Containment Control for High-Order Nonlinear Multiagent Systems.

PubMed

Li, Yafeng; Hua, Changchun; Wu, Shuangshuang; Guan, Xinping

2017-01-31

In this paper, we study the problem of output feedback distributed containment control for a class of high-order nonlinear multiagent systems under a fixed undirected graph and a fixed directed graph, respectively. Only the output signals of the systems can be measured. The novel reduced order dynamic gain observer is constructed to estimate the unmeasured state variables of the system with the less conservative condition on nonlinear terms than traditional Lipschitz one. Via the backstepping method, output feedback distributed nonlinear controllers for the followers are designed. By means of the novel first virtual controllers, we separate the estimated state variables of different agents from each other. Consequently, the designed controllers show independence on the estimated state variables of neighbors except outputs information, and the dynamics of each agent can be greatly different, which make the design method have a wider class of applications. Finally, a numerical simulation is presented to illustrate the effectiveness of the proposed method.

A stage structure pest management model with impulsive state feedback control

NASA Astrophysics Data System (ADS)

Pang, Guoping; Chen, Lansun; Xu, Weijian; Fu, Gang

2015-06-01

A stage structure pest management model with impulsive state feedback control is investigated. We get the sufficient condition for the existence of the order-1 periodic solution by differential equation geometry theory and successor function. Further, we obtain a new judgement method for the stability of the order-1 periodic solution of the semi-continuous systems by referencing the stability analysis for limit cycles of continuous systems, which is different from the previous method of analog of Poincarè criterion. Finally, we analyze numerically the theoretical results obtained.

Response cost, reinforcement, and children's Porteus Maze qualitative performance.

PubMed

Neenan, D M; Routh, D K

1986-09-01

Sixty fourth-grade children were given two different series of the Porteus Maze Test. The first series was given as a baseline, and the second series was administered under one of four different experimental conditions: control, response cost, positive reinforcement, or negative verbal feedback. Response cost and positive reinforcement, but not negative verbal feedback, led to significant decreases in the number of all types of qualitative errors in relation to the control group. The reduction of nontargeted as well as targeted errors provides evidence for the generalized effects of response cost and positive reinforcement.

Paradigm Shifts in Voluntary Force Control and Motor Unit Behaviors with the Manipulated Size of Visual Error Perception

PubMed Central

Chen, Yi-Ching; Lin, Yen-Ting; Chang, Gwo-Ching; Hwang, Ing-Shiou

2017-01-01

The detection of error information is an essential prerequisite of a feedback-based movement. This study investigated the differential behavior and neurophysiological mechanisms of a cyclic force-tracking task using error-reducing and error-enhancing feedback. The discharge patterns of a relatively large number of motor units (MUs) were assessed with custom-designed multi-channel surface electromyography following mathematical decomposition of the experimentally-measured signals. Force characteristics, force-discharge relation, and phase-locking cortical activities in the contralateral motor cortex to individual MUs were contrasted among the low (LSF), normal (NSF), and high scaling factor (HSF) conditions, in which the sizes of online execution errors were displayed with various amplification ratios. Along with a spectral shift of the force output toward a lower band, force output with a more phase-lead became less irregular, and tracking accuracy was worse in the LSF condition than in the HSF condition. The coherent discharge of high phasic (HP) MUs with the target signal was greater, and inter-spike intervals were larger, in the LSF condition than in the HSF condition. Force-tracking in the LSF condition manifested with stronger phase-locked EEG activity in the contralateral motor cortex to discharge of the (HP) MUs (LSF > NSF, HSF). The coherent discharge of the (HP) MUs during the cyclic force-tracking predominated the force-discharge relation, which increased inversely to the error scaling factor. In conclusion, the size of visualized error gates motor unit discharge, force-discharge relation, and the relative influences of the feedback and feedforward processes on force control. A smaller visualized error size favors voluntary force control using a feedforward process, in relation to a selective central modulation that enhance the coherent discharge of (HP) MUs. PMID:28348530

Paradigm Shifts in Voluntary Force Control and Motor Unit Behaviors with the Manipulated Size of Visual Error Perception.

PubMed

Chen, Yi-Ching; Lin, Yen-Ting; Chang, Gwo-Ching; Hwang, Ing-Shiou

2017-01-01

The detection of error information is an essential prerequisite of a feedback-based movement. This study investigated the differential behavior and neurophysiological mechanisms of a cyclic force-tracking task using error-reducing and error-enhancing feedback. The discharge patterns of a relatively large number of motor units (MUs) were assessed with custom-designed multi-channel surface electromyography following mathematical decomposition of the experimentally-measured signals. Force characteristics, force-discharge relation, and phase-locking cortical activities in the contralateral motor cortex to individual MUs were contrasted among the low (LSF), normal (NSF), and high scaling factor (HSF) conditions, in which the sizes of online execution errors were displayed with various amplification ratios. Along with a spectral shift of the force output toward a lower band, force output with a more phase-lead became less irregular, and tracking accuracy was worse in the LSF condition than in the HSF condition. The coherent discharge of high phasic (HP) MUs with the target signal was greater, and inter-spike intervals were larger, in the LSF condition than in the HSF condition. Force-tracking in the LSF condition manifested with stronger phase-locked EEG activity in the contralateral motor cortex to discharge of the (HP) MUs (LSF > NSF, HSF). The coherent discharge of the (HP) MUs during the cyclic force-tracking predominated the force-discharge relation, which increased inversely to the error scaling factor. In conclusion, the size of visualized error gates motor unit discharge, force-discharge relation, and the relative influences of the feedback and feedforward processes on force control. A smaller visualized error size favors voluntary force control using a feedforward process, in relation to a selective central modulation that enhance the coherent discharge of (HP) MUs.

Plant-soil feedbacks: a comparative study on the relative importance of soil feedbacks in the greenhouse versus the field.

PubMed

Heinze, Johannes; Sitte, M; Schindhelm, A; Wright, J; Joshi, J

2016-06-01

Interactions between plants and soil microorganisms influence individual plant performance and thus plant-community composition. Most studies on such plant-soil feedbacks (PSFs) have been performed under controlled greenhouse conditions, whereas no study has directly compared PSFs under greenhouse and natural field conditions. We grew three grass species that differ in local abundance in grassland communities simultaneously in the greenhouse and field on field-collected soils either previously conditioned by these species or by the general grassland community. As soils in grasslands are typically conditioned by mixes of species through the patchy and heterogeneous plant species' distributions, we additionally compared the effects of species-specific versus non-specific species conditioning on PSFs in natural and greenhouse conditions. In almost all comparisons PSFs differed between the greenhouse and field. In the greenhouse, plant growth in species-specific and non-specific soils resulted in similar effects with neutral PSFs for the most abundant species and positive PSFs for the less abundant species. In contrast, in the field all grass species tested performed best in non-specific plots, whereas species-specific PSFs were neutral for the most abundant and varied for the less abundant species. This indicates a general beneficial effect of plant diversity on PSFs in the field. Controlled greenhouse conditions might provide valuable insights on the nominal effects of soils on plants. However, the PSFs observed in greenhouse conditions may not be the determining drivers in natural plant communities where their effects may be overwhelmed by the diversity of abiotic and biotic above- and belowground interactions in the field.

Stabilization of Inviscid Vortex Sheets

NASA Astrophysics Data System (ADS)

Protas, Bartosz; Sakajo, Takashi

2017-11-01

In this study we investigate the problem of stabilizing inviscid vortex sheets via feedback control. Such models, expressed in terms of the Birkhoff-Rott equation, are often used to describe the Kevin-Helmholtz instability of shear layers and are known to be strongly unstable to small-scale perturbations. First, we consider the linear stability of a straight vortex sheet in the periodic setting with actuation in the form of an array of point vortices or sources located a certain distance away from the sheet. We establish conditions under which this system is controllable and observable. Next, using methods of the linear control theory, we synthesize a feedback control strategy which stabilizes a straight vortex sheet in the linear regime. Given the poor conditioning of the discretized problem, reliable solution of the resulting algebraic Riccati equation requires the use of high-precision arithmetic. Finally, we demonstrate that this control approach also succeeds in the nonlinear regime, provided the magnitude of the initial perturbation is sufficiently small.

Distinguishing the roles of meteorology, emission control measures, regional transport, and co-benefits of reduced aerosol feedbacks in ;APEC Blue;

NASA Astrophysics Data System (ADS)

Gao, Meng; Liu, Zirui; Wang, Yuesi; Lu, Xiao; Ji, Dongsheng; Wang, Lili; Li, Meng; Wang, Zifa; Zhang, Qiang; Carmichael, Gregory R.

2017-10-01

Air quality are strongly influenced by both emissions and meteorological conditions. During the Asia Pacific Economic Cooperation (APEC) week (November 5-11, 2014), the Chinese government implemented unprecedented strict emission control measures in Beijing and surrounding provinces, and then a phenomenon referred to as ;APEC Blue; (rare blue sky) occurred. It is challenging to quantify the effectiveness of the implemented strict control measures solely based on observations. In this study, we use the WRF-Chem model to distinguish the roles of meteorology, emission control measures, regional transport, and co-benefits of reduced aerosol feedbacks during APEC week. In general, meteorological variables, PM2.5 concentrations and PM2.5 chemical compositions are well reproduced in Beijing. Positive weather conditions (lower temperature, lower relative humidity, higher wind speeds and enhanced boundary layer heights) play important roles in ;APEC Blue;. Applying strict emission control measures in Beijing and five surrounding provinces can only explain an average decrease of 17.7 μg/m3 (-21.8%) decreases in PM2.5 concentrations, roughly more than half of which is caused by emission controls that implemented in the five surrounding provinces (12.5 μg/m3). During the APEC week, non-local emissions contributed to 41.3% to PM2.5 concentrations in Beijing, and the effectiveness of implementing emission control measures hinges on dominant pathways and transport speeds. Besides, we also quantified the contribution of reduced aerosol feedbacks due to strict emission control measures in this study. During daytime, co-benefits of reduced aerosol feedbacks account for about 10.9% of the total decreases in PM2.5 concentrations in urban Beijing. The separation of contributions from aerosol absorption and scattering restates the importance of controlling BC to accelerate the effectiveness of aerosol pollution control.

The Sense of Agency during Continuous Action: Performance Is More Important than Action-Feedback Association

PubMed Central

Wen, Wen; Yamashita, Atsushi; Asama, Hajime

2015-01-01

The sense of agency refers to the feeling that one is controlling events through one’s own behavior. This study examined how task performance and the delay of events influence one’s sense of agency during continuous action accompanied by a goal. The participants were instructed to direct a moving dot into a square as quickly as possible by pressing the left and right keys on a keyboard to control the direction in which the dot traveled. The interval between the key press and response of the dot (i.e., direction change) was manipulated to vary task difficulty. Moreover, in the assisted condition, the computer ignored participants’ erroneous commands, resulting in improved task performance but a weaker association between the participants’ commands and actual movements of the dot relative to the condition in which all of the participants’ commands were executed (i.e., self-control condition). The results showed that participants’ sense of agency increased with better performance in the assisted condition relative to the self-control condition, even though a large proportion of their commands were not executed. We concluded that, when the action-feedback association was uncertain, cognitive inference was more dominant relative to the process of comparing predicted and perceived information in the judgment of agency. PMID:25893992

Robust iterative learning control for multi-phase batch processes: an average dwell-time method with 2D convergence indexes

NASA Astrophysics Data System (ADS)

Wang, Limin; Shen, Yiteng; Yu, Jingxian; Li, Ping; Zhang, Ridong; Gao, Furong

2018-01-01

In order to cope with system disturbances in multi-phase batch processes with different dimensions, a hybrid robust control scheme of iterative learning control combined with feedback control is proposed in this paper. First, with a hybrid iterative learning control law designed by introducing the state error, the tracking error and the extended information, the multi-phase batch process is converted into a two-dimensional Fornasini-Marchesini (2D-FM) switched system with different dimensions. Second, a switching signal is designed using the average dwell-time method integrated with the related switching conditions to give sufficient conditions ensuring stable running for the system. Finally, the minimum running time of the subsystems and the control law gains are calculated by solving the linear matrix inequalities. Meanwhile, a compound 2D controller with robust performance is obtained, which includes a robust extended feedback control for ensuring the steady-state tracking error to converge rapidly. The application on an injection molding process displays the effectiveness and superiority of the proposed strategy.

Learning to Obtain Reward, but Not Avoid Punishment, Is Affected by Presence of PTSD Symptoms in Male Veterans: Empirical Data and Computational Model

PubMed Central

Myers, Catherine E.; Moustafa, Ahmed A.; Sheynin, Jony; VanMeenen, Kirsten M.; Gilbertson, Mark W.; Orr, Scott P.; Beck, Kevin D.; Pang, Kevin C. H.; Servatius, Richard J.

2013-01-01

Post-traumatic stress disorder (PTSD) symptoms include behavioral avoidance which is acquired and tends to increase with time. This avoidance may represent a general learning bias; indeed, individuals with PTSD are often faster than controls on acquiring conditioned responses based on physiologically-aversive feedback. However, it is not clear whether this learning bias extends to cognitive feedback, or to learning from both reward and punishment. Here, male veterans with self-reported current, severe PTSD symptoms (PTSS group) or with few or no PTSD symptoms (control group) completed a probabilistic classification task that included both reward-based and punishment-based trials, where feedback could take the form of reward, punishment, or an ambiguous “no-feedback” outcome that could signal either successful avoidance of punishment or failure to obtain reward. The PTSS group outperformed the control group in total points obtained; the PTSS group specifically performed better than the control group on reward-based trials, with no difference on punishment-based trials. To better understand possible mechanisms underlying observed performance, we used a reinforcement learning model of the task, and applied maximum likelihood estimation techniques to derive estimated parameters describing individual participants’ behavior. Estimations of the reinforcement value of the no-feedback outcome were significantly greater in the control group than the PTSS group, suggesting that the control group was more likely to value this outcome as positively reinforcing (i.e., signaling successful avoidance of punishment). This is consistent with the control group’s generally poorer performance on reward trials, where reward feedback was to be obtained in preference to the no-feedback outcome. Differences in the interpretation of ambiguous feedback may contribute to the facilitated reinforcement learning often observed in PTSD patients, and may in turn provide new insight into how pathological behaviors are acquired and maintained in PTSD. PMID:24015254

Enhancing the Performance of Passive Teleoperation Systems via Cutaneous Feedback.

PubMed

Pacchierotti, Claudio; Tirmizi, Asad; Bianchini, Gianni; Prattichizzo, Domenico

2015-01-01

We introduce a novel method to improve the performance of passive teleoperation systems with force reflection. It consists of integrating kinesthetic haptic feedback provided by common grounded haptic interfaces with cutaneous haptic feedback. The proposed approach can be used on top of any time-domain control technique that ensures a stable interaction by scaling down kinesthetic feedback when this is required to satisfy stability conditions (e.g., passivity) at the expense of transparency. Performance is recovered by providing a suitable amount of cutaneous force through custom wearable cutaneous devices. The viability of the proposed approach is demonstrated through an experiment of perceived stiffness and an experiment of teleoperated needle insertion in soft tissue.

An analog RF gap voltage regulation system for the Advanced Photon Source storage ring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horan, D.

1999-04-13

An analog rf gap voltage regulation system has been designed and built at Argonne National Laboratory to maintain constant total storage ring rf gap voltage, independent of beam loading and cavity tuning effects. The design uses feedback control of the klystron mod-anode voltage to vary the amount of rf power fed to the storage ring cavities. The system consists of two independent feedback loops, each regulating the combined rf gap voltages of eight storage ring cavities by varying the output power of either one or two rf stations, depending on the mode of operation. It provides full operator control andmore » permissive logic to permit feedback control of the rf system output power only if proper conditions are met. The feedback system uses envelope-detected cavity field probe outputs as the feedback signal. Two different methods of combining the individual field probe signals were used to generate a relative DC level representing one-half of the total storage ring rf voltage, an envelope-detected vector sum of the field probe rf signals, and the DC sum of individual field probe envelope detector outputs. The merits of both methods are discussed. The klystron high-voltage power supply (HVPS) units are fitted with an analog interface for external control of the mod-anode voltage level, using a four-quadrant analog multiplier to modulate the HVPS mod-anode voltage regulator set-point in response to feedback system commands.« less

An experimental study of the correlates and consequences of perceiving oneself to be the target of gender discrimination.

PubMed

Brown, Christia Spears; Bigler, Rebecca S; Chu, Hui

2010-10-01

An experimental methodology was used to test hypotheses concerning the effects of contextual, cognitive-developmental, and individual difference factors on children's views of whether they have been the target of gender discrimination and the possible consequent effect of such views on two forms of state self-esteem: performance and social acceptance. Children (N=108, 5-11 years of age) completed theory of mind and gender attitude measures and a drawing task. Next, children received feedback that was designed to appear either gender biased (discrimination condition) or nonbiased (control condition). Children's attributions for the feedback and state self-esteem were assessed. As expected, children reported having been the target of gender discrimination more often in the discrimination condition than in the control condition. Older and more cognitively advanced children made fewer attributions to discrimination than their peers. Perceptions of discrimination were associated with higher performance state self-esteem and, among egalitarian children, lower social state self-esteem. Copyright 2010 Elsevier Inc. All rights reserved.

Auditory Proprioceptive Integration: Effects of Real-Time Kinematic Auditory Feedback on Knee Proprioception

PubMed Central

Ghai, Shashank; Schmitz, Gerd; Hwang, Tong-Hun; Effenberg, Alfred O.

2018-01-01

The purpose of the study was to assess the influence of real-time auditory feedback on knee proprioception. Thirty healthy participants were randomly allocated to control (n = 15), and experimental group I (15). The participants performed an active knee-repositioning task using their dominant leg, with/without additional real-time auditory feedback where the frequency was mapped in a convergent manner to two different target angles (40 and 75°). Statistical analysis revealed significant enhancement in knee re-positioning accuracy for the constant and absolute error with real-time auditory feedback, within and across the groups. Besides this convergent condition, we established a second divergent condition. Here, a step-wise transposition of frequency was performed to explore whether a systematic tuning between auditory-proprioceptive repositioning exists. No significant effects were identified in this divergent auditory feedback condition. An additional experimental group II (n = 20) was further included. Here, we investigated the influence of a larger magnitude and directional change of step-wise transposition of the frequency. In a first step, results confirm the findings of experiment I. Moreover, significant effects on knee auditory-proprioception repositioning were evident when divergent auditory feedback was applied. During the step-wise transposition participants showed systematic modulation of knee movements in the opposite direction of transposition. We confirm that knee re-positioning accuracy can be enhanced with concurrent application of real-time auditory feedback and that knee re-positioning can modulated in a goal-directed manner with step-wise transposition of frequency. Clinical implications are discussed with respect to joint position sense in rehabilitation settings. PMID:29568259

Youth fitness testing: the effect of percentile-based evaluative feedback on intrinsic motivation.

PubMed

Whitehead, J R; Corbin, C B

1991-06-01

This study was a test of Deci and Ryan's (1985) cognitive evaluation theory in a fitness testing situation. More specifically, it was a test of Proposition 2 of that theory, which posits that external events that increase or decrease perceived competence will increase or decrease intrinsic motivation. Seventh and eighth grade schoolchildren (N = 105) volunteered for an experiment that was ostensibly to collect data on a new youth fitness test (the Illinois Agility Run). After two untimed practice runs, a specially adapted version of the Intrinsic Motivation Inventory (IMI) was administered as a pretest of intrinsic motivation. Two weeks later when subjects ran again, they were apparently electronically timed. In reality, the subjects were given bogus feedback. Subjects in a positive feedback condition were told their scores were above the 80th percentile, while those in a negative feedback condition were told their scores were below the 20th percentile. Those in a control condition received no feedback. The IMI was again administered to the subjects after their runs. Multivariate and subsequent univariate tests were significant for all four subscale dependent variables (perceived interest-enjoyment, competence, effort, and pressure-tension). Positive feedback enhanced all aspects of intrinsic motivation, whereas negative feedback decreased them. In a further test of cognitive evaluation theory, path analysis results supported the prediction that perceived competence would mediate changes in the other IMI subscales. Taken together, these results clearly support cognitive evaluation theory and also may have important implications regarding motivation for those who administer youth fitness tests.

The light cycle controls the hatching rhythm in Bombyx mori via negative feedback loop of the circadian oscillator.

PubMed

Tao, Hui; Li, Xue; Qiu, Jian-Feng; Liu, Heng-Jiang; Zhang, Da-Yan; Chu, Feng; Sima, Yanghu; Xu, Shi-Qing

2017-10-01

Hatching behavior is a key target in silkworm (Bombyx mori) rearing, especially for the control of Lepidoptera pests. According to previous research, hatching rhythms appear to be controlled by a clock mechanism that restricts or "gates" hatching to a particular time. However, the underlying mechanism remains elusive. Under 12-h light:12-h dark photoperiod (LD) conditions, the transcriptional levels of the chitinase5 (Cht5) and hatching enzyme-like (Hel) genes, as well as the enzymatic activities of their gene products, oscillated in time with ambient light cycles, as did the transcriptional levels of the cryptochrome 1, cryptochrome 2, period (per), and timeless genes, which are key components of the negative feedback loop of the circadian rhythm. These changes were related to the expression profile of the ecdysteroid receptor gene and the hatching behavior of B. mori eggs. However, under continuous light or dark conditions, the hatching behavior, the expression levels of Cht5 and Hel, as well as the enzymatic activities of their gene products, were not synchronized unlike under LD conditions. In addition, immunohistochemistry experiments showed that light promoted the translocation of PER from the cytoplasm to the nucleus. In conclusion, LD cycles regulate the hatching rhythm of B. mori via negative feedback loop of the circadian oscillator. © 2017 Wiley Periodicals, Inc.

Design and implementation of a control system for a quadrotor MAV

NASA Astrophysics Data System (ADS)

Bawek, Dean

The quadrotor is a 200 g MAV with rapid-prototyped rotors that are driven by four brushless electric motors, capable of a collective thrust of around 400 g using an 11 V battery. The vehicle is compact with its largest dimension at 188 mm. Without any feedback control, the quadrotor is unstable. For flight stability, the vehicle incorporates a linear quadratic regulator to augment its dynamics for hover. The quadrotor's nonlinear dynamics are linearized about hover in order to be used in controller formulation. Feedback comes both directly from sensors and a Luenberger observer that computes the rotor velocities. A Simulink simulation uses hardware and software properties to serve as an environment for controller gain tuning prior to flight testing. The results from the simulation generate stabilizing control gains for the on-board attitude controller and for an off-board PC autopilot that uses the Vicon computer vision system for position feedback. Through the combined effort of the on-board and off-board controllers, the quadrotor successfully demonstrates stable hover in both nominal and disturbed conditions.

Selective and divided attention modulates auditory-vocal integration in the processing of pitch feedback errors.

PubMed

Liu, Ying; Hu, Huijing; Jones, Jeffery A; Guo, Zhiqiang; Li, Weifeng; Chen, Xi; Liu, Peng; Liu, Hanjun

2015-08-01

Speakers rapidly adjust their ongoing vocal productions to compensate for errors they hear in their auditory feedback. It is currently unclear what role attention plays in these vocal compensations. This event-related potential (ERP) study examined the influence of selective and divided attention on the vocal and cortical responses to pitch errors heard in auditory feedback regarding ongoing vocalisations. During the production of a sustained vowel, participants briefly heard their vocal pitch shifted up two semitones while they actively attended to auditory or visual events (selective attention), or both auditory and visual events (divided attention), or were not told to attend to either modality (control condition). The behavioral results showed that attending to the pitch perturbations elicited larger vocal compensations than attending to the visual stimuli. Moreover, ERPs were likewise sensitive to the attentional manipulations: P2 responses to pitch perturbations were larger when participants attended to the auditory stimuli compared to when they attended to the visual stimuli, and compared to when they were not explicitly told to attend to either the visual or auditory stimuli. By contrast, dividing attention between the auditory and visual modalities caused suppressed P2 responses relative to all the other conditions and caused enhanced N1 responses relative to the control condition. These findings provide strong evidence for the influence of attention on the mechanisms underlying the auditory-vocal integration in the processing of pitch feedback errors. In addition, selective attention and divided attention appear to modulate the neurobehavioral processing of pitch feedback errors in different ways. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

It's how you get there: walking down a virtual alley activates premotor and parietal areas.

PubMed

Wagner, Johanna; Solis-Escalante, Teodoro; Scherer, Reinhold; Neuper, Christa; Müller-Putz, Gernot

2014-01-01

Voluntary drive is crucial for motor learning, therefore we are interested in the role that motor planning plays in gait movements. In this study we examined the impact of an interactive Virtual Environment (VE) feedback task on the EEG patterns during robot assisted walking. We compared walking in the VE modality to two control conditions: walking with a visual attention paradigm, in which visual stimuli were unrelated to the motor task; and walking with mirror feedback, in which participants observed their own movements. Eleven healthy participants were considered. Application of independent component analysis to the EEG revealed three independent component clusters in premotor and parietal areas showing increased activity during walking with the adaptive VE training paradigm compared to the control conditions. During the interactive VE walking task spectral power in frequency ranges 8-12, 15-20, and 23-40 Hz was significantly (p ≤ 0.05) decreased. This power decrease is interpreted as a correlate of an active cortical area. Furthermore activity in the premotor cortex revealed gait cycle related modulations significantly different (p ≤ 0.05) from baseline in the frequency range 23-40 Hz during walking. These modulations were significantly (p ≤ 0.05) reduced depending on gait cycle phases in the interactive VE walking task compared to the control conditions. We demonstrate that premotor and parietal areas show increased activity during walking with the adaptive VE training paradigm, when compared to walking with mirror- and movement unrelated feedback. Previous research has related a premotor-parietal network to motor planning and motor intention. We argue that movement related interactive feedback enhances motor planning and motor intention. We hypothesize that this might improve gait recovery during rehabilitation.

Movement preparation and execution: differential functional activation patterns after traumatic brain injury.

PubMed

Gooijers, Jolien; Beets, Iseult A M; Albouy, Genevieve; Beeckmans, Kurt; Michiels, Karla; Sunaert, Stefan; Swinnen, Stephan P

2016-09-01

Years following the insult, patients with traumatic brain injury often experience persistent motor control problems, including bimanual coordination deficits. Previous studies revealed that such deficits are related to brain structural white and grey matter abnormalities. Here, we assessed, for the first time, cerebral functional activation patterns during bimanual movement preparation and performance in patients with traumatic brain injury, using functional magnetic resonance imaging. Eighteen patients with moderate-to-severe traumatic brain injury (10 females; aged 26.3 years, standard deviation = 5.2; age range: 18.4-34.6 years) and 26 healthy young adults (15 females; aged 23.6 years, standard deviation = 3.8; age range: 19.5-33 years) performed a complex bimanual tracking task, divided into a preparation (2 s) and execution (9 s) phase, and executed either in the presence or absence of augmented visual feedback. Performance on the bimanual tracking task, expressed as the average target error, was impaired for patients as compared to controls (P < 0.001) and for trials in the absence as compared to the presence of augmented visual feedback (P < 0.001). At the cerebral level, movement preparation was characterized by reduced neural activation in the patient group relative to the control group in frontal (bilateral superior frontal gyrus, right dorsolateral prefrontal cortex), parietal (left inferior parietal lobe) and occipital (right striate and extrastriate visual cortex) areas (P's < 0.05). During the execution phase, however, the opposite pattern emerged, i.e. traumatic brain injury patients showed enhanced activations compared with controls in frontal (left dorsolateral prefrontal cortex, left lateral anterior prefrontal cortex, and left orbitofrontal cortex), parietal (bilateral inferior parietal lobe, bilateral superior parietal lobe, right precuneus, right primary somatosensory cortex), occipital (right striate and extrastriate visual cortices), and subcortical (left cerebellum crus II) areas (P's < 0.05). Moreover, a significant interaction effect between Feedback Condition and Group in the primary motor area (bilaterally) (P < 0.001), the cerebellum (left) (P < 0.001) and caudate (left) (P < 0.05), revealed that controls showed less overlap of activation patterns accompanying the two feedback conditions than patients with traumatic brain injury (i.e. decreased neural differentiation). In sum, our findings point towards poorer predictive control in traumatic brain injury patients in comparison to controls. Moreover, irrespective of the feedback condition, overactivations were observed in traumatically brain injured patients during movement execution, pointing to more controlled processing of motor task performance. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Children’s Feedback Preferences in Response to an Experimentally Manipulated Peer Evaluation Outcome: The Role of Depressive Symptoms

PubMed Central

Dekovic, Maja; Vermande, Marjolijn; Telch, Michael J.

2007-01-01

The present study examined the linkage between pre-adolescent children’s depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total ‘likeability’ score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children’s self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation. PMID:17279340

Competence feedback improves CBT competence in trainee therapists: A randomized controlled pilot study.

PubMed

Weck, Florian; Kaufmann, Yvonne M; Höfling, Volkmar

2017-07-01

The development and improvement of therapeutic competencies are central aims in psychotherapy training; however, little is known about which training interventions are suitable for the improvement of competencies. In the current pilot study, the efficacy of feedback regarding therapeutic competencies was investigated in cognitive behavioural therapy (CBT). Totally 19 trainee therapists and 19 patients were allocated randomly to a competence feedback group (CFG) or control group (CG). Two experienced clinicians and feedback providers who were blind to the treatment conditions independently evaluated therapeutic competencies on the Cognitive Therapy Scale at five treatment times (i.e., at Sessions 1, 5, 9, 13, and 17). Whereas CFG and CG included regular supervision, only therapists in the CFG additionally received written qualitative and quantitative feedback regarding their demonstrated competencies in conducting CBT during treatment. We found a significant Time × Group interaction effect (η² = .09), which indicates a larger competence increase in the CFG in comparison to the CG. Competence feedback was demonstrated to be suitable for the improvement of therapeutic competencies in CBT. These findings may have important implications for psychotherapy training, clinical practice, and psychotherapy research. However, further research is necessary to ensure the replicability and generalizability of the findings.

Chaos synchronization of uncertain chaotic systems using composite nonlinear feedback based integral sliding mode control.

PubMed

Mobayen, Saleh

2018-06-01

This paper proposes a combination of composite nonlinear feedback and integral sliding mode techniques for fast and accurate chaos synchronization of uncertain chaotic systems with Lipschitz nonlinear functions, time-varying delays and disturbances. The composite nonlinear feedback method allows accurate following of the master chaotic system and the integral sliding mode control provides invariance property which rejects the perturbations and preserves the stability of the closed-loop system. Based on the Lyapunov- Krasovskii stability theory and linear matrix inequalities, a novel sufficient condition is offered for the chaos synchronization of uncertain chaotic systems. This method not only guarantees the robustness against perturbations and time-delays, but also eliminates reaching phase and avoids chattering problem. Simulation results demonstrate that the suggested procedure leads to a great control performance. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Turbulent Extreme Event Simulations for Lidar-Assisted Wind Turbine Control

NASA Astrophysics Data System (ADS)

Schlipf, David; Raach, Steffen

2016-09-01

This work presents a wind field generator which allows to shape wind fields in the time domain while maintaining the spectral properties. This is done by an iterative generation of wind fields and by minimizing the error between wind characteristics of the generated wind fields and desired values. The method leads towards realistic ultimate load calculations for lidar-assisted control. This is demonstrated by fitting a turbulent wind field to an Extreme Operating Gust. The wind field is then used to compare a baseline feedback controller alone against a combined feedback and feedforward controller using simulated lidar measurements. The comparison confirms that the lidar-assisted controller is still able to significantly reduce the ultimate loads on the tower base under this more realistic conditions.

Control of flexible beams using a free-free active truss

NASA Technical Reports Server (NTRS)

Clark, W. W.; Kimiavi, B.; Robertshaw, H. H.

1989-01-01

An analytical and experimental study involving controlling flexible beams using a free-free active truss is presented. This work extends previous work in controlling flexible continua with active trusses which were configured with fixed-free boundary conditions. The following describes the Lagrangian approach used to derive the equations of motion for the active truss and the beams attached to it. A partial-state feedback control law is derived for this system based on a full-state feedback Linear Quadratic Regulator method. The analytical model is examined via numerical simulations and the results are compared to a similar experimental apparatus described herein. The results show that control of a flexible continua is possible with a free-free active truss.

Expert monitoring and verbal feedback as sources of performance pressure.

PubMed

Buchanan, John J; Park, Inchon; Chen, Jing; Mehta, Ranjana K; McCulloch, Austin; Rhee, Joohyun; Wright, David L

2018-05-01

The influence of monitoring-pressure and verbal feedback on the performance of the intrinsically stable bimanual coordination patterns of in-phase and anti-phase was examined. The two bimanual patterns were produced under three conditions: 1) no-monitoring, 2) monitoring-pressure (viewed by experts), and 3) monitoring-pressure (viewed by experts) combined with verbal feedback emphasizing poor performance. The bimanual patterns were produced at self-paced movement frequencies. Anti-phase coordination was always less stable than in-phase coordination across all three conditions. When performed under conditions 2 and 3, both bimanual patterns were performed with less variability in relative phase across a wide range of self-paced movement frequencies compared to the no-monitoring condition. Thus, monitoring-pressure resulted in performance stabilization rather than degradation and the presence of verbal feedback had no impact on the influence of monitoring pressure. The current findings are inconsistent with the predictions of explicit monitoring theory; however, the findings are consistent with studies that have revealed increased stability for the system's intrinsic dynamics as a result of attentional focus and intentional control. The results are discussed within the contexts of the dynamic pattern theory of coordination, explicit monitoring theory, and action-focused theories as explanations for choking under pressure. Copyright © 2018. Published by Elsevier B.V.

Intermittent control: a computational theory of human control.

PubMed

Gawthrop, Peter; Loram, Ian; Lakie, Martin; Gollee, Henrik

2011-02-01

The paradigm of continuous control using internal models has advanced understanding of human motor control. However, this paradigm ignores some aspects of human control, including intermittent feedback, serial ballistic control, triggered responses and refractory periods. It is shown that event-driven intermittent control provides a framework to explain the behaviour of the human operator under a wider range of conditions than continuous control. Continuous control is included as a special case, but sampling, system matched hold, an intermittent predictor and an event trigger allow serial open-loop trajectories using intermittent feedback. The implementation here may be described as "continuous observation, intermittent action". Beyond explaining unimodal regulation distributions in common with continuous control, these features naturally explain refractoriness and bimodal stabilisation distributions observed in double stimulus tracking experiments and quiet standing, respectively. Moreover, given that human control systems contain significant time delays, a biological-cybernetic rationale favours intermittent over continuous control: intermittent predictive control is computationally less demanding than continuous predictive control. A standard continuous-time predictive control model of the human operator is used as the underlying design method for an event-driven intermittent controller. It is shown that when event thresholds are small and sampling is regular, the intermittent controller can masquerade as the underlying continuous-time controller and thus, under these conditions, the continuous-time and intermittent controller cannot be distinguished. This explains why the intermittent control hypothesis is consistent with the continuous control hypothesis for certain experimental conditions.

Designing feedback to mitigate teen distracted driving: A social norms approach.

PubMed

Merrikhpour, Maryam; Donmez, Birsen

2017-07-01

The purpose of this research is to investigate teens' perceived social norms and whether providing normative information can reduce distracted driving behaviors among them. Parents are among the most important social referents for teens; they have significant influences on teens' driving behaviors, including distracted driving which significantly contributes to teens' crash risks. Social norms interventions have been successfully applied in various domains including driving; however, this approach is yet to be explored for mitigating driver distraction among teens. Forty teens completed a driving simulator experiment while performing a self-paced visual-manual secondary task in four between-subject conditions: a) social norms feedback that provided a report at the end of each drive on teens' distracted driving behavior, comparing their distraction engagement to their parent's, b) post-drive feedback that provided just the report on teens' distracted driving behavior without information on their parents, c) real-time feedback in the form of auditory warnings based on eyes of road-time, and d) no feedback as control. Questionnaires were administered to collect data on these teens' and their parents' self-reported engagement in driver distractions and the associated social norms. Social norms and real-time feedback conditions resulted in significantly smaller average off-road glance duration, rate of long (>2s) off-road glances, and standard deviation of lane position compared to no feedback. Further, social norms feedback decreased brake response time and percentage of time not looking at the road compared to no feedback. No major effect was observed for post-drive feedback. Questionnaire results suggest that teens appeared to overestimate parental norms, but no effect of feedback was found on their perceptions. Feedback systems that leverage social norms can help mitigate driver distraction among teens. Overall, both social norms and real-time feedback induced positive driving behaviors, with social norms feedback outperforming real-time feedback. Copyright © 2017 Elsevier Ltd. All rights reserved.

Beer for "brohood": A laboratory simulation of masculinity confirmation through alcohol use behaviors in men.

PubMed

Fugitt, Jessica L; Ham, Lindsay S

2018-05-01

Though alcohol use is a widespread behavior, men tend to drink more and experience more alcohol-related negative consequences than do women. Research suggests that individuals are motivated to maintain ingroup status by engaging in behaviors prototypical of the ingroup when group status has been threatened, and that men are particularly likely to do this when masculine ingroup status is threatened. The present study investigated masculine drinking behaviors through a social lens, examining the impact of masculinity threat on alcohol consumption in a simulated bar laboratory. Sixty-five male students ages 21-29 years (Mage = 22.66; 74% White) consumed beer in a taste-test paradigm after being exposed to randomly assigned personality feedback relative to gender standards. This feedback suggested that they were either low in masculinity (threat condition, n = 22) or high in masculinity (control condition, n = 22). A third condition received the low-masculinity feedback and then were exposed to information to undermine masculine alcohol use norms (undermine condition, n = 21) to account for negative affect reduction motives for use. As hypothesized, individuals in the threat condition consumed significantly more alcohol than those in the control and undermine conditions, even though the threat and undermine conditions reported similar levels of negative affect following masculinity threat. These results suggest that consumption of alcohol by men in social contexts may be strongly motivated by the desire to confirm masculine status. This understanding may be used to enhance the effectiveness of alcohol use intervention protocols. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Evaluation of Alcohol-Related Personalized Normative Feedback With and Without an Injunctive Message

PubMed Central

Steers, Mai-Ly N.; Coffman, Amelia D.; Wickham, Robert E.; Bryan, Jennifer L.; Caraway, Lisa; Neighbors, Clayton

2016-01-01

Objective: Personalized normative feedback (PNF) has been used extensively to reduce alcohol consumption, particularly among heavy drinkers. However, the majority of PNF studies have used only descriptive norms (real or perceived pervasiveness of a given behavior). The purpose of the current study was to explore the efficacy of PNF both with and without an injunctive message indicating approval or disapproval based on the participants’ standing relative to other students’ drinking levels. This randomized trial evaluated two brief web-based alcohol intervention conditions (descriptive-norms-feedback–only condition versus a descriptive-plus-injunctive-message condition relative to an assessment-only control condition). Method: Participants included 176 students who had reported at least one heavy drinking episode in the past month. Participants completed baseline and follow-up assessments of perceived norms and drinking. Follow-up assessments were completed at 2 weeks post-intervention by 165 (94%) participants. Results: Analyses were conducted using zero-inflated negative binomial regression models. As expected, the descriptive-norms–only condition was effective in reducing drinking among heavier baseline drinkers at follow-up relative to the control condition. However, contrary to expectations, the descriptive-plus-injunctive-message condition did not predict less drinking at follow-up. Conclusions: This study was unique in using an injunctive message as an adjunct to descriptive-norms feedback within the context of drinking. Findings highlight the need for additional research into the role of defensiveness, which may serve as an impediment to using injunctive norms/messages in interventions for problematic substance use and other potentially stigmatizing behaviors. PMID:26997192

Influences of arm proprioception and degrees of freedom on postural control with light touch feedback.

PubMed

Rabin, Ely; DiZio, Paul; Ventura, Joel; Lackner, James R

2008-02-01

Lightly touching a stable surface with one fingertip strongly stabilizes standing posture. The three main features of this phenomenon are fingertip contact forces maintained at levels too low to provide mechanical support, attenuation of postural sway relative to conditions without fingertip touch, and center of pressure (CP) lags changes in fingertip shear forces by approximately 250 ms. In the experiments presented here, we tested whether accurate arm proprioception and also whether the precision fingertip contact afforded by the arm's many degrees of freedom are necessary for postural stabilization by finger contact. In our first experiment, we perturbed arm proprioception and control with biceps brachii vibration (120-Hz, 2-mm amplitude). This degraded postural control, resulting in greater postural sway amplitudes. In a second study, we immobilized the touching arm with a splint. This prevented precision fingertip contact but had no effect on postural sway amplitude. In both experiments, the correlation and latency of fingertip contact forces to postural sway were unaffected. We conclude that postural control is executed based on information about arm orientation as well as tactile feedback from light touch, although precision fingertip contact is not essential. The consistent correlation and timing of CP movement and fingertip forces across conditions in which postural sway amplitude and fingertip contact are differentially disrupted suggests posture and the fingertip are controlled in parallel with feedback from the fingertip in this task.

Improving the efficiency of cognitive-behavioural therapy by using formal client feedback.

PubMed

Janse, Pauline D; De Jong, Kim; Van Dijk, Maarten K; Hutschemaekers, Giel J M; Verbraak, Marc J P M

2017-09-01

Feedback from clients on their view of progress and the therapeutic relationship can improve effectiveness and efficiency of psychological treatments in general. However, what the added value is of client feedback specifically within cognitive-behavioural therapy (CBT), is not known. Therefore, the extent to which the outcome of CBT can be improved is investigated by providing feedback from clients to therapists using the Outcome Rating Scale (ORS) and Session Rating Scale (SRS). Outpatients (n = 1006) of a Dutch mental health organization either participated in the "treatment as usual" (TAU) condition, or in Feedback condition of the study. Clients were invited to fill in the ORS and SRS and in the Feedback condition therapists were asked to frequently discuss client feedback. Outcome on the SCL-90 was only improved specifically with mood disorders in the Feedback condition. Also, in the Feedback condition, in terms of process, the total number of required treatment sessions was on average two sessions fewer. Frequently asking feedback from clients using the ORS/SRS does not necessarily result in a better treatment outcome in CBT. However, for an equal treatment outcome significantly fewer sessions are needed within the Feedback condition, thus improving efficiency of CBT.

