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Sample records for adaptive sliding mode

  1. Adaptive fuzzy sliding-mode controller of uncertain nonlinear systems.

    PubMed

    Wu, Tai-Zu; Juang, Yau-Tarng

    2008-07-01

    This paper deals with the design of adaptive fuzzy sliding-mode controllers for the T-S fuzzy model based on the Lyapunov function. It is shown that the Lyapunov function can be used to establish fuzzy sliding surfaces by solving a set of linear matrix inequalities (LMIs). The design of the fuzzy sliding surfaces and the adaptive fuzzy sliding-mode controllers is proposed. The adaptive mechanism is also used to deal with unknown parameter perturbations and external disturbances. Two examples illustrate the feasibility of the proposed methods.

  2. Adaptive sliding mode control for a class of chaotic systems

    NASA Astrophysics Data System (ADS)

    Farid, R.; Ibrahim, A.; Zalam, B.

    2015-03-01

    Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.

  3. Adaptive sliding mode control for a class of chaotic systems

    SciTech Connect

    Farid, R.; Ibrahim, A.; Zalam, B.

    2015-03-30

    Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.

  4. Adaptive robust controller based on integral sliding mode concept

    NASA Astrophysics Data System (ADS)

    Taleb, M.; Plestan, F.

    2016-09-01

    This paper proposes, for a class of uncertain nonlinear systems, an adaptive controller based on adaptive second-order sliding mode control and integral sliding mode control concepts. The adaptation strategy solves the problem of gain tuning and has the advantage of chattering reduction. Moreover, limited information about perturbation and uncertainties has to be known. The control is composed of two parts: an adaptive one whose objective is to reject the perturbation and system uncertainties, whereas the second one is chosen such as the nominal part of the system is stabilised in zero. To illustrate the effectiveness of the proposed approach, an application on an academic example is shown with simulation results.

  5. An adaptive sliding mode control technology for weld seam tracking

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Hu, Youmin; Wu, Bo; Zhou, Kaibo; Ge, Mingfeng

    2015-03-01

    A novel adaptive sliding mode control algorithm is derived to deal with seam tracking control problem of welding robotic manipulator, during the process of large-scale structure component welding. The proposed algorithm does not require the precise dynamic model, and is more practical. Its robustness is verified by the Lyapunov stability theory. The analytical results show that the proposed algorithm enables better high-precision tracking performance with chattering-free than traditional sliding mode control algorithm under various disturbances.

  6. Sliding mode control of wind-induced vibrations using fuzzy sliding surface and gain adaptation

    NASA Astrophysics Data System (ADS)

    Thenozhi, Suresh; Yu, Wen

    2016-04-01

    Although fuzzy/adaptive sliding mode control can reduce the chattering problem in structural vibration control applications, they require the equivalent control and the upper bounds of the system uncertainties. In this paper, we used fuzzy logic to approximate the standard sliding surface and designed a dead-zone adaptive law for tuning the switching gain of the sliding mode control. The stability of the proposed controller is established using Lyapunov stability theory. A six-storey building prototype equipped with an active mass damper has been used to demonstrate the effectiveness of the proposed controller towards the wind-induced vibrations.

  7. Robust observer-based adaptive fuzzy sliding mode controller

    NASA Astrophysics Data System (ADS)

    Oveisi, Atta; Nestorović, Tamara

    2016-08-01

    In this paper, a new observer-based adaptive fuzzy integral sliding mode controller is proposed based on the Lyapunov stability theorem. The plant is subjected to a square-integrable disturbance and is assumed to have mismatch uncertainties both in state- and input-matrices. Based on the classical sliding mode controller, the equivalent control effort is obtained to satisfy the sufficient requirement of sliding mode controller and then the control law is modified to guarantee the reachability of the system trajectory to the sliding manifold. In order to relax the norm-bounded constrains on the control law and solve the chattering problem of sliding mode controller, a fuzzy logic inference mechanism is combined with the controller. An adaptive law is then introduced to tune the parameters of the fuzzy system on-line. Finally, for evaluating the controller and the robust performance of the closed-loop system, the proposed regulator is implemented on a real-time mechanical vibrating system.