Atypical valuation of monetary and cigarette rewards in substance dependent smokers.

PubMed

Baker, Travis E; Wood, Jonathan M A; Holroyd, Clay B

2016-02-01

Substance dependent (SD) relative to non-dependent (ND) individuals exhibit an attenuated reward positivity, an electrophysiological signal believed to index sensitivity of anterior cingulate cortex (ACC) to rewards. Here we asked whether this altered neural response reflects a specific devaluation of monetary rewards relative to drug-related rewards by ACC. We recorded the reward positivity from SD and ND individuals who currently smoke, following an overnight period of abstinence, while they engaged in two feedback tasks. In a money condition the feedback indicated either a monetary reward or no reward, and in a cigarette condition the feedback indicated either a drug-related reward or no reward. Overall, cigarette relative to monetary rewards elicited a larger reward positivity. Further, for the subjects who engaged in the money condition first, the reward positivity was smaller for the SD compared to the ND participants, but for the subjects who engaged in the cigarette condition first, the reward positivity was larger for the SD compared to the ND participants. Our results suggest that the initial category of feedback "primed" the response of the ACC to the alternative feedback type on subsequent trials, and that SD and ND individuals responded differently to this priming effect. We propose that for people who misuse addictive substances, the prospect of obtaining drug-related rewards engages the ACC to exert control over extended behaviors. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

The problem of automation: Inappropriate feedback and interaction, not overautomation

NASA Technical Reports Server (NTRS)

Norman, Donald A.

1989-01-01

As automation increasingly takes its place in industry, especially high-risk industry, it is often blamed for causing harm and increasing the chance of human error when failures occur. It is proposed that the problem is not the presence of automation, but rather its inappropriate design. The problem is that the operations are performed appropriately under normal conditions, but there is inadequate feedback and interaction with the humans who must control the overall conduct of the task. When the situations exceed the capabilities of the automatic equipment, then the inadequate feedback leads to difficulties for the human controllers. The problem is that the automation is at an intermediate level of intelligence, powerful enough to take over control that which used to be done by people, but not powerful enough to handle all abnormalities. Moreover, its level of intelligence is insufficient to provide the continual, appropriate feedback that occurs naturally among human operators. To solve this problem, the automation should either be made less intelligent or more so, but the current level is quite inappropriate. The overall message is that it is possible to reduce error through appropriate design considerations.

Negative feedback in ants: crowding results in less trail pheromone deposition

PubMed Central

Czaczkes, Tomer J.; Grüter, Christoph; Ratnieks, Francis L. W.

2013-01-01

Crowding in human transport networks reduces efficiency. Efficiency can be increased by appropriate control mechanisms, which are often imposed externally. Ant colonies also have distribution networks to feeding sites outside the nest and can experience crowding. However, ants do not have external controllers or leaders. Here, we report a self-organized negative feedback mechanism, based on local information, which downregulates the production of recruitment signals in crowded parts of a network by Lasius niger ants. We controlled crowding by manipulating trail width and the number of ants on a trail, and observed a 5.6-fold reduction in the number of ants depositing trail pheromone from least to most crowded conditions. We also simulated crowding by placing glass beads covered in nest-mate cuticular hydrocarbons on the trail. After 10 bead encounters over 20 cm, forager ants were 45 per cent less likely to deposit pheromone. The mechanism of negative feedback reported here is unusual in that it acts by downregulating the production of a positive feedback signal, rather than by direct inhibition or the production of an inhibitory signal. PMID:23365196

Decentralized-feedback pole placement of linear systems

NASA Technical Reports Server (NTRS)

Wang, X.; Martin, C. F.; Gilliam, D.; Byrnes, C. I.

1992-01-01

A projectile product spaces model is used to analyze decentralized systems. The degree of the pole placement map is computed. The conditions under which the degree is odd are also given. Twin lift systems are studied. It is proved that the poles of a twin lift system can be assigned to any values by local static and local dynamic feedback laws if and only if the system is jointly controllable.

Investigation of control system of traction electric drive with feedbacks on load

NASA Astrophysics Data System (ADS)

Kuznetsov, N. K.; Iov, I. A.; Iov, A. A.

2018-03-01

In the article, by the example of a walking excavator, the results of a study of a control system of traction electric drive with a rigid and flexible feedback on the load are mentioned. Based on the analysis of known works, the calculation scheme has been chosen; the equations of motion of the electromechanical system have been obtained, taking into account the elasticity of the rope and feedbacks on the load in the elastic element. A simulation model of this system has been developed and mathematical modeling of the transient processes to evaluate the influence of feedback on the dynamic characteristics of the mechanism and its efficiency of work was carried out. It is shown that the use of rigid and flexible feedbacks makes it possible to reduce dynamic loads in the traction mechanism and to limit the elastic oscillation of the executive mechanism in transient operating modes in comparison with the standard control system; however, there is some decrease in productivity. It has been also established that the sign-variable of the loading of the electric drive, connected with the opening of the backlashes in the gearbox due to the action of feedbacks on the load in the elastic element, under certain conditions, can lead to undesirable phenomena in the operation of the drive and a decrease in the reliability of its operation.

Comparing Feedback Types in Multimedia Learning of Speech by Young Children With Common Speech Sound Disorders: Research Protocol for a Pretest Posttest Independent Measures Control Trial.

PubMed

Doubé, Wendy; Carding, Paul; Flanagan, Kieran; Kaufman, Jordy; Armitage, Hannah

2018-01-01

Children with speech sound disorders benefit from feedback about the accuracy of sounds they make. Home practice can reinforce feedback received from speech pathologists. Games in mobile device applications could encourage home practice, but those currently available are of limited value because they are unlikely to elaborate "Correct"/"Incorrect" feedback with information that can assist in improving the accuracy of the sound. This protocol proposes a "Wizard of Oz" experiment that aims to provide evidence for the provision of effective multimedia feedback for speech sound development. Children with two common speech sound disorders will play a game on a mobile device and make speech sounds when prompted by the game. A human "Wizard" will provide feedback on the accuracy of the sound but the children will perceive the feedback as coming from the game. Groups of 30 young children will be randomly allocated to one of five conditions: four types of feedback and a control which does not play the game. The results of this experiment will inform not only speech sound therapy, but also other types of language learning, both in general, and in multimedia applications. This experiment is a cost-effective precursor to the development of a mobile application that employs pedagogically and clinically sound processes for speech development in young children.

Comparing Feedback Types in Multimedia Learning of Speech by Young Children With Common Speech Sound Disorders: Research Protocol for a Pretest Posttest Independent Measures Control Trial

PubMed Central

Doubé, Wendy; Carding, Paul; Flanagan, Kieran; Kaufman, Jordy; Armitage, Hannah

2018-01-01

Children with speech sound disorders benefit from feedback about the accuracy of sounds they make. Home practice can reinforce feedback received from speech pathologists. Games in mobile device applications could encourage home practice, but those currently available are of limited value because they are unlikely to elaborate “Correct”/”Incorrect” feedback with information that can assist in improving the accuracy of the sound. This protocol proposes a “Wizard of Oz” experiment that aims to provide evidence for the provision of effective multimedia feedback for speech sound development. Children with two common speech sound disorders will play a game on a mobile device and make speech sounds when prompted by the game. A human “Wizard” will provide feedback on the accuracy of the sound but the children will perceive the feedback as coming from the game. Groups of 30 young children will be randomly allocated to one of five conditions: four types of feedback and a control which does not play the game. The results of this experiment will inform not only speech sound therapy, but also other types of language learning, both in general, and in multimedia applications. This experiment is a cost-effective precursor to the development of a mobile application that employs pedagogically and clinically sound processes for speech development in young children. PMID:29674986

Feedback coupling in dynamical systems

NASA Astrophysics Data System (ADS)

Trimper, Steffen; Zabrocki, Knud

2003-05-01

Different evolution models are considered with feedback-couplings. In particular, we study the Lotka-Volterra system under the influence of a cumulative term, the Ginzburg-Landau model with a convolution memory term and chemical rate equations with time delay. The memory leads to a modified dynamical behavior. In case of a positive coupling the generalized Lotka-Volterra system exhibits a maximum gain achieved after a finite time, but the population will die out in the long time limit. In the opposite case, the time evolution is terminated in a crash. Due to the nonlinear feedback coupling the two branches of a bistable model are controlled by the the strength and the sign of the memory. For a negative coupling the system is able to switch over between both branches of the stationary solution. The dynamics of the system is further controlled by the initial condition. The diffusion-limited reaction is likewise studied in case the reacting entities are not available simultaneously. Whereas for an external feedback the dynamics is altered, but the stationary solution remain unchanged, a self-organized internal feedback leads to a time persistent solution.

Overreliance on auditory feedback may lead to sound/syllable repetitions: simulations of stuttering and fluency-inducing conditions with a neural model of speech production.

PubMed

Civier, Oren; Tasko, Stephen M; Guenther, Frank H

2010-09-01

This paper investigates the hypothesis that stuttering may result in part from impaired readout of feedforward control of speech, which forces persons who stutter (PWS) to produce speech with a motor strategy that is weighted too much toward auditory feedback control. Over-reliance on feedback control leads to production errors which if they grow large enough, can cause the motor system to "reset" and repeat the current syllable. This hypothesis is investigated using computer simulations of a "neurally impaired" version of the DIVA model, a neural network model of speech acquisition and production. The model's outputs are compared to published acoustic data from PWS' fluent speech, and to combined acoustic and articulatory movement data collected from the dysfluent speech of one PWS. The simulations mimic the errors observed in the PWS subject's speech, as well as the repairs of these errors. Additional simulations were able to account for enhancements of fluency gained by slowed/prolonged speech and masking noise. Together these results support the hypothesis that many dysfluencies in stuttering are due to a bias away from feedforward control and toward feedback control. The reader will be able to (a) describe the contribution of auditory feedback control and feedforward control to normal and stuttered speech production, (b) summarize the neural modeling approach to speech production and its application to stuttering, and (c) explain how the DIVA model accounts for enhancements of fluency gained by slowed/prolonged speech and masking noise.

Installation of PMV Operation Program in DDC Controller and Air Conditioning Control Using PMV Directly as Set Point

NASA Astrophysics Data System (ADS)

Haramoto, Ken-Ichi

In general, air conditioning control in a building is operated mainly by indoor air temperature control. Although the operators of the machine in the building accepted a claim for indoor air temperature presented by the building inhabitants, the indoor conditions have been often too cool or warm. Therefore, in an attempt to create better thermal environments, the author paid attention to the PMV that is a thermal comfort index. And then, the possibility of air conditioning control using the PMV directly as the set point was verified by employing actual equipment in an air conditioning testing room and an office building. Prior to the execution of this control, the operation program of the PMV was installed in a DDC controller for the air conditioning control. And information from indoor sensors and so on was inputted to the controller, and the computed PMV was used as the feedback variable.

Application of modern control theory to the design of optimum aircraft controllers

NASA Technical Reports Server (NTRS)

Power, L. J.

1973-01-01

The synthesis procedure presented is based on the solution of the output regulator problem of linear optimal control theory for time-invariant systems. By this technique, solution of the matrix Riccati equation leads to a constant linear feedback control law for an output regulator which will maintain a plant in a particular equilibrium condition in the presence of impulse disturbances. Two simple algorithms are presented that can be used in an automatic synthesis procedure for the design of maneuverable output regulators requiring only selected state variables for feedback. The first algorithm is for the construction of optimal feedforward control laws that can be superimposed upon a Kalman output regulator and that will drive the output of a plant to a desired constant value on command. The second algorithm is for the construction of optimal Luenberger observers that can be used to obtain feedback control laws for the output regulator requiring measurement of only part of the state vector. This algorithm constructs observers which have minimum response time under the constraint that the magnitude of the gains in the observer filter be less than some arbitrary limit.

Self-regulation of the anterior insula: Reinforcement learning using real-time fMRI neurofeedback.

PubMed

Lawrence, Emma J; Su, Li; Barker, Gareth J; Medford, Nick; Dalton, Jeffrey; Williams, Steve C R; Birbaumer, Niels; Veit, Ralf; Ranganatha, Sitaram; Bodurka, Jerzy; Brammer, Michael; Giampietro, Vincent; David, Anthony S

2014-03-01

The anterior insula (AI) plays a key role in affective processing, and insular dysfunction has been noted in several clinical conditions. Real-time functional MRI neurofeedback (rtfMRI-NF) provides a means of helping people learn to self-regulate activation in this brain region. Using the Blood Oxygenated Level Dependant (BOLD) signal from the right AI (RAI) as neurofeedback, we trained participants to increase RAI activation. In contrast, another group of participants was shown 'control' feedback from another brain area. Pre- and post-training affective probes were shown, with subjective ratings and skin conductance response (SCR) measured. We also investigated a reward-related reinforcement learning model of rtfMRI-NF. In contrast to the controls, we hypothesised a positive linear increase in RAI activation in participants shown feedback from this region, alongside increases in valence ratings and SCR to affective probes. Hypothesis-driven analyses showed a significant interaction between the RAI/control neurofeedback groups and the effect of self-regulation. Whole-brain analyses revealed a significant linear increase in RAI activation across four training runs in the group who received feedback from RAI. Increased activation was also observed in the caudate body and thalamus, likely representing feedback-related learning. No positive linear trend was observed in the RAI in the group receiving control feedback, suggesting that these data are not a general effect of cognitive strategy or control feedback. The control group did, however, show diffuse activation across the putamen, caudate and posterior insula which may indicate the representation of false feedback. No significant training-related behavioural differences were observed for valence ratings, or SCR. In addition, correlational analyses based on a reinforcement learning model showed that the dorsal anterior cingulate cortex underpinned learning in both groups. In summary, these data demonstrate that it is possible to regulate the RAI using rtfMRI-NF within one scanning session, and that such reward-related learning is mediated by the dorsal anterior cingulate. Copyright © 2013 Elsevier Inc. All rights reserved.

An evaluation of end-point trajectory planning during skilled kicking.

PubMed

Ford, Paul; Hodges, Nicola J; Mark Williams, A

2009-01-01

There is evidence that actions are planned by anticipation of their external effects, with the strength of this effect being dependent on the amount of prior practice. In Experiment 1, skilled soccer players performed a kicking task under four conditions: planning in terms of an external action effect (i.e., ball trajectory) or in terms of body movements, either with or without visual error feedback. When feedback was withheld, a ball focus resulted in more accurate outcomes than a body focus. When visual feedback was allowed, there was no difference between these two conditions. In Experiment 2, both skilled and novice soccer players were tested with the addition of a control condition and in the absence of visual feedback. For both groups there was evidence that a ball focus was more beneficial for performance than a body focus, particularly in terms of movement kinematics where correlations across the joints were generally higher for body rather than ball planning. Most skilled participants reported that ball planning felt more normal than body planning. These experiments provide some evidence that actions are planned in terms of their external action effects, supporting the common-coding hypothesis of action planning.

The human factors of workstation telepresence

NASA Technical Reports Server (NTRS)

Smith, Thomas J.; Smith, Karl U.

1990-01-01

The term workstation telepresence has been introduced to describe human-telerobot compliance, which enables the human operator to effectively project his/her body image and behavioral skills to control of the telerobot itself. Major human-factors considerations for establishing high fidelity workstation telepresence during human-telerobot operation are discussed. Telerobot workstation telepresence is defined by the proficiency and skill with which the operator is able to control sensory feedback from direct interaction with the workstation itself, and from workstation-mediated interaction with the telerobot. Numerous conditions influencing such control have been identified. This raises the question as to what specific factors most critically influence the realization of high fidelity workstation telepresence. The thesis advanced here is that perturbations in sensory feedback represent a major source of variability in human performance during interactive telerobot operation. Perturbed sensory feedback research over the past three decades has established that spatial transformations or temporal delays in sensory feedback engender substantial decrements in interactive task performance, which training does not completely overcome. A recently developed social cybernetic model of human-computer interaction can be used to guide this approach, based on computer-mediated tracking and control of sensory feedback. How the social cybernetic model can be employed for evaluating the various modes, patterns, and integrations of interpersonal, team, and human-computer interactions which play a central role is workstation telepresence are discussed.

Diagonal dominance for the multivariable Nyquist array using function minimization

NASA Technical Reports Server (NTRS)

Leininger, G. G.

1977-01-01

A new technique for the design of multivariable control systems using the multivariable Nyquist array method was developed. A conjugate direction function minimization algorithm is utilized to achieve a diagonal dominant condition over the extended frequency range of the control system. The minimization is performed on the ratio of the moduli of the off-diagonal terms to the moduli of the diagonal terms of either the inverse or direct open loop transfer function matrix. Several new feedback design concepts were also developed, including: (1) dominance control parameters for each control loop; (2) compensator normalization to evaluate open loop conditions for alternative design configurations; and (3) an interaction index to determine the degree and type of system interaction when all feedback loops are closed simultaneously. This new design capability was implemented on an IBM 360/75 in a batch mode but can be easily adapted to an interactive computer facility. The method was applied to the Pratt and Whitney F100 turbofan engine.

Effect of e-learning and repeated performance feedback on spirometry test quality in family practice: a cluster trial.

PubMed

Schermer, Tjard R; Akkermans, Reinier P; Crockett, Alan J; van Montfort, Marian; Grootens-Stekelenburg, Joke; Stout, Jim W; Pieters, Willem

2011-01-01

Spirometry has become an indispensable tool in primary care to exclude, diagnose, and monitor chronic respiratory conditions, but the quality of spirometry tests in family practices is a reason for concern. Aim of this study was to investigate whether a combination of e-learning and bimonthly performance feedback would improve spirometry test quality in family practices in the course of 1 year. Our study was a cluster trial with 19 family practices allocated to intervention or control conditions through minimization. Intervention consisted of e-learning and bimonthly feedback reports to practice nurses. Control practices received only the joint baseline workshop. Spirometry quality was assessed by independent lung function technicians. Two outcomes were defined, with the difference between rates of tests with 2 acceptable and repeatable blows being the primary outcome and the difference between rates of tests with 2 acceptable blows being the secondary outcome. We used multilevel logistic regression analysis to calculate odds ratios (ORs) for an adequate test in intervention group practices. We analyzed 1,135 tests. Rate of adequate tests was 33% in intervention and 30% in control group practices (OR = 1.3; P=.605). Adequacy of tests did not differ between groups but tended to increase with time: OR = 2.2 (P = .057) after 3 and OR = 2.0 (P = .086) in intervention group practices after 4 feedback reports. When ignoring test repeatability, these differences between the groups were slightly more pronounced: OR = 2.4 (P = .033) after 3 and OR=2.2 (P = .051) after 4 feedback reports. In the course of 1 year, we observed a small and late effect of e-learning and repeated feedback on the quality of spirometry as performed by family practice nurses. This intervention does not seem to compensate the lack of rigorous training and experience in performing spirometry tests in most practices.

Worry-inducing stimuli in an aversive Go/NoGo task enhance reactive control in individuals with lower trait-anxiety.

PubMed

Leue, Anja; Rodilla, Carmen Cano; Beauducel, André

2017-04-01

This study relates predictions on reactive and proactive cognitive control to findings on anxious apprehension/worry and ERN/Ne. We investigated whether worry-inducing stimuli in an aversive performance setting lead to a more pronounced increase of the ERN/Ne in individuals with lower anxious apprehension/worry. We also explored the N2 amplitude in the context of worry-inducing stimuli. Fifty-eight participants performed an extended Go/NoGo task. A neutral or fearful face was presented at the beginning of each trial, with the fearful face as a worry-inducing, distracting stimulus. In an aversive feedback condition, aversive feedback was provided for false or too slow responses. We found a more pronounced decrease of the ERN/Ne after worry-inducing stimuli compared to neutral stimuli in participants with lower anxious apprehension/worry. Moreover, less pronounced N2 amplitudes were associated with shorter reaction times in the aversive feedback condition. Implications for future research on error monitoring and trait-anxiety are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of video-feedback intervention on harmonious parent-child interaction and sensitive discipline of parents with intellectual disabilities: A randomized controlled trial.

PubMed

Hodes, M W; Meppelder, M; de Moor, M; Kef, S; Schuengel, C

2018-03-01

This study tested whether video-feedback intervention based on attachment and coercion theory increased harmonious parent-child interaction and sensitive discipline of parents with mild intellectual disabilities or borderline intellectual functioning. Observer ratings of video-recorded structured interaction tasks at home formed pretest, post-test, and 3-month follow-up outcome data in a randomized controlled trial with 85 families. Repeated measures analyses of variance and covariance were conducted to test for the intervention effect and possible moderation by IQ and adaptive functioning. The intervention effect on harmonious parent-child interaction was conditional on parental social adaptive behaviour at pretest, with lower adaptive functioning associated with stronger intervention benefit at post-test and follow-up compared to care as usual. Intervention effects were not conditional on parental IQ. Intervention effects for sensitive discipline were not found. Although the video-feedback intervention did not affect observed parenting for the average parent, it may benefit interaction between children and parents with lower parental adaptive functioning. © 2017 John Wiley & Sons Ltd.

Optimizing personalized normative feedback: the use of gender-specific referents.

PubMed

Lewis, Melissa A; Neighbors, Clayton

2007-03-01

Many brief interventions include personalized normative feedback (PNF) using gender-specific or gender-neutral referents. Several theories suggest that information pertaining to more socially proximal referents should have greater influence on one's behavior compared with more socially distal referents. The current research evaluated whether gender specificity of the normative referent employed in PNF related to intervention efficacy. Following baseline assessment, 185 college students (45.2% women) were randomly assigned to one of three intervention conditions: gender-specific feedback, gender-neutral feedback, or assessment-only control. Immediately after completing measures of perceived norms, alcohol consumption, and gender identity, participants in the gender-neutral and gender-specific intervention conditions were provided with computerized information detailing their own drinking behavior, their perceptions of student drinking, and actual student drinking. After a 1-month follow-up, the results indicated that normative feedback was effective in changing perceived norms and reducing alcohol consumption for both intervention groups for women and men. The results provide support, however, for changes in perceived gender-specific norms as a mediator of the effects of normative feedback on reduced drinking behavior for women only. Additionally, gender-specific feedback was found to be more effective for women higher in gender identity, relative to the gender-neutral feedback. A post-assessment follow-up telephone survey administered to assess potential demand characteristics corroborated the intervention effects. Results extend previous research documenting efficacy of computer delivered PNF. Gender specificity and gender identity appear to be important elements to consider for PNF intervention efficacy for women.

A new decentralised controller design method for a class of strongly interconnected systems

NASA Astrophysics Data System (ADS)

Duan, Zhisheng; Jiang, Zhong-Ping; Huang, Lin

2017-02-01

In this paper, two interconnected structures are first discussed, under which some closed-loop subsystems must be unstable to make the whole interconnected system stable, which can be viewed as a kind of strongly interconnected systems. Then, comparisons with small gain theorem are discussed and large gain interconnected characteristics are shown. A new approach for the design of decentralised controllers is presented by determining the Lyapunov function structure previously, which allows the existence of unstable subsystems. By fully utilising the orthogonal space information of input matrix, some new understandings are presented for the construction of Lyapunov matrix. This new method can deal with decentralised state feedback, static output feedback and dynamic output feedback controllers in a unified framework. Furthermore, in order to reduce the design conservativeness and deal with robustness, a new robust decentralised controller design method is given by combining with the parameter-dependent Lyapunov function method. Some basic rules are provided for the choice of initial variables in Lyapunov matrix or new introduced slack matrices. As byproducts, some linear matrix inequality based sufficient conditions are established for centralised static output feedback stabilisation. Effects of unstable subsystems in nonlinear Lur'e systems are further discussed. The corresponding decentralised controller design method is presented for absolute stability. The examples illustrate that the new method is significantly effective.

Influence of accurate and inaccurate 'split-time' feedback upon 10-mile time trial cycling performance.

PubMed

Wilson, Mathew G; Lane, Andy M; Beedie, Chris J; Farooq, Abdulaziz

2012-01-01

The objective of the study is to examine the impact of accurate and inaccurate 'split-time' feedback upon a 10-mile time trial (TT) performance and to quantify power output into a practically meaningful unit of variation. Seven well-trained cyclists completed four randomised bouts of a 10-mile TT on a SRM™ cycle ergometer. TTs were performed with (1) accurate performance feedback, (2) without performance feedback, (3) and (4) false negative and false positive 'split-time' feedback showing performance 5% slower or 5% faster than actual performance. There were no significant differences in completion time, average power output, heart rate or blood lactate between the four feedback conditions. There were significantly lower (p < 0.001) average [Formula: see text] (ml min(-1)) and [Formula: see text] (l min(-1)) scores in the false positive (3,485 ± 596; 119 ± 33) and accurate (3,471 ± 513; 117 ± 22) feedback conditions compared to the false negative (3,753 ± 410; 127 ± 27) and blind (3,772 ± 378; 124 ± 21) feedback conditions. Cyclists spent a greater amount of time in a '20 watt zone' 10 W either side of average power in the negative feedback condition (fastest) than the accurate feedback (slowest) condition (39.3 vs. 32.2%, p < 0.05). There were no significant differences in the 10-mile TT performance time between accurate and inaccurate feedback conditions, despite significantly lower average [Formula: see text] and [Formula: see text] scores in the false positive and accurate feedback conditions. Additionally, cycling with a small variation in power output (10 W either side of average power) produced the fastest TT. Further psycho-physiological research should examine the mechanism(s) why lower [Formula: see text] and [Formula: see text] scores are observed when cycling in a false positive or accurate feedback condition compared to a false negative or blind feedback condition.

Volitional Control of Heart Rate During Exercise Stress.

ERIC Educational Resources Information Center

LeFevers, Victoria A.

Thirty five volunteer college women were divided into three groups to determine if heart rate could be conditioned instrumentally and lowered during exercise stress on the treadmill. The three groups were a) experimental group I, 15 subjects who received instrumental conditioning with visual feedback; b) instrumental group II, 9 subjects who…

ERPs associated with monitoring and evaluation of monetary reward and punishment in children with ADHD.

PubMed

van Meel, Catharina S; Heslenfeld, Dirk J; Oosterlaan, Jaap; Luman, Marjolein; Sergeant, Joseph A

2011-09-01

Several models of attention-deficit hyperactivity disorder (ADHD) propose abnormalities in the response to behavioural contingencies. Using event-related potentials (ERPs), the present study investigated the monitoring and subsequent evaluation of performance feedback resulting in either reward or punishment in children with ADHD (N = 18) and normal controls (N = 18) aged 8 to 12 years. Children performed a time production task, in which visual performance feedback was given after each response. To manipulate its motivational salience, feedback was coupled with monetary gains, losses or no incentives. Performance feedback signalling omitted gains as well as omitted losses evoked a feedback-related negativity (FRN) in control children. The FRN, however, was entirely absent in children with ADHD in all conditions. Moreover, while losses elicited enhanced amplitudes of the late positive potential (LPP) in controls, omitted rewards had this effect in ADHD. The lack of modulation of the FRN by contingencies in ADHD suggests deficient detection of environmental cues as a function of their motivational significance. LPP findings suggest diminished response to punishment, but oversensitivity to the loss of desired rewards. These findings suggest that children with ADHD have problems assigning relative motivational significance to outcomes of their actions. © 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health.

Speed but not amplitude of visual feedback exacerbates force variability in older adults.

PubMed

Kim, Changki; Yacoubi, Basma; Christou, Evangelos A

2018-06-23

Magnification of visual feedback (VF) impairs force control in older adults. In this study, we aimed to determine whether the age-associated increase in force variability with magnification of visual feedback is a consequence of increased amplitude or speed of visual feedback. Seventeen young and 18 older adults performed a constant isometric force task with the index finger at 5% of MVC. We manipulated the vertical (force gain) and horizontal (time gain) aspect of the visual feedback so participants performed the task with the following VF conditions: (1) high amplitude-fast speed; (2) low amplitude-slow speed; (3) high amplitude-slow speed. Changing the visual feedback from low amplitude-slow speed to high amplitude-fast speed increased force variability in older adults but decreased it in young adults (P < 0.01). Changing the visual feedback from low amplitude-slow speed to high amplitude-slow speed did not alter force variability in older adults (P > 0.2), but decreased it in young adults (P < 0.01). Changing the visual feedback from high amplitude-slow speed to high amplitude-fast speed increased force variability in older adults (P < 0.01) but did not alter force variability in young adults (P > 0.2). In summary, increased force variability in older adults with magnification of visual feedback was evident only when the speed of visual feedback increased. Thus, we conclude that in older adults deficits in the rate of processing visual information and not deficits in the processing of more visual information impair force control.

IRAC Full-Scale Flight Testbed Capabilities

NASA Technical Reports Server (NTRS)

Lee, James A.; Pahle, Joseph; Cogan, Bruce R.; Hanson, Curtis E.; Bosworth, John T.

2009-01-01

Overview: Provide validation of adaptive control law concepts through full scale flight evaluation in a representative avionics architecture. Develop an understanding of aircraft dynamics of current vehicles in damaged and upset conditions Real-world conditions include: a) Turbulence, sensor noise, feedback biases; and b) Coupling between pilot and adaptive system. Simulated damage includes 1) "B" matrix (surface) failures; and 2) "A" matrix failures. Evaluate robustness of control systems to anticipated and unanticipated failures.

High-frequency rTMS on DLPFC increases prosocial attitude in case of decision to support people.

PubMed

Balconi, Michela; Canavesio, Ylenia

2014-02-01

Engaging in prosocial behavior was explored in the present research, by investigating the role of dorsolateral prefrontal cortex (DLPFC) in modulation of intention to support other people and of emotional attuning as it was expressed by facial feedback (electromiography, EMG). High-frequency rTMS was applied on DLPFC to 25 subjects when they were required to choose to directly intervene or not to support other people in emotionally valenced social situations (cooperative, noncooperative, conflictual, neutral contexts). Two control conditions were included in the experimental design to control the simple stimulation effect (sham condition with absence of TMS stimulation) and the location effect (control site condition with Pz stimulation). In comparison with sham and control condition, rTMS stimulation induced increased prosocial behavior in all the emotional situations. Moreover, as a function of valence, zygomatic (for positive situations) and corrugators (for negative situations) muscle activity was increased, with significant effect by DLPFC stimulation which induced a "facilitation effect". In addition, negative situations showed a higher rTMS impact for both behavioral and EMG responsiveness. Finally, prosocial behavior was found to be predicted (regression analysis) by EMG variations, as a function of the negative versus positive valence. The prefrontal circuit was suggested to support emotional responsiveness and facial feedback in order to facilitate the prosocial behavior.

Consensus for multi-agent systems with time-varying input delays

NASA Astrophysics Data System (ADS)

Yuan, Chengzhi; Wu, Fen

2017-10-01

This paper addresses the consensus control problem for linear multi-agent systems subject to uniform time-varying input delays and external disturbance. A novel state-feedback consensus protocol is proposed under the integral quadratic constraint (IQC) framework, which utilises not only the relative state information from neighbouring agents but also the real-time information of delays by means of the dynamic IQC system states for feedback control. Based on this new consensus protocol, the associated IQC-based control synthesis conditions are established and fully characterised as linear matrix inequalities (LMIs), such that the consensus control solution with optimal ? disturbance attenuation performance can be synthesised efficiently via convex optimisation. A numerical example is used to demonstrate the proposed approach.

Regional robust stabilisation and domain-of-attraction estimation for MIMO uncertain nonlinear systems with input saturation

NASA Astrophysics Data System (ADS)

Azizi, S.; Torres, L. A. B.; Palhares, R. M.

2018-01-01

The regional robust stabilisation by means of linear time-invariant state feedback control for a class of uncertain MIMO nonlinear systems with parametric uncertainties and control input saturation is investigated. The nonlinear systems are described in a differential algebraic representation and the regional stability is handled considering the largest ellipsoidal domain-of-attraction (DOA) inside a given polytopic region in the state space. A novel set of sufficient Linear Matrix Inequality (LMI) conditions with new auxiliary decision variables are developed aiming to design less conservative linear state feedback controllers with corresponding larger DOAs, by considering the polytopic description of the saturated inputs. A few examples are presented showing favourable comparisons with recently published similar control design methodologies.

Influence of Electrotactile Tongue Feedback on Controlling Upright Stance during Rotational and/or Translational Sway-referencing with Galvanic Vestibular Stimulation

NASA Technical Reports Server (NTRS)

Wood, Scott J.; Tyler, Mitchell E.; Bach-y-Rita, Paul; MacDougall, Hamish G.; Moore, Steven T.; Stallings, Valerie L.; Paloski, William H.; Black, F. Owen

2007-01-01

Integration of multi-sensory inputs to detect tilts relative to gravity is critical for sensorimotor control of upright orientation. Displaying body orientation using electrotactile feedback to the tongue has been developed by Bach-y-Rita and colleagues as a sensory aid to maintain upright stance with impaired vestibular feedback. MacDougall et al. (2006) recently demonstrated that unpredictably varying Galvanic vestibular stimulation (GVS) significantly increased anterior-posterior (AP) sway during rotational sway referencing with eyes closed. The purpose of this study was to assess the influence of electrotactile feedback on postural control performance with pseudorandom binaural bipolar GVS. Postural equilibrium was measured with a computerized hydraulic platform in 10 healthy adults (6M, 4F, 24-65 y). Tactile feedback (TF) of pitch and roll body orientation was derived from a two-axis linear accelerometer mounted on a torso belt and displayed on a 144-point electrotactile array held against the anterior dorsal tongue (BrainPort, Wicab, Inc., Middleton, WI). Subjects were trained to use TF by voluntarily swaying to draw figures on their tongue, both with and without GVS. Subjects were required to keep the intraoral display in their mouths on all trials, including those that did not provide TF. Subjects performed 24 randomized trials (20 s duration with eyes closed) including four support surface conditions (fixed, rotational sway-referenced, translating the support surface proportional to AP sway, and combined rotational-translational sway-referencing), each repeated twice with and without GVS, and with combined GVS and TF. Postural performance was assessed using deviations from upright (peak-to-peak and RMS sway) and convergence toward stability limits (time and distance to base of support boundaries). Postural stability was impaired with GVS in all platform conditions, with larger decrements in performance during trials with rotation sway-referencing. Electrotactile feedback improved performance with GVS toward non-GVS levels, again with the greatest improvement during trials with rotation sway-referencing. These results demonstrate the effectiveness of tongue electrotactile feedback in providing sensory substitution to maintain postural stability with distorted vestibular input.

Alterations in Neural Control of Constant Isometric Contraction with the Size of Error Feedback

PubMed Central

Hwang, Ing-Shiou; Lin, Yen-Ting; Huang, Wei-Min; Yang, Zong-Ru; Hu, Chia-Ling; Chen, Yi-Ching

2017-01-01

Discharge patterns from a population of motor units (MUs) were estimated with multi-channel surface electromyogram and signal processing techniques to investigate parametric differences in low-frequency force fluctuations, MU discharges, and force-discharge relation during static force-tracking with varying sizes of execution error presented via visual feedback. Fourteen healthy adults produced isometric force at 10% of maximal voluntary contraction through index abduction under three visual conditions that scaled execution errors with different amplification factors. Error-augmentation feedback that used a high amplification factor (HAF) to potentiate visualized error size resulted in higher sample entropy, mean frequency, ratio of high-frequency components, and spectral dispersion of force fluctuations than those of error-reducing feedback using a low amplification factor (LAF). In the HAF condition, MUs with relatively high recruitment thresholds in the dorsal interosseous muscle exhibited a larger coefficient of variation for inter-spike intervals and a greater spectral peak of the pooled MU coherence at 13–35 Hz than did those in the LAF condition. Manipulation of the size of error feedback altered the force-discharge relation, which was characterized with non-linear approaches such as mutual information and cross sample entropy. The association of force fluctuations and global discharge trace decreased with increasing error amplification factor. Our findings provide direct neurophysiological evidence that favors motor training using error-augmentation feedback. Amplification of the visualized error size of visual feedback could enrich force gradation strategies during static force-tracking, pertaining to selective increases in the discharge variability of higher-threshold MUs that receive greater common oscillatory inputs in the β-band. PMID:28125658

? PID output-feedback control under event-triggered protocol

NASA Astrophysics Data System (ADS)

Zhao, Di; Wang, Zidong; Ding, Derui; Wei, Guoliang; Alsaadi, Fuad E.

2018-07-01

This paper is concerned with the ? proportional-integral-derivative (PID) output-feedback control problem for a class of linear discrete-time systems under event-triggered protocols. The controller and the actuators are connected through a communication network of limited bandwidth, and an event-triggered communication mechanism is adopted to decide when a certain control signal should be transmitted to the respective actuator. Furthermore, a novel PID output-feedback controller is designed where the accumulative sum-loop (the counterpart to the integral-loop in the continues-time setting) operates on a limited time-window with hope to mitigate the effect from the past measurement data. The main objective of the problem under consideration is to design a desired PID controller such that the closed-loop system is exponentially stable and the prescribed ? disturbance rejection attenuation level is guaranteed under event-triggered protocols. By means of the Lyapunov stability theory combined with the orthogonal decomposition, sufficient conditions are established under which the addressed PID controller design problem is recast into a linear convex optimization one that can be easily solved via available software packages. Finally, a simulation example is exploited to illustrate the usefulness and effectiveness of the established control scheme.

Control of birhythmicity: A self-feedback approach

NASA Astrophysics Data System (ADS)

Biswas, Debabrata; Banerjee, Tanmoy; Kurths, Jürgen

2017-06-01

Birhythmicity occurs in many natural and artificial systems. In this paper, we propose a self-feedback scheme to control birhythmicity. To establish the efficacy and generality of the proposed control scheme, we apply it on three birhythmic oscillators from diverse fields of natural science, namely, an energy harvesting system, the p53-Mdm2 network for protein genesis (the OAK model), and a glycolysis model (modified Decroly-Goldbeter model). Using the harmonic decomposition technique and energy balance method, we derive the analytical conditions for the control of birhythmicity. A detailed numerical bifurcation analysis in the parameter space establishes that the control scheme is capable of eliminating birhythmicity and it can also induce transitions between different forms of bistability. As the proposed control scheme is quite general, it can be applied for control of several real systems, particularly in biochemical and engineering systems.

A simulator-based nuclear reactor emergency response training exercise.

PubMed

Waller, Edward; Bereznai, George; Shaw, John; Chaput, Joseph; Lafortune, Jean-Francois

Training offsite emergency response personnel basic awareness of onsite control room operations during nuclear power plant emergency conditions was the primary objective of a week-long workshop conducted on a CANDU® virtual nuclear reactor simulator available at the University of Ontario Institute of Technology, Oshawa, Canada. The workshop was designed to examine both normal and abnormal reactor operating conditions, and to observe the conditions in the control room that may have impact on the subsequent offsite emergency response. The workshop was attended by participants from a number of countries encompassing diverse job functions related to nuclear emergency response. Objectives of the workshop were to provide opportunities for participants to act in the roles of control room personnel under different reactor operating scenarios, providing a unique experience for participants to interact with the simulator in real-time, and providing increased awareness of control room operations during accident conditions. The ability to "pause" the simulator during exercises allowed the instructors to evaluate and critique the performance of participants, and to provide context with respect to potential offsite emergency actions. Feedback from the participants highlighted (i) advantages of observing and participating "hands-on" with operational exercises, (ii) their general unfamiliarity with control room operational procedures and arrangements prior to the workshop, (iii) awareness of the vast quantity of detailed control room procedures for both normal and transient conditions, and (iv) appreciation of the increased workload for the operators in the control room during a transient from normal operations. Based upon participant feedback, it was determined that the objectives of the training had been met, and that future workshops should be conducted.

Switching State-Feedback LPV Control with Uncertain Scheduling Parameters

NASA Technical Reports Server (NTRS)

He, Tianyi; Al-Jiboory, Ali Khudhair; Swei, Sean Shan-Min; Zhu, Guoming G.

2017-01-01

This paper presents a new method to design Robust Switching State-Feedback Gain-Scheduling (RSSFGS) controllers for Linear Parameter Varying (LPV) systems with uncertain scheduling parameters. The domain of scheduling parameters are divided into several overlapped subregions to undergo hysteresis switching among a family of simultaneously designed LPV controllers over the corresponding subregion with the guaranteed H-infinity performance. The synthesis conditions are given in terms of Parameterized Linear Matrix Inequalities that guarantee both stability and performance at each subregion and associated switching surfaces. The switching stability is ensured by descent parameter-dependent Lyapunov function on switching surfaces. By solving the optimization problem, RSSFGS controller can be obtained for each subregion. A numerical example is given to illustrate the effectiveness of the proposed approach over the non-switching controllers.

The impact of immediate or delayed feedback on driving behaviour in a simulated Pay-As-You-Drive system.

PubMed

Dijksterhuis, Chris; Lewis-Evans, Ben; Jelijs, Bart; de Waard, Dick; Brookhuis, Karel; Tucha, Oliver

2015-02-01

Pay-As-You-Drive (PAYD) insurance links an individual's driving behaviour to the insurance fee that they pay, making car insurance more actuarially accurate. The best known PAYD insurance format is purely mileage based and is estimated to reduce accidents by about 15% (Litman, 2011). However, these benefits could be further enhanced by incorporating a wider range of driving behaviours, such as lateral and longitudinal accelerations and speeding behaviour, thereby stimulating not only a safe but also an eco-friendly driving style. Currently, feedback on rewards and driver behaviour is mostly provided through a web-based interface, which is presented temporally separated from driving. However, providing immediate feedback within the vehicle itself could elicit more effect. To investigate this hypothesis, two groups of 20 participants drove with a behavioural based PAYD system in a driving simulator and were provided with either delayed feedback through a website, or immediate feedback through an in-car interface, allowing them to earn up to €6 extra. To be clear, every participant in the web group did actually view their feedback during the one week between sessions. Results indicate clear driving behaviour improvements for both PAYD groups as compared to baseline rides and an equal sized control group. After both PAYD groups had received feedback, the initial advantage of the in-car group was reduced substantially. Taken together with usability ratings and driving behaviours in specific situations these results show a moderate advantage of using immediate in-car feedback. However, the study also showed that under conditions of feedback certainty, the effectiveness of delayed feedback approaches that of immediate feedback as compared to a naïve control group. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of feedback on attitudes toward cellular phone use while driving: a comparison between novice and experienced drivers.

PubMed

Wang, Ying; Zhang, Wei; Reimer, Bryan; Lavallière, Martin; Lesch, Mary F; Horrey, William J; Wu, Su

2010-10-01

To assess and compare the effectiveness of a simulation-based approach to change drivers' attitudes toward cellular phone use while driving for younger novice and older experienced drivers. Thirty young novice drivers were tested on a driving simulator in this study. Their performance in dealing with driving tasks was measured for a single task and dual tasks (driving while using a cellular phone) and compared to 30 older experienced drivers tested previously in another study. Half of the younger drivers received video-based feedback regarding their performance in the two conditions, with an emphasis on the contribution of dual-tasking to degraded performance. The other half did not receive any performance feedback. Drivers' perceptions and attitudes toward cellular phone use while driving were investigated by a questionnaire before, immediately after, and again one month following the simulation-based testing for both groups of drivers (feedback; no feedback). All drivers (including the novice and experienced) reported willingness to engage in driving and talking on a cellular phone in some situations. The simulated driving test showed that a secondary cellular phone task significantly degraded driving performance for both the novice and the experienced drivers. The feedback treatment group (both the novice and the experienced) showed significant attitude change toward cellular phone use while driving (toward being less favorable), whereas the control group had no attitude change. At the one-month follow-up, the benefit of feedback was sustained more so in the experienced driver group than the novice driver group, although both groups still benefited relative to the control conditions. Simulation-based feedback training is promising for short-term education in novice drivers but may be more effective in the long-term for drivers with higher levels of experience. Drivers with more experience appear to have a greater, more sustained benefit from the training than novices. Additional research is needed to better tailor this education method toward novice drivers. Simulation-based participative education approach through feedback needs to be better tailored toward novice drivers.

mHealth or eHealth? Efficacy, Use, and Appreciation of a Web-Based Computer-Tailored Physical Activity Intervention for Dutch Adults: A Randomized Controlled Trial.

PubMed

Gomez Quiñonez, Stefanie; Walthouwer, Michel Jean Louis; Schulz, Daniela Nadine; de Vries, Hein

2016-11-09

Until a few years ago, Web-based computer-tailored interventions were almost exclusively delivered via computer (eHealth). However, nowadays, interventions delivered via mobile phones (mHealth) are an interesting alternative for health promotion, as they may more easily reach people 24/7. The first aim of this study was to compare the efficacy of an mHealth and an eHealth version of a Web-based computer-tailored physical activity intervention with a control group. The second aim was to assess potential differences in use and appreciation between the 2 versions. We collected data among 373 Dutch adults at 5 points in time (baseline, after 1 week, after 2 weeks, after 3 weeks, and after 6 months). We recruited participants from a Dutch online research panel and randomly assigned them to 1 of 3 conditions: eHealth (n=138), mHealth (n=108), or control condition (n=127). All participants were asked to complete questionnaires at the 5 points in time. Participants in the eHealth and mHealth group received fully automated tailored feedback messages about their current level of physical activity. Furthermore, they received personal feedback aimed at increasing their amount of physical activity when needed. We used analysis of variance and linear regression analyses to examine differences between the 2 study groups and the control group with regard to efficacy, use, and appreciation. Participants receiving feedback messages (eHealth and mHealth together) were significantly more physically active after 6 months than participants in the control group (B=8.48, df=2, P=.03, Cohen d=0.27). We found a small effect size favoring the eHealth condition over the control group (B=6.13, df=2, P=.09, Cohen d=0.21). The eHealth condition had lower dropout rates (117/138, 84.8%) than the mHealth condition (81/108, 75.0%) and the control group (91/127, 71.7%). Furthermore, in terms of usability and appreciation, the eHealth condition outperformed the mHealth condition with regard to participants receiving (t 182 =3.07, P=.002) and reading the feedback messages (t 181 =2.34, P=.02), as well as the clarity of the messages (t 181 =1.99, P=.049). We tested 2 Web-based computer-tailored physical activity intervention versions (mHealth and eHealth) against a control condition with regard to efficacy, use, usability, and appreciation. The overall effect was mainly caused by the more effective eHealth intervention. The mHealth app was rated inferior to the eHealth version with regard to usability and appreciation. More research is needed to assess how both methods can complement each other. Netherlands Trial Register: NTR4503; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4503 (Archived by WebCite at http://www.webcitation.org/6lEi1x40s). ©Stefanie Gomez Quiñonez, Michel Jean Louis Walthouwer, Daniela Nadine Schulz, Hein de Vries. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 09.11.2016.

Sex-ratio control erodes sexual selection, revealing evolutionary feedback from adaptive plasticity.

PubMed

Fawcett, Tim W; Kuijper, Bram; Weissing, Franz J; Pen, Ido

2011-09-20

Female choice is a powerful selective force, driving the elaboration of conspicuous male ornaments. This process of sexual selection has profound implications for many life-history decisions, including sex allocation. For example, females with attractive partners should produce more sons, because these sons will inherit their father's attractiveness and enjoy high mating success, thereby yielding greater fitness returns than daughters. However, previous research has overlooked the fact that there is a reciprocal feedback from life-history strategies to sexual selection. Here, using a simple mathematical model, we show that if mothers adaptively control offspring sex in relation to their partner's attractiveness, sexual selection is weakened and male ornamentation declines. This weakening occurs because the ability to determine offspring sex reduces the fitness difference between females with attractive and unattractive partners. We use individual-based, evolutionary simulations to show that this result holds under more biologically realistic conditions. Sexual selection and sex allocation thus interact in a dynamic fashion: The evolution of conspicuous male ornaments favors sex-ratio adjustment, but this conditional strategy then undermines the very same process that generated it, eroding sexual selection. We predict that, all else being equal, the most elaborate sexual displays should be seen in species with little or no control over offspring sex. The feedback process we have described points to a more general evolutionary principle, in which a conditional strategy weakens directional selection on another trait by reducing fitness differences.

A neutral functional differential equation of Lurie type. [on asymptotic stability of feedback control

NASA Technical Reports Server (NTRS)

Chukwu, E. N.

1980-01-01

The problem of Lurie is posed for systems described by a functional differential equation of neutral type. Sufficient conditions are obtained for absolute stability for the controlled system if it is assumed that the uncontrolled plant equation is uniformly asymptotically stable. Both the direct and indirect control cases are treated.

Pitch matching accuracy of trained singers, untrained subjects with talented singing voices, and untrained subjects with nontalented singing voices in conditions of varying feedback.

PubMed

Watts, Christopher; Murphy, Jessica; Barnes-Burroughs, Kathryn

2003-06-01

At a physiological level, the act of singing involves control and coordination of several systems involved in the production of sound, including respiration, phonation, resonance, and afferent systems used to monitor production. The ability to produce a melodious singing voice (eg, in tune with accurate pitch) is dependent on control over these motor and sensory systems. To test this position, trained singers and untrained subjects with and without expressed singing talent were asked to match pitches of target pure tones. The ability to match pitch reflected the ability to accurately integrate sensory perception with motor planning and execution. Pitch-matching accuracy was measured at the onset of phonation (prephonatory set) before external feedback could be utilized to adjust the voiced source, during phonation when external auditory feedback could be utilized, and during phonation when external auditory feedback was masked. Results revealed trained singers and untrained subjects with singing talent were no different in their pitch-matching abilities when measured before or after external feedback could be utilized. The untrained subjects with singing talent were also significantly more accurate than the trained singers when external auditory feedback was masked. Both groups were significantly more accurate than the untrained subjects without singing talent.

Non-linguistic learning in aphasia: Effects of training method and stimulus characteristics

PubMed Central

Vallila-Rohter, Sofia; Kiran, Swathi

2013-01-01

Purpose The purpose of the current study was to explore non-linguistic learning ability in patients with aphasia, examining the impact of stimulus typicality and feedback on success with learning. Method Eighteen patients with aphasia and eight healthy controls participated in this study. All participants completed four computerized, non-linguistic category-learning tasks. We probed learning ability under two methods of instruction: feedback-based (FB) and paired-associate (PA). We also examined the impact of task complexity on learning ability, comparing two stimulus conditions: typical (Typ) and atypical (Atyp). Performance was compared between groups and across conditions. Results Results demonstrated that healthy controls were able to successfully learn categories under all conditions. For our patients with aphasia, two patterns of performance arose. One subgroup of patients was able to maintain learning across task manipulations and conditions. The other subgroup of patients demonstrated a sensitivity to task complexity, learning successfully only in the typical training conditions. Conclusions Results support the hypothesis that impairments of general learning are present in aphasia. Some patients demonstrated the ability to extract category information under complex training conditions, while others learned only under conditions that were simplified and emphasized salient category features. Overall, the typical training condition facilitated learning for all participants. Findings have implications for therapy, which are discussed. PMID:23695914

Robust Stabilization of Uncertain Systems Based on Energy Dissipation Concepts

NASA Technical Reports Server (NTRS)

Gupta, Sandeep

1996-01-01

Robust stability conditions obtained through generalization of the notion of energy dissipation in physical systems are discussed in this report. Linear time-invariant (LTI) systems which dissipate energy corresponding to quadratic power functions are characterized in the time-domain and the frequency-domain, in terms of linear matrix inequalities (LMls) and algebraic Riccati equations (ARE's). A novel characterization of strictly dissipative LTI systems is introduced in this report. Sufficient conditions in terms of dissipativity and strict dissipativity are presented for (1) stability of the feedback interconnection of dissipative LTI systems, (2) stability of dissipative LTI systems with memoryless feedback nonlinearities, and (3) quadratic stability of uncertain linear systems. It is demonstrated that the framework of dissipative LTI systems investigated in this report unifies and extends small gain, passivity, and sector conditions for stability. Techniques for selecting power functions for characterization of uncertain plants and robust controller synthesis based on these stability results are introduced. A spring-mass-damper example is used to illustrate the application of these methods for robust controller synthesis.

Methane Feedback on Atmospheric Chemistry: Methods, Models, and Mechanisms

NASA Astrophysics Data System (ADS)

Holmes, Christopher D.

2018-04-01

The atmospheric methane (CH4) chemical feedback is a key process for understanding the behavior of atmospheric CH4 and its environmental impact. This work reviews how the feedback is defined and used, then examines the meteorological, chemical, and emission factors that control the feedback strength. Geographical and temporal variations in the feedback are described and explained by HOx (HOx = OH + HO2) production and partitioning. Different CH4 boundary conditions used by models, however, make no meaningful difference to the feedback calculation. The strength of the CH4 feedback depends on atmospheric composition, particularly the atmospheric CH4 burden, and is therefore not constant. Sensitivity tests show that the feedback depends very weakly on temperature, insolation, water vapor, and emissions of NO. While the feedback strength has likely remained within 10% of its present value over the industrial era and likely will over the twenty-first century, neglecting these changes biases our understanding of CH4 impacts. Most environmental consequences per kg of CH4 emissions, including its global warming potential (GWP), scale with the perturbation time, which may have grown as much as 40% over the industrial era and continues to rise.

Effects of voice style, noise level, and acoustic feedback on objective and subjective voice evaluations

PubMed Central

Bottalico, Pasquale; Graetzer, Simone; Hunter, Eric J.

2015-01-01

Speakers adjust their vocal effort when communicating in different room acoustic and noise conditions and when instructed to speak at different volumes. The present paper reports on the effects of voice style, noise level, and acoustic feedback on vocal effort, evaluated as sound pressure level, and self-reported vocal fatigue, comfort, and control. Speakers increased their level in the presence of babble and when instructed to talk in a loud style, and lowered it when acoustic feedback was increased and when talking in a soft style. Self-reported responses indicated a preference for the normal style without babble noise. PMID:26723357

Global neural dynamic surface tracking control of strict-feedback systems with application to hypersonic flight vehicle.

PubMed

Xu, Bin; Yang, Chenguang; Pan, Yongping

2015-10-01

This paper studies both indirect and direct global neural control of strict-feedback systems in the presence of unknown dynamics, using the dynamic surface control (DSC) technique in a novel manner. A new switching mechanism is designed to combine an adaptive neural controller in the neural approximation domain, together with the robust controller that pulls the transient states back into the neural approximation domain from the outside. In comparison with the conventional control techniques, which could only achieve semiglobally uniformly ultimately bounded stability, the proposed control scheme guarantees all the signals in the closed-loop system are globally uniformly ultimately bounded, such that the conventional constraints on initial conditions of the neural control system can be relaxed. The simulation studies of hypersonic flight vehicle (HFV) are performed to demonstrate the effectiveness of the proposed global neural DSC design.

Optimizing Personalized Normative Feedback: The Use of Gender-Specific Referents*

PubMed Central

LEWIS, MELISSA A.; NEIGHBORS, CLAYTON

2008-01-01

Objective Many brief interventions include personalized normative feedback (PNF) using gender-specific or gender-neutral referents. Several theories suggest that information pertaining to more socially proximal referents should have greater influence on one’s behavior compared with more socially distal referents. The current research evaluated whether gender specificity of the normative referent employed in PNF related to intervention efficacy. Method Following baseline assessment, 185 college students (45.2% women) were randomly assigned to one of three intervention conditions: gender-specific feedback, gender-neutral feedback, or assessment-only control. Immediately after completing measures of perceived norms, alcohol consumption, and gender identity, participants in the gender-neutral and gender-specific intervention conditions were provided with computerized information detailing their own drinking behavior, their perceptions of student drinking, and actual student drinking. Results After a 1-month follow-up, the results indicated that normative feedback was effective in changing perceived norms and reducing alcohol consumption for both intervention groups for women and men. The results provide support, however, for changes in perceived gender-specific norms as a mediator of the effects of normative feedback on reduced drinking behavior for women only. Additionally, gender-specific feedback was found to be more effective for women higher in gender identity, relative to the gender-neutral feedback. A post-assessment follow-up telephone survey administered to assess potential demand characteristics corroborated the intervention effects. Conclusions Results extend previous research documenting efficacy of computer delivered PNF. Gender specificity and gender identity appear to be important elements to consider for PNF intervention efficacy for women. PMID:17286341

Similar brain networks for detecting visuo-motor and visuo-proprioceptive synchrony.

PubMed

Balslev, Daniela; Nielsen, Finn A; Lund, Torben E; Law, Ian; Paulson, Olaf B

2006-05-15

The ability to recognize feedback from own movement as opposed to the movement of someone else is important for motor control and social interaction. The neural processes involved in feedback recognition are incompletely understood. Two competing hypotheses have been proposed: the stimulus is compared with either (a) the proprioceptive feedback or with (b) the motor command and if they match, then the external stimulus is identified as feedback. Hypothesis (a) predicts that the neural mechanisms or brain areas involved in distinguishing self from other during passive and active movement are similar, whereas hypothesis (b) predicts that they are different. In this fMRI study, healthy subjects saw visual cursor movement that was either synchronous or asynchronous with their active or passive finger movements. The aim was to identify the brain areas where the neural activity depended on whether the visual stimulus was feedback from own movement and to contrast the functional activation maps for active and passive movement. We found activity increases in the right temporoparietal cortex in the condition with asynchronous relative to synchronous visual feedback from both active and passive movements. However, no statistically significant difference was found between these sets of activated areas when the active and passive movement conditions were compared. With a posterior probability of 0.95, no brain voxel had a contrast effect above 0.11% of the whole-brain mean signal. These results do not support the hypothesis that recognition of visual feedback during active and passive movement relies on different brain areas.

Impact of social pressure on stereotypes about obese people.

PubMed

Harper, Jessica; Carels, Robert A

2014-01-01

This study was designed to test the effects of different types of influence on the expression of stereotypes towards people who are obese. It was hypothesized that public social pressure would more significantly impact the expression of stereotypes towards obese people than other types of influence. One-hundred fifty-eight undergraduate students were randomly assigned to one of three conditions or a control condition. Participants completed measures of stereotypes towards obese people prior to and after receiving manipulated feedback depicting purported stereotypes possessed by others (anonymously or publically) or scientific information about the base rates of these stereotypical traits in the obese population (i.e., trait prevalence). Participants also completed a measure of weight bias unrelated to the manipulated feedback. Explicit beliefs were influenced more when people perceived that others' views were inconsistent with their own in a public setting than an anonymous setting or when they received trait prevalence feedback. However, levels of weight bias on a separate measure were unchanged. Strong, public manipulations of social feedback have great potential to impact, at least, the short-term expression of stereotypes towards obese people.

Influence of facial feedback during a cooperative human-robot task in schizophrenia.

PubMed

Cohen, Laura; Khoramshahi, Mahdi; Salesse, Robin N; Bortolon, Catherine; Słowiński, Piotr; Zhai, Chao; Tsaneva-Atanasova, Krasimira; Di Bernardo, Mario; Capdevielle, Delphine; Marin, Ludovic; Schmidt, Richard C; Bardy, Benoit G; Billard, Aude; Raffard, Stéphane

2017-11-03

Rapid progress in the area of humanoid robots offers tremendous possibilities for investigating and improving social competences in people with social deficits, but remains yet unexplored in schizophrenia. In this study, we examined the influence of social feedbacks elicited by a humanoid robot on motor coordination during a human-robot interaction. Twenty-two schizophrenia patients and twenty-two matched healthy controls underwent a collaborative motor synchrony task with the iCub humanoid robot. Results revealed that positive social feedback had a facilitatory effect on motor coordination in the control participants compared to non-social positive feedback. This facilitatory effect was not present in schizophrenia patients, whose social-motor coordination was similarly impaired in social and non-social feedback conditions. Furthermore, patients' cognitive flexibility impairment and antipsychotic dosing were negatively correlated with patients' ability to synchronize hand movements with iCub. Overall, our findings reveal that patients have marked difficulties to exploit facial social cues elicited by a humanoid robot to modulate their motor coordination during human-robot interaction, partly accounted for by cognitive deficits and medication. This study opens new perspectives for comprehension of social deficits in this mental disorder.

Tracking performance under time sharing conditions with a digit processing task: A feedback control theory analysis. [attention sharing effect on operator performance

NASA Technical Reports Server (NTRS)

Gopher, D.; Wickens, C. D.

1975-01-01

A one dimensional compensatory tracking task and a digit processing reaction time task were combined in a three phase experiment designed to investigate tracking performance in time sharing. Adaptive techniques, elaborate feedback devices, and on line standardization procedures were used to adjust task difficulty to the ability of each individual subject and manipulate time sharing demands. Feedback control analysis techniques were employed in the description of tracking performance. The experimental results show that when the dynamics of a system are constrained, in such a manner that man machine system stability is no longer a major concern of the operator, he tends to adopt a first order control describing function, even with tracking systems of higher order. Attention diversion to a concurrent task leads to an increase in remnant level, or nonlinear power. This decrease in linearity is reflected both in the output magnitude spectra of the subjects, and in the linear fit of the amplitude ratio functions.

The SpeechEasy device in stuttering and nonstuttering adults: fluency effects while speaking and reading.

PubMed

Foundas, Anne L; Mock, Jeffrey R; Corey, David M; Golob, Edward J; Conture, Edward G

2013-08-01

The SpeechEasy is an electronic device designed to alleviate stuttering by manipulating auditory feedback via time delays and frequency shifts. Device settings (control, default, custom), ear-placement (left, right), speaking task, and cognitive variables were examined in people who stutter (PWS) (n=14) compared to controls (n=10). Among the PWS there was a significantly greater reduction in stuttering (compared to baseline) with custom device settings compared to the non-altered feedback (control) condition. Stuttering was reduced the most during reading, followed by narrative and conversation. For the conversation task, stuttering was reduced more when the device was worn in the left ear. Those individuals with a more severe stuttering rate at baseline had a greater benefit from the use of the device compared to individuals with less severe stuttering. Our results support the view that overt stuttering is associated with defective speech-language monitoring that can be influenced by manipulating auditory feedback. Copyright © 2013 Elsevier Inc. All rights reserved.

Design Of Combined Stochastic Feedforward/Feedback Control

NASA Technical Reports Server (NTRS)

Halyo, Nesim

1989-01-01

Methodology accommodates variety of control structures and design techniques. In methodology for combined stochastic feedforward/feedback control, main objectives of feedforward and feedback control laws seen clearly. Inclusion of error-integral feedback, dynamic compensation, rate-command control structure, and like integral element of methodology. Another advantage of methodology flexibility to develop variety of techniques for design of feedback control with arbitrary structures to obtain feedback controller: includes stochastic output feedback, multiconfiguration control, decentralized control, or frequency and classical control methods. Control modes of system include capture and tracking of localizer and glideslope, crab, decrab, and flare. By use of recommended incremental implementation, control laws simulated on digital computer and connected with nonlinear digital simulation of aircraft and its systems.

Effects of speech and print feedback on spelling performance of a child with cerebral palsy using a speech generating device.

PubMed

Raghavendra, Parimala; Oaten, Rebecca

2007-09-01

The aim of the study was to investigate the effectiveness of three feedback conditions, using a speech-generating device, on spelling performance of Tom, an 11-year-old boy with cerebral palsy and complex communication needs. Tom was taught to spell 12 words under three feedback conditions. In the SPEECH condition, he received only speech feedback from the device and in the PRINT condition he received only the orthographic feedback on the display of the device. In the SPEECH-PRINT condition, Tom received both speech output and orthographic feedback. An adapted alternating treatment design was used to investigate the effects of the three-feedback conditions. To strengthen the reliability and increase the internal validity of the findings, an intrasubject direct replication was carried out using the same procedure, but teaching 12 different spelling words to Tom. Tom reached criterion with the PRINT feedback condition first, followed by SPEECH and SPEECH-PRINT conditions simultaneously for the first 12 words, and the same order for the second set of 12 words. Overall, the PRINT condition was most efficient for Tom. The results are discussed in terms of evidence for learning style preferences within spelling instruction for a child with complex communication needs. Furthermore, the implications for targeting intervention to optimise spelling achievement amongst this group are considered.

Delay-feedback control strategy for reducing CO2 emission of traffic flow system

NASA Astrophysics Data System (ADS)

Zhang, Li-Dong; Zhu, Wen-Xing

2015-06-01

To study the signal control strategy for reducing traffic emission theoretically, we first presented a kind of discrete traffic flow model with relative speed term based on traditional coupled map car-following model. In the model, the relative speed difference between two successive running cars is incorporated into following vehicle's acceleration running equation. Then we analyzed its stability condition with discrete control system stability theory. Third, we designed a delay-feedback controller to suppress traffic jam and decrease traffic emission based on modern controller theory. Last, numerical simulations are made to support our theoretical results, including the comparison of models' stability analysis, the influence of model type and signal control on CO2 emissions. The results show that the temporal behavior of our model is superior to other models, and the traffic signal controller has good effect on traffic jam suppression and traffic CO2 emission, which fully supports the theoretical conclusions.

The Role of Audio-Visual Feedback in a Thought-Based Control of a Humanoid Robot: A BCI Study in Healthy and Spinal Cord Injured People.

PubMed

Tidoni, Emmanuele; Gergondet, Pierre; Fusco, Gabriele; Kheddar, Abderrahmane; Aglioti, Salvatore M

2017-06-01

The efficient control of our body and successful interaction with the environment are possible through the integration of multisensory information. Brain-computer interface (BCI) may allow people with sensorimotor disorders to actively interact in the world. In this study, visual information was paired with auditory feedback to improve the BCI control of a humanoid surrogate. Healthy and spinal cord injured (SCI) people were asked to embody a humanoid robot and complete a pick-and-place task by means of a visual evoked potentials BCI system. Participants observed the remote environment from the robot's perspective through a head mounted display. Human-footsteps and computer-beep sounds were used as synchronous/asynchronous auditory feedback. Healthy participants achieved better placing accuracy when listening to human footstep sounds relative to a computer-generated sound. SCI people demonstrated more difficulty in steering the robot during asynchronous auditory feedback conditions. Importantly, subjective reports highlighted that the BCI mask overlaying the display did not limit the observation of the scenario and the feeling of being in control of the robot. Overall, the data seem to suggest that sensorimotor-related information may improve the control of external devices. Further studies are required to understand how the contribution of residual sensory channels could improve the reliability of BCI systems.

ACOSS Six (Active Control of Space Structures)

DTIC Science & Technology

1981-10-01

modes, specially useful simpler conditions for ensuring closed-loop asymptotic stability are also derived. In addition, conditions for robustness of...in this initial study of FOCL stability and robustness . Such a condition is strong but not unreasonable nor unrealistic. Many useful simple in- sights...smallest possible feedback gains) and many interesting numerical results on closed-loop stability and robustness of the modal-dashpot designs. The

Controlling Chaos Via Knowledge of Initial Condition for a Curved Structure

NASA Technical Reports Server (NTRS)

Maestrello, L.

2000-01-01

Nonlinear response of a flexible curved panel exhibiting bifurcation to fully developed chaos is demonstrated along with the sensitivity to small perturbation from the initial conditions. The response is determined from the measured time series at two fixed points. The panel is forced by an external nonharmonic multifrequency and monofrequency sound field. Using a low power time-continuous feedback control, carefully tuned at each initial condition, produces large long-term effects on the dynamics toward taming chaos. Without the knowledge of the initial conditions, control may be achieved by destructive interference. In this case, the control power is proportional to the loading power. Calculation of the correlation dimension and the estimation of positive Lyapunov exponents, in practice, are the proof of chaotic response.

A biomolecular proportional integral controller based on feedback regulations of protein level and activity.

PubMed

Mairet, Francis

2018-02-01

Homeostasis is the capacity of living organisms to keep internal conditions regulated at a constant level, despite environmental fluctuations. Integral feedback control is known to play a key role in this behaviour. Here, I show that a feedback system involving transcriptional and post-translational regulations of the same executor protein acts as a proportional integral (PI) controller, leading to enhanced transient performances in comparison with a classical integral loop. Such a biomolecular controller-which I call a level and activity-PI controller (LA-PI)-is involved in the regulation of ammonium uptake by Escherichia coli through the transporter AmtB. The P II molecules, which reflect the nitrogen status of the cell, inhibit both the production of AmtB and its activity (via the NtrB-NtrC system and the formation of a complex with GlnK, respectively). Other examples of LA-PI controller include copper and zinc transporters, and the redox regulation in photosynthesis. This scheme has thus emerged through evolution in many biological systems, surely because of the benefits it offers in terms of performances (rapid and perfect adaptation) and economy (protein production according to needs).

Pilot-in-the-Loop Evaluation of a Yaw Rate to Throttle Feedback Control with Enhanced Engine Response

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Guo, Ten-Huei; Sowers, T. Shane; Chicatelli, Amy K.; Fulton, Christopher E.; May, Ryan D.; Owen, A. Karl

2012-01-01

This paper describes the implementation and evaluation of a yaw rate to throttle feedback system designed to replace a damaged rudder. It can act as a Dutch roll damper and as a means to facilitate pilot input for crosswind landings. Enhanced propulsion control modes were implemented to increase responsiveness and thrust level of the engine, which impact flight dynamics and performance. Piloted evaluations were performed to determine the capability of the engines to substitute for the rudder function under emergency conditions. The results showed that this type of implementation is beneficial, but the engines' capability to replace the rudder is limited.

Condition sensor system and method

NASA Technical Reports Server (NTRS)

Polhemus, J. T.; Morgan, J. E.; Mandell, A. (Inventor)

1978-01-01

The condition sensor system comprises a condition detector which produces a pulse when a parameter of the monitored condition exceeds a desired threshold. A resettable condition counter counts each pulse. A resettable timer is preset to produce a particular time frame. The counter produces a condition signal when the accumulated number of pulses within the time frame is equal to or greater than a preset count. Control means responsive to the incoming pulses and to the condition signal produce control signals that control utilization devices. After a suitable delay, the last detected pulse simultaneously resets the pulse counter and the timer, and prepares them for sensing another condition occurrence within the time frame. The invention has particular utility in the process of detecting rocking motions of blind people. A controlled, audible, bio-feedback signal is provided which constitutes a warning to the blind person that he is rocking.

Voluntarily controlled but not merely observed visual feedback affects postural sway

PubMed Central

Asai, Tomohisa; Hiromitsu, Kentaro; Imamizu, Hiroshi

2018-01-01

Online stabilization of human standing posture utilizes multisensory afferences (e.g., vision). Whereas visual feedback of spontaneous postural sway can stabilize postural control especially when observers concentrate on their body and intend to minimize postural sway, the effect of intentional control of visual feedback on postural sway itself remains unclear. This study assessed quiet standing posture in healthy adults voluntarily controlling or merely observing visual feedback. The visual feedback (moving square) had either low or high gain and was either horizontally flipped or not. Participants in the voluntary-control group were instructed to minimize their postural sway while voluntarily controlling visual feedback, whereas those in the observation group were instructed to minimize their postural sway while merely observing visual feedback. As a result, magnified and flipped visual feedback increased postural sway only in the voluntary-control group. Furthermore, regardless of the instructions and feedback manipulations, the experienced sense of control over visual feedback positively correlated with the magnitude of postural sway. We suggest that voluntarily controlled, but not merely observed, visual feedback is incorporated into the feedback control system for posture and begins to affect postural sway. PMID:29682421

Teleoperation of steerable flexible needles by combining kinesthetic and vibratory feedback.

PubMed

Pacchierotti, Claudio; Abayazid, Momen; Misra, Sarthak; Prattichizzo, Domenico

2014-01-01

Needle insertion in soft-tissue is a minimally invasive surgical procedure that demands high accuracy. In this respect, robotic systems with autonomous control algorithms have been exploited as the main tool to achieve high accuracy and reliability. However, for reasons of safety and responsibility, autonomous robotic control is often not desirable. Therefore, it is necessary to focus also on techniques enabling clinicians to directly control the motion of the surgical tools. In this work, we address that challenge and present a novel teleoperated robotic system able to steer flexible needles. The proposed system tracks the position of the needle using an ultrasound imaging system and computes needle's ideal position and orientation to reach a given target. The master haptic interface then provides the clinician with mixed kinesthetic-vibratory navigation cues to guide the needle toward the computed ideal position and orientation. Twenty participants carried out an experiment of teleoperated needle insertion into a soft-tissue phantom, considering four different experimental conditions. Participants were provided with either mixed kinesthetic-vibratory feedback or mixed kinesthetic-visual feedback. Moreover, we considered two different ways of computing ideal position and orientation of the needle: with or without set-points. Vibratory feedback was found more effective than visual feedback in conveying navigation cues, with a mean targeting error of 0.72 mm when using set-points, and of 1.10 mm without set-points.

Effects of aging on pointing movements under restricted visual feedback conditions.

PubMed

Zhang, Liancun; Yang, Jiajia; Inai, Yoshinobu; Huang, Qiang; Wu, Jinglong

2015-04-01

The goal of this study was to investigate the effects of aging on pointing movements under restricted visual feedback of hand movement and target location. Fifteen young subjects and fifteen elderly subjects performed pointing movements under four restricted visual feedback conditions that included full visual feedback of hand movement and target location (FV), no visual feedback of hand movement and target location condition (NV), no visual feedback of hand movement (NM) and no visual feedback of target location (NT). This study suggested that Fitts' law applied for pointing movements of the elderly adults under different visual restriction conditions. Moreover, significant main effect of aging on movement times has been found in all four tasks. The peripheral and central changes may be the key factors for these different characteristics. Furthermore, no significant main effects of age on the mean accuracy rate under condition of restricted visual feedback were found. The present study suggested that the elderly subjects made a very similar use of the available sensory information as young subjects under restricted visual feedback conditions. In addition, during the pointing movement, information about the hand's movement was more useful than information about the target location for young and elderly subjects. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhancing synchronization stability in a multi-area power grid

PubMed Central

Wang, Bing; Suzuki, Hideyuki; Aihara, Kazuyuki

2016-01-01

Maintaining a synchronous state of generators is of central importance to the normal operation of power grids, in which many networks are generally interconnected. In order to understand the condition under which the stability can be optimized, it is important to relate network stability with feedback control strategies as well as network structure. Here, we present a stability analysis on a multi-area power grid by relating it with several control strategies and topological design of network structure. We clarify the minimal feedback gain in the self-feedback control, and build the optimal communication network for the local and global control strategies. Finally, we consider relationship between the interconnection pattern and the synchronization stability; by optimizing the network interlinks, the obtained network shows better synchronization stability than the original network does, in particular, at a high power demand. Our analysis shows that interlinks between spatially distant nodes will improve the synchronization stability. The results seem unfeasible to be implemented in real systems but provide a potential guide for the design of stable power systems. PMID:27225708

Undisturbed stance control in healthy adults is achieved differently along anteroposterior and mediolateral axes: evidence from visual feedback of various signals from center of pressure trajectories.

PubMed

Rougier, Patrice R

2009-05-01

Provided through the screen of a monitor, the participant's resultant center of pressure (CPRes) movements from a force platform device, modified the postural performance of a healthy individual. However, these effects could largely vary with the axis that researchers consider (mediolateral [ML] or anteroposterior [AP]), because they know these controls are involved in 2 distinct ankle and hip mechanisms. To demonstrate this organization, the author tested a group of healthy adults in several conditions that gave the whole or some part of the information in the CPRes displacements. Compared with the CPRes feedback, left and right plantar CP or body weight distribution feedback deteriorated the control of the vertically projected center of gravity (CGv) along the ML and AP axes, whose amplitudes increased, respectively. These data highlight the primary role of loading or unloading and pressure variations in the achievement of postural control along each ML or AP axis, respectively. It is interesting that merging these 2 pieces of information (CPRes displacements) helped participants optimize their postural performance.

Wing box transonic-flutter suppression using piezoelectric self-sensing actuators attached to skin

NASA Astrophysics Data System (ADS)

Otiefy, R. A. H.; Negm, H. M.

2010-12-01

The main objective of this research is to study the capability of piezoelectric (PZT) self-sensing actuators to suppress the transonic wing box flutter, which is a flow-structure interaction phenomenon. The unsteady general frequency modified transonic small disturbance (TSD) equation is used to model the transonic flow about the wing. The wing box structure and piezoelectric actuators are modeled using the equivalent plate method, which is based on the first order shear deformation plate theory (FSDPT). The piezoelectric actuators are bonded to the skin. The optimal electromechanical coupling conditions between the piezoelectric actuators and the wing are collected from previous work. Three main different control strategies, a linear quadratic Gaussian (LQG) which combines the linear quadratic regulator (LQR) with the Kalman filter estimator (KFE), an optimal static output feedback (SOF), and a classic feedback controller (CFC), are studied and compared. The optimum actuator and sensor locations are determined using the norm of feedback control gains (NFCG) and norm of Kalman filter estimator gains (NKFEG) respectively. A genetic algorithm (GA) optimization technique is used to calculate the controller and estimator parameters to achieve a target response.

'Battling my biology': psychological effects of genetic testing for risk of weight gain.

PubMed

Meisel, S F; Wardle, J

2014-04-01

The availability of genetic tests for multifactorial conditions such as obesity raises concerns that higher-risk results could lead to fatalistic reactions or lower-risk results to complacency. No study has investigated the effects of genetic test feedback for the risk of obesity in non-clinical samples. The present study explored psychological and behavioral reactions to genetic test feedback for a weight related gene (FTO) in a volunteer sample (n = 18) using semi-structured interviews. Respondents perceived the gene test result as scientifically objective; removing some of the emotion attached to the issue of weight control. Those who were struggling with weight control reported relief of self-blame. There was no evidence for either complacency or fatalism; all respondents emphasized the importance of lifestyle choices in long-term weight management, although they recognized the role of both genes and environment. Regardless of the test result, respondents evaluated the testing positively and found it motivating and informative. Genetic test feedback for risk of weight gain may offer psychological benefits beyond its objectively limited clinical utility. As the role of genetic counselors is likely to expand, awareness of reasons for genetic testing for common, complex conditions and reactions to the test result is important.

Early Huntington's Disease Affects Movements in Transformed Sensorimotor Mappings

ERIC Educational Resources Information Center

Boulet, C.; Lemay, M.; Bedard, M.A.; Chouinard, M.J.; Chouinard, S.; Richer, F.

2005-01-01

This study examined the effect of transformed visual feedback on movement control in Huntington's disease (HD). Patients in the early stages of HD and controls performed aiming movements towards peripheral targets on a digitizing tablet and emphasizing precision. In a baseline condition, HD patients were slower but showed few precision problems in…

The Effect of Conscious Control on Handwriting in Children with Attention Deficit Hyperactivity Disorder

ERIC Educational Resources Information Center

Tucha, Oliver; Lange, Klaus W.

2005-01-01

Two experiments were performed regarding the effect of conscious control on handwriting fluency in healthy adults and ADHD children. First, 26 healthy students were asked to write a sentence under different conditions. The results indicate that automated handwriting movements are independent from visual feedback. Second, the writing performance of…

Virtual reality and exercise: behavioral and psychological effects of visual feedback.

PubMed

Mestre, Daniel R; Ewald, Marine; Maiano, Christophe

2011-01-01

We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback, VR feedback and VR feedback with the presence of a virtual coach, acting as a pacer. In VR feedback conditions, we observed a decreased level of perceived exertion and an increased level of enjoyment of physical activity, when compared to a regular exercise situation (no VR feedback). We also observed a shift in the subjects' attentional focus, from association (in the absence of VR feedback) to dissociation (in VR feedback conditions). Moreover, the presence of a virtual coach in the VR environment triggered a systematic regulation of the (virtual) displacement speed, whose relationship with perceived enjoyment and exertion require further work.

Fuzzy self-learning control for magnetic servo system

NASA Technical Reports Server (NTRS)

Tarn, J. H.; Kuo, L. T.; Juang, K. Y.; Lin, C. E.

1994-01-01

It is known that an effective control system is the key condition for successful implementation of high-performance magnetic servo systems. Major issues to design such control systems are nonlinearity; unmodeled dynamics, such as secondary effects for copper resistance, stray fields, and saturation; and that disturbance rejection for the load effect reacts directly on the servo system without transmission elements. One typical approach to design control systems under these conditions is a special type of nonlinear feedback called gain scheduling. It accommodates linear regulators whose parameters are changed as a function of operating conditions in a preprogrammed way. In this paper, an on-line learning fuzzy control strategy is proposed. To inherit the wealth of linear control design, the relations between linear feedback and fuzzy logic controllers have been established. The exercise of engineering axioms of linear control design is thus transformed into tuning of appropriate fuzzy parameters. Furthermore, fuzzy logic control brings the domain of candidate control laws from linear into nonlinear, and brings new prospects into design of the local controllers. On the other hand, a self-learning scheme is utilized to automatically tune the fuzzy rule base. It is based on network learning infrastructure; statistical approximation to assign credit; animal learning method to update the reinforcement map with a fast learning rate; and temporal difference predictive scheme to optimize the control laws. Different from supervised and statistical unsupervised learning schemes, the proposed method learns on-line from past experience and information from the process and forms a rule base of an FLC system from randomly assigned initial control rules.

On a program manifold's stability of one contour automatic control systems

NASA Astrophysics Data System (ADS)

Zumatov, S. S.

2017-12-01

Methodology of analysis of stability is expounded to the one contour systems automatic control feedback in the presence of non-linearities. The methodology is based on the use of the simplest mathematical models of the nonlinear controllable systems. Stability of program manifolds of one contour automatic control systems is investigated. The sufficient conditions of program manifold's absolute stability of one contour automatic control systems are obtained. The Hurwitz's angle of absolute stability was determined. The sufficient conditions of program manifold's absolute stability of control systems by the course of plane in the mode of autopilot are obtained by means Lyapunov's second method.

Robust fuzzy output feedback controller for affine nonlinear systems via T-S fuzzy bilinear model: CSTR benchmark.

PubMed

Hamdy, M; Hamdan, I

2015-07-01

In this paper, a robust H∞ fuzzy output feedback controller is designed for a class of affine nonlinear systems with disturbance via Takagi-Sugeno (T-S) fuzzy bilinear model. The parallel distributed compensation (PDC) technique is utilized to design a fuzzy controller. The stability conditions of the overall closed loop T-S fuzzy bilinear model are formulated in terms of Lyapunov function via linear matrix inequality (LMI). The control law is robustified by H∞ sense to attenuate external disturbance. Moreover, the desired controller gains can be obtained by solving a set of LMI. A continuous stirred tank reactor (CSTR), which is a benchmark problem in nonlinear process control, is discussed in detail to verify the effectiveness of the proposed approach with a comparative study. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Development of flank wear model of cutting tool by using adaptive feedback linear control system on machining AISI D2 steel and AISI 4340 steel

NASA Astrophysics Data System (ADS)

Orra, Kashfull; Choudhury, Sounak K.

2016-12-01

The purpose of this paper is to build an adaptive feedback linear control system to check the variation of cutting force signal to improve the tool life. The paper discusses the use of transfer function approach in improving the mathematical modelling and adaptively controlling the process dynamics of the turning operation. The experimental results shows to be in agreement with the simulation model and error obtained is less than 3%. The state space approach model used in this paper successfully check the adequacy of the control system through controllability and observability test matrix and can be transferred from one state to another by appropriate input control in a finite time. The proposed system can be implemented to other machining process under varying range of cutting conditions to improve the efficiency and observability of the system.