  8. Adaptive backstepping sliding mode control for feedforward uncertain systems

    NASA Astrophysics Data System (ADS)

    Koshkouei, Ali J.; Burnham, Keith J.

    2011-12-01

    Output tracking backstepping sliding mode control for feedforward uncertain systems is considered in this article. Feedforward systems are not usually transformable to the parametric semi-strict feedback form, and they may include unmatched uncertainties consisting of disturbances and unmodelled dynamics terms. The backstepping method presented in this article, even without uncertainties differs from that of Ríos-Bolívar and Zinober [Ríos-Bolívar, M. and Zinober, A.S.I. (1999), 'Dynamical Adaptive Sliding Mode Control of Observable Minimum Phase Uncertain Nonlinear Systems', in Variable Structure Systems: Variable Structure Systems, Sliding Mode and Nonlinear Control, eds., K.D. Young and Ü. Özgüner. Ozguner, London, Springer-Verlag, pp. 211-236; Ríos-Bolívar, M., and Zinober, A.S.I. (1997a), 'Dynamical Adaptive Backstepping Control Design via Symbolic Computation', in Proceedings of the 3rd European Control Conference, Brussels]. In this article, the backstepping is not a dynamical method as in Ríos-Bolívar and Zinober (1997a, 1999), since at each step, the control and map input remain intact, and the differentiations of the control are not used. Therefore, the method can be introduced as static backstepping. Two different controllers are designed based upon the backstepping approach with and without sliding mode. The dynamic and static backstepping methods are applied to a gravity-flow/pipeline system to compare two methods.

  9. Adaptive second-order sliding mode control with uncertainty compensation

    NASA Astrophysics Data System (ADS)

    Bartolini, G.; Levant, A.; Pisano, A.; Usai, E.

    2016-09-01

    This paper endows the second-order sliding mode control (2-SMC) approach with additional capabilities of learning and control adaptation. We present a 2-SMC scheme that estimates and compensates for the uncertainties affecting the system dynamics. It also adjusts the discontinuous control effort online, so that it can be reduced to arbitrarily small values. The proposed scheme is particularly useful when the available information regarding the uncertainties is conservative, and the classical `fixed-gain' SMC would inevitably lead to largely oversized discontinuous control effort. Benefits from the viewpoint of chattering reduction are obtained, as confirmed by computer simulations.

  10. Adaptive backstepping slide mode control of pneumatic position servo system

    NASA Astrophysics Data System (ADS)

    Ren, Haipeng; Fan, Juntao

    2016-09-01

    With the price decreasing of the pneumatic proportional valve and the high performance micro controller, the simple structure and high tracking performance pneumatic servo system demonstrates more application potential in many fields. However, most existing control methods with high tracking performance need to know the model information and to use pressure sensor. This limits the application of the pneumatic servo system. An adaptive backstepping slide mode control method is proposed for pneumatic position servo system. The proposed method designs adaptive slide mode controller using backstepping design technique. The controller parameter adaptive law is derived from Lyapunov analysis to guarantee the stability of the system. A theorem is testified to show that the state of closed-loop system is uniformly bounded, and the closed-loop system is stable. The advantages of the proposed method include that system dynamic model parameters are not required for the controller design, uncertain parameters bounds are not need, and the bulk and expensive pressure sensor is not needed as well. Experimental results show that the designed controller can achieve better tracking performance, as compared with some existing methods.

  11. Enhanced adaptive fuzzy sliding mode control for uncertain nonlinear systems

    NASA Astrophysics Data System (ADS)

    Roopaei, Mehdi; Zolghadri, Mansoor; Meshksar, Sina

    2009-09-01

    In this article, a novel Adaptive Fuzzy Sliding Mode Control (AFSMC) methodology is proposed based on the integration of Sliding Mode Control (SMC) and Adaptive Fuzzy Control (AFC). Making use of the SMC design framework, we propose two fuzzy systems to be used as reaching and equivalent parts of the SMC. In this way, we make use of the fuzzy logic to handle uncertainty/disturbance in the design of the equivalent part and provide a chattering free control for the design of the reaching part. To construct the equivalent control law, an adaptive fuzzy inference engine is used to approximate the unknown parts of the system. To get rid of the chattering, a fuzzy logic model is assigned for reaching control law, which acting like the saturation function technique. The main advantage of our proposed methodology is that the structure of the system is unknown and no knowledge of the bounds of parameters, uncertainties and external disturbance are required in advance. Using Lyapunov stability theory and Barbalat's lemma, the closed-loop system is proved to be stable and convergence properties of the system is assured. Simulation examples are presented to verify the effectiveness of the method. Results are compared with some other methods proposed in the past research.