Optimizing Tailored Communications for Health Risk Assessment: A Randomized Factorial Experiment of the Effects of Expectancy Priming, Autonomy Support, and Exemplification

PubMed Central

Ribisl, Kurt M; Mayer, Deborah K; Tate, Deborah F

2018-01-01

Background Health risk assessments with tailored feedback plus health education have been shown to be effective for promoting health behavior change. However, there is limited evidence to guide the development and delivery of online automated tailored feedback. Objective The goal of this study was to optimize tailored feedback messages for an online health risk assessment to promote enhanced user engagement, self-efficacy, and behavioral intentions for engaging in healthy behaviors. We examined the effects of three theory-based message factors used in developing tailored feedback messages on levels of engagement, self-efficacy, and behavioral intentions. Methods We conducted a randomized factorial experiment to test three different components of tailored feedback messages: tailored expectancy priming, autonomy support, and use of an exemplar. Individuals (N=1945) were recruited via Amazon Mechanical Turk and randomly assigned to one of eight different experimental conditions within one of four behavioral assessment and feedback modules (tobacco use, physical activity [PA], eating habits, and weight). Participants reported self-efficacy and behavioral intentions pre- and postcompletion of an online health behavior assessment with tailored feedback. Engagement and message perceptions were assessed at follow-up. Results For the tobacco module, there was a significant main effect of the exemplar factor (P=.04); participants who received exemplar messages (mean 3.31, SE 0.060) rated their self-efficacy to quit tobacco higher than those who did not receive exemplar messages (mean 3.14, SE 0.057). There was a three-way interaction between the effect of message conditions on self-efficacy to quit tobacco (P=.02), such that messages with tailored priming and an exemplar had the greatest impact on self-efficacy to quit tobacco. Across PA, eating habits, and weight modules, there was a three-way interaction among conditions on self-efficacy (P=.048). The highest self-efficacy scores were reported among those who were in the standard priming condition and received both autonomy supportive and exemplar messages. In the PA module, autonomy supportive messages had a stronger effect on self-efficacy for PA in the standard priming condition. For PA, eating habits, and weight-related behaviors, the main effect of exemplar messages on behavioral intentions was in the hypothesized direction but did not reach statistical significance (P=.08). When comparing the main effects of different message conditions, there were no differences in engagement and message perceptions. Conclusions Findings suggest that tailored feedback messages that use exemplars helped improve self-efficacy related to tobacco cessation, PA, eating habits, and weight control. Combining standard priming and autonomy supportive message components shows potential for optimizing tailored feedback for tobacco cessation and PA behaviors. PMID:29496652

Vibrotactile grasping force and hand aperture feedback for myoelectric forearm prosthesis users.

PubMed

Witteveen, Heidi J B; Rietman, Hans S; Veltink, Peter H

2015-06-01

User feedback about grasping force and hand aperture is very important in object handling with myoelectric forearm prostheses but is lacking in current prostheses. Vibrotactile feedback increases the performance of healthy subjects in virtual grasping tasks, but no extensive validation on potential users has been performed. Investigate the performance of upper-limb loss subjects in grasping tasks with vibrotactile stimulation, providing hand aperture, and grasping force feedback. Cross-over trial. A total of 10 subjects with upper-limb loss performed virtual grasping tasks while perceiving vibrotactile feedback. Hand aperture feedback was provided through an array of coin motors and grasping force feedback through a single miniature stimulator or an array of coin motors. Objects with varying sizes and weights had to be grasped by a virtual hand. Percentages correctly applied hand apertures and correct grasping force levels were all higher for the vibrotactile feedback condition compared to the no-feedback condition. With visual feedback, the results were always better compared to the vibrotactile feedback condition. Task durations were comparable for all feedback conditions. Vibrotactile grasping force and hand aperture feedback improves grasping performance of subjects with upper-limb loss. However, it should be investigated whether this is of additional value in daily-life tasks. This study is a first step toward the implementation of sensory vibrotactile feedback for users of myoelectric forearm prostheses. Grasping force feedback is crucial for optimal object handling, and hand aperture feedback is essential for reduction of required visual attention. Grasping performance with feedback is evaluated for the potential users. © The International Society for Prosthetics and Orthotics 2014.

The Impact of Different Visual Feedbacks in User Training on Motor Imagery Control in BCI.

PubMed

Zapała, Dariusz; Francuz, Piotr; Zapała, Ewelina; Kopiś, Natalia; Wierzgała, Piotr; Augustynowicz, Paweł; Majkowski, Andrzej; Kołodziej, Marcin

2018-03-01

The challenges of research into brain-computer interfaces (BCI) include significant individual differences in learning pace and in the effective operation of BCI devices. The use of neurofeedback training is a popular method of improving the effectiveness BCI operation. The purpose of the present study was to determine to what extent it is possible to improve the effectiveness of operation of sensorimotor rhythm-based brain-computer interfaces (SMR-BCI) by supplementing user training with elements modifying the characteristics of visual feedback. Four experimental groups had training designed to reinforce BCI control by: visual feedback in the form of dummy faces expressing emotions (Group 1); flashing the principal elements of visual feedback (Group 2) and giving both visual feedbacks in one condition (Group 3). The fourth group participated in training with no modifications (Group 4). Training consisted of a series of trials where the subjects directed a ball into a basket located to the right or left side of the screen. In Group 1 a schematic image a face, placed on the controlled object, showed various emotions, depending on the accuracy of control. In Group 2, the cue and targets were flashed with different frequency (4 Hz) than the remaining elements visible on the monitor. Both modifications were also used simultaneously in Group 3. SMR activity during the task was recorded before and after the training. In Group 3 there was a significant improvement in SMR control, compared to subjects in Group 2 and 4 (control). Differences between subjects in Groups 1, 2 and 4 (control) were insignificant. This means that relatively small changes in the training procedure may significantly impact the effectiveness of BCI control. Analysis of behavioural data acquired from all participants at training showed greater effectiveness in directing the object towards the right side of the screen. Subjects with the greatest improvement in SMR control showed a significantly lower difference in the accuracy of rightward and leftward movement than others.

Low noise charge ramp electrometer

DOEpatents

Morgan, John P.; Piper, Thomas C.

1992-01-01

An electrometer capable of measuring small currents without the use of a feedback resistor which tends to contribute a large noise factor to the measured data. The electrometer eliminates the feedback resistor through the use of a feedback capacitor located across the electrometer amplifier. The signal from the electrometer amplifier is transferred to a electrometer buffer amplifier which serves to transfer the signal to several receptors. If the electrometer amplifier is approaching saturation, the buffer amplifier signals a reset discriminator which energizes a coil whose magnetic field closes a magnetic relay switch which in turn resets or zeros the feedback capacitor. In turn, a reset complete discriminator restarts the measurement process when the electrometer amplifier approaches its initial condition. The buffer amplifier also transmits the voltage signal from the electrometer amplifier to a voltage-to-frequency converter. The signals from the voltage-to-frequency converter are counted over a fixed period of time and the information is relayed to a data processor. The timing and sequencing of the small current measuring system is under the control of a sequence control logic unit.

Low noise charge ramp electrometer

DOEpatents

Morgan, J.P.; Piper, T.C.

1992-10-06

An electrometer capable of measuring small currents without the use of a feedback resistor which tends to contribute a large noise factor to the measured data. The electrometer eliminates the feedback resistor through the use of a feedback capacitor located across the electrometer amplifier. The signal from the electrometer amplifier is transferred to a electrometer buffer amplifier which serves to transfer the signal to several receptors. If the electrometer amplifier is approaching saturation, the buffer amplifier signals a reset discriminator which energizes a coil whose magnetic field closes a magnetic relay switch which in turn resets or zeros the feedback capacitor. In turn, a reset complete discriminator restarts the measurement process when the electrometer amplifier approaches its initial condition. The buffer amplifier also transmits the voltage signal from the electrometer amplifier to a voltage-to-frequency converter. The signals from the voltage-to-frequency converter are counted over a fixed period of time and the information is relayed to a data processor. The timing and sequencing of the small current measuring system is under the control of a sequence control logic unit. 2 figs.

Work first then play: Prior task difficulty increases motivation-related brain responses in a risk game.

PubMed

Schmidt, Barbara; Mussel, Patrick; Osinsky, Roman; Rasch, Björn; Debener, Stefan; Hewig, Johannes

2017-05-01

Task motivation depends on what we did before. A recent theory differentiates between tasks that we want to do and tasks that we have to do. After a have-to task, motivation shifts towards a want-to task. We measured this shift of motivation via brain responses to monetary feedback in a risk game that was used as want-to task in our study. We tested 20 healthy participants that were about 28 years old in a within-subjects design. Participants worked on a Stroop task (have-to task) or an easier version of the Stroop task as a control condition and played a risk game afterwards (want-to task). After the Stroop task, brain responses to monetary feedback in the risk game were larger compared to the easier control task, especially for feedback indicating higher monetary rewards. We conclude that higher amplitudes of feedback-related brain responses in the risk game reflect the shift of motivation after a have-to task towards a want-to task. Copyright © 2017 Elsevier B.V. All rights reserved.

Nocturnal illumination maintains reproductive function and simulates the period-lengthening effect of constant light in the mature male Djungarian hamster (Phodopus sungorus)

NASA Technical Reports Server (NTRS)

Ferraro, J. S.

1990-01-01

Mature male Djungarian hamsters (Phodopus sungorus) were placed in individual light-tight, sound attenuated chambers and exposed to one of four lighting conditions for a duration of approximately seven weeks. The four lighting conditions were: constant light (LL); constant dark (DD); feedback lighting (LDFB; a condition that illuminates the cage in response to locomotor activity); or a feedback lighting neighbor control (LDFB NC; the animal receives the same light pattern as a paired animal in feedback lighting, but has no control over it). Exposure of hamsters to LL or LDFB produced significantly and similarly longer free-running periods of the locomotor activity rhythm than exposure of animals to DD. Hamsters exposed to LDFB NC did not free-run or entrain, but rather displayed "relative coordination". The paired testes and sex accessory glands weights suggest that in the Djungarian hamster, LL and LDFB exposed animals maintained reproductive function, whereas DD exposed animals did not. Animals exposed to LDFB NC had intermediate paired testes weights. Since several previous studies have demonstrated that short pulses of light, which are coincident with the subjective night, are photostimulatory, it is not surprising that LDFB maintained reproductive function in the mature Djungarian hamster. Feedback lighting, however, has been shown to be an insufficient stimulus to maintain reproductive function of mature male and female Syrian hamsters, and to the reproductive maturation of immature Djungarian hamsters. The results suggest that there may be slight, but significant differences in the way these two species interpret photoperiod, as well as a developmental change in the photoperiodic response of Djungarian hamsters.

A biomolecular proportional integral controller based on feedback regulations of protein level and activity

PubMed Central

2018-01-01

Homeostasis is the capacity of living organisms to keep internal conditions regulated at a constant level, despite environmental fluctuations. Integral feedback control is known to play a key role in this behaviour. Here, I show that a feedback system involving transcriptional and post-translational regulations of the same executor protein acts as a proportional integral (PI) controller, leading to enhanced transient performances in comparison with a classical integral loop. Such a biomolecular controller—which I call a level and activity-PI controller (LA-PI)—is involved in the regulation of ammonium uptake by Escherichia coli through the transporter AmtB. The PII molecules, which reflect the nitrogen status of the cell, inhibit both the production of AmtB and its activity (via the NtrB-NtrC system and the formation of a complex with GlnK, respectively). Other examples of LA-PI controller include copper and zinc transporters, and the redox regulation in photosynthesis. This scheme has thus emerged through evolution in many biological systems, surely because of the benefits it offers in terms of performances (rapid and perfect adaptation) and economy (protein production according to needs). PMID:29515895

You make me tired: An experimental test of the role of interpersonal operant conditioning in fatigue.

PubMed

Lenaert, Bert; Jansen, Rebecca; van Heugten, Caroline M

2018-04-01

Chronic fatigue is highly prevalent in the general population as well as in multiple chronic diseases and psychiatric disorders. Its etiology however remains poorly understood and cannot be explained by biological factors alone. Occurring in a psychosocial context, the experience and communication of fatigue may be shaped by social interactions. In particular, interpersonal operant conditioning may strengthen and perpetuate fatigue complaints. In this experiment, individuals (N = 44) repeatedly rated their currently experienced fatigue while engaging in cognitive effort (working memory task). Subtle social reward was given when fatigue increased relative to the previous rating; or disapproval when fatigue decreased. In the control condition, only neutral feedback was given. Although all participants became more fatigued during cognitive effort, interpersonal operant conditioning led to increased fatigue reporting relative to neutral feedback. This effect occurred independently of conscious awareness. Interestingly, the experimental condition also performed worse on the working memory task. Results suggest that fatigue complaints (and cognitive performance) may become controlled by their consequences such as social reward, and not exclusively by their antecedents such as effort. Results have implications for treatment development and suggest that interpersonal operant conditioning may contribute to fatigue becoming a chronic symptom. Copyright © 2018 Elsevier Ltd. All rights reserved.

An experimental test of control theory-based interventions for physical activity.

PubMed

Prestwich, Andrew; Conner, Mark; Hurling, Robert; Ayres, Karen; Morris, Ben

2016-11-01

To provide an experimental test of control theory to promote physical activity. Parallel groups, simple randomized design with an equal chance of allocation to any group. Participants not meeting recommended levels of physical activity but physically safe to do so (N = 124) were recruited on a UK university campus and randomized to goal-setting + self-monitoring + feedback (GS + SM + F, n = 40), goal-setting + self-monitoring (GS + SM, n = 40), or goal-setting only (GS, n = 44) conditions that differentially tapped the key features of control theory. Accelerometers assessed physical activity (primary outcome) as well as self-report over a 7-day period directly before/after the start of the intervention. The participants in the GS + SM + F condition significantly outperformed those in the GS condition, d = 0.62, 95% CI d = 0.15-1.08, and marginally outperformed those in the GS + SM condition in terms of total physical activity at follow-up on the accelerometer measure, d = 0.33, 95% CI d = -0.13 to 0.78. The feedback manipulation (GS + SM + F vs. GS + SM and GS) was most effective when baseline intentions were weak. These patterns did not emerge on the self-report measure but, on the basis of this measure, the feedback manipulation increased the risk that participants coasted in relation to their goal in the first few days of the intervention period. Using behaviour change techniques consistent with control theory can lead to significant short-term improvements on objectively assessed physical activity. Further research is needed to examine the underlying theoretical principles of the model. Statement of contribution What is already known on this subject? Interventions incorporating more techniques that are consistent with control theory are associated with larger positive changes in health behaviours and related outcomes (see reviews by Dombrowski et al., ; Michie et al., ). However, none of the studies included in these reviews were explicitly based on control theory (see Prestwich et al., ). What does this study add? This study is the first experimental test of the cumulative effects of behaviour change techniques as proposed by control theory. Intervening on all aspects of the feedback loop noted by control theory leads to more change; however, the risk that some participants coast in relation to their set goal is significant. This approach increased physical activity more in those with weaker intentions pre-intervention. © 2016 The British Psychological Society.

Psychophysiological Control of Acognitive Task Using Adaptive Automation

NASA Technical Reports Server (NTRS)

Freeman, Frederick; Pope, Alan T. (Technical Monitor)

2001-01-01

The major focus of the present proposal was to examine psychophysiological variables related to hazardous states of awareness induced by monitoring automated systems. With the increased use of automation in today's work environment, people's roles in the work place are being redefined from that of active participant to one of passive monitor. Although the introduction of automated systems has a number of benefits, there are also a number of disadvantages regarding worker performance. Byrne and Parasuraman have argued for the use of psychophysiological measures in the development and the implementation of adaptive automation. While both performance based and model based adaptive automation have been studied, the use of psychophysiological measures, especially EEG, offers the advantage of real time evaluation of the state of the subject. The current study used the closed-loop system, developed at NASA-Langley Research Center, to control the state of awareness of subjects while they performed a cognitive vigilance task. Previous research in our laboratory, supported by NASA, has demonstrated that, in an adaptive automation, closed-loop environment, subjects perform a tracking task better under a negative than a positive, feedback condition. In addition, this condition produces less subjective workload and larger P300 event related potentials to auditory stimuli presented in a concurrent oddball task. We have also recently shown that the closed-loop system used to control the level of automation in a tracking task can also be used to control the event rate of stimuli in a vigilance monitoring task. By changing the event rate based on the subject's index of arousal, we have been able to produce improved monitoring, relative to various control groups. We have demonstrated in our initial closed-loop experiments with the the vigilance paradigm that using a negative feedback contingency (i.e. increasing event rates when the EEG index is low and decreasing event rates when the EEG index is high) results in a marked decrease of the vigilance decrement over a 40 minute session. This effect is in direct contrast to performance of a positive feedback group, as well as a number of other control groups which demonstrated the typical vigilance decrement. Interestingly, however, the negative feedback group performed at virtually the same level as a yoked control group. The yoked control group received the same order of changes in event rate that were generated by the negative feedback subjects using the closed-loop system. Thus it would appear to be possible to optimize vigilance performance by controlling the stimuli which subjects are asked to process.

Marginally perceptible outcome feedback, motor learning and implicit processes.

PubMed

Masters, Rich S W; Maxwell, Jon P; Eves, Frank F

2009-09-01

Participants struck 500 golf balls to a concealed target. Outcome feedback was presented at the subjective or objective threshold of awareness of each participant or at a supraliminal threshold. Participants who received fully perceptible (supraliminal) feedback learned to strike the ball onto the target, as did participants who received feedback that was only marginally perceptible (subjective threshold). Participants who received feedback that was not perceptible (objective threshold) showed no learning. Upon transfer to a condition in which the target was unconcealed, performance increased in both the subjective and the objective threshold condition, but decreased in the supraliminal condition. In all three conditions, participants reported minimal declarative knowledge of their movements, suggesting that deliberate hypothesis testing about how best to move in order to perform the motor task successfully was disrupted by the impoverished disposition of the visual outcome feedback. It was concluded that sub-optimally perceptible visual feedback evokes implicit processes.

Testing a Dutch web-based tailored lifestyle programme among adults: a study protocol.

PubMed

Schulz, Daniela N; Kremers, Stef Pj; van Osch, Liesbeth Adm; Schneider, Francine; van Adrichem, Mathieu Jg; de Vries, Hein

2011-02-16

Smoking, high alcohol consumption, unhealthy eating habits and physical inactivity often lead to (chronic) diseases, such as cardiovascular diseases and cancer. Tailored online interventions have been proven to be effective in changing health behaviours. The aim of this study is to test and compare the effectiveness of two different tailoring strategies for changing lifestyle compared to a control group using a multiple health behaviour web-based approach. In our Internet-based tailored programme, the five lifestyle behaviours of smoking, alcohol intake, fruit consumption, vegetable consumption, and physical activity are addressed. This randomized controlled trial, conducted among Dutch adults, includes two experimental groups (i.e., a sequential behaviour tailoring condition and a simultaneous behaviour tailoring condition) and a control group. People in the sequential behaviour tailoring condition obtain feedback on whether their lifestyle behaviours meet the Dutch recommendations. Using a step-by-step approach, they are stimulated to continue with a computer tailored module to change only one unhealthy behaviour first. In the course of the study, they can proceed to change a second behaviour. People in the simultaneous behaviour tailoring condition receive computer tailored feedback about all their unhealthy behaviours during their first visit as a stimulation to change all unhealthy behaviours. The experimental groups can re-visit the website and can then receive ipsative feedback (i.e., current scores are compared to previous scores in order to give feedback about potential changes). The (difference in) effectiveness of the different versions of the programme will be tested and compared to a control group, in which respondents only receive a short health risk appraisal. Programme evaluations will assess satisfaction with and appreciation and personal relevance of the intervention among the respondents. Finally, potential subgroup differences pertaining to gender, age and socioeconomic status regarding the behaviour effects and programme evaluation will be assessed. Research regarding multiple behaviour change is in its infancy. We study how to offer multiple behaviour change interventions optimally. Using these results could strengthen the effectiveness of web-based computer-tailoring lifestyle programmes. This study will yield new results about the need for differential lifestyle approaches using Internet-based expert systems and potential differences in subgroups concerning the effectiveness and appreciation. Dutch Trial Register NTR2168.

Design and hardware-in-loop implementation of collision avoidance algorithms for heavy commercial road vehicles

NASA Astrophysics Data System (ADS)

Rajaram, Vignesh; Subramanian, Shankar C.

2016-07-01

An important aspect from the perspective of operational safety of heavy road vehicles is the detection and avoidance of collisions, particularly at high speeds. The development of a collision avoidance system is the overall focus of the research presented in this paper. The collision avoidance algorithm was developed using a sliding mode controller (SMC) and compared to one developed using linear full state feedback in terms of performance and controller effort. Important dynamic characteristics such as load transfer during braking, tyre-road interaction, dynamic brake force distribution and pneumatic brake system response were considered. The effect of aerodynamic drag on the controller performance was also studied. The developed control algorithms have been implemented on a Hardware-in-Loop experimental set-up equipped with the vehicle dynamic simulation software, IPG/TruckMaker®. The evaluation has been performed for realistic traffic scenarios with different loading and road conditions. The Hardware-in-Loop experimental results showed that the SMC and full state feedback controller were able to prevent the collision. However, when the discrepancies in the form of parametric variations were included, the SMC provided better results in terms of reduced stopping distance and lower controller effort compared to the full state feedback controller.

Head control: volitional aspects of rehabilitation training in patients with multiple sclerosis compared with healthy subjects.

PubMed

Cattaneo, Davide; Ferrarin, Maurizio; Frasson, William; Casiraghi, Anna

2005-07-01

To investigate the role of voluntary mechanisms and motor learning in head stability and the impact of longitudinal biofeedback training in head control. Crossover trial and single-subject research design. Neurorehabilitation research institute. Head stability during treadmill gait was measured in healthy subjects and patients with multiple sclerosis (MS). The experimental condition in which subjects walked on the treadmill was compared with that in which the head was voluntarily stabilized. In another experimental condition, augmented feedback of head displacement was provided by means of a laser mounted on the head that projected a laser beam on a screen. The motor learning was investigated with biofeedback training sessions. Positional feedback was represented by the laser beam, with subjects having to stabilize the beam while walking on the treadmill. Head angular oscillation in the sagittal and frontal planes. Results showed that on verbal request, healthy subjects and patients further stabilized the head during gait, especially in the sagittal plane. Short-term feedback of head displacement was no better than self-stabilization at improving head control. Conversely, the motor learning was evident in the rehabilitation protocol: after 10 to 15 training sessions, patients with MS showed a clinically relevant decrease of head angular oscillations. Voluntary mechanisms play a role in head stabilization during gait. Augmented biofeedback of head displacement may be effective in reducing head oscillations.

Can performance on summative evaluation of wax-added dental anatomy projects be better predicted from the combination of supervised and unsupervised practice than from supervised practice alone?

PubMed

Radjaeipour, G; Chambers, D W; Geissberger, M

2016-11-01

The study explored the effects of adding student-directed projects in pre-clinical dental anatomy laboratory on improving the predictability of students' eventual performance on summative evaluation exercises, given the presence of intervening faculty-controlled, in-class practice. All students from four consecutive classes (n = 555) completed wax-added home projects (HP), spending as much or as little time as desired and receiving no faculty feedback; followed by similar laboratory projects (LP) with time limits and feedback; and then summative practical projects (PP) in a timed format but without faculty feedback. Path analysis was used to assess if the student-directed HP had any effect over and above the laboratory projects. Average scores were HP = 0.785 (SD = 0.089); LP = 0.736 (SD = 0.092); and PP = 0.743 (SD = 0.108). Path analysis was applied to show the effects of including a student-controlled home practice exercise on summative exercise performance. HP contributed 57% direct effect and 37% mediated effect through the LP condition. Student-directed home practice provided a measureable improvement in ability to predict eventual performance in summative test cases over and above the predictive contribution of intervening faculty-controlled practice conditions. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Enhancing the learning of sport skills through external-focus feedback.

PubMed

Wulf, Gabriele; McConnel, Nathan; Gärtner, Matthias; Schwarz, Andreas

2002-06-01

The authors examined how the effectiveness of feedback for the learning of complex motor skills is affected by the focus of attention it induces. The feedback referred specifically either to body movements (internal focus) or to movement effects (external focus). In Experiment 1, groups of novices and advanced volleyball players (N = 48) practiced "tennis" serves under internal-focus or external-focus feedback conditions in a 2 (expertise) x 2 (feedback type) design. Type of feedback did not differentially affect movement quality, but external-focus feedback resulted in greater accuracy of the serves than internal-focus feedback during both practice and retention, independent of the level of expertise. In Experiment 2, the effects of relative feedback frequency as a function of attentional focus were examined. A 2 (feedback frequency: 100% vs. 33%) x 2 (feedback type) design was used. Experienced soccer players (N = 52) were required to shoot lofted passes at a target. External-focus feedback resulted in greater accuracy than internal-focus feedback did. In addition, reduced feedback frequency was beneficial under internal-focus feedback conditions, whereas 100% and 33% feedback were equally effective under external-focus conditions. The results demonstrate the effectiveness of effect-related, as opposed to movement-related, feedback and also suggest that there is a need to revise current views regarding the role of feedback for motor learning.

LMI-based adaptive reliable H∞ static output feedback control against switched actuator failures

NASA Astrophysics Data System (ADS)

An, Liwei; Zhai, Ding; Dong, Jiuxiang; Zhang, Qingling

2017-08-01

This paper investigates the H∞ static output feedback (SOF) control problem for switched linear system under arbitrary switching, where the actuator failure models are considered to depend on switching signal. An active reliable control scheme is developed by combination of linear matrix inequality (LMI) method and adaptive mechanism. First, by exploiting variable substitution and Finsler's lemma, new LMI conditions are given for designing the SOF controller. Compared to the existing results, the proposed design conditions are more relaxed and can be applied to a wider class of no-fault linear systems. Then a novel adaptive mechanism is established, where the inverses of switched failure scaling factors are estimated online to accommodate the effects of actuator failure on systems. Two main difficulties arise: first is how to design the switched adaptive laws to prevent the missing of estimating information due to switching; second is how to construct a common Lyapunov function based on a switched estimate error term. It is shown that the new method can give less conservative results than that for the traditional control design with fixed gain matrices. Finally, simulation results on the HiMAT aircraft are given to show the effectiveness of the proposed approaches.

Learning to trust: social feedback normalizes trust behavior in first-episode psychosis and clinical high risk.

PubMed

Lemmers-Jansen, Imke L J; Fett, Anne-Kathrin J; Hanssen, Esther; Veltman, Dick J; Krabbendam, Lydia

2018-06-13

Psychosis is characterized by problems in social functioning that exist well before illness onset, and in individuals at clinical high risk (CHR) for psychosis. Trust is an essential element for social interactions that is impaired in psychosis. In the trust game, chronic patients showed reduced baseline trust, impaired response to positive social feedback, and attenuated brain activation in reward and mentalizing areas. We investigated whether first-episode psychosis patients (FEP) and CHR show similar abnormalities in the neural and behavioral mechanisms underlying trust. Twenty-two FEP, 17 CHR, and 43 healthy controls performed two trust games, with a cooperative and an unfair partner in the fMRI scanner. Region of interest analyses were performed on mentalizing and reward processing areas, during the investment and outcome phases of the games. Compared with healthy controls, FEP and CHR showed reduced baseline trust, but like controls, learned to trust in response to cooperative and unfair feedback. Symptom severity was not associated with baseline trust, however in FEP associated with reduced response to feedback. The only group differences in brain activation were that CHR recruited the temporo-parietal junction (TPJ) more than FEP and controls during investment in the unfair condition. This hyper-activation in CHR was associated with greater symptom severity. Reduced baseline trust may be associated with risk for psychotic illness, or generally with poor mental health. Feedback learning is still intact in CHR and FEP, as opposed to chronic patients. CHR however show distinct neural activation patterns of hyper-activation of the TPJ.

Rapid control and feedback rates enhance neuroprosthetic control

PubMed Central

Shanechi, Maryam M.; Orsborn, Amy L.; Moorman, Helene G.; Gowda, Suraj; Dangi, Siddharth; Carmena, Jose M.

2017-01-01

Brain-machine interfaces (BMI) create novel sensorimotor pathways for action. Much as the sensorimotor apparatus shapes natural motor control, the BMI pathway characteristics may also influence neuroprosthetic control. Here, we explore the influence of control and feedback rates, where control rate indicates how often motor commands are sent from the brain to the prosthetic, and feedback rate indicates how often visual feedback of the prosthetic is provided to the subject. We developed a new BMI that allows arbitrarily fast control and feedback rates, and used it to dissociate the effects of each rate in two monkeys. Increasing the control rate significantly improved control even when feedback rate was unchanged. Increasing the feedback rate further facilitated control. We also show that our high-rate BMI significantly outperformed state-of-the-art methods due to higher control and feedback rates, combined with a different point process mathematical encoding model. Our BMI paradigm can dissect the contribution of different elements in the sensorimotor pathway, providing a unique tool for studying neuroprosthetic control mechanisms. PMID:28059065

Rapid control and feedback rates enhance neuroprosthetic control

NASA Astrophysics Data System (ADS)

Shanechi, Maryam M.; Orsborn, Amy L.; Moorman, Helene G.; Gowda, Suraj; Dangi, Siddharth; Carmena, Jose M.

2017-01-01

Brain-machine interfaces (BMI) create novel sensorimotor pathways for action. Much as the sensorimotor apparatus shapes natural motor control, the BMI pathway characteristics may also influence neuroprosthetic control. Here, we explore the influence of control and feedback rates, where control rate indicates how often motor commands are sent from the brain to the prosthetic, and feedback rate indicates how often visual feedback of the prosthetic is provided to the subject. We developed a new BMI that allows arbitrarily fast control and feedback rates, and used it to dissociate the effects of each rate in two monkeys. Increasing the control rate significantly improved control even when feedback rate was unchanged. Increasing the feedback rate further facilitated control. We also show that our high-rate BMI significantly outperformed state-of-the-art methods due to higher control and feedback rates, combined with a different point process mathematical encoding model. Our BMI paradigm can dissect the contribution of different elements in the sensorimotor pathway, providing a unique tool for studying neuroprosthetic control mechanisms.

Evasion in the plane

NASA Technical Reports Server (NTRS)

Leitmann, G.; Liu, H. S.

1977-01-01

Dynamic systems were considered subject to control by two agents, one of whom desires that no trajectory of the system emanating from outside a given set, intersects that set no matter what the admissible actions of the other agent. Constructive conditions sufficient to yield a feedback control for the agent seeking avoidance were employed to deduce an evader control for the planar pursuit-evasion problem with bounded normal accelerations.

Robust parameter design for automatically controlled systems and nanostructure synthesis

NASA Astrophysics Data System (ADS)

Dasgupta, Tirthankar

2007-12-01

This research focuses on developing comprehensive frameworks for developing robust parameter design methodology for dynamic systems with automatic control and for synthesis of nanostructures. In many automatically controlled dynamic processes, the optimal feedback control law depends on the parameter design solution and vice versa and therefore an integrated approach is necessary. A parameter design methodology in the presence of feedback control is developed for processes of long duration under the assumption that experimental noise factors are uncorrelated over time. Systems that follow a pure-gain dynamic model are considered and the best proportional-integral and minimum mean squared error control strategies are developed by using robust parameter design. The proposed method is illustrated using a simulated example and a case study in a urea packing plant. This idea is also extended to cases with on-line noise factors. The possibility of integrating feedforward control with a minimum mean squared error feedback control scheme is explored. To meet the needs of large scale synthesis of nanostructures, it is critical to systematically find experimental conditions under which the desired nanostructures are synthesized reproducibly, at large quantity and with controlled morphology. The first part of the research in this area focuses on modeling and optimization of existing experimental data. Through a rigorous statistical analysis of experimental data, models linking the probabilities of obtaining specific morphologies to the process variables are developed. A new iterative algorithm for fitting a Multinomial GLM is proposed and used. The optimum process conditions, which maximize the above probabilities and make the synthesis process less sensitive to variations of process variables around set values, are derived from the fitted models using Monte-Carlo simulations. The second part of the research deals with development of an experimental design methodology, tailor-made to address the unique phenomena associated with nanostructure synthesis. A sequential space filling design called Sequential Minimum Energy Design (SMED) for exploring best process conditions for synthesis of nanowires. The SMED is a novel approach to generate sequential designs that are model independent, can quickly "carve out" regions with no observable nanostructure morphology, and allow for the exploration of complex response surfaces.

Multimodal decoding and congruent sensory information enhance reaching performance in subjects with cervical spinal cord injury.

PubMed

Corbett, Elaine A; Sachs, Nicholas A; Körding, Konrad P; Perreault, Eric J

2014-01-01

Cervical spinal cord injury (SCI) paralyzes muscles of the hand and arm, making it difficult to perform activities of daily living. Restoring the ability to reach can dramatically improve quality of life for people with cervical SCI. Any reaching system requires a user interface to decode parameters of an intended reach, such as trajectory and target. A challenge in developing such decoders is that often few physiological signals related to the intended reach remain under voluntary control, especially in patients with high cervical injuries. Furthermore, the decoding problem changes when the user is controlling the motion of their limb, as opposed to an external device. The purpose of this study was to investigate the benefits of combining disparate signal sources to control reach in people with a range of impairments, and to consider the effect of two feedback approaches. Subjects with cervical SCI performed robot-assisted reaching, controlling trajectories with either shoulder electromyograms (EMGs) or EMGs combined with gaze. We then evaluated how reaching performance was influenced by task-related sensory feedback, testing the EMG-only decoder in two conditions. The first involved moving the arm with the robot, providing congruent sensory feedback through their remaining sense of proprioception. In the second, the subjects moved the robot without the arm attached, as in applications that control external devices. We found that the multimodal-decoding algorithm worked well for all subjects, enabling them to perform straight, accurate reaches. The inclusion of gaze information, used to estimate target location, was especially important for the most impaired subjects. In the absence of gaze information, congruent sensory feedback improved performance. These results highlight the importance of proprioceptive feedback, and suggest that multi-modal decoders are likely to be most beneficial for highly impaired subjects and in tasks where such feedback is unavailable.

Comparison of human and humanoid robot control of upright stance.

PubMed

Peterka, Robert J

2009-01-01

There is considerable recent interest in developing humanoid robots. An important substrate for many motor actions in both humans and biped robots is the ability to maintain a statically or dynamically stable posture. Given the success of the human design, one would expect there are lessons to be learned in formulating a postural control mechanism for robots. In this study we limit ourselves to considering the problem of maintaining upright stance. Human stance control is compared to a suggested method for robot stance control called zero moment point (ZMP) compensation. Results from experimental and modeling studies suggest there are two important subsystems that account for the low- and mid-frequency (DC to approximately 1Hz) dynamic characteristics of human stance control. These subsystems are (1) a "sensory integration" mechanism whereby orientation information from multiple sensory systems encoding body kinematics (i.e. position, velocity) is flexibly combined to provide an overall estimate of body orientation while allowing adjustments (sensory re-weighting) that compensate for changing environmental conditions and (2) an "effort control" mechanism that uses kinetic-related (i.e., force-related) sensory information to reduce the mean deviation of body orientation from upright. Functionally, ZMP compensation is directly analogous to how humans appear to use kinetic feedback to modify the main sensory integration feedback loop controlling body orientation. However, a flexible sensory integration mechanism is missing from robot control leaving the robot vulnerable to instability in conditions where humans are able to maintain stance. We suggest the addition of a simple form of sensory integration to improve robot stance control. We also investigate how the biological constraint of feedback time delay influences the human stance control design. The human system may serve as a guide for improved robot control, but should not be directly copied because the constraints on robot and human control are different.

Successful inhibitory control over an immediate reward is associated with attentional disengagement in visual processing areas.

PubMed

O'Connor, David A; Rossiter, Sarah; Yücel, Murat; Lubman, Dan I; Hester, Robert

2012-09-01

We examined the neural basis of the capacity to resist an immediately rewarding stimulus in order to obtain a larger delayed reward. This was investigated with a Go/No-go task employing No-go targets that provided two types of reward outcomes. These were contingent on inhibitory control performance: failure to inhibit Reward No-go targets provided a small monetary reward with immediate feedback; while successful inhibitory control resulted in larger rewards with delayed feedback based on the highest number of consecutive inhibitions. We observed faster Go trial responses with maintained levels of inhibition accuracy during the Reward No-go condition compared to a neutral No-go condition. Comparisons between conditions of BOLD activity showed successful inhibitory control over rewarding No-Go targets was associated with hypoactivity in regions previously associated with regulating emotion and inhibitory control, including insula and right inferior frontal gyrus. In addition, regions previously associated with visual processing centers that are modulated as a function of visual attention, namely the left fusiform and right superior temporal gyri, were hypoactive. These findings suggest a role for attentional disengagement as an aid to withholding response over a rewarding stimulus and are consistent with the notion that gratification can be delayed by directing attention away from immediate rewards. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

Motivation from control.

PubMed

Eitam, Baruch; Kennedy, Patrick M; Tory Higgins, E

2013-09-01

Human motivation is sensitive to value-to the outcomes of actions. People invest mental and physical resources for obtaining desired results or for stopping and reversing undesired ones. Accordingly, people's motivation is sensitive to information about their standing in relation to outcome attainment ('outcome feedback'). In this paper, we argue and present the first evidence for the existence of another motivational sensitivity in humans-a sensitivity to our degree of control on the environment and hence to information about that control ('control feedback'). We show that when actions have even trivial and constant perceptual effects, participants' motivation to perform is enhanced. We then show that increased motivation is not because more information about task performance is available and that motivation is increased only in conditions in which control over the effects can be firmly established by the mind. We speculate on the implications for understanding motivation, and potentially, physical and mental health.

Eye Movement Analysis of Information Processing under Different Testing Conditions.

ERIC Educational Resources Information Center

Dillon, Ronna F.

1985-01-01

Undergraduates were given complex figural analogies items, and eye movements were observed under three types of feedback: (1) elaborate feedback; (2) subjects verbalized their thinking and application of rules; and (3) no feedback. Both feedback conditions enhanced the rule-governed information processing during inductive reasoning. (Author/GDC)

Organizational/Memory Tools: A Technique for Improving Problem Solving Skills.

ERIC Educational Resources Information Center

Steinberg, Esther R.; And Others

1986-01-01

This study was conducted to determine whether students would use a computer-presented organizational/memory tool as an aid in problem solving, and whether and how locus of control would affect tool use and problem-solving performance. Learners did use the tools, which were most effective in the learner control with feedback condition. (MBR)

Impaired Feedforward Control and Enhanced Feedback Control of Speech in Patients with Cerebellar Degeneration

PubMed Central

Agnew, Zarinah; Nagarajan, Srikantan; Houde, John; Ivry, Richard B.

2017-01-01

The cerebellum has been hypothesized to form a crucial part of the speech motor control network. Evidence for this comes from patients with cerebellar damage, who exhibit a variety of speech deficits, as well as imaging studies showing cerebellar activation during speech production in healthy individuals. To date, the precise role of the cerebellum in speech motor control remains unclear, as it has been implicated in both anticipatory (feedforward) and reactive (feedback) control. Here, we assess both anticipatory and reactive aspects of speech motor control, comparing the performance of patients with cerebellar degeneration and matched controls. Experiment 1 tested feedforward control by examining speech adaptation across trials in response to a consistent perturbation of auditory feedback. Experiment 2 tested feedback control, examining online corrections in response to inconsistent perturbations of auditory feedback. Both male and female patients and controls were tested. The patients were impaired in adapting their feedforward control system relative to controls, exhibiting an attenuated anticipatory response to the perturbation. In contrast, the patients produced even larger compensatory responses than controls, suggesting an increased reliance on sensory feedback to guide speech articulation in this population. Together, these results suggest that the cerebellum is crucial for maintaining accurate feedforward control of speech, but relatively uninvolved in feedback control. SIGNIFICANCE STATEMENT Speech motor control is a complex activity that is thought to rely on both predictive, feedforward control as well as reactive, feedback control. While the cerebellum has been shown to be part of the speech motor control network, its functional contribution to feedback and feedforward control remains controversial. Here, we use real-time auditory perturbations of speech to show that patients with cerebellar degeneration are impaired in adapting feedforward control of speech but retain the ability to make online feedback corrections; indeed, the patients show an increased sensitivity to feedback. These results indicate that the cerebellum forms a crucial part of the feedforward control system for speech but is not essential for online, feedback control. PMID:28842410

Goal impact influences the evaluative component of performance monitoring: Evidence from ERPs.

PubMed

Severo, Mario Carlo; Walentowska, Wioleta; Moors, Agnes; Pourtois, Gilles

2017-10-01

Successful performance monitoring (PM) requires continuous assessment of context and action outcomes. Electrophysiological studies have reliably identified event-related potential (ERP) markers for evaluative feedback processing during PM: the Feedback-Related Negativity (FRN) and P3 components. The functional significance of FRN remains debated in the literature, with recent research suggesting that feedback's goal relevance can account for FRN (amplitude) modulation, apart from its valence or expectedness alone. Extending this account, the present study assessed whether graded differentiations in feedback's relevance or importance to one's goal (referred to as goal impact) would influence PM at the FRN (and P3) level. To this end, we ran a within-subject crossover design experiment in which 40 participants completed two standard cognitive control tasks (Go/No Go and Simon), while 64-channel electroencephalography was recorded. Critically, both tasks entailed similar reward processing but systematically varied in goal impact assignment (high vs. low), manipulated through their supposed diagnosticity for daily life functioning and activation of social comparison. ERP results showed that goal impact reliably modulated FRN in a general manner. Irrespective of feedback valence, it was overall less negative in the high compared to the low impact condition, suggesting a general decrease in feedback monitoring in the former compared to the latter condition. These findings lend support to the idea that PM is best conceived operating not solely based on motor cues, but is shaped by motivational demands. Copyright © 2017 Elsevier B.V. All rights reserved.

Feedback associated with expectation for larger-reward improves visuospatial working memory performances in children with ADHD.

PubMed

Hammer, Rubi; Tennekoon, Michael; Cooke, Gillian E; Gayda, Jessica; Stein, Mark A; Booth, James R

2015-08-01

We tested the interactive effect of feedback and reward on visuospatial working memory in children with ADHD. Seventeen boys with ADHD and 17 Normal Control (NC) boys underwent functional magnetic resonance imaging (fMRI) while performing four visuospatial 2-back tasks that required monitoring the spatial location of letters presented on a display. Tasks varied in reward size (large; small) and feedback availability (no-feedback; feedback). While the performance of NC boys was high in all conditions, boys with ADHD exhibited higher performance (similar to those of NC boys) only when they received feedback associated with large-reward. Performance pattern in both groups was mirrored by neural activity in an executive function neural network comprised of few distinct frontal brain regions. Specifically, neural activity in the left and right middle frontal gyri of boys with ADHD became normal-like only when feedback was available, mainly when feedback was associated with large-reward. When feedback was associated with small-reward, or when large-reward was expected but feedback was not available, boys with ADHD exhibited altered neural activity in the medial orbitofrontal cortex and anterior insula. This suggests that contextual support normalizes activity in executive brain regions in children with ADHD, which results in improved working memory. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

To make people save energy tell them what others do but also who they are: a preliminary study

PubMed Central

Graffeo, Michele; Ritov, Ilana; Bonini, Nicolao; Hadjichristidis, Constantinos

2015-01-01

A way to make people save energy is by informing them that “comparable others” save more. We investigated whether, one can further improve this nudge by manipulating Who the “comparable others” are. We asked participants to imagine receiving feedback stating that their energy consumption exceeded that of “comparable others” by 10%. We varied Who the “comparable others” were in a 2 × 2 design: they were a household that was located either in the same neighborhood as themselves or in a different neighborhood, and its members were either identified (by names and a photograph) or unidentified. We also included two control conditions: one where no feedback was provided, and one where only statistical feedback was provided (feedback about an average household). We found that it matters Who the “comparable others” are. The most effective feedback was when the referent household was from the same neighborhood as the individual's and its members were not identified. PMID:26379603

Comparison of Human and Humanoid Robot Control of Upright Stance

PubMed Central

Peterka, Robert J.

2009-01-01

There is considerable recent interest in developing humanoid robots. An important substrate for many motor actions in both humans and biped robots is the ability to maintain a statically or dynamically stable posture. Given the success of the human design, one would expect there are lessons to be learned in formulating a postural control mechanism for robots. In this study we limit ourselves to considering the problem of maintaining upright stance. Human stance control is compared to a suggested method for robot stance control called zero moment point (ZMP) compensation. Results from experimental and modeling studies suggest there are two important subsystems that account for the low- and mid-frequency (DC to ~1 Hz) dynamic characteristics of human stance control. These subsystems are 1) a “sensory integration” mechanism whereby orientation information from multiple sensory systems encoding body kinematics (i.e. position, velocity) is flexibly combined to provide an overall estimate of body orientation while allowing adjustments (sensory re-weighting) that compensate for changing environmental conditions, and 2) an “effort control” mechanism that uses kinetic-related (i.e., force-related) sensory information to reduce the mean deviation of body orientation from upright. Functionally, ZMP compensation is directly analogous to how humans appear to use kinetic feedback to modify the main sensory integration feedback loop controlling body orientation. However, a flexible sensory integration mechanism is missing from robot control leaving the robot vulnerable to instability in conditions were humans are able to maintain stance. We suggest the addition of a simple form of sensory integration to improve robot stance control. We also investigate how the biological constraint of feedback time delay influences the human stance control design. The human system may serve as a guide for improved robot control, but should not be directly copied because the constraints on robot and human control are different. PMID:19665564

Neurofeedback in children with attention-deficit/hyperactivity disorder (ADHD)--a controlled multicenter study of a non-pharmacological treatment approach.

PubMed

Holtmann, Martin; Pniewski, Benjamin; Wachtlin, Daniel; Wörz, Sonja; Strehl, Ute

2014-08-13

Attention-deficit/hyperactivity disorder (ADHD) is the most common neurobehavioral disorder of childhood and has often a chronic course persisting into adulthood. However, up to 30% of children treated with stimulants either fail to show an improvement or suffer adverse side effects, including decreased appetite, insomnia and irritability and there is no evidence of long term efficacy of stimulants for ADHD. A series of studies has shown that neurofeedback is an effective additional or alternative treatment for children with ADHD, leading to e.g. significant and stable improvement in behavior, attention and IQ. Significant treatment effects of neurofeedback have also been verified in meta-analyses. Most of the trials, however, have been criticized for methodological difficulties, particularly lacking appropriate control conditions and number of patients included. This randomized study examines the efficacy of slow cortical potentials (SCP) -neurofeedback, controlling unspecific effects of the setting by comparing two active treatment modalities. A total of 144 patients with ADHD, older than six and younger than ten years, in some cases with additional pharmacological treatment, are included in this trial. In five trial centres patients are treated either with SCP-feedback or electromyographic (EMG) -feedback in 25 sessions within 3 months. A comprehensive test battery is conducted before and after treatment and at follow-up 6 month later, to assess core symptoms of ADHD, general psychopathology, attentional performance, comorbid symptoms, intelligence, quality of life and cortical arousal. The efficacy of SCP-feedback training for children with ADHD is evaluated in this randomized controlled study. In addition to behavior ratings and psychometric tests neurophysiological parameters serve as dependent variables. Further, the choice of EMG-biofeedback as an active control condition is debated. Current Controlled Trials ISRCTN76187185. Registered 5 February 2009.

Mikrosensor-gesteuerte Rückkopplungs- Bioaktuatoren auf Halbleiterbasis zur biophysikalischen Krebsbehandlung

NASA Astrophysics Data System (ADS)

Wolf, Bernhard; Kraus, Michael

Acidic microenvironmental conditions combined with large hypoxic areas are ubiquitous hallmarks of most solid tumors. They result from a poorly organized vascularization and a deviant energy metabolism. There is convincing evidence supporting the hypothesis that such physico-chemical conditions promote the microevolution of malignant cells, inhibit the cellular immune response, and favor tumor cell invasion. In agreement with published data, our cell biological analyses and computer simulations indicate that treatment schemes which restore a tumor microenvironment reflecting that one found in normal tissues might improve the efficiency of immunotherapies and classical methods for cancer treatment. We suggest that the tumor microenvironment could be effectively monitored and manipulated by means of silicon-based feedback bioactuators which are controlled by integrated microsensors. In principle, miniaturized bioactuators can be implanted directly at the sites of inoperable tumors and metastases where they function as a "pH clamp" and thereby can reconstitute normal physico-chemical conditions. Drug application could be precisely controlled by an integrated microprocessor. Our paper summarizes the current state of development of microsensor-based feedback bioactuators and outlines possible applications in biophysical cancer treatment.

A Nonlinear Physics-Based Optimal Control Method for Magnetostrictive Actuators

NASA Technical Reports Server (NTRS)

Smith, Ralph C.

1998-01-01

This paper addresses the development of a nonlinear optimal control methodology for magnetostrictive actuators. At moderate to high drive levels, the output from these actuators is highly nonlinear and contains significant magnetic and magnetomechanical hysteresis. These dynamics must be accommodated by models and control laws to utilize the full capabilities of the actuators. A characterization based upon ferromagnetic mean field theory provides a model which accurately quantifies both transient and steady state actuator dynamics under a variety of operating conditions. The control method consists of a linear perturbation feedback law used in combination with an optimal open loop nonlinear control. The nonlinear control incorporates the hysteresis and nonlinearities inherent to the transducer and can be computed offline. The feedback control is constructed through linearization of the perturbed system about the optimal system and is efficient for online implementation. As demonstrated through numerical examples, the combined hybrid control is robust and can be readily implemented in linear PDE-based structural models.

Adaptive critic designs for optimal control of uncertain nonlinear systems with unmatched interconnections.

PubMed

Yang, Xiong; He, Haibo

2018-05-26

In this paper, we develop a novel optimal control strategy for a class of uncertain nonlinear systems with unmatched interconnections. To begin with, we present a stabilizing feedback controller for the interconnected nonlinear systems by modifying an array of optimal control laws of auxiliary subsystems. We also prove that this feedback controller ensures a specified cost function to achieve optimality. Then, under the framework of adaptive critic designs, we use critic networks to solve the Hamilton-Jacobi-Bellman equations associated with auxiliary subsystem optimal control laws. The critic network weights are tuned through the gradient descent method combined with an additional stabilizing term. By using the newly established weight tuning rules, we no longer need the initial admissible control condition. In addition, we demonstrate that all signals in the closed-loop auxiliary subsystems are stable in the sense of uniform ultimate boundedness by using classic Lyapunov techniques. Finally, we provide an interconnected nonlinear plant to validate the present control scheme. Copyright © 2018 Elsevier Ltd. All rights reserved.

Bimanual Coordination Learning with Different Augmented Feedback Modalities and Information Types

PubMed Central

Chiou, Shiau-Chuen; Chang, Erik Chihhung

2016-01-01

Previous studies have shown that bimanual coordination learning is more resistant to the removal of augmented feedback when acquired with auditory than with visual channel. However, it is unclear whether this differential “guidance effect” between feedback modalities is due to enhanced sensorimotor integration via the non-dominant auditory channel or strengthened linkage to kinesthetic information under rhythmic input. The current study aimed to examine how modalities (visual vs. auditory) and information types (continuous visuospatial vs. discrete rhythmic) of concurrent augmented feedback influence bimanual coordination learning. Participants either learned a 90°-out-of-phase pattern for three consecutive days with Lissajous feedback indicating the integrated position of both arms, or with visual or auditory rhythmic feedback reflecting the relative timing of the movement. The results showed diverse performance change after practice when the feedback was removed between Lissajous and the other two rhythmic groups, indicating that the guidance effect may be modulated by the type of information provided during practice. Moreover, significant performance improvement in the dual-task condition where the irregular rhythm counting task was applied as a secondary task also suggested that lower involvement of conscious control may result in better performance in bimanual coordination. PMID:26895286

Bimanual Coordination Learning with Different Augmented Feedback Modalities and Information Types.

PubMed

Chiou, Shiau-Chuen; Chang, Erik Chihhung

2016-01-01

Previous studies have shown that bimanual coordination learning is more resistant to the removal of augmented feedback when acquired with auditory than with visual channel. However, it is unclear whether this differential "guidance effect" between feedback modalities is due to enhanced sensorimotor integration via the non-dominant auditory channel or strengthened linkage to kinesthetic information under rhythmic input. The current study aimed to examine how modalities (visual vs. auditory) and information types (continuous visuospatial vs. discrete rhythmic) of concurrent augmented feedback influence bimanual coordination learning. Participants either learned a 90°-out-of-phase pattern for three consecutive days with Lissajous feedback indicating the integrated position of both arms, or with visual or auditory rhythmic feedback reflecting the relative timing of the movement. The results showed diverse performance change after practice when the feedback was removed between Lissajous and the other two rhythmic groups, indicating that the guidance effect may be modulated by the type of information provided during practice. Moreover, significant performance improvement in the dual-task condition where the irregular rhythm counting task was applied as a secondary task also suggested that lower involvement of conscious control may result in better performance in bimanual coordination.

Eyes on the prize or nose to the grindstone? The effects of level of goal evaluation on mood and motivation.

PubMed

Houser-Marko, Linda; Sheldon, Kennon M

2008-11-01

These studies tested the hypothesis that evaluating goal feedback in terms of a primary, longer term goal can be risky for future motivation. Study 1 was a 2 x 2 experiment in which framing level (primary goal/subgoal) and feedback valence (success/failure) were manipulated for participants during a verbal skills task. In the primary goal failure condition, there was increased negative mood and decreased positive mood and expectancy for subsequent trials, even while controlling for goal difficulty and importance. Study 2 was an 8-week study throughout which participants were asked to evaluate their progress regarding a primary goal (class grade goal) or subgoal (weekly study hours goal), and success or failure varied naturally. When progress was lacking, participants in the primary goal condition experienced the largest decreases in mood and expectancy. These results suggest that it is optimal to evaluate goal progress at the lower, subgoal level, particularly after failure feedback.

The Effect of Mystery Shopper Reports on Age Verification for Tobacco Purchases

PubMed Central

KREVOR, BRAD S.; PONICKI, WILLIAM R.; GRUBE, JOEL W.; DeJONG, WILLIAM

2011-01-01

Mystery shops (MS) involving attempted tobacco purchases by young buyers have been employed to monitor retail stores’ performance in refusing underage sales. Anecdotal evidence suggests that MS visits with immediate feedback to store personnel can improve age verification. This study investigated the impact of monthly and twice-monthly MS reports on age verification. Forty-five Walgreens stores were each visited 20 times by mystery shoppers. The stores were randomly assigned to one of three conditions. Control group stores received no feedback, whereas two treatment groups received feedback communications every visit (twice monthly) or every second visit (monthly) after baseline. Logit regression models tested whether each treatment group improved verification rates relative to the control group. Post-baseline verification rates were higher in both treatment groups than in the control group, but only the stores receiving monthly communications had a significantly greater improvement than control group stores. Verification rates increased significantly during the study period for all three groups, with delayed improvement among control group stores. Communication between managers regarding the MS program may account for the delayed age-verification improvements observed in the control group stores. Encouraging inter-store communication might extend the benefits of MS programs beyond those stores that receive this intervention. PMID:21541874

Leader-Follower Formation Control of UUVs with Model Uncertainties, Current Disturbances, and Unstable Communication

PubMed Central

Yan, Zheping; Xu, Da; Chen, Tao; Zhang, Wei; Liu, Yibo

2018-01-01

Unmanned underwater vehicles (UUVs) have rapidly developed as mobile sensor networks recently in the investigation, survey, and exploration of the underwater environment. The goal of this paper is to develop a practical and efficient formation control method to improve work efficiency of multi-UUV sensor networks. Distributed leader-follower formation controllers are designed based on a state feedback and consensus algorithm. Considering that each vehicle is subject to model uncertainties and current disturbances, a second-order integral UUV model with a nonlinear function is established using the state feedback linearized method under current disturbances. For unstable communication among UUVs, communication failure and acoustic link noise interference are considered. Two-layer random switching communication topologies are proposed to solve the problem of communication failure. For acoustic link noise interference, accurate representation of valid communication information and noise stripping when designing controllers is necessary. Effective communication topology weights are designed to represent the validity of communication information interfered by noise. Utilizing state feedback and noise stripping, sufficient conditions for design formation controllers are proposed to ensure UUV formation achieves consensus under model uncertainties, current disturbances, and unstable communication. The stability of formation controllers is proven by the Lyapunov-Razumikhin theorem, and the validity is verified by simulation results. PMID:29473919

The effect of mystery shopper reports on age verification for tobacco purchases.

PubMed

Krevor, Brad S; Ponicki, William R; Grube, Joel W; DeJong, William

2011-09-01

Mystery shops involving attempted tobacco purchases by young buyers have been implemented in order to monitor retail stores' performance in refusing underage sales. Anecdotal evidence suggests that mystery shop visits with immediate feedback to store personnel can improve age verification. This study investigated the effect of monthly and twice-monthly mystery shop reports on age verification. Mystery shoppers visited 45 Walgreens stores 20 times. The stores were randomly assigned to 1 of 3 conditions. Control group stores received no feedback, whereas 2 treatment groups received feedback communications on every visit (twice monthly) or on every second visit (monthly) after baseline. Logit regression models tested whether each treatment group improved verification rates relative to the control group. Postbaseline verification rates were higher in both treatment groups than in the control group, but only the stores receiving monthly communications had a significantly greater improvement compared with the control group stores. Verification rates increased significantly during the study period for all 3 groups, with delayed improvement among control group stores. Communication between managers regarding the mystery shop program may account for the delayed age-verification improvements observed in the control group stores. Encouraging interstore communication might extend the benefits of mystery shop programs beyond those stores that receive this intervention. Copyright © Taylor & Francis Group, LLC

Development of a neurofeedback protocol targeting the frontal pole using near-infrared spectroscopy.

PubMed

Kinoshita, Akihide; Takizawa, Ryu; Yahata, Noriaki; Homae, Fumitaka; Hashimoto, Ryuichiro; Sakakibara, Eisuke; Kawasaki, Shingo; Nishimura, Yukika; Koike, Shinsuke; Kasai, Kiyoto

2016-11-01

Neurofeedback has been studied with the aim of controlling cerebral activity. Near-infrared spectroscopy is a non-invasive neuroimaging technique used for measuring hemoglobin concentration changes in cortical surface areas with high temporal resolution. Thus, near-infrared spectroscopy may be useful for neurofeedback, which requires real-time feedback of repeated brain activation measurements. However, no study has specifically targeted neurofeedback, using near-infrared spectroscopy, in the frontal pole cortex. We developed an original near-infrared spectroscopy neurofeedback system targeting the frontal pole cortex. Over a single day of testing, each healthy participant (n = 24) received either correct or incorrect (Sham) feedback from near-infrared spectroscopy signals, based on a crossover design. Under correct feedback conditions, significant activation was observed in the frontal pole cortex (P = 0.000073). Additionally, self-evaluation of control and metacognitive beliefs were associated with near-infrared spectroscopy signals (P = 0.006). The neurofeedback system developed in this study might be useful for developing control of frontal pole cortex activation. © 2016 The Authors. Psychiatry and Clinical Neurosciences © 2016 Japanese Society of Psychiatry and Neurology.

Comparative study of flare control laws

NASA Technical Reports Server (NTRS)

Nadkarni, A. A.

1981-01-01

The development of a digital, three dimensional, automatic control law designed to achieve an optimal transition of a B-737 aircraft between glide slope conditions and the desired final touchdown condition is presented. The digital control law is a time invariant, state estimate feedback law, and the design is capable of using the microwave landing system. Major emphasis is placed on the reduction of aircraft noise in communities surroundings airports, the reduction of fuel consumption, the reduction of the effects of adverse weather conditions on aircraft operations, and the efficient use of airspace in congested terminal areas. Attention is also given to the development of the capability to perform automatic flares from steep glide slopes to precise touchdown locations.

Effects of Task-Specific Augmented Feedback on Deficit Modification During Performance of the Tuck-Jump Exercise

PubMed Central

Stroube, Benjamin W.; Myer, Gregory D.; Brent, Jensen L.; Ford, Kevin R.; Heidt, Robert S.; Hewett, Timothy E.

2014-01-01

Context Anterior cruciate ligament (ACL) injuries are prevalent in female athletes. Specific factors have possible links to increasing a female athlete’s chances of suffering an ACL injury. However, it is unclear if augmented feedback may be able to decrease possible risk factors. Objective To compare the effects of task-Specific feedback on a repeated tuck-jump maneuver. Design Double-blind randomized controlled trial. Setting Sports-medicine biodynamics center. Patients 37 female subjects (14.7 ± 1.5 y, 160.9 ± 6.8 cm, 54.5 ± 7.2 kg). Intervention All athletes received standard off-season training consisting of strength training, plyometrics, and conditioning. They were also videotaped during each session while running on a treadmill at a standardized speed (8 miles/h) and while performing a repeated tuck-jump maneuver for 10 s. The augmented feedback group (AF) received feedback on deficiencies present in a 10-s tuck jump, while the control group (CTRL) received feedback on 10-s treadmill running. Main Outcome Measures Outcome measurements of tuck-jump deficits were scored by a blinded rater to determine the effects of group (CTRL vs AF) and time (pre- vs posttesting) on changes in measured deficits. Results A significant interaction of time by group was noted with the task-Specific feedback training (P = .03). The AF group reduced deficits measured during the tuck-jump assessment by 23.6%, while the CTRL training reduced deficits by 10.6%. Conclusions The results of the current study indicate that task-Specific feedback is effective for reducing biomechanical risk factors associated with ACL injury. The data also indicate that Specific components of the tuck-jump assessment are potentially more modifiable than others. PMID:23238301

Locomotor sensory organization test: a novel paradigm for the assessment of sensory contributions in gait.

PubMed

Chien, Jung Hung; Eikema, Diderik-Jan Anthony; Mukherjee, Mukul; Stergiou, Nicholas

2014-12-01

Feedback based balance control requires the integration of visual, proprioceptive and vestibular input to detect the body's movement within the environment. When the accuracy of sensory signals is compromised, the system reorganizes the relative contributions through a process of sensory recalibration, for upright postural stability to be maintained. Whereas this process has been studied extensively in standing using the Sensory Organization Test (SOT), less is known about these processes in more dynamic tasks such as locomotion. In the present study, ten healthy young adults performed the six conditions of the traditional SOT to quantify standing postural control when exposed to sensory conflict. The same subjects performed these six conditions using a novel experimental paradigm, the Locomotor SOT (LSOT), to study dynamic postural control during walking under similar types of sensory conflict. To quantify postural control during walking, the net Center of Pressure sway variability was used. This corresponds to the Performance Index of the center of pressure trajectory, which is used to quantify postural control during standing. Our results indicate that dynamic balance control during locomotion in healthy individuals is affected by the systematic manipulation of multisensory inputs. The sway variability patterns observed during locomotion reflect similar balance performance with standing posture, indicating that similar feedback processes may be involved. However, the contribution of visual input is significantly increased during locomotion, compared to standing in similar sensory conflict conditions. The increased visual gain in the LSOT conditions reflects the importance of visual input for the control of locomotion. Since balance perturbations tend to occur in dynamic tasks and in response to environmental constraints not present during the SOT, the LSOT may provide additional information for clinical evaluation on healthy and deficient sensory processing.

Introducing a feedback training system for guided home rehabilitation.

PubMed

Kohler, Fabian; Schmitz-Rode, Thomas; Disselhorst-Klug, Catherine

2010-01-15

As the number of people requiring orthopaedic intervention is growing, individualized physiotherapeutic rehabilitation and adequate postoperative care becomes increasingly relevant. The chances of improvement in the patients condition is directly related to the performance and consistency of the physiotherapeutic exercises.In this paper a smart, cost-effective and easy to use Feedback Training System for home rehabilitation based on standard resistive elements is introduced. This ensures high accuracy of the exercises performed and offers guidance and control to the patient by offering direct feedback about the performance of the movements.46 patients were recruited and performed standard physiotherapeutic training to evaluate the system. The results show a significant increase in the patient's ability to reproduce even simple physiotherapeutic exercises when being supported by the Feedback Training System. Thus physiotherapeutic training can be extended into the home environment whilst ensuring a high quality of training.

Exploring consequences of short- and long-term deafness on speech production: a lip-tube perturbation study.

PubMed

Turgeon, Christine; Prémont, Amélie; Trudeau-Fisette, Paméla; Ménard, Lucie

2015-05-01

Studies have reported strong links between speech production and perception. We aimed to evaluate the role of long- and short-term auditory feedback alteration on speech production. Eleven adults with normal hearing (controls) and 17 cochlear implant (CI) users (7 pre-lingually deaf and 10 post-lingually deaf adults) were recruited. Short-term auditory feedback deprivation was induced by turning off the CI or by providing masking noise. Acoustic and articulatory measures were obtained during the production of /u/, with and without a tube inserted between the lips (perturbation), and with and without auditory feedback. F1 values were significantly different between the implant OFF and ON conditions for the pre-lingually deaf participants. In the absence of auditory feedback, the pre-lingually deaf participants moved the tongue more forward. Thus, a lack of normal auditory experience of speech may affect the internal representation of a vowel.

Online Personalized Normative Alcohol Feedback for Parents of First Year College Students

PubMed Central

Napper, Lucy E.; LaBrie, Joseph W.; Earle, Andrew

2016-01-01

This study examined the efficacy of a personalized normative feedback (PNF) alcohol intervention for parents of students transitioning into college. A sample of 399 parent-student dyads were recruited to take part in the intervention during the summer prior to matriculation. Parents were randomly assigned to receive either normative feedback regarding student drinking and other college parents’ alcohol-related communication or general college health norm information. Students completed measures of alcohol use, alcohol consequences, and parent-child alcohol-specific communication both 1- and 6-months after matriculation. The results indicated that in comparison to the control condition parents who received PNF reported immediate changes in their perceptions of other parents’ behaviors; however, these changes in parent perceived norms did not translate into long-term changes in student drinking behaviors or parent-child communication. Findings highlight the need to consider content beyond normative feedback for parent based alcohol intervention. PMID:27819429

Effect of Temperature on Synthetic Positive and Negative Feedback Gene Networks

NASA Astrophysics Data System (ADS)

Charlebois, Daniel A.; Marshall, Sylvia; Balazsi, Gabor

Synthetic biological systems are built and tested under well controlled laboratory conditions. How altering the environment, such as the ambient temperature affects their function is not well understood. To address this question for synthetic gene networks with positive and negative feedback, we used mathematical modeling coupled with experiments in the budding yeast Saccharomyces cerevisiae. We found that cellular growth rates and gene expression dose responses change significantly at temperatures above and below the physiological optimum for yeast. Gene expression distributions for the negative feedback-based circuit changed from unimodal to bimodal at high temperature, while the bifurcation point of the positive feedback circuit shifted up with temperature. These results demonstrate that synthetic gene network function is context-dependent. Temperature effects should thus be tested and incorporated into their design and validation for real-world applications. NSERC Postdoctoral Fellowship (Grant No. PDF-453977-2014).

Development of kinesthetic-motor and auditory-motor representations in school-aged children.

PubMed

Kagerer, Florian A; Clark, Jane E

2015-07-01

In two experiments using a center-out task, we investigated kinesthetic-motor and auditory-motor integrations in 5- to 12-year-old children and young adults. In experiment 1, participants moved a pen on a digitizing tablet from a starting position to one of three targets (visuo-motor condition), and then to one of four targets without visual feedback of the movement. In both conditions, we found that with increasing age, the children moved faster and straighter, and became less variable in their feedforward control. Higher control demands for movements toward the contralateral side were reflected in longer movement times and decreased spatial accuracy across all age groups. When feedforward control relies predominantly on kinesthesia, 7- to 10-year-old children were more variable, indicating difficulties in switching between feedforward and feedback control efficiently during that age. An inverse age progression was found for directional endpoint error; larger errors increasing with age likely reflect stronger functional lateralization for the dominant hand. In experiment 2, the same visuo-motor condition was followed by an auditory-motor condition in which participants had to move to acoustic targets (either white band or one-third octave noise). Since in the latter directional cues come exclusively from transcallosally mediated interaural time differences, we hypothesized that auditory-motor representations would show age effects. The results did not show a clear age effect, suggesting that corpus callosum functionality is sufficient in children to allow them to form accurate auditory-motor maps already at a young age.

Development of kinesthetic-motor and auditory-motor representations in school-aged children

PubMed Central

Clark, Jane E.

2015-01-01

In two experiments using a center-out task, we investigated kinesthetic-motor and auditory-motor integrations in 5- to 12-year-old children and young adults. In experiment 1, participants moved a pen on a digitizing tablet from a starting position to one of three targets (visuo-motor condition), and then to one of four targets without visual feedback of the movement. In both conditions, we found that with increasing age, the children moved faster and straighter, and became less variable in their feedforward control. Higher control demands for movements toward the contralateral side were reflected in longer movement times and decreased spatial accuracy across all age groups. When feedforward control relies predominantly on kinesthesia, 7- to 10-year-old children were more variable, indicating difficulties in switching between feedforward and feedback control efficiently during that age. An inverse age progression was found for directional endpoint error; larger errors increasing with age likely reflect stronger functional lateralization for the dominant hand. In experiment 2, the same visuo-motor condition was followed by an auditory-motor condition in which participants had to move to acoustic targets (either white band or one-third octave noise). Since in the latter directional cues come exclusively from transcallosally mediated interaural time differences, we hypothesized that auditory-motor representations would show age effects. The results did not show a clear age effect, suggesting that corpus callosum functionality is sufficient in children to allow them to form accurate auditory-motor maps already at a young age. PMID:25912609

Optimisation of strain selection in evolutionary continuous culture

NASA Astrophysics Data System (ADS)

Bayen, T.; Mairet, F.

2017-12-01

In this work, we study a minimal time control problem for a perfectly mixed continuous culture with n ≥ 2 species and one limiting resource. The model that we consider includes a mutation factor for the microorganisms. Our aim is to provide optimal feedback control laws to optimise the selection of the species of interest. Thanks to Pontryagin's Principle, we derive optimality conditions on optimal controls and introduce a sub-optimal control law based on a most rapid approach to a singular arc that depends on the initial condition. Using adaptive dynamics theory, we also study a simplified version of this model which allows to introduce a near optimal strategy.

Virtual Constraint Control of a Powered Prosthetic Leg: From Simulation to Experiments with Transfemoral Amputees.

PubMed

Gregg, Robert D; Lenzi, Tommaso; Hargrove, Levi J; Sensinger, Jonathon W

2014-12-01

Recent powered (or robotic) prosthetic legs independently control different joints and time periods of the gait cycle, resulting in control parameters and switching rules that can be difficult to tune by clinicians. This challenge might be addressed by a unifying control model used by recent bipedal robots, in which virtual constraints define joint patterns as functions of a monotonic variable that continuously represents the gait cycle phase. In the first application of virtual constraints to amputee locomotion, this paper derives exact and approximate control laws for a partial feedback linearization to enforce virtual constraints on a prosthetic leg. We then encode a human-inspired invariance property called effective shape into virtual constraints for the stance period. After simulating the robustness of the partial feedback linearization to clinically meaningful conditions, we experimentally implement this control strategy on a powered transfemoral leg. We report the results of three amputee subjects walking overground and at variable cadences on a treadmill, demonstrating the clinical viability of this novel control approach.

Virtual Constraint Control of a Powered Prosthetic Leg: From Simulation to Experiments with Transfemoral Amputees

PubMed Central

Lenzi, Tommaso; Hargrove, Levi J.; Sensinger, Jonathon W.

2014-01-01

Recent powered (or robotic) prosthetic legs independently control different joints and time periods of the gait cycle, resulting in control parameters and switching rules that can be difficult to tune by clinicians. This challenge might be addressed by a unifying control model used by recent bipedal robots, in which virtual constraints define joint patterns as functions of a monotonic variable that continuously represents the gait cycle phase. In the first application of virtual constraints to amputee locomotion, this paper derives exact and approximate control laws for a partial feedback linearization to enforce virtual constraints on a prosthetic leg. We then encode a human-inspired invariance property called effective shape into virtual constraints for the stance period. After simulating the robustness of the partial feedback linearization to clinically meaningful conditions, we experimentally implement this control strategy on a powered transfemoral leg. We report the results of three amputee subjects walking overground and at variable cadences on a treadmill, demonstrating the clinical viability of this novel control approach. PMID:25558185

Use of Network Inference to Unravel the Mechanisms of Action and Specificity of Aromatase Inhibitors

EPA Science Inventory

The vertebrate hypothalamus-pituitary-gonadal (HPG) axis is controlled through various feedback mechanisms in order to maintain a dynamic homeostasis during changing environmental conditions, including exposure to chemical stressors. In this study, three aromatase inhibitors, fad...

Dynamic Nature of Alterations in the Endocrine System of Fathead Minnows Exposed to Prochloraz

EPA Science Inventory

The vertebrate hypothalamic-pituitary-gonadal (HPG) axis is controlled through various feedback mechanisms, ideally maintaining dynamic homeostasis in the face of changing environmental conditions, including exposure to chemical stressors. These studies assessed the effects of t...

H∞ robust fault-tolerant controller design for an autonomous underwater vehicle's navigation control system

NASA Astrophysics Data System (ADS)

Cheng, Xiang-Qin; Qu, Jing-Yuan; Yan, Zhe-Ping; Bian, Xin-Qian

2010-03-01

In order to improve the security and reliability for autonomous underwater vehicle (AUV) navigation, an H∞ robust fault-tolerant controller was designed after analyzing variations in state-feedback gain. Operating conditions and the design method were then analyzed so that the control problem could be expressed as a mathematical optimization problem. This permitted the use of linear matrix inequalities (LMI) to solve for the H∞ controller for the system. When considering different actuator failures, these conditions were then also mathematically expressed, allowing the H∞ robust controller to solve for these events and thus be fault-tolerant. Finally, simulation results showed that the H∞ robust fault-tolerant controller could provide precise AUV navigation control with strong robustness.

The impact of feedback valence and communication style on intrinsic motivation in middle childhood: Experimental evidence and generalization across individual differences.

PubMed

Mabbe, Elien; Soenens, Bart; De Muynck, Gert-Jan; Vansteenkiste, Maarten

2018-06-01

Prior research among adolescents and emerging adults has provided evidence for the beneficial effects of positive (relative to negative) feedback and an autonomy-supportive (relative to a controlling) communication style on students' intrinsic motivation. Unfortunately, similar experimental research in middle childhood is lacking. Moreover, little attention has been paid to the question of whether individual differences in personality and perceived parenting play a role in these effects. In the current experimental study (N = 110; M age  = 10.71 years), children completed puzzles at school under one of four experimental conditions, thereby crossing normative feedback valence (i.e., positive vs. negative) with communication style (i.e., autonomy supportive vs. controlling). Prior to the experiment, children filled out questionnaires tapping into the Big Five personality traits and into perceived maternal autonomy support and psychological control. After the experimental induction, children rated several motivational constructs (i.e., intrinsic motivation and need-based experiences). In addition, their voluntary behavioral persistence in a subsequent challenging puzzle task was recorded objectively. Providing positive normative feedback in an autonomy-supportive way yielded the most favorable motivational outcomes. Both feedback valence and communication style yielded an independent impact on children's experiences of competence and autonomy during task engagement, which in turn helped to explain children's elevated intrinsic motivation, as reflected by their perceived interest and behavioral persistence. A few effects were moderated by children's perceived parenting and personality traits, but the number of interactions was limited. The discussion focuses on the motivating role of positive normative feedback and an autonomy-supportive communication style for children. Copyright © 2018 Elsevier Inc. All rights reserved.

Effect of visual distraction and auditory feedback on patient effort during robot-assisted movement training after stroke

PubMed Central

2011-01-01

Background Practicing arm and gait movements with robotic assistance after neurologic injury can help patients improve their movement ability, but patients sometimes reduce their effort during training in response to the assistance. Reduced effort has been hypothesized to diminish clinical outcomes of robotic training. To better understand patient slacking, we studied the role of visual distraction and auditory feedback in modulating patient effort during a common robot-assisted tracking task. Methods Fourteen participants with chronic left hemiparesis from stroke, five control participants with chronic right hemiparesis and fourteen non-impaired healthy control participants, tracked a visual target with their arms while receiving adaptive assistance from a robotic arm exoskeleton. We compared four practice conditions: the baseline tracking task alone; tracking while also performing a visual distracter task; tracking with the visual distracter and sound feedback; and tracking with sound feedback. For the distracter task, symbols were randomly displayed in the corners of the computer screen, and the participants were instructed to click a mouse button when a target symbol appeared. The sound feedback consisted of a repeating beep, with the frequency of repetition made to increase with increasing tracking error. Results Participants with stroke halved their effort and doubled their tracking error when performing the visual distracter task with their left hemiparetic arm. With sound feedback, however, these participants increased their effort and decreased their tracking error close to their baseline levels, while also performing the distracter task successfully. These effects were significantly smaller for the participants who used their non-paretic arm and for the participants without stroke. Conclusions Visual distraction decreased participants effort during a standard robot-assisted movement training task. This effect was greater for the hemiparetic arm, suggesting that the increased demands associated with controlling an affected arm make the motor system more prone to slack when distracted. Providing an alternate sensory channel for feedback, i.e., auditory feedback of tracking error, enabled the participants to simultaneously perform the tracking task and distracter task effectively. Thus, incorporating real-time auditory feedback of performance errors might improve clinical outcomes of robotic therapy systems. PMID:21513561

Electrotactile EMG feedback improves the control of prosthesis grasping force

NASA Astrophysics Data System (ADS)

Schweisfurth, Meike A.; Markovic, Marko; Dosen, Strahinja; Teich, Florian; Graimann, Bernhard; Farina, Dario

2016-10-01

Objective. A drawback of active prostheses is that they detach the subject from the produced forces, thereby preventing direct mechanical feedback. This can be compensated by providing somatosensory feedback to the user through mechanical or electrical stimulation, which in turn may improve the utility, sense of embodiment, and thereby increase the acceptance rate. Approach. In this study, we compared a novel approach to closing the loop, namely EMG feedback (emgFB), to classic force feedback (forceFB), using electrotactile interface in a realistic task setup. Eleven intact-bodied subjects and one transradial amputee performed a routine grasping task while receiving emgFB or forceFB. The two feedback types were delivered through the same electrotactile interface, using a mixed spatial/frequency coding to transmit 8 discrete levels of the feedback variable. In emgFB, the stimulation transmitted the amplitude of the processed myoelectric signal generated by the subject (prosthesis input), and in forceFB the generated grasping force (prosthesis output). The task comprised 150 trials of routine grasping at six forces, randomly presented in blocks of five trials (same force). Interquartile range and changes in the absolute error (AE) distribution (magnitude and dispersion) with respect to the target level were used to assess precision and overall performance, respectively. Main results. Relative to forceFB, emgFB significantly improved the precision of myoelectric commands (min/max of the significant levels) for 23%/36% as well as the precision of force control for 12%/32%, in intact-bodied subjects. Also, the magnitude and dispersion of the AE distribution were reduced. The results were similar in the amputee, showing considerable improvements. Significance. Using emgFB, the subjects therefore decreased the uncertainty of the forward pathway. Since there is a correspondence between the EMG and force, where the former anticipates the latter, the emgFB allowed for predictive control, as the subjects used the feedback to adjust the desired force even before the prosthesis contacted the object. In conclusion, the online emgFB was superior to the classic forceFB in realistic conditions that included electrotactile stimulation, limited feedback resolution (8 levels), cognitive processing delay, and time constraints (fast grasping).

Optimizing Tailored Communications for Health Risk Assessment: A Randomized Factorial Experiment of the Effects of Expectancy Priming, Autonomy Support, and Exemplification.

PubMed

Valle, Carmina G; Queen, Tara L; Martin, Barbara A; Ribisl, Kurt M; Mayer, Deborah K; Tate, Deborah F

2018-03-01

Health risk assessments with tailored feedback plus health education have been shown to be effective for promoting health behavior change. However, there is limited evidence to guide the development and delivery of online automated tailored feedback. The goal of this study was to optimize tailored feedback messages for an online health risk assessment to promote enhanced user engagement, self-efficacy, and behavioral intentions for engaging in healthy behaviors. We examined the effects of three theory-based message factors used in developing tailored feedback messages on levels of engagement, self-efficacy, and behavioral intentions. We conducted a randomized factorial experiment to test three different components of tailored feedback messages: tailored expectancy priming, autonomy support, and use of an exemplar. Individuals (N=1945) were recruited via Amazon Mechanical Turk and randomly assigned to one of eight different experimental conditions within one of four behavioral assessment and feedback modules (tobacco use, physical activity [PA], eating habits, and weight). Participants reported self-efficacy and behavioral intentions pre- and postcompletion of an online health behavior assessment with tailored feedback. Engagement and message perceptions were assessed at follow-up. For the tobacco module, there was a significant main effect of the exemplar factor (P=.04); participants who received exemplar messages (mean 3.31, SE 0.060) rated their self-efficacy to quit tobacco higher than those who did not receive exemplar messages (mean 3.14, SE 0.057). There was a three-way interaction between the effect of message conditions on self-efficacy to quit tobacco (P=.02), such that messages with tailored priming and an exemplar had the greatest impact on self-efficacy to quit tobacco. Across PA, eating habits, and weight modules, there was a three-way interaction among conditions on self-efficacy (P=.048). The highest self-efficacy scores were reported among those who were in the standard priming condition and received both autonomy supportive and exemplar messages. In the PA module, autonomy supportive messages had a stronger effect on self-efficacy for PA in the standard priming condition. For PA, eating habits, and weight-related behaviors, the main effect of exemplar messages on behavioral intentions was in the hypothesized direction but did not reach statistical significance (P=.08). When comparing the main effects of different message conditions, there were no differences in engagement and message perceptions. Findings suggest that tailored feedback messages that use exemplars helped improve self-efficacy related to tobacco cessation, PA, eating habits, and weight control. Combining standard priming and autonomy supportive message components shows potential for optimizing tailored feedback for tobacco cessation and PA behaviors. ©Carmina G Valle, Tara L Queen, Barbara A Martin, Kurt M Ribisl, Deborah K Mayer, Deborah F Tate. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 01.03.2018.

Toward a new generation of vaccines: the anti-cytokine therapeutic vaccines.

PubMed

Zagury, D; Burny, A; Gallo, R C

2001-07-03

Pathological conditions, such as cancers, viral infections, and autoimmune diseases, are associated with abnormal cytokine production, and the morbidity associated with many medical disorders is often directly a result of cytokine production. Because of the absence of negative feedback control occurring in some pathophysiologic situations, a given cytokine may flood and accumulate in the extracellular compartment of tissues or tumors thereby impairing the cytokine network homeostasis and contributing to local pathogenesis. To evaluate whether the rise of anti-cytokine Abs by vaccination is an effective way to treat these pathological conditions without being harmful to the organism, we have analyzed each step of the cytokine process (involving cytokine production, target response, and feedback regulation) and have considered them in the local context of effector--target cell microenvironment and in the overall context of the macroenvironment of the immune system of the organism. In pathologic tissues, Abs of high affinity, as raised by anti-cytokine vaccination, should neutralize the pool of cytokines ectopically accumulated in the extracellular compartment, thus counteracting their pathogenic effects. In contrast, the same Abs should not interfere with cytokine processes occurring in normal tissues, because under physiologic conditions cytokine production by effector cells (induced by activation but controlled by negative feedback regulation) does not accumulate in the extracellular compartment. These concepts are consistent with results showing that following animal and human anti-cytokine vaccination, induction of high-affinity Abs has proven to be safe and effective and encourages this approach as a pioneering avenue of therapy.

Interactions of genes and environment in myopia.

PubMed

Feldkämper, Marita; Schaeffel, Frank

2003-01-01

Myopia is a condition in which the eye is too long for the focal length of cornea and lens, and the plane of sharp focus ends up in front of the retina. Given that the growth of the length of the eye is normally controlled with extreme precision by an image-processing feedback mechanism in the retina, myopia can either be the result of inappropriate visual stimulation, genetically determined changes in the gain or offset of the feedback loops or of inappropriate responses of the target tissues. There is no doubt that an environmental component is involved and extended near work appears to be the major risk factor. However, there is also no doubt that myopia is inherited since myopic parents are much more likely to have myopic children, and myopia is far more frequent in Asian populations than in the USA or Europe, even if groups are compared that have performed similar amounts of near work. A number of systemic or ophthalmic diseases are associated with myopia, indicating that metabolic conditions may interfere either with the gains of the feedback loops or the responses of the target tissue, the sclera. Since there is still no therapy against myopia development, research is directed toward the identification of genes that control the axial elongation of the eye.

Impaired Feedforward Control and Enhanced Feedback Control of Speech in Patients with Cerebellar Degeneration.