  12. Adaptive suboptimal second-order sliding mode control for microgrids

    NASA Astrophysics Data System (ADS)

    Incremona, Gian Paolo; Cucuzzella, Michele; Ferrara, Antonella

    2016-09-01

    This paper deals with the design of adaptive suboptimal second-order sliding mode (ASSOSM) control laws for grid-connected microgrids. Due to the presence of the inverter, of unpredicted load changes, of switching among different renewable energy sources, and of electrical parameters variations, the microgrid model is usually affected by uncertain terms which are bounded, but with unknown upper bounds. To theoretically frame the control problem, the class of second-order systems in Brunovsky canonical form, characterised by the presence of matched uncertain terms with unknown bounds, is first considered. Four adaptive strategies are designed, analysed and compared to select the most effective ones to be applied to the microgrid case study. In the first two strategies, the control amplitude is continuously adjusted, so as to arrive at dominating the effect of the uncertainty on the controlled system. When a suitable control amplitude is attained, the origin of the state space of the auxiliary system becomes attractive. In the other two strategies, a suitable blend between two components, one mainly working during the reaching phase, the other being the predominant one in a vicinity of the sliding manifold, is generated, so as to reduce the control amplitude in steady state. The microgrid system in a grid-connected operation mode, controlled via the selected ASSOSM control strategies, exhibits appreciable stability properties, as proved theoretically and shown in simulation.

  13. A novel adaptive sliding mode control with application to MEMS gyroscope.

    PubMed

    Fei, Juntao; Batur, Celal

    2009-01-01

    This paper presents a new adaptive sliding mode controller for MEMS gyroscope; an adaptive tracking controller with a proportional and integral sliding surface is proposed. The adaptive sliding mode control algorithm can estimate the angular velocity and the damping and stiffness coefficients in real time. A proportional and integral sliding surface, instead of a conventional sliding surface is adopted. An adaptive sliding mode controller that incorporates both matched and unmatched uncertainties and disturbances is derived and the stability of the closed-loop system is established. The numerical simulation is presented to verify the effectiveness of the proposed control scheme. It is shown that the proposed adaptive sliding mode control scheme offers several advantages such as the consistent estimation of gyroscope parameters including angular velocity and large robustness to parameter variations and external disturbances.

  14. Tensor product model transformation based adaptive integral-sliding mode controller: equivalent control method.

    PubMed

    Zhao, Guoliang; Sun, Kaibiao; Li, Hongxing

    2013-01-01

    This paper proposes new methodologies for the design of adaptive integral-sliding mode control. A tensor product model transformation based adaptive integral-sliding mode control law with respect to uncertainties and perturbations is studied, while upper bounds on the perturbations and uncertainties are assumed to be unknown. The advantage of proposed controllers consists in having a dynamical adaptive control gain to establish a sliding mode right at the beginning of the process. Gain dynamics ensure a reasonable adaptive gain with respect to the uncertainties. Finally, efficacy of the proposed controller is verified by simulations on an uncertain nonlinear system model.

  15. Tensor Product Model Transformation Based Adaptive Integral-Sliding Mode Controller: Equivalent Control Method

    PubMed Central

    Zhao, Guoliang; Li, Hongxing

    2013-01-01

    This paper proposes new methodologies for the design of adaptive integral-sliding mode control. A tensor product model transformation based adaptive integral-sliding mode control law with respect to uncertainties and perturbations is studied, while upper bounds on the perturbations and uncertainties are assumed to be unknown. The advantage of proposed controllers consists in having a dynamical adaptive control gain to establish a sliding mode right at the beginning of the process. Gain dynamics ensure a reasonable adaptive gain with respect to the uncertainties. Finally, efficacy of the proposed controller is verified by simulations on an uncertain nonlinear system model. PMID:24453897

  16. Model reference, sliding mode adaptive control for flexible structures

    NASA Technical Reports Server (NTRS)

    Yurkovich, S.; Ozguner, U.; Al-Abbass, F.