PubMed

Parrell, Benjamin; Agnew, Zarinah; Nagarajan, Srikantan; Houde, John; Ivry, Richard B

2017-09-20

The cerebellum has been hypothesized to form a crucial part of the speech motor control network. Evidence for this comes from patients with cerebellar damage, who exhibit a variety of speech deficits, as well as imaging studies showing cerebellar activation during speech production in healthy individuals. To date, the precise role of the cerebellum in speech motor control remains unclear, as it has been implicated in both anticipatory (feedforward) and reactive (feedback) control. Here, we assess both anticipatory and reactive aspects of speech motor control, comparing the performance of patients with cerebellar degeneration and matched controls. Experiment 1 tested feedforward control by examining speech adaptation across trials in response to a consistent perturbation of auditory feedback. Experiment 2 tested feedback control, examining online corrections in response to inconsistent perturbations of auditory feedback. Both male and female patients and controls were tested. The patients were impaired in adapting their feedforward control system relative to controls, exhibiting an attenuated anticipatory response to the perturbation. In contrast, the patients produced even larger compensatory responses than controls, suggesting an increased reliance on sensory feedback to guide speech articulation in this population. Together, these results suggest that the cerebellum is crucial for maintaining accurate feedforward control of speech, but relatively uninvolved in feedback control. SIGNIFICANCE STATEMENT Speech motor control is a complex activity that is thought to rely on both predictive, feedforward control as well as reactive, feedback control. While the cerebellum has been shown to be part of the speech motor control network, its functional contribution to feedback and feedforward control remains controversial. Here, we use real-time auditory perturbations of speech to show that patients with cerebellar degeneration are impaired in adapting feedforward control of speech but retain the ability to make online feedback corrections; indeed, the patients show an increased sensitivity to feedback. These results indicate that the cerebellum forms a crucial part of the feedforward control system for speech but is not essential for online, feedback control. Copyright © 2017 the authors 0270-6474/17/379249-10$15.00/0.

Effects of Feedback on the Vigilance Task Performance of Hyperactive and Hypoactive Children.

ERIC Educational Resources Information Center

Ozolins, Delmar A.; Anderson, Robert P.

1980-01-01

The effects of feedback on the approaches of 20 hyperactive and 20 hypoactive children (ages 6 to 10) to a vigilance task were studied. Results showed that hyperactive Ss had more errors than hypoactive Ss under the feedback for correct responses condition and fewer errors under the feedback for false alarms condition. (PHR)

Altered neural processing of reward and punishment in adolescents with Major Depressive Disorder.

PubMed

Landes, I; Bakos, S; Kohls, G; Bartling, J; Schulte-Körne, G; Greimel, E

2018-05-01

Altered reward and punishment function has been suggested as an important vulnerability factor for the development of Major Depressive Disorder (MDD). Prior ERP studies found evidence for neurophysiological dysfunctions in reinforcement processes in adults with MDD. To date, only few ERP studies have examined the neural underpinnings of reinforcement processing in adolescents diagnosed with MDD. The present event-related potential (ERP) study aimed to investigate neurophysiological mechanisms of anticipation and consumption of reward and punishment in adolescents with MDD in one comprehensive paradigm. During ERP recording, 25 adolescents with MDD and 29 healthy controls (12-17 years) completed a Monetary Incentive Delay Task comprising both a monetary reward and a monetary punishment condition. During anticipation, the cue-P3 signaling attentional allocation was recorded. During consumption, the feedback-P3 and Reward Positivity (RewP) were recorded to capture attentional allocation and outcome evaluation, respectively. Compared to controls, adolescents with MDD showed prolonged cue-P3 latencies to reward cues. Furthermore, unlike controls, adolescents with MDD displayed shorter feedback-P3 latencies in the reward versus punishment condition. RewPs did not differ between groups. It remains unanswered whether the observed alterations in adolescent MDD represent a state or trait. Delayed neural processing of reward cues corresponds to the clinical presentation of adolescent MDD with reduced motivational tendencies to obtain rewards. Relatively shorter feedback-P3 latencies in the reward versus punishment condition could indicate a high salience of performance-contingent reward. Frequent exposure of negatively biased adolescents with MDD to performance-contingent rewards might constitute a promising intervention approach. Copyright © 2018 Elsevier B.V. All rights reserved.

Impact of visual and somatosensory deprivation on dynamic balance in adolescent idiopathic scoliosis.

PubMed

Kuo, Fang-Chuan; Wang, Nai-Hwei; Hong, Chang-Zern

2010-11-01

A cross-sectional study of balance control in adolescents with idiopathic scoliosis (AIS). To investigate the impact of visual and somatosensory deprivation on the dynamic balance in AIS patients and to discuss electromyographic (EMG) and posture sway findings. Most studies focus on posture sway in quiet standing controls with little effort on examining muscle-activated patterns in dynamic standing controls. Twenty-two AIS patients and 22 age-matched normal subjects were studied. To understand how visual and somatosensory information could modulate standing balance, balance tests with the Biodex stability system were performed on a moving platform under 3 conditions: visual feedback provided (VF), eyes closed (EC), and standing on a sponge pad with visual feedback provided (SV). Muscular activities of bilateral lumbar multifidi, gluteus medii, and gastrocnemii muscles were recorded with a telemetry EMG system. AIS patients had normal balance index and amplitude and duration of EMG similar to those of normal subjects in the balance test. However, the onset latency of right gastrocnemius was earlier in AIS patients than in normal subjects. In addition, body-side asymmetry was noted on muscle strength and onset latency in AIS subjects. Under EC condition, lumbar multifidi, and gluteus medii activities were higher than those under SV and VF conditions (P < 0.05). Under SV condition, the medial-lateral tilting angle was less than that under VF and EC conditions. In addition, the active duration of right gluteus medius was shorter under SV condition (P < 0.05). The dynamic balance control is particularly disruptive under visual deprivation with increasing lumbar multifidi and gluteus medii activities for compensation. Sponge pad can cause decrease in frontal plane tilting and gluteus medii effort. The asymmetric muscle strength and onset timing are attributed to anatomic deformation as opposed to neurologic etiological factors.

Systems and methods for controlling energy use during a demand limiting period

DOEpatents

Wenzel, Michael J.; Drees, Kirk H.

2016-04-26

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Integrating Planning and Control for Constrained Dynamical Systems

DTIC Science & Technology

2007-12-01

38 4.2 Mapping from polygonal cell to disk . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.3 Convergent potential ...some idealized potential function. The feedback control policies defined in this thesis are specifically designed to satisfy the low-level constraints...problem into different parts, only focusing on one part, and leaving the rest to others. Some techniques work only in ideal conditions; while others solve

Alleviating Parenting Stress in Parents with Intellectual Disabilities: A Randomized Controlled Trial of a Video-Feedback Intervention to Promote Positive Parenting

ERIC Educational Resources Information Center

Hodes, Marja W.; Meppelder, Marieke; Moor, Marleen; Kef, Sabina; Schuengel, Carlo

2017-01-01

Background: Adapted parenting support may alleviate the high levels of parenting stress experienced by many parents with intellectual disabilities. Methods: Parents with mild intellectual disabilities or borderline intellectual functioning were randomized to experimental (n = 43) and control (n = 42) conditions. Parents in both groups received…

Energy management and attitude control for spacecraft

NASA Astrophysics Data System (ADS)

Costic, Bret Thomas

2001-07-01

This PhD dissertation describes the design and implementation of various control strategies centered around spacecraft applications: (i) an attitude control system for spacecraft, (ii) flywheels used for combined attitude and energy tracking, and (iii) an adaptive autobalancing control algorithm. The theory found in each of these sections is demonstrated through simulation or experimental results. An introduction to each of these three primary chapters can be found in chapter one. The main problem addressed in the second chapter is the quaternion-based, attitude tracking control of rigid spacecraft without angular velocity measurements and in the presence of an unknown inertia matrix. As a stepping-stone, an adaptive, full-state feedback controller that compensates for parametric uncertainty while ensuring asymptotic attitude tracking errors is designed. The adaptive, full-state feedback controller is then redesigned such that the need for angular velocity measurements is eliminated. The proposed adaptive, output feedback controller ensures asymptotic attitude tracking. This work uses a four-parameter representation of the spacecraft attitude that does not exhibit singular orientations as in the case of the previous three-parameter representation-based results. To the best of my knowledge, this represents the first solution to the adaptive, output feedback, attitude tracking control problem for the quaternion representation. Simulation results are included to illustrate the performance of the proposed output feedback control strategy. The third chapter is devoted to the use of multiple flywheels that integrate the energy storage and attitude control functions in space vehicles. This concept, which is referred to as an Integrated Energy Management and Attitude Control (IEMAC) system, reduces the space vehicle bus mass, volume, cost, and maintenance requirements while maintaining or improving the space vehicle performance. To this end, two nonlinear IEMAC strategies (model-based and adaptive) that simultaneously track a desired attitude trajectory and desired energy/power profile are presented. Both strategies ensure asymptotic tracking while the adaptive controller compensates for uncertain spacecraft inertia. In the final chapter, a control strategy is designed for a rotating, unbalanced disk. The control strategy, which is composed of a control torque and two control forces, regulates the disk displacement and ensures angular velocity tracking. The controller uses a desired compensation adaptation law and a gain adjusted forgetting factor to achieve exponential stability despite the lack of knowledge of the imbalance-related parameters, provided a mild persistency of excitation condition is satisfied.

Patterns and reliability of EEG during error monitoring for internal versus external feedback in schizophrenia.

PubMed

Llerena, Katiah; Wynn, Jonathan K; Hajcak, Greg; Green, Michael F; Horan, William P

2016-07-01

Accurately monitoring one's performance on daily life tasks, and integrating internal and external performance feedback are necessary for guiding productive behavior. Although internal feedback processing, as indexed by the error-related negativity (ERN), is consistently impaired in schizophrenia, initial findings suggest that external performance feedback processing, as indexed by the feedback negativity (FN), may actually be intact. The current study evaluated internal and external feedback processing task performance and test-retest reliability in schizophrenia. 92 schizophrenia outpatients and 63 healthy controls completed a flanker task (ERN) and a time estimation task (FN). Analyses examined the ΔERN and ΔFN defined as difference waves between correct/positive versus error/negative feedback conditions. A temporal principal component analysis was conducted to distinguish the ΔERN and ΔFN from overlapping neural responses. We also assessed test-retest reliability of ΔERN and ΔFN in patients over a 4-week interval. Patients showed reduced ΔERN accompanied by intact ΔFN. In patients, test-retest reliability for both ΔERN and ΔFN over a four-week period was fair to good. Individuals with schizophrenia show a pattern of impaired internal, but intact external, feedback processing. This pattern has implications for understanding the nature and neural correlates of impaired feedback processing in schizophrenia. Published by Elsevier B.V.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2017-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and [Formula: see text] robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and H2 robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:28959117

Active Fault Tolerant Control for Ultrasonic Piezoelectric Motor

NASA Astrophysics Data System (ADS)

Boukhnifer, Moussa

2012-07-01

Ultrasonic piezoelectric motor technology is an important system component in integrated mechatronics devices working on extreme operating conditions. Due to these constraints, robustness and performance of the control interfaces should be taken into account in the motor design. In this paper, we apply a new architecture for a fault tolerant control using Youla parameterization for an ultrasonic piezoelectric motor. The distinguished feature of proposed controller architecture is that it shows structurally how the controller design for performance and robustness may be done separately which has the potential to overcome the conflict between performance and robustness in the traditional feedback framework. A fault tolerant control architecture includes two parts: one part for performance and the other part for robustness. The controller design works in such a way that the feedback control system will be solely controlled by the proportional plus double-integral PI2 performance controller for a nominal model without disturbances and H∞ robustification controller will only be activated in the presence of the uncertainties or an external disturbances. The simulation results demonstrate the effectiveness of the proposed fault tolerant control architecture.

Evaluating Personalized Feedback Intervention Framing with a Randomized Controlled Trial to Reduce Young Adult Alcohol-Related Sexual Risk Taking.

PubMed

Lewis, Melissa A; Rhew, Isaac C; Fairlie, Anne M; Swanson, Alex; Anderson, Judyth; Kaysen, Debra

2018-03-06

The purpose of this study was to evaluate personalized feedback intervention (PFI) framing with two web-delivered PFIs aimed to reduce young adult alcohol-related risky sexual behavior (RSB). Combined PFIs typically use an additive approach whereby independent components on drinking and components on RSB are presented without the discussion of the influence of alcohol on RSB. In contrast, an integrated PFI highlights the RSB-alcohol connection by presenting integrated alcohol and RSB components that focus on the role of intoxication as a barrier to risk reduction in sexual situations. In a randomized controlled trial, 402 (53.98% female) sexually active young adults aged 18-25 were randomly assigned to a combined PFI, an integrated PFI, or attention control. All assessment and intervention procedures were web-based. At the 1-month follow-up, those randomly assigned to the integrated condition had a lower likelihood of having any casual sex partners compared to those in the control group. At the 6-month follow-up, the combined condition had a lower likelihood of having any casual sex partners compared to those in the control group. When examining alcohol-related RSB, at the 1-month follow-up, both interventions showed a lower likelihood of any drinking prior to sex compared to the control group. When examining alcohol-related sexual consequences, results showed a reduction in the non-zero count of consequences in the integrated condition compared to the control at the 1-month follow-up. For typical drinks per week, those in the combined condition showed a greater reduction in the non-zero count of drinks than those in the control condition at the 1-month follow-up. While there were no significant differences between the two interventions, the current findings highlight the utility of two efficacious web-based alcohol and RSB interventions among a national sample of at-risk young adults.

Iterative inversion of deformation vector fields with feedback control.

PubMed

Dubey, Abhishek; Iliopoulos, Alexandros-Stavros; Sun, Xiaobai; Yin, Fang-Fang; Ren, Lei

2018-05-14

Often, the inverse deformation vector field (DVF) is needed together with the corresponding forward DVF in four-dimesional (4D) reconstruction and dose calculation, adaptive radiation therapy, and simultaneous deformable registration. This study aims at improving both accuracy and efficiency of iterative algorithms for DVF inversion, and advancing our understanding of divergence and latency conditions. We introduce a framework of fixed-point iteration algorithms with active feedback control for DVF inversion. Based on rigorous convergence analysis, we design control mechanisms for modulating the inverse consistency (IC) residual of the current iterate, to be used as feedback into the next iterate. The control is designed adaptively to the input DVF with the objective to enlarge the convergence area and expedite convergence. Three particular settings of feedback control are introduced: constant value over the domain throughout the iteration; alternating values between iteration steps; and spatially variant values. We also introduce three spectral measures of the displacement Jacobian for characterizing a DVF. These measures reveal the critical role of what we term the nontranslational displacement component (NTDC) of the DVF. We carry out inversion experiments with an analytical DVF pair, and with DVFs associated with thoracic CT images of six patients at end of expiration and end of inspiration. The NTDC-adaptive iterations are shown to attain a larger convergence region at a faster pace compared to previous nonadaptive DVF inversion iteration algorithms. By our numerical experiments, alternating control yields smaller IC residuals and inversion errors than constant control. Spatially variant control renders smaller residuals and errors by at least an order of magnitude, compared to other schemes, in no more than 10 steps. Inversion results also show remarkable quantitative agreement with analysis-based predictions. Our analysis captures properties of DVF data associated with clinical CT images, and provides new understanding of iterative DVF inversion algorithms with a simple residual feedback control. Adaptive control is necessary and highly effective in the presence of nonsmall NTDCs. The adaptive iterations or the spectral measures, or both, may potentially be incorporated into deformable image registration methods. © 2018 American Association of Physicists in Medicine.

Development of a digital automatic control law for steep glideslope capture and flare

NASA Technical Reports Server (NTRS)

Halyo, N.

1977-01-01

A longitudinal digital guidance and control law for steep glideslopes using MLS (Microwave Landing System) data is developed for CTOL aircraft using modern estimation and control techniques. The control law covers the final approach phases of glideslope capture, glideslope tracking, and flare to touchdown for automatic landings under adverse weather conditions. The control law uses a constant gain Kalman filter to process MLS and body-mounted accelerometer data to form estimates of flight path errors and wind velocities including wind shear. The flight path error estimates and wind estimates are used for feedback in generating control surface commands. Results of a digital simulation of the aircraft dynamics and the guidance and control law are presented for various wind conditions.

Factors affecting feeling-of-knowing in a medical intelligent tutoring system: the role of immediate feedback as a metacognitive scaffold.

PubMed

El Saadawi, Gilan M; Azevedo, Roger; Castine, Melissa; Payne, Velma; Medvedeva, Olga; Tseytlin, Eugene; Legowski, Elizabeth; Jukic, Drazen; Crowley, Rebecca S

2010-03-01

Previous studies in our laboratory have shown the benefits of immediate feedback on cognitive performance for pathology residents using an intelligent tutoring system (ITS) in pathology. In this study, we examined the effect of immediate feedback on metacognitive performance, and investigated whether other metacognitive scaffolds will support metacognitive gains when immediate feedback is faded. Twenty-three participants were randomized into intervention and control groups. For both groups, periods working with the ITS under varying conditions were alternated with independent computer-based assessments. On day 1, a within-subjects design was used to evaluate the effect of immediate feedback on cognitive and metacognitive performance. On day 2, a between-subjects design was used to compare the use of other metacognitive scaffolds (intervention group) against no metacognitive scaffolds (control group) on cognitive and metacognitive performance, as immediate feedback was faded. Measurements included learning gains (a measure of cognitive performance), as well as several measures of metacognitive performance, including Goodman-Kruskal gamma correlation (G), bias, and discrimination. For the intervention group, we also computed metacognitive measures during tutoring sessions. Results showed that immediate feedback in an intelligent tutoring system had a statistically significant positive effect on learning gains, G and discrimination. Removal of immediate feedback was associated with decreasing metacognitive performance, and this decline was not prevented when students used a version of the tutoring system that provided other metacognitive scaffolds. Results obtained directly from the ITS suggest that other metacognitive scaffolds do have a positive effect on G and discrimination, as immediate feedback is faded. We conclude that immediate feedback had a positive effect on both metacognitive and cognitive gains in a medical tutoring system. Other metacognitive scaffolds were not sufficient to replace immediate feedback in this study. However, results obtained directly from the tutoring system are not consistent with results obtained from assessments. In order to facilitate transfer to real-world tasks, further research will be needed to determine the optimum methods for supporting metacognition as immediate feedback is faded.

Factors Affecting Feeling-of-knowing in a Medical Intelligent Tutoring System – the role of Immediate Feedback as a Metacognitive Scaffold

PubMed Central

El Saadawi, Gilan M.; Azevedo, Roger; Castine, Melissa; Payne, Velma; Medvedeva, Olga; Tseytlin, Eugene; Legowski, Elizabeth; Jukic, Drazen; Crowley, Rebecca S.

2009-01-01

Objective Previous studies in our laboratory have shown the benefits of immediate feedback on cognitive performance for pathology residents using an Intelligent Tutoring System in Pathology. In this study, we examined the effect of immediate feedback on metacognitive performance, and investigated whether other metacognitive scaffolds will support metacognitive gains when immediate feedback is faded. Methods Twenty-three (23) participants were randomized into intervention and control groups. For both groups, periods working with the ITS under varying conditions were alternated with independent computer-based assessments. On day 1, a within-subjects design was used to evaluate the effect of immediate feedback on cognitive and metacognitive performance. On day 2, a between-subjects design was used to compare the use of other metacognitive scaffolds (intervention group) against no metacognitive scaffolds (control group) on cognitive and metacognitive performance, as immediate feedback was faded. Measurements included learning gains (a measure of cognitive performance), as well as several measures of metacognitive performance, including Goodman-Kruskal Gamma correlation (G), Bias, and Discrimination. For the intervention group, we also computed metacognitive measures during tutoring sessions. Results Results showed that immediate feedback in an intelligent tutoring system had a statistically significant positive effect on learning gains, G and discrimination. Removal of immediate feedback was associated with decreasing metacognitive performance, and this decline was not prevented when students used a version of the tutoring system that provided other metacognitive scaffolds. Results obtained directly from the ITS suggest that other metacognitive scaffolds do have a positive effect on G and Discrimination, as immediate feedback is faded. Conclusions Immediate feedback had a positive effect on both metacognitive and cognitive gains in a medical tutoring system. Other metacognitive scaffolds were not sufficient to replace immediate feedback in this study. However, results obtained directly from the tutoring system are not consistent with results obtained from assessments. In order to facilitate transfer to real-world tasks, further research will be needed to determine the optimum methods for supporting metacognition as immediate feedback is faded. PMID:19434508

Delay-range-dependent chaos synchronization approach under varying time-lags and delayed nonlinear coupling.

PubMed

Zaheer, Muhammad Hamad; Rehan, Muhammad; Mustafa, Ghulam; Ashraf, Muhammad

2014-11-01

This paper proposes a novel state feedback delay-range-dependent control approach for chaos synchronization in coupled nonlinear time-delay systems. The coupling between two systems is esteemed to be nonlinear subject to time-lags. Time-varying nature of both the intrinsic and the coupling delays is incorporated to broad scope of the present study for a better-quality synchronization controller synthesis. Lyapunov-Krasovskii (LK) functional is employed to derive delay-range-dependent conditions that can be solved by means of the conventional linear matrix inequality (LMI)-tools. The resultant control approach for chaos synchronization of the master-slave time-delay systems considers non-zero lower bound of the intrinsic as well as the coupling time-delays. Further, the delay-dependent synchronization condition has been established as a special case of the proposed LK functional treatment. Furthermore, a delay-range-dependent condition, independent of the delay-rate, has been provided to address the situation when upper bound of the delay-derivative is unknown. A robust state feedback control methodology is formulated for synchronization of the time-delay chaotic networks against the L2 norm bounded perturbations by minimizing the L2 gain from the disturbance to the synchronization error. Numerical simulation results are provided for the time-delay chaotic networks to show effectiveness of the proposed delay-range-dependent chaos synchronization methodologies. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Electronic Maxwell demon in the coherent strong-coupling regime

NASA Astrophysics Data System (ADS)

Schaller, Gernot; Cerrillo, Javier; Engelhardt, Georg; Strasberg, Philipp

2018-05-01

We consider an external feedback control loop implementing the action of a Maxwell demon. Applying control actions that are conditioned on measurement outcomes, the demon may transport electrons against a bias voltage and thereby effectively converts information into electric power. While the underlying model—a feedback-controlled quantum dot that is coupled to two electronic leads—is well explored in the limit of small tunnel couplings, we can address the strong-coupling regime with a fermionic reaction-coordinate mapping. This exact mapping transforms the setup into a serial triple quantum dot coupled to two leads. We find that a continuous projective measurement of the central dot occupation would lead to a complete suppression of electronic transport due to the quantum Zeno effect. In contrast, by using a microscopic detector model we can implement a weak measurement, which allows for closure of the control loop without transport blockade. Then, in the weak-coupling regime, the energy flows associated with the feedback loop are negligible, and dominantly the information gained in the measurement induces a bound for the generated electric power. In the strong coupling limit, the protocol may require more energy for operating the control loop than electric power produced, such that the whole device is no longer information dominated and can thus not be interpreted as a Maxwell demon.

Differential contributions of the superior and inferior parietal cortex to feedback versus feedforward control of tools.

PubMed

Macuga, Kristen L; Frey, Scott H

2014-05-15

Damage to the superior and/or inferior parietal lobules (SPL, IPL) (Sirigu et al., 1996) or cerebellum (Grealy and Lee, 2011) can selectively disrupt motor imagery, motivating the hypothesis that these regions participate in predictive (i.e., feedforward) control. If so, then the SPL, IPL, and cerebellum should show greater activity as the demands on feedforward control increase from visually-guided execution (closed-loop) to execution without visual feedback (open-loop) to motor imagery. Using fMRI and a Fitts' reciprocal aiming task with tools directed at targets in far space, we found that the SPL and cerebellum exhibited greater activity during closed-loop control. Conversely, open-loop and imagery conditions were associated with increased activity within the IPL and prefrontal areas. These results are consistent with a superior-to-inferior gradient in the representation of feedback-to-feedforward control within the posterior parietal cortex. Additionally, the anterior SPL displayed greater activity when aiming movements were performed with a stick vs. laser pointer. This may suggest that it is involved in the remapping of far into near (reachable) space (Maravita and Iriki, 2004), or in distalization of the end-effector from hand to stick (Arbib et al., 2009). Copyright © 2014 Elsevier Inc. All rights reserved.

The 'problem' with automation - Inappropriate feedback and interaction, not 'over-automation'

NASA Technical Reports Server (NTRS)

Norman, D. A.

1990-01-01

Automation in high-risk industry is often blamed for causing harm and increasing the chance of human error when failures occur. It is proposed that the problem is not the presence of automation, but rather its inappropriate design. The problem is that the operations are performed appropriately under normal conditions, but there is inadequate feedback and interaction with the humans who must control the overall conduct of the task. The problem is that the automation is at an intermediate level of intelligence, powerful enough to take over control which used to be done by people, but not powerful enough to handle all abnormalities. Moreover, its level of intelligence is insufficient to provide the continual, appropriate feedback that occurs naturally among human operators. To solve this problem, the automation should either be made less intelligent or more so, but the current level is quite inappropriate. The overall message is that it is possible to reduce error through appropriate design considerations.

Self-controlled video feedback on tactical skills for soccer teams results in more active involvement of players.

PubMed

van Maarseveen, Mariëtte J J; Oudejans, Raôul R D; Savelsbergh, Geert J P

2018-02-01

Many studies have shown that self-controlled feedback is beneficial for learning motor tasks, and that learners prefer to receive feedback after supposedly good trials. However, to date all studies conducted on self-controlled learning have used individual tasks and mainly relatively simple skills. Therefore, the aim of this study was to examine self-controlled feedback on tactical skills in small-sided soccer games. Highly talented youth soccer players were assigned to a self-control or yoked group and received video feedback on their offensive performance in 3 vs. 2 small-sided games. The results showed that the self-control group requested feedback mostly after good trials, that is, after they scored a goal. In addition, the perceived performance of the self-control group was higher on feedback than on no-feedback trials. Analyses of the conversations around the video feedback revealed that the players and coach discussed good and poor elements of performance and how to improve it. Although the coach had a major role in these conversations, the players of the self-control group spoke more and showed more initiative compared to the yoked group. The results revealed no significant beneficial effect of self-controlled feedback on performance as judged by the coach. Overall, the findings suggest that in such a complex situation as small-sided soccer games, self-controlled feedback is used both to confirm correct performance elements and to determine and correct errors, and that self-controlled learning stimulates the involvement of the learner in the learning process. Copyright © 2017 Elsevier B.V. All rights reserved.

Empirical Analysis of EEG and ERPs for Psychophysiological Adaptive Task Allocation

NASA Technical Reports Server (NTRS)

Prinzel, Lawrence J., III; Pope, Alan T.; Freeman, Frederick G.; Scerbo, Mark W.; Mikulka, Peter J.

2001-01-01

The present study was designed to test the efficacy of using Electroencephalogram (EEG) and Event-Related Potentials (ERPs) for making task allocation decisions. Thirty-six participants were randomly assigned to an experimental, yoked, or control group condition. Under the experimental condition, a tracking task was switched between task modes based upon the participant's EEG. The results showed that the use of adaptive aiding improved performance and lowered subjective workload under negative feedback as predicted. Additionally, participants in the adaptive group had significantly lower RMSE and NASA-TLX ratings than participants in either the yoked or control group conditions. Furthermore, the amplitudes of the N1 and P3 ERP components were significantly larger under the experimental group condition than under either the yoked or control group conditions. These results are discussed in terms of the implications for adaptive automation design.

Effects of visual feedback with a mirror on balance ability in patients with stroke.

PubMed

In, Tae-Sung; Cha, Yu-Ri; Jung, Jin-Hwa; Jung, Kyoung-Sim

2016-01-01

[Purpose] This study aimed to examine the effects of a visual feedback obtained from a mirror on balance ability during quiet standing in patients with stroke. [Subjects] Fifteen patients with stroke (9 males, 6 females) enrolled in the study. [Methods] Experimental trials (duration, 20s) included three visual conditions (eyes closed, eyes open, and mirror feedback) and two support surface conditions (stable, and unstable). Center of pressure (COP) displacements in the mediolateral and anteroposterior directions were recorded using a force platform. [Results] No effect of condition was observed along all directions on the stable surface. An effect of condition was observed on the unstable surface, with a smaller mediolateral COP distance in the mirror feedback as compared to the other two conditions. Similar results were observed for the COP speed. [Conclusion] Visual feedback from a mirror is beneficial for improving balance ability during quiet standing on an unstable surface in patients with stroke.

Chaos control by electric current in an enzymatic reaction.

PubMed

Lekebusch, A; Förster, A; Schneider, F W

1996-09-01

We apply the continuous delayed feedback method of Pyragas to control chaos in the enzymatic Peroxidase-Oxidase (PO) reaction, using the electric current as the control parameter. At each data point in the time series, a time delayed feedback function applies a small amplitude perturbation to inert platinum electrodes, which causes redox processes on the surface of the electrodes. These perturbations are calculated as the difference between the previous (time delayed) signal and the actual signal. Unstable periodic P1, 1(1), and 1(2) orbits (UPOs) were stabilized in the CSTR (continuous stirred tank reactor) experiments. The stabilization is demonstrated by at least three conditions: A minimum in the experimental dispersion function, the equality of the delay time with the period of the stabilized attractor and the embedment of the stabilized periodic attractor in the chaotic attractor.

How to control chaotic behaviour and population size with proportional feedback

NASA Astrophysics Data System (ADS)

Liz, Eduardo

2010-01-01

We study the control of chaos in one-dimensional discrete maps as they often occur in modelling population dynamics. For managing the population, we seek to suppress any possible chaotic behavior, leading the system to a stable equilibrium. In this Letter, we make a rigorous analysis of the proportional feedback method under certain conditions fulfilled by a wide family of maps. We show that it is possible to stabilize the chaotic dynamics towards a globally stable positive equilibrium, that can be chosen among a broad range of possible values. In particular, the size of the population can be enhanced by control in form of population reduction. This paradoxical phenomenon is known as the hydra effect, and it has important implications in the design of strategies in such areas as fishing, pest management, and conservation biology.

Error mapping controller: a closed loop neuroprosthesis controlled by artificial neural networks.

PubMed

Pedrocchi, Alessandra; Ferrante, Simona; De Momi, Elena; Ferrigno, Giancarlo

2006-10-09

The design of an optimal neuroprostheses controller and its clinical use presents several challenges. First, the physiological system is characterized by highly inter-subjects varying properties and also by non stationary behaviour with time, due to conditioning level and fatigue. Secondly, the easiness to use in routine clinical practice requires experienced operators. Therefore, feedback controllers, avoiding long setting procedures, are required. The error mapping controller (EMC) here proposed uses artificial neural networks (ANNs) both for the design of an inverse model and of a feedback controller. A neuromuscular model is used to validate the performance of the controllers in simulations. The EMC performance is compared to a Proportional Integral Derivative (PID) included in an anti wind-up scheme (called PIDAW) and to a controller with an ANN as inverse model and a PID in the feedback loop (NEUROPID). In addition tests on the EMC robustness in response to variations of the Plant parameters and to mechanical disturbances are carried out. The EMC shows improvements with respect to the other controllers in tracking accuracy, capability to prolong exercise managing fatigue, robustness to parameter variations and resistance to mechanical disturbances. Different from the other controllers, the EMC is capable of balancing between tracking accuracy and mapping of fatigue during the exercise. In this way, it avoids overstressing muscles and allows a considerable prolongation of the movement. The collection of the training sets does not require any particular experimental setting and can be introduced in routine clinical practice.

Error mapping controller: a closed loop neuroprosthesis controlled by artificial neural networks

PubMed Central

Pedrocchi, Alessandra; Ferrante, Simona; De Momi, Elena; Ferrigno, Giancarlo

2006-01-01

Background The design of an optimal neuroprostheses controller and its clinical use presents several challenges. First, the physiological system is characterized by highly inter-subjects varying properties and also by non stationary behaviour with time, due to conditioning level and fatigue. Secondly, the easiness to use in routine clinical practice requires experienced operators. Therefore, feedback controllers, avoiding long setting procedures, are required. Methods The error mapping controller (EMC) here proposed uses artificial neural networks (ANNs) both for the design of an inverse model and of a feedback controller. A neuromuscular model is used to validate the performance of the controllers in simulations. The EMC performance is compared to a Proportional Integral Derivative (PID) included in an anti wind-up scheme (called PIDAW) and to a controller with an ANN as inverse model and a PID in the feedback loop (NEUROPID). In addition tests on the EMC robustness in response to variations of the Plant parameters and to mechanical disturbances are carried out. Results The EMC shows improvements with respect to the other controllers in tracking accuracy, capability to prolong exercise managing fatigue, robustness to parameter variations and resistance to mechanical disturbances. Conclusion Different from the other controllers, the EMC is capable of balancing between tracking accuracy and mapping of fatigue during the exercise. In this way, it avoids overstressing muscles and allows a considerable prolongation of the movement. The collection of the training sets does not require any particular experimental setting and can be introduced in routine clinical practice. PMID:17029636

Investigation of Spatial Control Strategies for AHWR: A Comparative Study

NASA Astrophysics Data System (ADS)

Munje, R. K.; Patre, B. M.; Londhe, P. S.; Tiwari, A. P.; Shimjith, S. R.

2016-04-01

Large nuclear reactors such as the Advanced Heavy Water Reactor (AHWR), are susceptible to xenon-induced spatial oscillations in which, though the core average power remains constant, the power distribution may be nonuniform as well as it might experience unstable oscillations. Such oscillations influence the operation and control philosophy and could also drive safety issues. Therefore, large nuclear reactors are equipped with spatial controllers which maintain the core power distribution close to desired distribution during all the facets of operation and following disturbances. In this paper, the case of AHWR has been considered, for which a number of different types of spatial controllers have been designed during the last decade. Some of these designs are based on output feedback while the others are based on state feedback. Also, both the conventional and modern control concepts, such as linear quadratic regulator theory, sliding mode control, multirate output feedback control and fuzzy control have been investigated. The designs of these different controllers for the AHWR have been carried out using a 90th order model, which is highly stiff. Hence, direct application of design methods suffers with numerical ill-conditioning. Singular perturbation and time-scale methods have been applied whereby the design problem for the original higher order system is decoupled into two or three subproblems, each of which is solved separately. Nonlinear simulations have been carried out to obtain the transient responses of the system with different types of controllers and their performances have been compared.

Biased Feedback in Spatial Recall Yields a Violation of Delta Rule Learning

PubMed Central

Lipinski, John; Spencer, John P.; Samuelson, Larissa K.

2010-01-01

This study investigates whether inductive processes influencing spatial memory performance generalize to supervised learning scenarios with differential feedback. After providing a location memory response in a spatial recall task, participants received visual feedback showing the target location. In critical blocks, feedback was systematically biased either 4° towards the vertical axis (Towards condition) or 4° further away from the vertical axis (Away condition). Results showed that the weaker teaching signal (i.e., a smaller difference between the remembered location and the feedback location) in the Away condition produced a stronger experience-dependent change over blocks than in the Towards condition. This violates delta rule learning. Subsequent simulations of the Dynamic Field Theory of spatial cognition provide a theoretically unified account of these results. PMID:20702881

Biased feedback in spatial recall yields a violation of delta rule learning.

PubMed

Lipinski, John; Spencer, John P; Samuelson, Larissa K

2010-08-01

This study investigates whether inductive processes influencing spatial memory performance generalize to supervised learning scenarios with differential feedback. After providing a location memory response in a spatial recall task, participants received visual feedback showing the target location. In critical blocks, feedback was systematically biased either 4 degrees toward the vertical axis (toward condition) or 4 degrees farther away from the vertical axis (away condition). Results showed that the weaker teaching signal (i.e., a smaller difference between the remembered location and the feedback location) produced a stronger experience-dependent change over blocks in the away condition than in the toward condition. This violates delta rule learning. Subsequent simulations of the dynamic field theory of spatial cognition provide a theoretically unified account of these results.

The effect of Nintendo® Wii® on balance in people with multiple sclerosis: a pilot randomized control study.

PubMed

Brichetto, Giampaolo; Spallarossa, Patricio; de Carvalho, Maria L Lopes; Battaglia, Mario A

2013-08-01

Improvement of sensory strategies is a relevant part of balance rehabilitation in multiple sclerosis (MS). This study aimed to Assess the effectiveness of visual-feedback exercises in improving balance in MS. We divided 36 patients into Wii and control-treated groups that underwent balance rehabilitation. Outcomes were obtained for Berg Balance Scale (BBS), Modified Fatigue Impact Scale, and sway area under conditions of opened and closed eyes. BBS showed a statistically significant improvement (from 49.6 to 54.6 points, p < 0.05) in the Wii group. Interactive visual-feedback exercises such as Wii could be more effective than the current standard protocol in improving balance disorders in MS.

Jump resonant frequency islands in nonlinear feedback control systems

NASA Technical Reports Server (NTRS)

Koenigsberg, W. D.; Dunn, J. C.

1975-01-01

A new type of jump resonance is predicted and observed in certain nonlinear feedback control systems. The new jump resonance characteristic is described as a 'frequency island' due to the fact that a portion of the input-output transfer characteristic is disjoint from the main body. The presence of such frequency islands was predicted by using a sinusoidal describing function characterization of the dynamics of an inertial gyro employing nonlinear ternary rebalance logic. While the general conditions under which such islands are possible has not been examined, a numerical approach is presented which can aid in establishing their presence. The existence of the frequency islands predicted for the ternary rebalanced gyro was confirmed by simulating the nonlinear system and measuring the transfer function.

An expanding universe of circadian networks in higher plants.

PubMed

Pruneda-Paz, Jose L; Kay, Steve A

2010-05-01

Extensive circadian clock networks regulate almost every biological process in plants. Clock-controlled physiological responses are coupled with daily oscillations in environmental conditions resulting in enhanced fitness and growth vigor. Identification of core clock components and their associated molecular interactions has established the basic network architecture of plant clocks, which consists of multiple interlocked feedback loops. A hierarchical structure of transcriptional feedback overlaid with regulated protein turnover sets the pace of the clock and ultimately drives all clock-controlled processes. Although originally described as linear entities, increasing evidence suggests that many signaling pathways can act as both inputs and outputs within the overall network. Future studies will determine the molecular mechanisms involved in these complex regulatory loops. 2010 Elsevier Ltd. All rights reserved.

Electrorheological Fluid Based Force Feedback Device

NASA Technical Reports Server (NTRS)

Pfeiffer, Charles; Bar-Cohen, Yoseph; Mavroidis, Constantinos; Dolgin, Benjamin

1999-01-01

Parallel to the efforts to develop fully autonomous robots, it is increasingly being realized that there are applications where it is essential to have a fully controlled robot and "feel" its operating conditions, i.e. telepresence. This trend is a result of the increasing efforts to address tasks where humans can perform significantly better but, due to associated hazards, distance, physical limitations and other causes, only robots can be employed to perform these tasks. Such robots need to be assisted by a human that remotely controls the operation. To address the goal of operating robots as human surrogates, the authors launched a study of mechanisms that provide mechanical feedback. For this purpose, electrorheological fluids (ERF) are being investigated for the potential application as miniature haptic devices. This family of electroactive fluids has the property of changing the viscosity during electrical stimulation. Consequently, ERF can be used to produce force feedback haptic devices for tele-operated control of medical and space robotic systems. Forces applied at the robot end-effector due to a compliant environment are reflected to the user using an ERF device where a change in the system viscosity will occur proportionally to the transmitted force. Analytical model and control algorithms are being developed taking into account the non-linearities of these type of devices. This paper will describe the concept and the developed mechanism of ERF based force feedback. The test process and the physical properties of this device will be described and the results of preliminary tests will be presented.

Feedback-Equivalence of Nonlinear Systems with Applications to Power System Equations.

NASA Astrophysics Data System (ADS)

Marino, Riccardo

The key concept of the dissertation is feedback equivalence among systems affine in control. Feedback equivalence to linear systems in Brunovsky canonical form and the construction of the corresponding feedback transformation are used to: (i) design a nonlinear regulator for a detailed nonlinear model of a synchronous generator connected to an infinite bus; (ii) establish which power system network structures enjoy the feedback linearizability property and design a stabilizing control law for these networks with a constraint on the control space which comes from the use of d.c. lines. It is also shown that the feedback linearizability property allows the use of state feedback to contruct a linear controllable system with a positive definite linear Hamiltonian structure for the uncontrolled part if the state space is even; a stabilizing control law is derived for such systems. Feedback linearizability property is characterized by the involutivity of certain nested distributions for strongly accessible analytic systems; if the system is defined on a manifold M diffeomorphic to the Euclidean space, it is established that the set where the property holds is a submanifold open and dense in M. If an analytic output map is defined, a set of nested involutive distributions can be always defined and that allows the introduction of an observability property which is the dual concept, in some sense, to feedback linearizability: the goal is to investigate when a nonlinear system affine in control with an analytic output map is feedback equivalent to a linear controllable and observable system. Finally a nested involutive structure of distributions is shown to guarantee the existence of a state feedback that takes a nonlinear system affine in control to a single input one, both feedback equivalent to linear controllable systems, preserving one controlled vector field.

Patient DF's visual brain in action: Visual feedforward control in visual form agnosia.

PubMed

Whitwell, Robert L; Milner, A David; Cavina-Pratesi, Cristiana; Barat, Masihullah; Goodale, Melvyn A

2015-05-01

Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when asked to open her thumb and forefinger a matching amount. Remarkably, however, DF adjusts her hand aperture to accommodate the width of objects when reaching out to pick them up (grip scaling). While this spared ability to grasp objects is presumed to be mediated by visuomotor modules in her relatively intact dorsal stream, it is possible that it may rely abnormally on online visual or haptic feedback. We report here that DF's grip scaling remained intact when her vision was completely suppressed during grasp movements, and it still dissociated sharply from her poor perceptual estimates of target size. We then tested whether providing trial-by-trial haptic feedback after making such perceptual estimates might improve DF's performance, but found that they remained significantly impaired. In a final experiment, we re-examined whether DF's grip scaling depends on receiving veridical haptic feedback during grasping. In one condition, the haptic feedback was identical to the visual targets. In a second condition, the haptic feedback was of a constant intermediate width while the visual target varied trial by trial. Despite this incongruent feedback, DF still scaled her grip aperture to the visual widths of the target blocks, showing only normal adaptation to the false haptically-experienced width. Taken together, these results strengthen the view that DF's spared grasping relies on a normal mode of dorsal-stream functioning, based chiefly on visual feedforward processing. Copyright © 2014 Elsevier B.V. All rights reserved.

Memory-guided force control in healthy younger and older adults.