    1988-01-01

    A decentralized model reference adaptive approach using a variable-structure sliding model control has been developed for the vibration suppression of large flexible structures. Local models are derived based upon the desired damping and response time in a model-following scheme, and variable structure controllers are then designed which employ colocated angular rate and position feedback. Numerical simulations have been performed using NASA's flexible grid experimental apparatus.

  17. Sliding Mode Control of Dynamic Voltage Restorer by Using a New Adaptive Reaching Law

    NASA Astrophysics Data System (ADS)

    Pandey, Achala; Agrawal, Rekha; Mandloi, Ravindra S.; Sarkar, Biswaroop

    2017-08-01

    This paper presents a new kind of adaptive reaching law for sliding mode control of Dynamic Voltage Restorer (DVR). Such an adaptive reaching law follows under-damped sinusoidal nature that causes the initial state to reach the sliding regime in extremely less time with negligible chattering. Moreover, it is robust in the sense the trajectory does not deviate from the sliding surface. This new approach is developed and successfully applied to DVR. The simulation results are presented that show its robustness.

  18. Adaptive sliding mode control of tethered satellite deployment with input limitation

    NASA Astrophysics Data System (ADS)

    Ma, Zhiqiang; Sun, Guanghui

    2016-10-01

    This paper proposes a novel adaptive sliding mode tension control method for the deployment of tethered satellite, where the input tension limitation is taken into account. The underactuated governing equations of the tethered satellites system are firstly derived based on Lagrangian mechanics theory. Considering the fact that the tether can only resist axial stretching, the tension input is modelled as input limitation. New adaptive sliding mode laws are addressed to guarantee the stability of the tethered satellite deployment with input disturbance, meanwhile to eliminate the effect of the limitation features of the tension input. Compared with the classic control strategy, the newly proposed adaptive sliding mode control law can deploy the satellite with smaller overshoot of the in-plane angle and implement the tension control reasonably and effectively in engineering practice. The numerical results validate the effectiveness of the proposed methods.

  19. Adaptive uniform finite-/fixed-time convergent second-order sliding-mode control

    NASA Astrophysics Data System (ADS)

    Basin, Michael; Bharath Panathula, Chandrasekhara; Shtessel, Yuri

    2016-09-01

    This paper presents an adaptive gain algorithm for second-order sliding-mode control (2-SMC), specifically a super-twisting (STW)-like controller, with uniform finite/fixed convergence time, that is robust to perturbations with unknown bounds. It is shown that a second-order sliding mode is established as exact finite-time convergence to the origin if the adaptive gain does not have the ability to get reduced and converge to a small vicinity of the origin if the adaptation algorithm does not overestimate the control gain. The estimate of fixed convergence time of the studied adaptive STW-like controller is derived based on the Lyapunov analysis. The efficacy of the proposed adaptive algorithm is illustrated in a tutorial example, where the adaptive STW-like controller with uniform finite/fixed convergence time is compared to the adaptive STW controller with non-uniform finite convergence time.

  20. Certainty equivalence adaptation combined with super-twisting sliding-mode control

    NASA Astrophysics Data System (ADS)

    Barth, A.; Reichhartinger, M.; Wulff, K.; Horn, M.; Reger, J.

    2016-09-01

    In this paper, a Lyapunov-based control concept is presented that combines variable structure and adaptive control. The considered system class consists of nonlinear single input systems which are affected by matched structured and unstructured uncertainties. Resorting to the certainty equivalence principle, the controller exploits advantages of both the sliding-mode and the adaptive control methodology. It is demonstrated that the gains of the discontinuous control action may be reduced remarkably when compared with pure sliding-mode-based approaches. The efficiency of the presented concept is demonstrated in detail, using results of numerical simulations.