PubMed

Neely, Kristina A; Samimy, Shaadee; Blouch, Samantha L; Wang, Peiyuan; Chennavasin, Amanda; Diaz, Michele T; Dennis, Nancy A

2017-08-01

Successful performance of a memory-guided motor task requires participants to store and then recall an accurate representation of the motor goal. Further, participants must monitor motor output to make adjustments in the absence of visual feedback. The goal of this study was to examine memory-guided grip force in healthy younger and older adults and compare it to performance on behavioral tasks of working memory. Previous work demonstrates that healthy adults decrease force output as a function of time when visual feedback is not available. We hypothesized that older adults would decrease force output at a faster rate than younger adults, due to age-related deficits in working memory. Two groups of participants, younger adults (YA: N = 32, mean age 21.5 years) and older adults (OA: N = 33, mean age 69.3 years), completed four 20-s trials of isometric force with their index finger and thumb, equal to 25% of their maximum voluntary contraction. In the full-vision condition, visual feedback was available for the duration of the trial. In the no vision condition, visual feedback was removed for the last 12 s of each trial. Participants were asked to maintain constant force output in the absence of visual feedback. Participants also completed tasks of word recall and recognition and visuospatial working memory. Counter to our predictions, when visual feedback was removed, younger adults decreased force at a faster rate compared to older adults and the rate of decay was not associated with behavioral performance on tests of working memory.

Decentralized control of large flexible structures by joint decoupling

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Juang, Jer-Nan

1992-01-01

A decentralized control design method is presented for large complex flexible structures by using the idea of joint decoupling. The derivation is based on a coupled substructure state-space model, which is obtained from enforcing conditions of interface compatibility and equilibrium to the substructure state-space models. It is shown that by restricting the control law to be localized state feedback and by setting the joint actuator input commands to decouple joint 'degrees of freedom' (dof) from interior dof, the global structure control design problem can be decomposed into several substructure control design problems. The substructure control gains and substructure observers are designed based on modified substructure state-space models. The controllers produced by the proposed method can operate successfully at the individual substructure level as well as at the global structure level. Therefore, not only control design but also control implementation is decentralized. Stability and performance requirement of the closed-loop system can be achieved by using any existing state feedback control design method. A two-component mass-spring damper system and a three-truss structure are used as examples to demonstrate the proposed method.

Can virtual reality reduce reality distortion? Impact of performance feedback on symptom change in schizophrenia patients.

PubMed

Moritz, Steffen; Voigt, Miriam; Köther, Ulf; Leighton, Lucy; Kjahili, Besiane; Babur, Zehra; Jungclaussen, David; Veckenstedt, Ruth; Grzella, Karsten

2014-06-01

There is emerging evidence that the induction of doubt can reduce positive symptoms in patients with schizophrenia. Based on prior investigations indicating that brief psychological interventions may attenuate core aspects of delusions, we set up a proof of concept study using a virtual reality experiment. We explored whether feedback for false judgments positively influences delusion severity. A total of 33 patients with schizophrenia participated in the experiment. Following a short practice trial, patients were instructed to navigate through a virtual street on two occasions (noise versus no noise), where they met six different pedestrians in each condition. Subsequently, patients were asked to recollect the pedestrians and their corresponding facial affect in a recognition task graded for confidence. Before and after the experiment, the Paranoia Checklist (frequency subscale) was administered. The Paranoia Checklist score declined significantly from pre to post at a medium effect size. We split the sample into those with some improvement versus those that either showed no improvement, or worsened. Improvement was associated with lower confidence ratings (both during the experiment, particularly for incorrect responses, and according to retrospect assessment). No control condition, unclear if improvement is sustained. The study tentatively suggests that a brief virtual reality experiment involving error feedback may ameliorate delusional ideas. Randomized controlled trials and dismantling studies are now needed to substantiate the findings and to pinpoint the underlying therapeutic mechanisms, for example error feedback or fostering attenuation of confidence judgments in the face of incomplete evidence. Copyright © 2013 Elsevier Ltd. All rights reserved.

Control theory for scanning probe microscopy revisited.

PubMed

Stirling, Julian

2014-01-01

We derive a theoretical model for studying SPM feedback in the context of control theory. Previous models presented in the literature that apply standard models for proportional-integral-derivative controllers predict a highly unstable feedback environment. This model uses features specific to the SPM implementation of the proportional-integral controller to give realistic feedback behaviour. As such the stability of SPM feedback for a wide range of feedback gains can be understood. Further consideration of mechanical responses of the SPM system gives insight into the causes of exciting mechanical resonances of the scanner during feedback operation.

Effects of Anisometropic Amblyopia on Visuomotor Behavior, Part 2: Visually Guided Reaching

PubMed Central

Niechwiej-Szwedo, Ewa; Goltz, Herbert C.; Chandrakumar, Manokaraananthan; Hirji, Zahra; Crawford, J. Douglas; Wong, Agnes M. F.

2016-01-01

Purpose The effects of impaired spatiotemporal vision in amblyopia on visuomotor skills have rarely been explored in detail. The goal of this study was to examine the influences of amblyopia on visually guided reaching. Methods Fourteen patients with anisometropic amblyopia and 14 control subjects were recruited. Participants executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation in three viewing conditions: binocular, monocular amblyopic eye, and monocular fellow eye viewing (left and right monocular viewing for control subjects). Visual feedback of the target was removed on 50% of the trials at the initiation of reaching. Results Reaching accuracy was comparable between patients and control subjects during all three viewing conditions. Patients’ reaching responses were slightly less precise during amblyopic eye viewing, but their precision was normal during binocular or fellow eye viewing. Reaching reaction time was not affected by amblyopia. The duration of the acceleration phase was longer in patients than in control subjects under all viewing conditions, whereas the duration of the deceleration phase was unaffected. Peak acceleration and peak velocity were also reduced in patients. Conclusions Amblyopia affects both the programming and the execution of visually guided reaching. The increased duration of the acceleration phase, as well as the reduced peak acceleration and peak velocity, might reflect a strategy or adaptation of feedforward/feedback control of the visuomotor system to compensate for degraded spatiotemporal vision in amblyopia, allowing patients to optimize their reaching performance. PMID:21051723

Stability of Nonlinear Systems with Unknown Time-varying Feedback Delay

NASA Astrophysics Data System (ADS)

Chunodkar, Apurva A.; Akella, Maruthi R.

2013-12-01

This paper considers the problem of stabilizing a class of nonlinear systems with unknown bounded delayed feedback wherein the time-varying delay is 1) piecewise constant 2) continuous with a bounded rate. We also consider application of these results to the stabilization of rigid-body attitude dynamics. In the first case, the time-delay in feedback is modeled specifically as a switch among an arbitrarily large set of unknown constant values with a known strict upper bound. The feedback is a linear function of the delayed states. In the case of linear systems with switched delay feedback, a new sufficiency condition for average dwell time result is presented using a complete type Lyapunov-Krasovskii (L-K) functional approach. Further, the corresponding switched system with nonlinear perturbations is proven to be exponentially stable inside a well characterized region of attraction for an appropriately chosen average dwell time. In the second case, the concept of the complete type L-K functional is extended to a class of nonlinear time-delay systems with unknown time-varying time-delay. This extension ensures stability robustness to time-delay in the control design for all values of time-delay less than the known upper bound. Model-transformation is used in order to partition the nonlinear system into a nominal linear part that is exponentially stable with a bounded perturbation. We obtain sufficient conditions which ensure exponential stability inside a region of attraction estimate. A constructive method to evaluate the sufficient conditions is presented together with comparison with the corresponding constant and piecewise constant delay. Numerical simulations are performed to illustrate the theoretical results of this paper.

Station Keeping of Small Outboard-Powered Boats

NASA Technical Reports Server (NTRS)

Fisher, A. D.; VanZwieten, J. H., Jr.; VanZwieten, T. S.

2010-01-01

Three station keeping controllers have been developed which work to minimize displacement of a small outboard-powered vessel from a desired location. Each of these three controllers has a common initial layer that uses fixed-gain feedback control to calculate the desired heading of the vessel. A second control layer uses a common fixed-gain feedback controller to calculate the net forward thrust, one of two algorithms for controlling engine angle (Fixed-Gain Proportional-integral-derivative (PID) or PID with Adaptively Augmented Gains), and one of two algorithms for differential throttle control (Fixed-Gain PID and PID with Adaptive Differential Throttle gains), which work together to eliminate heading error. The three selected controllers are evaluated using a numerical simulation of a 33-foot center console vessel with twin outboards that is subject to wave, wind, and current disturbances. Each controller is tested for its ability to maintain position in the presence of three sets of environmental disturbances. These algorithms were tested with current velocity of 1.5 m/s, significant wave height of 0.5 m, and wind speeds of 2, 5, and 10 m/s. These values were chosen to model conditions a small vessel may experience in the Gulf Stream off of Fort Lauderdale. The Fixed-gain PID controller progressively got worse as wind speeds increased, while the controllers using adaptive methodologies showed consistent performance over all weather conditions and decreased heading error by as much as 20%. Thus, enhanced robustness to environmental changes has been gained by using an adaptive algorithm.

Realizing actual feedback control of complex network

NASA Astrophysics Data System (ADS)

Tu, Chengyi; Cheng, Yuhua

2014-06-01

In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

Learning feedback and feedforward control in a mirror-reversed visual environment.

PubMed

Kasuga, Shoko; Telgen, Sebastian; Ushiba, Junichi; Nozaki, Daichi; Diedrichsen, Jörn

2015-10-01

When we learn a novel task, the motor system needs to acquire both feedforward and feedback control. Currently, little is known about how the learning of these two mechanisms relate to each other. In the present study, we tested whether feedforward and feedback control need to be learned separately, or whether they are learned as common mechanism when a new control policy is acquired. Participants were trained to reach to two lateral and one central target in an environment with mirror (left-right)-reversed visual feedback. One group was allowed to make online movement corrections, whereas the other group only received visual information after the end of the movement. Learning of feedforward control was assessed by measuring the accuracy of the initial movement direction to lateral targets. Feedback control was measured in the responses to sudden visual perturbations of the cursor when reaching to the central target. Although feedforward control improved in both groups, it was significantly better when online corrections were not allowed. In contrast, feedback control only adaptively changed in participants who received online feedback and remained unchanged in the group without online corrections. Our findings suggest that when a new control policy is acquired, feedforward and feedback control are learned separately, and that there may be a trade-off in learning between feedback and feedforward controllers. Copyright © 2015 the American Physiological Society.

Learning feedback and feedforward control in a mirror-reversed visual environment

PubMed Central

Kasuga, Shoko; Telgen, Sebastian; Ushiba, Junichi; Nozaki, Daichi

2015-01-01

When we learn a novel task, the motor system needs to acquire both feedforward and feedback control. Currently, little is known about how the learning of these two mechanisms relate to each other. In the present study, we tested whether feedforward and feedback control need to be learned separately, or whether they are learned as common mechanism when a new control policy is acquired. Participants were trained to reach to two lateral and one central target in an environment with mirror (left-right)-reversed visual feedback. One group was allowed to make online movement corrections, whereas the other group only received visual information after the end of the movement. Learning of feedforward control was assessed by measuring the accuracy of the initial movement direction to lateral targets. Feedback control was measured in the responses to sudden visual perturbations of the cursor when reaching to the central target. Although feedforward control improved in both groups, it was significantly better when online corrections were not allowed. In contrast, feedback control only adaptively changed in participants who received online feedback and remained unchanged in the group without online corrections. Our findings suggest that when a new control policy is acquired, feedforward and feedback control are learned separately, and that there may be a trade-off in learning between feedback and feedforward controllers. PMID:26245313

Effects of mediated social touch on affective experiences and trust.

PubMed

Erk, Stefanie M; Toet, Alexander; Van Erp, Jan B F

2015-01-01

This study investigated whether communication via mediated hand pressure during a remotely shared experience (watching an amusing video) can (1) enhance recovery from sadness, (2) enhance the affective quality of the experience, and (3) increase trust towards the communication partner. Thereto participants first watched a sad movie clip to elicit sadness, followed by a funny one to stimulate recovery from sadness. While watching the funny clip they signaled a hypothetical fellow participant every time they felt amused. In the experimental condition the participants responded by pressing a hand-held two-way mediated touch device (a Frebble), which also provided haptic feedback via simulated hand squeezes. In the control condition they responded by pressing a button and they received abstract visual feedback. Objective (heart rate, galvanic skin conductance, number and duration of joystick or Frebble presses) and subjective (questionnaires) data were collected to assess the emotional reactions of the participants. The subjective measurements confirmed that the sad movie successfully induced sadness while the funny movie indeed evoked more positive feelings. Although their ranking agreed with the subjective measurements, the physiological measurements confirmed this conclusion only for the funny movie. The results show that recovery from movie induced sadness, the affective experience of the amusing movie, and trust towards the communication partner did not differ between both experimental conditions. Hence, feedback via mediated hand touching did not enhance either of these factors compared to visual feedback. Further analysis of the data showed that participants scoring low on Extraversion (i.e., persons that are more introvert) or low on Touch Receptivity (i.e., persons who do not like to be touched by others) felt better understood by their communication partner when receiving mediated touch feedback instead of visual feedback, while the opposite was found for participants scoring high on these factors. The implications of these results for further research are discussed, and some suggestions for follow-up experiments are presented.

Effects of mediated social touch on affective experiences and trust

PubMed Central

Erk, Stefanie M.; Van Erp, Jan B.F.

2015-01-01

This study investigated whether communication via mediated hand pressure during a remotely shared experience (watching an amusing video) can (1) enhance recovery from sadness, (2) enhance the affective quality of the experience, and (3) increase trust towards the communication partner. Thereto participants first watched a sad movie clip to elicit sadness, followed by a funny one to stimulate recovery from sadness. While watching the funny clip they signaled a hypothetical fellow participant every time they felt amused. In the experimental condition the participants responded by pressing a hand-held two-way mediated touch device (a Frebble), which also provided haptic feedback via simulated hand squeezes. In the control condition they responded by pressing a button and they received abstract visual feedback. Objective (heart rate, galvanic skin conductance, number and duration of joystick or Frebble presses) and subjective (questionnaires) data were collected to assess the emotional reactions of the participants. The subjective measurements confirmed that the sad movie successfully induced sadness while the funny movie indeed evoked more positive feelings. Although their ranking agreed with the subjective measurements, the physiological measurements confirmed this conclusion only for the funny movie. The results show that recovery from movie induced sadness, the affective experience of the amusing movie, and trust towards the communication partner did not differ between both experimental conditions. Hence, feedback via mediated hand touching did not enhance either of these factors compared to visual feedback. Further analysis of the data showed that participants scoring low on Extraversion (i.e., persons that are more introvert) or low on Touch Receptivity (i.e., persons who do not like to be touched by others) felt better understood by their communication partner when receiving mediated touch feedback instead of visual feedback, while the opposite was found for participants scoring high on these factors. The implications of these results for further research are discussed, and some suggestions for follow-up experiments are presented. PMID:26557429

Analysis of the Auditory Feedback and Phonation in Normal Voices.

PubMed

Arbeiter, Mareike; Petermann, Simon; Hoppe, Ulrich; Bohr, Christopher; Doellinger, Michael; Ziethe, Anke

2018-02-01

The aim of this study was to investigate the auditory feedback mechanisms and voice quality during phonation in response to a spontaneous pitch change in the auditory feedback. Does the pitch shift reflex (PSR) change voice pitch and voice quality? Quantitative and qualitative voice characteristics were analyzed during the PSR. Twenty-eight healthy subjects underwent transnasal high-speed video endoscopy (HSV) at 8000 fps during sustained phonation [a]. While phonating, the subjects heard their sound pitched up for 700 cents (interval of a fifth), lasting 300 milliseconds in their auditory feedback. The electroencephalography (EEG), acoustic voice signal, electroglottography (EGG), and high-speed-videoendoscopy (HSV) were analyzed to compare feedback mechanisms for the pitched and unpitched condition of the phonation paradigm statistically. Furthermore, quantitative and qualitative voice characteristics were analyzed. The PSR was successfully detected within all signals of the experimental tools (EEG, EGG, acoustic voice signal, HSV). A significant increase of the perturbation measures and an increase of the values of the acoustic parameters during the PSR were observed, especially for the audio signal. The auditory feedback mechanism seems not only to control for voice pitch but also for voice quality aspects.

Effect of vibrotactile feedback on an EMG-based proportional cursor control system.

PubMed

Li, Shunchong; Chen, Xingyu; Zhang, Dingguo; Sheng, Xinjun; Zhu, Xiangyang

2013-01-01

Surface electromyography (sEMG) has been introduced into the bio-mechatronics systems, however, most of them are lack of the sensory feedback. In this paper, the effect of vibrotactile feedback for a myoelectric cursor control system is investigated quantitatively. Simultaneous and proportional control signals are extracted from EMG using a muscle synergy model. Different types of feedback including vibrotactile feedback and visual feedback are added, assessed and compared with each other. The results show that vibrotactile feedback is capable of improving the performance of EMG-based human machine interface.

Systems and methods for controlling energy use in a building management system using energy budgets

DOEpatents

Wenzel, Michael J; Drees, Kirk H

2014-09-23

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Nonlinear feedback guidance law for aero-assisted orbit transfer maneuvers

NASA Technical Reports Server (NTRS)

Menon, P. K. A.

1992-01-01

Aero-assisted orbit transfer vehicles have the potential for significantly reducing the fuel requirements in certain classes of orbit transfer operations. Development of a nonlinear feedback guidance law for performing aero-assisted maneuvers that accomplish simultaneous change of all the orbital elements with least vehicle acceleration magnitude is discussed. The analysis is based on a sixth order nonlinear point-mass vehicle model with lift, bank angle, thrust and drag modulation as the control variables. The guidance law uses detailed vehicle aerodynamic and the atmosphere models in the feedback loop. Higher-order gravitational harmonics, planetary atmosphere rotation and ambient winds are included in the formulation. Due to modest computational requirements, the guidance law is implementable on-board an orbit transfer vehicle. The guidance performance is illustrated for three sets of boundary conditions.

Self-organization and feedback effects in the shock compressed media

NASA Astrophysics Data System (ADS)

Khantuleva, Tatyana

2005-07-01

New theoretical approach to the transport in condensed matter far from equilibrium combines methods of statistical mechanics and cybernetic physics in order to construct closed mathematical model of a system with self-organization and self-regulation. Mesoscopic effects are considered as a result of the structure formation and the feedback effects in an open system under dynamic loading. Nonequilibrium state equations had been involved to incorporate the velocity dispersion. Integrodifferential balance equations describe both wave and dissipative transport properties. Boundary conditions determine the internal scale spectra. The model is completed by the feedback that introduces the structure evolution basing the methods of cybernetic physics. The obtained results open a wide prospective for the control methods in applications to new technologies, intellectual systems and prediction of catastrophic phenomena.

Visual feedback attenuates mean concentric barbell velocity loss, and improves motivation, competitiveness, and perceived workload in male adolescent athletes.

PubMed

Weakley, Jonathon Js; Wilson, Kyle M; Till, Kevin; Read, Dale B; Darrall-Jones, Joshua; Roe, Gregory; Phibbs, Padraic J; Jones, Ben

2017-07-12

It is unknown whether instantaneous visual feedback of resistance training outcomes can enhance barbell velocity in younger athletes. Therefore, the purpose of this study was to quantify the effects of visual feedback on mean concentric barbell velocity in the back squat, and to identify changes in motivation, competitiveness, and perceived workload. In a randomised-crossover design (Feedback vs. Control) feedback of mean concentric barbell velocity was or was not provided throughout a set of 10 repetitions in the barbell back squat. Magnitude-based inferences were used to assess changes between conditions, with almost certainly greater differences in mean concentric velocity between the Feedback (0.70 ±0.04 m·s) and Control (0.65 ±0.05 m·s) observed. Additionally, individual repetition mean concentric velocity ranged from possibly (repetition number two: 0.79 ±0.04 vs. 0.78 ±0.04 m·s) to almost certainly (repetition number 10: 0.58 ±0.05 vs. 0.49 ±0.05 m·s) greater when provided feedback, while almost certain differences were observed in motivation, competitiveness, and perceived workload, respectively. Providing adolescent male athletes with visual kinematic information while completing resistance training is beneficial for the maintenance of barbell velocity during a training set, potentially enhancing physical performance. Moreover, these improvements were observed alongside increases in motivation, competitiveness and perceived workload providing insight into the underlying mechanisms responsible for the performance gains observed. Given the observed maintenance of barbell velocity during a training set, practitioners can use this technique to manipulate training outcomes during resistance training.

Patient-centered feedback on the results of personality testing increases early engagement in residential substance use disorder treatment: a pilot randomized controlled trial.

PubMed

Blonigen, Daniel M; Timko, Christine; Jacob, Theodore; Moos, Rudolf H

2015-03-14

Patient-centered models of assessment have shown considerable promise for increasing patients' readiness for mental health treatment in general, but have not been used to facilitate patients' engagement in substance use disorder (SUD) treatment. We developed a brief patient-centered intervention using assessment and feedback of personality data and examined its acceptability and efficacy to increase early engagement in residential SUD treatment. Thirty patients entering a 90-day residential SUD treatment program were randomly assigned to a feedback (n = 17) or control (n = 13; assessment-only) condition. Normal-range personality was assessed with the NEO Personality Inventory-Revised (NEO PI-R). Patients were re-interviewed one month after treatment entry to obtain information on their satisfaction with the intervention, as well as their adjustment to the residential milieu. Electronic medical records were reviewed to obtain information on patients' length of stay in the program and discharge status. Univariate ANOVAs and chi-square tests were conducted to examine group differences on outcomes. Patients' ratings indicated strong satisfaction with the feedback intervention and expectations that it would have a positive impact on their treatment experiences. Among patients who had not previously been treated in the residential program, the feedback intervention was associated with more positive relationships with other residents in treatment and a stronger alliance with the treatment program one month after treatment entry. The feedback intervention was also associated with a longer length of stay in treatment, although this effect did not reach statistical significance. The findings highlight the clinical utility of providing SUD patients with patient-centered feedback based on the results of personality testing, and provide preliminary support for the acceptability and efficacy of this intervention to facilitate early engagement in residential SUD treatment.

Testing the efficacy of web-based cognitive behavioural therapy for adult patients with chronic fatigue syndrome (CBIT): study protocol for a randomized controlled trial.

PubMed

Janse, Anthonie; Worm-Smeitink, Margreet; Bussel-Lagarde, José; Bleijenberg, Gijs; Nikolaus, Stephanie; Knoop, Hans

2015-08-12

Cognitive behavioural therapy (CBT) is an effective treatment for fatigue and disabilities in patients with chronic fatigue syndrome (CFS). However, treatment capacity is limited. Providing web-based CBT and tailoring the amount of contact with the therapist to the individual needs of the patient may increase the efficiency of the intervention. Web-based CBT for adolescents with CFS has proven to be effective in reducing fatigue and increasing school attendance. In the proposed study the efficacy of a web-based CBT intervention for adult patients with CFS will be explored. Two different formats of web-based CBT will be tested. In the first format named protocol driven feedback, patients report on their progress and receive feedback from a therapist according to a preset schedule. In the second format named support on demand, feedback and support of the therapist is only given when patients ask for it. The primary objective of the study is to determine the efficacy of a web-based CBT intervention on fatigue severity. A randomized clinical trial will be conducted. Two-hundred-forty adults who have been diagnosed with CFS according to the US Centers for Disease Control and Prevention (CDC) consensus criteria will be recruited and randomized to one of three conditions: web-based CBT with protocol driven feedback, web-based CBT with support on demand, or wait list. Feedback will be delivered by therapists specialized in CBT for CFS. Each of the web-based CBT interventions will be compared to a wait list condition with respect to its effect on the primary outcome measure; fatigue severity. Secondary outcome measures are level of disability, physical functioning, psychological distress, and the proportion of patients with clinical significant improvement in fatigue severity. Outcomes will be assessed at baseline and six months post randomization. The web-based CBT formats will be compared with respect to the time therapists need to deliver the intervention. As far as we know this is the first randomized controlled trial (RCT) that evaluates the efficacy of a web-based CBT intervention for adult patients with CFS. NTR4013.

Solving a Local Boundary Value Problem for a Nonlinear Nonstationary System in the Class of Feedback Controls

NASA Astrophysics Data System (ADS)

Kvitko, A. N.

2018-01-01

An algorithm convenient for numerical implementation is proposed for constructing differentiable control functions that transfer a wide class of nonlinear nonstationary systems of ordinary differential equations from an initial state to a given point of the phase space. Constructive sufficient conditions imposed on the right-hand side of the controlled system are obtained under which this transfer is possible. The control of a robotic manipulator is considered, and its numerical simulation is performed.

Voluntary modulation of anterior cingulate response to negative feedback.

PubMed

Shane, Matthew S; Weywadt, Christina R

2014-01-01

Anterior cingulate and medial frontal cortex (dACC/mFC) response to negative feedback represents the actions of a generalized error-monitoring system critical for the management of goal-directed behavior. Magnitude of dACC/mFC response to negative feedback correlates with levels of post-feedback behavioral change, and with proficiency of operant learning processes. With this in mind, it follows that an ability to alter dACC/mFC response to negative feedback may lead to representative changes in operant learning proficiency. To this end, the present study investigated the extent to which healthy individuals would show modulation of their dACC/mFC response when instructed to try to either maximize or minimize their neural response to the presentation of contingent negative feedback. Participants performed multiple runs of a standard time-estimation task, during which they received feedback regarding their ability to accurately estimate a one-second duration. On Watch runs, participants were simply instructed to try to estimate as closely as possible the one second duration. On Increase and Decrease runs, participants performed the same task, but were instructed to "try to increase [decrease] their brain's response every time they received negative feedback". Results indicated that participants showed changes in dACC/mFC response under these differing instructional conditions: dACC/mFC activity following negative feedback was higher in the Increase condition, and dACC activity trended lower in the Decrease condition, compared to the Watch condition. Moreover, dACC activity correlated with post-feedback performance adjustments, and these adjustments were highest in the Increase condition. Potential implications for neuromodulation and facilitated learning are discussed.

Simulation and design of feedback control on resistive wall modes in Keda Torus eXperiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chenguang; Liu, Wandong; Li, Hong

2014-12-15

The feedback control of resistive wall modes (RWMs) in Keda Torus eXperiment (KTX) (Liu et al., Plasma Phys. Controlled Fusion 56, 094009 (2014)) is investigated by simulation. A linear model is built to describe the growth of the unstable modes in the absence of feedback and the resulting mode suppression due to feedback, given the typical reversed field pinch plasma equilibrium. The layout of KTX with two shell structures (the vacuum vessel and the stabilizing shell) is taken into account. The feedback performance is explored both in the scheme of “clean mode control” (Zanca et al., Nucl. Fusion 47, 1425more » (2007)) and “raw mode control.” The discrete time control model with specific characteristic times will mimic the real feedback control action and lead to the favored control cycle. Moreover, the conceptual design of feedback control system is also presented, targeting on both RWMs and tearing modes.« less

Effects of control laws and relaxed static stability on vertical ride quality of flexible aircraft

NASA Technical Reports Server (NTRS)

Roberts, P. A.; Swaim, R. L.; Schmidt, D. K.; Hinsdale, A. J.

1977-01-01

State variable techniques are utilized to generate the RMS vertical load factors for the B-52H and B-1 bombers at low level, mission critical, cruise conditions. A ride quality index is proposed to provide meaningful comparisons between different controls or conditions. Ride quality is shown to be relatively invariant under various popular control laws. Handling quality variations are shown to be major contributors to ride quality variations on both vehicles. Relaxed static stability is artificially implemented on the study vehicles to investigate its effects on ride quality. The B-52H ride quality is generally degraded when handling characteristics are automatically restored by a feedback control to the original values from relaxed stability conditions. The B-1 airplane shows little ride quality sensitivity to the same analysis due to the small rigid body contribution to load factors at the flight condition investigated.

A review of active control approaches in stabilizing combustion systems in aerospace industry

NASA Astrophysics Data System (ADS)

Zhao, Dan; Lu, Zhengli; Zhao, He; Li, X. Y.; Wang, Bing; Liu, Peijin

2018-02-01

Self-sustained combustion instabilities are one of the most plaguing challenges and problems in lean-conditioned propulsion and land-based engine systems, such as rocket motors, gas turbines, industrial furnace and boilers, and turbo-jet thrust augmenters. Either passive or active control in open- or closed-loop configurations can be implemented to mitigate such instabilities. One of the classical disadvantages of passive control is that it is only implementable to a designed combustor over a limited frequency range and can not respond to the changes in operating conditions. Compared with passive control approaches, active control, especially in closed-loop configuration is more adaptive and has inherent capacity to be implemented in practice. The key components in closed-loop active control are 1) sensor, 2) controller (optimization algorithm) and 3) dynamic actuator. The present work is to outline the current status, technical challenges and development progress of the active control approaches (in open- or closed-loop configurations). A brief description of feedback control, adaptive control, model-based control and sliding mode control are provided first by introducing a simplified Rijke-type combustion system. The modelled combustion system provides an invaluable platform to evaluate the performance of these feedback controllers and a transient growth controller. The performance of these controllers are compared and discussed. An outline of theoretical, numerical and experimental investigations are then provided to overview the research and development progress made during the last 4 decades. Finally, potential, challenges and issues involved with the design, application and implementation of active combustion control strategies on a practical engine system are highlighted.

Vehicle dynamics control of four in-wheel motor drive electric vehicle using gain scheduling based on tyre cornering stiffness estimation

NASA Astrophysics Data System (ADS)

Xiong, Lu; Yu, Zhuoping; Wang, Yang; Yang, Chen; Meng, Yufeng

2012-06-01

This paper focuses on the vehicle dynamic control system for a four in-wheel motor drive electric vehicle, aiming at improving vehicle stability under critical driving conditions. The vehicle dynamics controller is composed of three modules, i.e. motion following control, control allocation and vehicle state estimation. Considering the strong nonlinearity of the tyres under critical driving conditions, the yaw motion of the vehicle is regulated by gain scheduling control based on the linear quadratic regulator theory. The feed-forward and feedback gains of the controller are updated in real-time by online estimation of the tyre cornering stiffness, so as to ensure the control robustness against environmental disturbances as well as parameter uncertainty. The control allocation module allocates the calculated generalised force requirements to each in-wheel motor based on quadratic programming theory while taking the tyre longitudinal/lateral force coupling characteristic into consideration. Simulations under a variety of driving conditions are carried out to verify the control algorithm. Simulation results indicate that the proposed vehicle stability controller can effectively stabilise the vehicle motion under critical driving conditions.

Fitts' Law in the Control of Isometric Grip Force With Naturalistic Targets.

PubMed

Thumser, Zachary C; Slifkin, Andrew B; Beckler, Dylan T; Marasco, Paul D

2018-01-01

Fitts' law models the relationship between amplitude, precision, and speed of rapid movements. It is widely used to quantify performance in pointing tasks, study human-computer interaction, and generally to understand perceptual-motor information processes, including research to model performance in isometric force production tasks. Applying Fitts' law to an isometric grip force task would allow for quantifying grasp performance in rehabilitative medicine and may aid research on prosthetic control and design. We examined whether Fitts' law would hold when participants attempted to accurately produce their intended force output while grasping a manipulandum when presented with images of various everyday objects (we termed this the implicit task). Although our main interest was the implicit task, to benchmark it and establish validity, we examined performance against a more standard visual feedback condition via a digital force-feedback meter on a video monitor (explicit task). Next, we progressed from visual force feedback with force meter targets to the same targets without visual force feedback (operating largely on feedforward control with tactile feedback). This provided an opportunity to see if Fitts' law would hold without vision, and allowed us to progress toward the more naturalistic implicit task (which does not include visual feedback). Finally, we changed the nature of the targets from requiring explicit force values presented as arrows on a force-feedback meter (explicit targets) to the more naturalistic and intuitive target forces implied by images of objects (implicit targets). With visual force feedback the relation between task difficulty and the time to produce the target grip force was predicted by Fitts' law (average r 2 = 0.82). Without vision, average grip force scaled accurately although force variability was insensitive to the target presented. In contrast, images of everyday objects generated more reliable grip forces without the visualized force meter. In sum, population means were well-described by Fitts' law for explicit targets with vision ( r 2 = 0.96) and implicit targets ( r 2 = 0.89), but not as well-described for explicit targets without vision ( r 2 = 0.54). Implicit targets should provide a realistic see-object-squeeze-object test using Fitts' law to quantify the relative speed-accuracy relationship of any given grasper.

LMI Based Robust Blood Glucose Regulation in Type-1 Diabetes Patient with Daily Multi-meal Ingestion

NASA Astrophysics Data System (ADS)

Mandal, S.; Bhattacharjee, A.; Sutradhar, A.

2014-04-01

This paper illustrates the design of a robust output feedback H ∞ controller for the nonlinear glucose-insulin (GI) process in a type-1 diabetes patient to deliver insulin through intravenous infusion device. The H ∞ design specification have been realized using the concept of linear matrix inequality (LMI) and the LMI approach has been used to quadratically stabilize the GI process via output feedback H ∞ controller. The controller has been designed on the basis of full 19th order linearized state-space model generated from the modified Sorensen's nonlinear model of GI process. The resulting controller has been tested with the nonlinear patient model (the modified Sorensen's model) in presence of patient parameter variations and other uncertainty conditions. The performance of the controller was assessed in terms of its ability to track the normoglycemic set point of 81 mg/dl with a typical multi-meal disturbance throughout a day that yields robust performance and noise rejection.

Stabilizing detached Bridgman melt crystal growth: Proportional-integral feedback control

NASA Astrophysics Data System (ADS)

Yeckel, Andrew; Daoutidis, Prodromos; Derby, Jeffrey J.

2012-10-01

The dynamics, operability limits, and tuning of a proportional-integral feedback controller to stabilize detached vertical Bridgman crystal growth are analyzed using a capillary model of shape stability. The manipulated variable is the pressure difference between upper and lower vapor spaces, and the controlled variable is the gap width at the triple-phase line. Open and closed loop dynamics of step changes in these state variables are analyzed under both shape stable and shape unstable growth conditions. Effects of step changes in static contact angle and growth angle are also studied. Proportional and proportional-integral control can stabilize unstable growth, but only within tight operability limits imposed by the narrow range of allowed meniscus shapes. These limits are used to establish safe operating ranges of controller gain. Strong nonlinearity of the capillary model restricts the range of perturbations that can be stabilized, and under some circumstances, stabilizes a spurious operating state far from the set point. Stabilizing detachment at low growth angle proves difficult and becomes impossible at zero growth angle.

Control Augmented Structural Synthesis

NASA Technical Reports Server (NTRS)

Lust, Robert V.; Schmit, Lucien A.

1988-01-01

A methodology for control augmented structural synthesis is proposed for a class of structures which can be modeled as an assemblage of frame and/or truss elements. It is assumed that both the plant (structure) and the active control system dynamics can be adequately represented with a linear model. The structural sizing variables, active control system feedback gains and nonstructural lumped masses are treated simultaneously as independent design variables. Design constraints are imposed on static and dynamic displacements, static stresses, actuator forces and natural frequencies to ensure acceptable system behavior. Multiple static and dynamic loading conditions are considered. Side constraints imposed on the design variables protect against the generation of unrealizable designs. While the proposed approach is fundamentally more general, here the methodology is developed and demonstrated for the case where: (1) the dynamic loading is harmonic and thus the steady state response is of primary interest; (2) direct output feedback is used for the control system model; and (3) the actuators and sensors are collocated.

The control gain region for synchronization in non-diffusively coupled complex networks

NASA Astrophysics Data System (ADS)

Gequn, Liu; Wenhui, Li; Huijie, Yang; Knowles, Gareth

2014-07-01

The control gain region for synchronization of non-diffusively coupled networks was studied with respect to three conditions: synchronization, synchronization in finite time, and synchronization in the minimum time. Based on cancellation control methodology and master stability function formalism, we found that a complete feasible control gain region may be bounded, unbounded, empty or a union of several bounded and unbounded regions, with a similar shape to the synchronized region. An interesting possibility emerged that a network could be synchronized by both negative and positive feedback control simultaneously. By bridging synchronizability and synchronizing response speeds with a settling time index, we have developed timed synchronized region (TSR) as a substitute for the classical synchronized region to study finite time synchronization. As for the last condition, a graphical method was developed to estimate control gain with the minimum synchronization time (CGMST). Each condition has examples provided for illustration and verification.

Real-time control of geometry and stiffness in adaptive structures

NASA Technical Reports Server (NTRS)

Ramesh, A. V.; Utku, S.; Wada, B. K.

1991-01-01

The basic theory is presented for the geometry, stiffness, and damping control of adaptive structures, with emphasis on adaptive truss structures. Necessary and sufficient conditions are given for stress-free geometry control in statically determinate and indeterminate adaptive discrete structures. Two criteria for selecting the controls are proposed, and their use in real-time control is illustrated by numerical simulation results. It is shown that the stiffness and damping control of adaptive truss structures for vibration suppression is possible by elongation and elongation rate dependent feedback forces from the active elements.

Design Criteria for the Future of Flight Controls. Proceedings of the Flight Dynamics Laboratory Flying Qualities and Flight Control Symposium 2-5 March 1982.

DTIC Science & Technology

1982-07-01

robustness of the closed-loop system as compared to state feedback. The observer theory of Luenberger specifies the conditions that must be satisfied for...No. ID-17SI-F-l, October 1963. 8. Rynaski, E. G. and Whitbeck, R. F.: "The Theory and Application of Linear Optimal Control," Calspan Report No. IH...pilots tend to control them open-loop. Frequencies much beyond 10 rad/sec are generally beyond pilots’ control capability. Control theory indicates a need

Stability and performance of notch filter control for unbalance response

NASA Technical Reports Server (NTRS)

Knospe, C. R.

1992-01-01

Many current applications of magnetic bearings for rotating machinery employ notch filters in the feedback control loop to reduce the synchronous forces transmitted through the bearings. The capabilities and limitations of notch filter control are investigated. First, a rigid rotor is examined with some classical root locus techniques. Notch filter control is shown to result in conditional stability whenever complete synchronous attenuation is required. Next, a nondimensional parametric symmetric flexible three mass rotor model is constructed. An examination of this model for several test cases illustrates the limited attenuation possible with notch filters at and near the system critical speeds when the bearing damping is low. The notch filter's alteration of the feedback loop is shown to cause stability problems which limits performance. Poor transient response may also result. A high speed compressor is then examined as a candidate for notch filter control. A collocated 22 mass station model with lead-lag control is used. The analysis confirms the reduction in stability robustness that can occur with notch filter control. It is concluded that other methods of synchronous vibration control yield greater performance without compromising stability.

SOS based robust H(∞) fuzzy dynamic output feedback control of nonlinear networked control systems.

PubMed

Chae, Seunghwan; Nguang, Sing Kiong

2014-07-01

In this paper, a methodology for designing a fuzzy dynamic output feedback controller for discrete-time nonlinear networked control systems is presented where the nonlinear plant is modelled by a Takagi-Sugeno fuzzy model and the network-induced delays by a finite state Markov process. The transition probability matrix for the Markov process is allowed to be partially known, providing a more practical consideration of the real world. Furthermore, the fuzzy controller's membership functions and premise variables are not assumed to be the same as the plant's membership functions and premise variables, that is, the proposed approach can handle the case, when the premise of the plant are not measurable or delayed. The membership functions of the plant and the controller are approximated as polynomial functions, then incorporated into the controller design. Sufficient conditions for the existence of the controller are derived in terms of sum of square inequalities, which are then solved by YALMIP. Finally, a numerical example is used to demonstrate the validity of the proposed methodology.

Active vibration mitigation of distributed parameter, smart-type structures using Pseudo-Feedback Optimal Control (PFOC)

NASA Technical Reports Server (NTRS)

Patten, W. N.; Robertshaw, H. H.; Pierpont, D.; Wynn, R. H.

1989-01-01

A new, near-optimal feedback control technique is introduced that is shown to provide excellent vibration attenuation for those distributed parameter systems that are often encountered in the areas of aeroservoelasticity and large space systems. The technique relies on a novel solution methodology for the classical optimal control problem. Specifically, the quadratic regulator control problem for a flexible vibrating structure is first cast in a weak functional form that admits an approximate solution. The necessary conditions (first-order) are then solved via a time finite-element method. The procedure produces a low dimensional, algebraic parameterization of the optimal control problem that provides a rigorous basis for a discrete controller with a first-order like hold output. Simulation has shown that the algorithm can successfully control a wide variety of plant forms including multi-input/multi-output systems and systems exhibiting significant nonlinearities. In order to firmly establish the efficacy of the algorithm, a laboratory control experiment was implemented to provide planar (bending) vibration attenuation of a highly flexible beam (with a first clamped-free mode of approximately 0.5 Hz).

Hybrid PD and effective multi-mode positive position feedback control for slewing and vibration suppression of a smart flexible manipulator

NASA Astrophysics Data System (ADS)

Lou, Jun-qiang; Wei, Yan-ding; Yang, Yi-ling; Xie, Feng-ran

2015-03-01

A hybrid control strategy for slewing and vibration suppression of a smart flexible manipulator is presented in this paper. It consists of a proportional derivative controller to realize motion control, and an effective multi-mode positive position feedback (EMPPF) controller to suppress the multi-mode vibration. Rather than treat each mode equally as the standard multi-mode PPF, the essence of the EMPPF is that control forces of different modes are applied according to the mode parameters of the respective modes, so the vibration modes with less vibration energy receive fewer control forces. Stability conditions for the close loop system are established through stability analysis. Optimal parameters of the EMPPF controller are obtained using the method of root locus analysis. The performance of the proposed strategy is demonstrated by simulation and experiments. Experimental results show that the first two vibration modes of the manipulator are effectively suppressed. The setting time of the setup descends approximately 55%, reaching 3.12 s from 5.67 s.

Functional neural correlates of social approval in schizophrenia

PubMed Central

Lepage, Martin

2016-01-01

Social approval is a reward that uses abstract social reinforcers to guide interpersonal interactions. Few studies have specifically explored social reward processing and its related neural substrates in schizophrenia. Fifteen patients with schizophrenia and fifteen healthy controls participated in a two-part study to explore the functional neural correlates of social approval. In the first session, participants were led to believe their personality would be assessed based on their results from various questionnaires and an interview. Participants were then presented with the results of their supposed evaluation in the scanner, while engaging in a relevant fMRI social approval task. Subjects provided subjective reports of pleasure associated with receiving self-directed positive or negative feedback. Higher activation of the right parietal lobe was found in controls compared with individuals with schizophrenia. Both groups rated traits from the high social reward condition as more pleasurable than the low social reward condition, while intergroup differences emerged in the low social reward condition. Positive correlations were found in patients only between subjective ratings of positive feedback and right insula activation, and a relevant behavioural measure. Evidence suggests potential neural substrates underlying the cognitive representation of social reputation in schizophrenia. PMID:26516171

Looking beyond the face: a training to improve perceivers' impressions of people with facial paralysis.

PubMed

Bogart, Kathleen R; Tickle-Degnen, Linda

2015-02-01

Healthcare providers and lay people alike tend to form inaccurate first impressions of people with facial movement disorders such as facial paralysis (FP) because of the natural tendency to base impressions on the face. This study tested the effectiveness of the first interpersonal sensitivity training for FP. Undergraduate participants were randomly assigned to one of two training conditions or an untrained control. Education raised awareness about FP symptoms and experiences and instructed participants to form their impressions based on cues from the body and voice rather than the face. Education+feedback added feedback about the correctness of participants' judgments. Subsequently, participants watched 30s video clips of people with FP and rated their extraversion. Participants' bias and accuracy in the two training conditions did not significantly differ, but they were significantly less biased than controls. Training did not improve the more challenging task of accurately detecting individual differences in extraversion. Educating people improves bias, but not accuracy, of impressions of people with FP. Information from the education condition could be delivered in a pamphlet to those likely to interact with this population such as healthcare providers and educators. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Determining optimal parameters in magnetic spacecraft stabilization via attitude feedback

NASA Astrophysics Data System (ADS)

Bruni, Renato; Celani, Fabio

2016-10-01

The attitude control of a spacecraft using magnetorquers can be achieved by a feedback control law which has four design parameters. However, the practical determination of appropriate values for these parameters is a critical open issue. We propose here an innovative systematic approach for finding these values: they should be those that minimize the convergence time to the desired attitude. This a particularly diffcult optimization problem, for several reasons: 1) such time cannot be expressed in analytical form as a function of parameters and initial conditions; 2) design parameters may range over very wide intervals; 3) convergence time depends also on the initial conditions of the spacecraft, which are not known in advance. To overcome these diffculties, we present a solution approach based on derivative-free optimization. These algorithms do not need to write analytically the objective function: they only need to compute it in a number of points. We also propose a fast probing technique to identify which regions of the search space have to be explored densely. Finally, we formulate a min-max model to find robust parameters, namely design parameters that minimize convergence time under the worst initial conditions. Results are very promising.

Multivariable manual control with simultaneous visual and auditory presentation of information. [for improved compensatory tracking performance of human operator

NASA Technical Reports Server (NTRS)

Uhlemann, H.; Geiser, G.

1975-01-01

Multivariable manual compensatory tracking experiments were carried out in order to determine typical strategies of the human operator and conditions for improvement of his performance if one of the visual displays of the tracking errors is supplemented by an auditory feedback. Because the tracking error of the system which is only visually displayed is found to decrease, but not in general that of the auditorally supported system, it was concluded that the auditory feedback unloads the visual system of the operator who can then concentrate on the remaining exclusively visual displays.

Autogenic-feedback training: A countermeasure for orthostatic intolerance

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.; Pickering, Thomas G.

1991-01-01

NASA has identified cardiovascular deconditioning as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder and the resulting orthostatic intolerance experienced by crewmembers upon their return to the 1g norm of Earth. The present study was designed to examine the feasibility of training human subjects to control their own cardiovascular responses to gravitational stimulation (i.e., a tilt table). Using an operant conditioning procedure, Autogenic-Feedback Training (AFT), we would determine if subjects could learn to increase their own blood pressure voluntarily.

Self-regulation of inter-hemispheric visual cortex balance through real-time fMRI neurofeedback training.

PubMed

Robineau, F; Rieger, S W; Mermoud, C; Pichon, S; Koush, Y; Van De Ville, D; Vuilleumier, P; Scharnowski, F

2014-10-15

Recent advances in neurofeedback based on real-time functional magnetic resonance imaging (fMRI) allow for learning to control spatially localized brain activity in the range of millimeters across the entire brain. Real-time fMRI neurofeedback studies have demonstrated the feasibility of self-regulating activation in specific areas that are involved in a variety of functions, such as perception, motor control, language, and emotional processing. In most of these previous studies, participants trained to control activity within one region of interest (ROI). In the present study, we extended the neurofeedback approach by now training healthy participants to control the interhemispheric balance between their left and right visual cortices. This was accomplished by providing feedback based on the difference in activity between a target visual ROI and the corresponding homologue region in the opposite hemisphere. Eight out of 14 participants learned to control the differential feedback signal over the course of 3 neurofeedback training sessions spread over 3 days, i.e., they produced consistent increases in the visual target ROI relative to the opposite visual cortex. Those who learned to control the differential feedback signal were subsequently also able to exert that control in the absence of neurofeedback. Such learning to voluntarily control the balance between cortical areas of the two hemispheres might offer promising rehabilitation approaches for neurological or psychiatric conditions associated with pathological asymmetries in brain activity patterns, such as hemispatial neglect, dyslexia, or mood disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

Closed-loop motor control using high-speed fiber optics

NASA Technical Reports Server (NTRS)

Dawson, Reginald (Inventor); Rodriquiz, Dagobert (Inventor)

1991-01-01

A closed-loop control system for controlling the operation of one or more servo motors or other controllable devices is described. The system employs a fiber optics link immune to electromagnetic interference, for transmission of control signals from a controller or controllers at a remote station to the power electronics located in proximity to the motors or other devices at the local station. At the remote station the electrical control signals are time-multiplexed, converted to a formatted serial bit stream, and converted to light signals for transmission over a single fiber of the fiber optics link. At the local station, the received optical signals are reconstructed as electrical control signals for the controlled motors or other devices. At the local station, an encoder sensor linked to the driven device generates encoded feedback signals which provide information as to a condition of the controlled device. The encoded signals are placed in a formatted serial bit stream, multiplexed, and transmitted as optical signals over a second fiber of the fiber optic link which closes the control loop of the closed-loop motor controller. The encoded optical signals received at the remote station are demultiplexed, reconstructed and coupled to the controller(s) as electrical feedback signals.

Active Combustion Control for Aircraft Gas-Turbine Engines-Experimental Results for an Advanced, Low-Emissions Combustor Prototype

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

2012-01-01

Lean combustion concepts for aircraft engine combustors are prone to combustion instabilities. Mitigation of instabilities is an enabling technology for these low-emissions combustors. NASA Glenn Research Center s prior activity has demonstrated active control to suppress a high-frequency combustion instability in a combustor rig designed to emulate an actual aircraft engine instability experience with a conventional, rich-front-end combustor. The current effort is developing further understanding of the problem specifically as applied to future lean-burning, very low-emissions combustors. A prototype advanced, low-emissions aircraft engine combustor with a combustion instability has been identified and previous work has characterized the dynamic behavior of that combustor prototype. The combustor exhibits thermoacoustic instabilities that are related to increasing fuel flow and that potentially prevent full-power operation. A simplified, non-linear oscillator model and a more physics-based sectored 1-D dynamic model have been developed to capture the combustor prototype s instability behavior. Utilizing these models, the NASA Adaptive Sliding Phasor Average Control (ASPAC) instability control method has been updated for the low-emissions combustor prototype. Active combustion instability suppression using the ASPAC control method has been demonstrated experimentally with this combustor prototype in a NASA combustion test cell operating at engine pressures, temperatures, and flows. A high-frequency fuel valve was utilized to perturb the combustor fuel flow. Successful instability suppression was shown using a dynamic pressure sensor in the combustor for controller feedback. Instability control was also shown with a pressure feedback sensor in the lower temperature region upstream of the combustor. It was also demonstrated that the controller can prevent the instability from occurring while combustor operation was transitioning from a stable, low-power condition to a normally unstable high-power condition, thus enabling the high-power condition.

Feedback-controlled robotics-assisted treadmill exercise to assess and influence aerobic capacity early after stroke: a proof-of-concept study.

PubMed

Stoller, Oliver; Schindelholz, Matthias; Bichsel, Lukas; Schuster, Corina; de Bie, Rob A; de Bruin, Eling D; Hunt, Kenneth J

2014-07-01

The majority of post-stroke individuals suffer from low exercise capacity as a secondary reaction to immobility. The aim of this study was to prove the concept of feedback-controlled robotics-assisted treadmill exercise (RATE) to assess aerobic capacity and guide cardiovascular exercise in severely impaired individuals early after stroke. Subjects underwent constant load and incremental exercise testing using a human-in-the-loop feedback system within a robotics-assisted exoskeleton (Lokomat, Hocoma AG, CH). Inclusion criteria were: stroke onset ≤8 weeks, stable medical condition, non-ambulatory status, moderate motor control of the lower limbs and appropriate cognitive function. Outcome measures included oxygen uptake kinetics, peak oxygen uptake (VO2peak), gas exchange threshold (GET), peak heart rate (HRpeak), peak work rate (Ppeak) and accuracy of reaching target work rate (P-RMSE). Three subjects (18-42 d post-stroke) were included. Oxygen uptake kinetics during constant load ranged from 42.0 to 60.2 s. Incremental exercise testing showed: VO2peak range 19.7-28.8 ml/min/kg, GET range 11.6-12.7 ml/min/kg, and HRpeak range 115-161 bpm. Ppeak range was 55.2-110.9 W and P-RMSE range was 3.8-7.5 W. The concept of feedback-controlled RATE for assessment of aerobic capacity and guidance of cardiovascular exercise is feasible. Further research is warranted to validate the method on a larger scale. Aerobic capacity is seriously reduced in post-stroke individuals as a secondary reaction to immobility. Robotics-assisted walking devices may have substantial clinical relevance regarding assessment and improvement of aerobic capacity early after stroke. Feedback-controlled robotics-assisted treadmill exercise represents a new concept for cardiovascular assessment and intervention protocols for severely impaired individuals.

Optimization and testing of solid thin film lubrication deposition processes

NASA Astrophysics Data System (ADS)

Danyluk, Michael J.

A novel method for testing solid thin films in rolling contact fatigue (RCF) under ultra-high vacuum (UHV) and high rotational speeds (130 Hz) is presented in this thesis. The UHV-RCF platform is used to quantify the adhesion and lubrication aspects of two thin film coatings deposited on ball-bearings using a physical vapor deposition ion plating process. Plasma properties during ion plating were measured using a Langmuir probe and there is a connection between ion flux, film stress, film adhesion, process voltage, pressure, and RCF life. The UHV-RCF platform and vacuum chamber were constructed using off-the-shelf components and 88 RCF tests in high vacuum have been completed. Maximum RCF life was achieved by maintaining an ion flux between 10 13 to 1015 (cm-2 s-1) with a process voltage and pressure near 1.5 kV and 15 mTorr. Two controller schemes were investigated to maintain optimal plasma conditions for maximum RCF life: PID and LQR. Pressure disturbances to the plasma have a detrimental effect on RCF life. Control algorithms that mitigate pressure and voltage disturbances already exist. However, feedback from the plasma to detect disturbances has not been explored related to deposition processes in the thin-film science literature. Manometer based pressure monitoring systems have a 1 to 2 second delay time and are too slow to detect common pressure bursts during the deposition process. Plasma diagnostic feedback is much faster, of the order of 0.1 second. Plasma total-current feedback was used successfully to detect a typical pressure disturbance associated with the ion plating process. Plasma current is related to ion density and process pressure. A real-time control application was used to detect the pressure disturbance by monitoring plasma-total current and converting it to feedback-input to a pressure control system. Pressure overshoot was eliminated using a nominal PID controller with feedback from a plasma-current diagnostic measurement tool.

Evaluating Internal Model Strength and Performance of Myoelectric Prosthesis Control Strategies.

PubMed

Shehata, Ahmed W; Scheme, Erik J; Sensinger, Jonathon W

2018-05-01

On-going developments in myoelectric prosthesis control have provided prosthesis users with an assortment of control strategies that vary in reliability and performance. Many studies have focused on improving performance by providing feedback to the user but have overlooked the effect of this feedback on internal model development, which is key to improve long-term performance. In this paper, the strength of internal models developed for two commonly used myoelectric control strategies: raw control with raw feedback (using a regression-based approach) and filtered control with filtered feedback (using a classifier-based approach), were evaluated using two psychometric measures: trial-by-trial adaptation and just-noticeable difference. The performance of both strategies was also evaluated using Schmidt's style target acquisition task. Results obtained from 24 able-bodied subjects showed that although filtered control with filtered feedback had better short-term performance in path efficiency ( ), raw control with raw feedback resulted in stronger internal model development ( ), which may lead to better long-term performance. Despite inherent noise in the control signals of the regression controller, these findings suggest that rich feedback associated with regression control may be used to improve human understanding of the myoelectric control system.

Winning in Time: Enabling Naturalistic Decision Making in Command and Control

DTIC Science & Technology

2000-11-01

non-linear with non-linearity defined as a condition master chess player , the NBA basketball player , the in which a system disobeys principles of great...are made up of basic others identified in the successive sectors, are feedback structures which have known behavioral points of leverage for policy

Dynamic Nature of Alterations in the Endocrine System of Fathead Minnows Exposed to the Fungicide Prochloraz, Presentation

EPA Science Inventory

The vertebrate hypothalamic-pituitary-gonadal (HPG) axis is controlled through various feedback mechanisms that ideally serve to maintain a dynamic homeostasis of the system in the face of changing environmental conditions, including exposure to chemical stressors. In these stud...

Cognitive flexibility: A distinct element of performance impairment due to sleep deprivation.

PubMed

Honn, K A; Hinson, J M; Whitney, P; Van Dongen, H P A

2018-03-14

In around-the-clock operations, reduced alertness due to circadian misalignment and sleep loss causes performance impairment, which can lead to catastrophic errors and accidents. There is mounting evidence that performance on different tasks is differentially affected, but the general principles underlying this differentiation are not well understood. One factor that may be particularly relevant is the degree to which tasks require executive control, that is, control over the initiation, monitoring, and termination of actions in order to achieve goals. A key aspect of this is cognitive flexibility, i.e., the deployment of cognitive control resources to adapt to changes in events. Loss of cognitive flexibility due to sleep deprivation has been attributed to "feedback blunting," meaning that feedback on behavioral outcomes has reduced salience - and that feedback is therefore less effective at driving behavior modification under changing circumstances. The cognitive mechanisms underlying feedback blunting are as yet unknown. Here we present data from an experiment that investigated the effects of sleep deprivation on performance after an unexpected reversal of stimulus-response mappings, requiring cognitive flexibility to maintain good performance. Nineteen healthy young adults completed a 4-day in-laboratory study. Subjects were randomized to either a total sleep deprivation condition (n = 11) or a control condition (n = 8). Athree-phase reversal learning decision task was administered at baseline, and again after 30.5 h of sleep deprivation, or matching well-rested control. The task was based on a go/no go task paradigm, in which stimuli were assigned to either a go (response) set or a no go (no response) set. Each phase of the task included four stimuli (two in the go set and two in the no go set). After each stimulus presentation, subjects could make a response within 750 ms or withhold their response. They were then shown feedback on the accuracy of their response. In phase 1 of the task, subjects were explicitly told which stimuli were assigned to the go and no go sets. In phases 2 and 3, new stimuli were used that were different from those used in phase 1. Subjects were not explicitly told the go/no go mappings and were instead required to use accuracy feedback to learn which stimuli were in the go and nogo sets. Phase 3 continued directly from phase 2 and retained the same stimuli as in phase 2, but there was an unannounced reversal of the stimulus-response mappings. Task results confirmed that sleep deprivation resulted in loss of cognitive flexibility through feedback blunting, and that this effect was not produced solely by (1) general performance impairment because of overwhelming sleep drive; (2) reduced working memory resources available to perform the task; (3) incomplete learning of stimulus-response mappings before the unannounced reversal; or (4) interference with stimulus identification through lapses in vigilant attention. Overall, the results suggest that sleep deprivation causes a fundamental problem with dynamic attentional control. This element of performance impairment due to sleep deprivation appears to be distinct from vigilant attention deficits, and represents a particularly significant challenge for fatigue risk management. Copyright © 2018. Published by Elsevier Ltd.

Strategies in probabilistic feedback learning in Parkinson patients OFF medication.

PubMed

Bellebaum, C; Kobza, S; Ferrea, S; Schnitzler, A; Pollok, B; Südmeyer, M

2016-04-21

Studies on classification learning suggested that altered dopamine function in Parkinson's Disease (PD) specifically affects learning from feedback. In patients OFF medication, enhanced learning from negative feedback has been described. This learning bias was not seen in observational learning from feedback, indicating different neural mechanisms for this type of learning. The present study aimed to compare the acquisition of stimulus-response-outcome associations in PD patients OFF medication and healthy control subjects in active and observational learning. 16 PD patients OFF medication and 16 controls were examined with three parallel learning tasks each, two feedback-based (active and observational) and one non-feedback-based paired associates task. No acquisition deficit was seen in the patients for any of the tasks. More detailed analyses on the learning strategies did, however, reveal that the patients showed more lose-shift responses during active feedback learning than controls, and that lose-shift and win-stay responses more strongly determined performance accuracy in patients than controls. For observational feedback learning, the performance of both groups correlated similarly with the performance in non-feedback-based paired associates learning and with the accuracy of observed performance. Also, patients and controls showed comparable evidence of feedback processing in observational learning. In active feedback learning, PD patients use alternative learning strategies than healthy controls. Analyses on observational learning did not yield differences between patients and controls, adding to recent evidence of a differential role of the human striatum in active and observational learning from feedback. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Computer-Based Feedback and Goal Intervention: Learning Effects

ERIC Educational Resources Information Center

Valdez, Alfred

2012-01-01

This study investigated how a goal intervention influences the learning effects gained from feedback when acquiring concepts and rules pertaining to the topic of descriptive statistics. Three feedback conditions; knowledge of correct response feedback (KCRF), principle-based feedback (PBF), and no-feedback (NF), were crossed with two goal…

Patient and Partner Feedback Reports to Improve Statin Medication Adherence: A Randomized Control Trial.

PubMed

Reddy, Ashok; Huseman, Tiffany L; Canamucio, Anne; Marcus, Steven C; Asch, David A; Volpp, Kevin; Long, Judith A

2017-03-01

Simple nudges such as reminders and feedback reports to either a patient or a partner may facilitate improved medication adherence. To test the impact of a pill bottle used to monitor adherence, deliver a daily alarm, and generate weekly medication adherence feedback reports on statin adherence. Three-month, three-arm randomized clinical trial (ClinicalTrials.gov identifier: NCT02480530). One hundred and twenty-six veterans with known coronary artery disease and poor adherence (medication possession ratio <80 %). Patients were randomized to one of three groups: (1) a control group (n = 36) that received a pill-monitoring device with no alarms or feedback; (2) an individual feedback group (n = 36) that received a daily alarm and a weekly medication adherence feedback report; and (3) a partner feedback group (n = 54) that received an alarm and a weekly feedback report that was shared with a friend, family member, or a peer. The intervention continued for 3 months, and participants were followed for an additional 3 months after the intervention period. Adherence as measured by pill bottle. Secondary outcomes included change in LDL (mg/dl), patient activation, and social support. During the 3-month intervention period, medication adherence was higher in both feedback arms than in the control arm (individual feedback group 89 %, partner feedback group 86 %, control group 67 %; p < 0.001 and = 0.001). At 6 months, there was no difference in medication adherence between either of the feedback groups and the control (individual feedback 60 %, partner feedback 52 %, control group 54 %; p = 0.75 and 0.97). Daily alarms combined with individual or partner feedback reports improved statin medication adherence. While neither an individual feedback nor partner feedback strategy created a sustainable medication adherence habit, the intervention itself is relatively easy to implement and low cost.

False feedback and beliefs influence name recall in younger and older adults.

PubMed

Strickland-Hughes, Carla M; West, Robin Lea; Smith, Kimberly A; Ebner, Natalie C

2017-09-01

Feedback is an important self-regulatory process that affects task effort and subsequent performance. Benefits of positive feedback for list recall have been explored in research on goals and feedback, but the effect of negative feedback on memory has rarely been studied. The current research extends knowledge of memory and feedback effects by investigating face-name association memory and by examining the potential mediation of feedback effects, in younger and older adults, through self-evaluative beliefs. Beliefs were assessed before and after name recognition and name recall testing. Repeated presentation of false positive feedback was compared to false negative feedback and a no feedback condition. Results showed that memory self-efficacy declined over time for participants in the negative and no feedback conditions but was sustained for those receiving positive feedback. Furthermore, participants who received negative feedback felt older after testing than before testing. For name recall, the positive feedback group outperformed the negative feedback and no feedback groups combined, with no age interactions. The observed feedback-related effects on memory were fully mediated by changes in memory self-efficacy. These findings advance our understanding of how beliefs are related to feedback in memory and inform future studies examining the importance of self-regulation in memory.

Removing own-limb visual input using mixed reality (MR) produces a "telescoping" illusion in healthy individuals.

PubMed

Thøgersen, Mikkel; Hansen, John; Arendt-Nielsen, Lars; Flor, Herta; Petrini, Laura

2018-07-16

The purpose of the present study was to assess changes in body perception when visual feedback was removed from the hand and arm with the purpose of resembling the visual deprivation arising from amputation. The illusion was created by removing the visual feedback from the participants' own left forearm using a mixed reality (MR) and green screen environment. Thirty healthy persons (15 female) participated in the study. Each subject experienced two MR conditions, one with and one without visual feedback from the left hand, and a baseline condition with normal vision of the limb (no MR). Body perception was assessed using proprioceptive drift, questionnaires on body perception, and thermal sensitivity measures (cold, warm, heat pain and cold pain detection thresholds). The proprioceptive drift showed a significant shift of the tip of the index finger (p<0.001) towards the elbow in the illusion condition (mean drift: -3.71 cm). Self-report showed a significant decrease in ownership (p<0.001), shift in perceptual distortions, (e.g. "It feels as if my lower arm has become shorter") (p=0.025), and changes in sensations of the hand (tingling, tickling) (p=0.025). A significant decrease was also observed in cold detection threshold (p<0.001), i.e. the detection threshold was cooler than for the control conditions. The proprioceptive drift together with the self-reported questionnaire showed that the participants felt a proximal retraction of their limb, resembling the telescoping experienced by phantom limb patients. The study highlights the influence of missing visual feedback and its possible contribution to phantom limb phenomena. Copyright © 2018 Elsevier B.V. All rights reserved.

Observer-Based Adaptive Neural Network Control for Nonlinear Systems in Nonstrict-Feedback Form.

PubMed

Chen, Bing; Zhang, Huaguang; Lin, Chong

2016-01-01

This paper focuses on the problem of adaptive neural network (NN) control for a class of nonlinear nonstrict-feedback systems via output feedback. A novel adaptive NN backstepping output-feedback control approach is first proposed for nonlinear nonstrict-feedback systems. The monotonicity of system bounding functions and the structure character of radial basis function (RBF) NNs are used to overcome the difficulties that arise from nonstrict-feedback structure. A state observer is constructed to estimate the immeasurable state variables. By combining adaptive backstepping technique with approximation capability of radial basis function NNs, an output-feedback adaptive NN controller is designed through backstepping approach. It is shown that the proposed controller guarantees semiglobal boundedness of all the signals in the closed-loop systems. Two examples are used to illustrate the effectiveness of the proposed approach.

Low-to-Medium Power Single Chip Digital Controlled DC-DC Regulator for Point-of-Load Applications

NASA Technical Reports Server (NTRS)

Adell, Philippe C. (Inventor); Bakkaloglu, Bertan (Inventor); Vermeire, Bert (Inventor); Liu, Tao (Inventor)

2015-01-01

A DC-DC converter for generating a DC output voltage includes: a digitally controlled pulse width modulator (DPWM) for controlling a switching power stage to supply a varying voltage to an inductor; and a digital voltage feedback circuit for controlling the DPWM in accordance with a feedback voltage corresponding to the DC output voltage, the digital voltage feedback circuit including: a first voltage controlled oscillator for converting the feedback voltage into a first frequency signal and to supply the first frequency signal to a first frequency discriminator; a second voltage controlled oscillator for converting a reference voltage into a second frequency signal and to supply the second frequency signal to a second frequency discriminator; a digital comparator for comparing digital outputs of the first and second frequency discriminators and for outputting a digital feedback signal; and a controller for controlling the DPWM in accordance with the digital feedback signal.

Servo control booster system for minimizing following error

DOEpatents

Wise, William L.

1985-01-01

A closed-loop feedback-controlled servo system is disclosed which reduces command-to-response error to the system's position feedback resolution least increment, .DELTA.S.sub.R, on a continuous real-time basis for all operating speeds. The servo system employs a second position feedback control loop on a by exception basis, when the command-to-response error .gtoreq..DELTA.S.sub.R, to produce precise position correction signals. When the command-to-response error is less than .DELTA.S.sub.R, control automatically reverts to conventional control means as the second position feedback control loop is disconnected, becoming transparent to conventional servo control means. By operating the second unique position feedback control loop used herein at the appropriate clocking rate, command-to-response error may be reduced to the position feedback resolution least increment. The present system may be utilized in combination with a tachometer loop for increased stability.

Role of measurement in feedback-controlled quantum engines

NASA Astrophysics Data System (ADS)

Yi, Juyeon; Kim, Yong Woon

2018-01-01

In feedback controls, measurement is an essential step in designing protocols according to outcomes. For quantum mechanical systems, measurement has another effect; to supply energy to the measured system. We verify that in feedback-controlled quantum engines, measurement plays a dual role; not only as an auxiliary to perform feedback control but also as an energy supply to drive the engines. We consider a specific engine cycle exploiting feedback control followed by projective measurement and show that the maximum bound of the extractable work is set by both the efficacy of the feedback control and the energy change caused by projective measurement. We take a concrete example of an engine using an immobile spin-1/2 particle as a working substance and suggest two possible scenarios for work extraction.

Torsional Dynamics of Steerable Needles: Modeling and Fluoroscopic Guidance

PubMed Central

Swensen, John P.; Lin, MingDe; Okamura, Allison M.; Cowan, Noah J.

2017-01-01

Needle insertions underlie a diversity of medical interventions. Steerable needles provide a means by which to enhance existing needle-based interventions and facilitate new ones. Tip-steerable needles follow a curved path and can be steered by twisting the needle base during insertion, but this twisting excites torsional dynamics that introduce a discrepancy between the base and tip twist angles. Here, we model the torsional dynamics of a flexible rod—such as a tip-steerable needle—during subsurface insertion and develop a new controller based on the model. The torsional model incorporates time-varying mode shapes to capture the changing boundary conditions inherent during insertion. Numerical simulations and physical experiments using two distinct setups—stereo camera feedback in semi-transparent artificial tissue and feedback control with real-time X-ray imaging in optically opaque artificial tissue— demonstrate the need to account for torsional dynamics in control of the needle tip. PMID:24860026

Simple robot suggests physical interlimb communication is essential for quadruped walking

PubMed Central

Owaki, Dai; Kano, Takeshi; Nagasawa, Ko; Tero, Atsushi; Ishiguro, Akio

2013-01-01

Quadrupeds have versatile gait patterns, depending on the locomotion speed, environmental conditions and animal species. These locomotor patterns are generated via the coordination between limbs and are partly controlled by an intraspinal neural network called the central pattern generator (CPG). Although this forms the basis for current control paradigms of interlimb coordination, the mechanism responsible for interlimb coordination remains elusive. By using a minimalistic approach, we have developed a simple-structured quadruped robot, with the help of which we propose an unconventional CPG model that consists of four decoupled oscillators with only local force feedback in each leg. Our robot exhibits good adaptability to changes in weight distribution and walking speed simply by responding to local feedback, and it can mimic the walking patterns of actual quadrupeds. Our proposed CPG-based control method suggests that physical interaction between legs during movements is essential for interlimb coordination in quadruped walking. PMID:23097501

Simple robot suggests physical interlimb communication is essential for quadruped walking.

PubMed

Owaki, Dai; Kano, Takeshi; Nagasawa, Ko; Tero, Atsushi; Ishiguro, Akio

2013-01-06

Quadrupeds have versatile gait patterns, depending on the locomotion speed, environmental conditions and animal species. These locomotor patterns are generated via the coordination between limbs and are partly controlled by an intraspinal neural network called the central pattern generator (CPG). Although this forms the basis for current control paradigms of interlimb coordination, the mechanism responsible for interlimb coordination remains elusive. By using a minimalistic approach, we have developed a simple-structured quadruped robot, with the help of which we propose an unconventional CPG model that consists of four decoupled oscillators with only local force feedback in each leg. Our robot exhibits good adaptability to changes in weight distribution and walking speed simply by responding to local feedback, and it can mimic the walking patterns of actual quadrupeds. Our proposed CPG-based control method suggests that physical interaction between legs during movements is essential for interlimb coordination in quadruped walking.

Blind lineup administration as a prophylactic against the postidentification feedback effect.

PubMed

Dysart, Jennifer E; Lawson, Victoria Z; Rainey, Anna

2012-08-01

Confidence and other testimony-relevant judgments may be distorted when witnesses are given confirming postidentification feedback, and double-blind procedures-wherein the lineup administrator does not know the identity of the suspect-are a commonly proposed, but untested, remedy for this effect. In the current study, mock witnesses viewed a staged crime video followed by a target-present or target-absent lineup where the administrator was or was not presumed to know the identity of the suspect. After making an identification decision, witnesses were or were not given realistic, but nonidentification-specific, feedback, and then confidence and other judgments were assessed. A significant interaction was found between blind condition and feedback such that feedback inflated confidence and other judgments in presumed nonblind conditions only; feedback had no effect on participants in presumed blind conditions. As predicted by the selective cue integration framework-a theoretical model suggested to explain the interaction between presumed blind administration and feedback-this interaction was significant only for inaccurate participants. These results suggest that blind administration may serve as a prophylactic against the negative effects of postidentification feedback. In addition, the effectiveness of our subtle feedback in influencing judgments suggests that lineup administrators should take care not to provide any feedback to eyewitnesses. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

Evaluation of AllergiSense Smartphone Tools for Adrenaline Injection Training.

PubMed

Hernandez-Munoz, Luis U; Woolley, Sandra I; Luyt, David; Stiefel, Gary; Kirk, Kerrie; Makwana, Nick; Melchior, Cathryn; Dawson, Tom C; Wong, Gabriel; Collins, Tim; Diwakar, Lavanya

2017-01-01

Anaphylaxis is an increasingly prevalent life-threatening allergic condition that requires people with anaphylaxis and their caregivers to be trained in the avoidance of allergen triggers and in the administration of adrenaline autoinjectors. The prompt and correct administration of autoinjectors in the event of an anaphylactic reaction is a significant challenge in the management of anaphylaxis. Unfortunately, many people do not know how to use autoinjectors and either fail to use them or fail to use them correctly. This is due in part to deficiencies in training and also to the lack of a system encouraging continuous practice with feedback. Assistive smartphone healthcare technologies have demonstrated potential to support the management of chronic conditions such as diabetes and cardiovascular disease, but there have been deficiencies in their evaluation and there has been a lack of application to anaphylaxis. This paper describes AllergiSense, a smartphone app and sensing system for anaphylaxis management, and presents the results of a randomized, controlled, prepost evaluation of AllergiSense injection training and feedback tools with healthy participants. Participants whose training was supplemented with AllergiSense injection feedback achieved significantly better practiced injections with 90.5% performing correct injections compared to only 28.6% in the paper-only control group. In addition, the results provide insights into possible self-efficacy failings in traditional training and the benefits of embedding self-efficacy theory into the technology design process.

The Consequences of Providing Drinkers with Blood Alcohol Concentration Information on Assessments of Alcohol Impairment and Drunk-Driving Risk*

PubMed Central

JOHNSON, MARK B.; VOAS, ROBERT B.; KELLEY-BAKER, TARA; FURR-HOLDEN, C. DEBRA M.

2009-01-01

Objective We examined the effect of providing drinkers with blood alcohol concentration (BAC) information on subjective assessments of alcohol impairment and drunk-driving risk. Method We sampled 959 drinking participants from a natural drinking environment and asked them to self-administer a personal saliva-based alcohol test. Participants then were asked to rate their alcohol impairment and to indicate whether they could drive legally under one of four BAC feedback conditions (assigned at random): (1) control condition (no BAC feedback provided before the ratings); (2) categorical BAC information (low, high, and highest risk) from the saliva test; (3) categorical BAC information corroborated by a calibrated police breath alcohol analyzer; and (4) precise (three-digit) BAC information from the breath alcohol analyzer. Results Both control participants and participants who received precise BAC feedback gave subjective impairment ratings that correlated with actual BACs. For participants who received categorical BAC information from the saliva test, subjective impairment did not correlate with the actual BAC. Providing drinkers with BAC information, however, did help them predict more accurately if their BAC was higher than the legal BAC driving limit. Conclusions Although BAC information can influence drinkers’ assessments of alcohol impairment and drunk-driving risk, there is no strong evidence that personal saliva-based alcohol tests are particularly useful. PMID:18612570

Residue detection for real-time removal of paint from metallic surfaces

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph; Bao, Xiaoqi; Dolgin, Benjamin; Marzwell, Neville

2001-01-01

Paint stripping from large steel ships and other metallic surfaces is a major issue in the maintenance and refurbishing of structures, and environmental concerns are greatly limiting the possible options. As a result, waterjet with water recycling has become the leading form of paint stripping and robotic manipulators with scanning bridges were constructed by various manufacturers to address this need. The application of such scanning bridges is slow and their access is constrained by the complex shape of the ship hull and various features on the surface. To overcome these limitations, a robotic system that is called Ultrastrip (UltraStrip Systems, Inc., Stuart, FL) is developed. This system uses magnetic wheels to attach the stripper to the structure and travel on it while performing paint stripping. To assure efficient paint stripping feedback data is required to control the travel speed by monitoring the paint thickness before and during the stripping process. Efforts at JPL are currently underway to develop the required feedback capability to assure effective paint stripping. Various possible sensors were considered and issues that can affect the sensitivity, reliability and applicability of the sensors are being investigated with emphasis on measuring the initial conditions of the paint. Issues that affect the sensory data in dynamic conditions are addressed while providing real-time real feedback for the control of the paint stripper speed of travel.

Sequence Learning Under Uncertainty in Children: Self-Reflection vs. Self-Assertion

PubMed Central

Lange-Küttner, Christiane; Averbeck, Bruno B.; Hirsch, Silvia V.; Wießner, Isabel; Lamba, Nishtha

2012-01-01

We know that stochastic feedback impairs children’s associative stimulus–response (S–R) learning (Crone et al., 2004a; Eppinger et al., 2009), but the impact of stochastic feedback on sequence learning that involves deductive reasoning has not been not tested so far. In the current study, 8- to 11-year-old children (N = 171) learned a sequence of four left and right button presses, LLRR, RRLL, LRLR, RLRL, LRRL, and RLLR, which needed to be deduced from feedback because no directional cues were given. One group of children experienced consistent feedback only (deterministic feedback, 100% correct). In this condition, green feedback on the screen indicated that the children had been right when they were right, and red feedback indicated that the children had been wrong when they were wrong. Another group of children experienced inconsistent feedback (stochastic feedback, 85% correct, 15% false), where in some trials, green feedback on the screen could signal that children were right when in fact they were wrong, and red feedback could indicate that they were wrong when in fact they had been right. Independently of age, children’s sequence learning in the stochastic condition was initially much lower than in the deterministic condition, but increased gradually and improved with practice. Responses toward positive vs. negative feedback varied with age. Children were increasingly able to understand that they could have been wrong when feedback indicated they were right (self-reflection), but they remained unable to understand that they could have been right when feedback indicated they were wrong (self-assertion). PMID:22563324

Sequence Learning Under Uncertainty in Children: Self-Reflection vs. Self-Assertion.

PubMed

Lange-Küttner, Christiane; Averbeck, Bruno B; Hirsch, Silvia V; Wießner, Isabel; Lamba, Nishtha

2012-01-01

We know that stochastic feedback impairs children's associative stimulus-response (S-R) learning (Crone et al., 2004a; Eppinger et al., 2009), but the impact of stochastic feedback on sequence learning that involves deductive reasoning has not been not tested so far. In the current study, 8- to 11-year-old children (N = 171) learned a sequence of four left and right button presses, LLRR, RRLL, LRLR, RLRL, LRRL, and RLLR, which needed to be deduced from feedback because no directional cues were given. One group of children experienced consistent feedback only (deterministic feedback, 100% correct). In this condition, green feedback on the screen indicated that the children had been right when they were right, and red feedback indicated that the children had been wrong when they were wrong. Another group of children experienced inconsistent feedback (stochastic feedback, 85% correct, 15% false), where in some trials, green feedback on the screen could signal that children were right when in fact they were wrong, and red feedback could indicate that they were wrong when in fact they had been right. Independently of age, children's sequence learning in the stochastic condition was initially much lower than in the deterministic condition, but increased gradually and improved with practice. Responses toward positive vs. negative feedback varied with age. Children were increasingly able to understand that they could have been wrong when feedback indicated they were right (self-reflection), but they remained unable to understand that they could have been right when feedback indicated they were wrong (self-assertion).

Autogenic-feedback training improves pilot performance during emergency flying conditions

NASA Technical Reports Server (NTRS)

Kellar, Michael A.; Folen, Raymond A.; Cowings, Patricia S.; Toscano, William B.; Hisert, Glen L.

1994-01-01

Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group comprised three pilots of HC-130 Hercules aircraft and four HH-65 Dolphin helicopter pilots; the control group comprised three pilots of HC-130's and six Dolphin helicopter pilots. During an initial flight, physiological data were recorded for each crew member and individual crew performance was rated by an instructor pilot. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training (AFT). The remaining subjects received no training. During a second flight, treatment subjects showed significant improvement in performance, while controls did not improve. The results indicate that AFT management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

Autogenic-feedback training improves pilot performance during emergency flying conditions

NASA Technical Reports Server (NTRS)

Kellar, Michael A.; Folen, Raymond A.; Cowings, Patricia S.; Toscano, William B.; Hisert, Glen L.

1993-01-01

Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. The effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance was examined. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group comprised four pilots of HC-130 Hercules aircraft and four HH-65 Dolphin helicopter pilots; the control group comprised three pilots of HC-130's and six Dolphin helicopter pilots. During an initial flight physiological data were recorded for each crewmember and individual crew performance and rated by an instructor pilot. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training (AFT). The remaining subjects received no training. During a second flight, treatment subjects showed significant improvement in performance, while controls did not improve. The results indicate that AFT management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

Autogenic Feedback Training Exercise and pilot performance: enhanced functioning under search-and-rescue flying conditions.

PubMed

Cowings, P S; Kellar, M A; Folen, R A; Toscano, W B; Burge, J D

2001-01-01

Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group contained 4 pilots from HC-130 Hercules aircraft and 4 HH-65 Dolphin helicopter pilots; the control group contained 3 pilots of HC-130s and 6 helicopter pilots. During an initial flight, physiological data were recorded on each crewmember and an instructor pilot rated individual crew performance. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training Exercise (AFTE). The remaining participants received no training. During a second flight, treatment participants showed significant improvement in performance (rated by the same instructor pilot as in pretests) while controls did not improve. The results indicate that AFTE management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

Autogenic Feedback Training Exercise and pilot performance: enhanced functioning under search-and-rescue flying conditions

NASA Technical Reports Server (NTRS)

Cowings, P. S.; Kellar, M. A.; Folen, R. A.; Toscano, W. B.; Burge, J. D.

2001-01-01

Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group contained 4 pilots from HC-130 Hercules aircraft and 4 HH-65 Dolphin helicopter pilots; the control group contained 3 pilots of HC-130s and 6 helicopter pilots. During an initial flight, physiological data were recorded on each crewmember and an instructor pilot rated individual crew performance. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training Exercise (AFTE). The remaining participants received no training. During a second flight, treatment participants showed significant improvement in performance (rated by the same instructor pilot as in pretests) while controls did not improve. The results indicate that AFTE management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

Development of closed-loop neural interface technology in a rat model: combining motor cortex operant conditioning with visual cortex microstimulation.

PubMed

Marzullo, Timothy Charles; Lehmkuhle, Mark J; Gage, Gregory J; Kipke, Daryl R

2010-04-01

Closed-loop neural interface technology that combines neural ensemble decoding with simultaneous electrical microstimulation feedback is hypothesized to improve deep brain stimulation techniques, neuromotor prosthetic applications, and epilepsy treatment. Here we describe our iterative results in a rat model of a sensory and motor neurophysiological feedback control system. Three rats were chronically implanted with microelectrode arrays in both the motor and visual cortices. The rats were subsequently trained over a period of weeks to modulate their motor cortex ensemble unit activity upon delivery of intra-cortical microstimulation (ICMS) of the visual cortex in order to receive a food reward. Rats were given continuous feedback via visual cortex ICMS during the response periods that was representative of the motor cortex ensemble dynamics. Analysis revealed that the feedback provided the animals with indicators of the behavioral trials. At the hardware level, this preparation provides a tractable test model for improving the technology of closed-loop neural devices.

The experience of agency in sequence production with altered auditory feedback.

PubMed

Couchman, Justin J; Beasley, Robertson; Pfordresher, Peter Q

2012-03-01

When speaking or producing music, people rely in part on auditory feedback - the sounds associated with the performed action. Three experiments investigated the degree to which alterations of auditory feedback (AAF) during music performances influence the experience of agency (i.e., the sense that your actions led to auditory events) and the possible link between agency and the disruptive effect of AAF on production. Participants performed short novel melodies from memory on a keyboard. Auditory feedback during performances was manipulated with respect to its pitch contents and/or its synchrony with actions. Participants rated their experience of agency after each trial. In all experiments, AAF reduced judgments of agency across conditions. Performance was most disrupted (measured by error rates and slowing) when AAF led to an ambiguous experience of agency, suggesting that there may be some causal relationship between agency and disruption. However, analyses revealed that these two effects were probably independent. A control experiment verified that performers can make veridical judgments of agency. Published by Elsevier Inc.