  1. Adaptive backstepping sliding mode control with fuzzy monitoring strategy for a kind of mechanical system.

    PubMed

    Song, Zhankui; Sun, Kaibiao

    2014-01-01

    A novel adaptive backstepping sliding mode control (ABSMC) law with fuzzy monitoring strategy is proposed for the tracking-control of a kind of nonlinear mechanical system. The proposed ABSMC scheme combining the sliding mode control and backstepping technique ensure that the occurrence of the sliding motion in finite-time and the trajectory of tracking-error converge to equilibrium point. To obtain a better perturbation rejection property, an adaptive control law is employed to compensate the lumped perturbation. Furthermore, we introduce fuzzy monitoring strategy to improve adaptive capacity and soften the control signal. The convergence and stability of the proposed control scheme are proved by using Lyaponov's method. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.

  2. Chattering free adaptive multivariable sliding mode controller for systems with matched and mismatched uncertainty.

    PubMed

    Mondal, Sanjoy; Mahanta, Chitralekha

    2013-05-01

    In this paper, a chattering free adaptive sliding mode controller (SMC) is proposed for stabilizing a class of multi-input multi-output (MIMO) systems affected by both matched and mismatched types of uncertainties. The proposed controller uses a proportional plus integral sliding surface whose gain is adaptively tuned to prevent overestimation. A vertical take-off and landing (VTOL) aircraft system is simulated to demonstrate the effectiveness of the proposed control scheme. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Generalized projective synchronization of the fractional-order chaotic system using adaptive fuzzy sliding mode control

    NASA Astrophysics Data System (ADS)

    Wang, Li-Ming; Tang, Yong-Guang; Chai, Yong-Quan; Wu, Feng

    2014-10-01

    An adaptive fuzzy sliding mode strategy is developed for the generalized projective synchronization of a fractional-order chaotic system, where the slave system is not necessarily known in advance. Based on the designed adaptive update laws and the linear feedback method, the adaptive fuzzy sliding controllers are proposed via the fuzzy design, and the strength of the designed controllers can be adaptively adjusted according to the external disturbances. Based on the Lyapunov stability theorem, the stability and the robustness of the controlled system are proved theoretically. Numerical simulations further support the theoretical results of the paper and demonstrate the efficiency of the proposed method. Moreover, it is revealed that the proposed method allows us to manipulate arbitrarily the response dynamics of the slave system by adjusting the desired scaling factor λi and the desired translating factor ηi, which may be used in a channel-independent chaotic secure communication.

  4. Sliding mode disturbance observer-based adaptive integral backstepping control of a piezoelectric nano-manipulator

    NASA Astrophysics Data System (ADS)

    Zhang, Yangming; Yan, Peng

    2016-12-01

    This paper investigates a systematic modeling and control methodology for a multi-axis PZT (piezoelectric transducer) actuated servo stage supporting nano-manipulations. A sliding mode disturbance observer-based adaptive integral backstepping control method with an estimated inverse model compensation scheme is proposed to achieve ultra high precision tracking in the presence of the hysteresis nonlinearities, model uncertainties, and external disturbances. By introducing a time rate of the input signal, an enhanced rate-dependent Prandtl-Ishlinskii model is developed to describe the hysteresis behaviors, and its inverse is also constructed to mitigate their adverse effects. In particular, the corresponding inverse compensation error is analyzed and its boundedness is proven. Subsequently, the sliding mode disturbance observer-based adaptive integral backstepping controller is designed to guarantee the convergence of the tracking error, where the sliding mode disturbance observer can track the total disturbances in a finite time, while the integral action is incorporated into the adaptive backstepping design to improve the steady-state control accuracy. Finally, real time implementations of the proposed algorithm are applied on the PZT actuated servo system, where excellent tracking performance with tracking precision error around 6‰ for circular contour tracking is achieved in the experimental results.

  5. Adaptive terminal sliding-mode control strategy for DC-DC buck converters.

    PubMed

    Komurcugil, Hasan

    2012-11-01

    This paper presents an adaptive terminal sliding mode control (ATSMC) strategy for DC-DC buck converters. The idea behind this strategy is to use the terminal sliding mode control (TSMC) approach to assure finite time convergence of the output voltage error to the equilibrium point and integrate an adaptive law to the TSMC strategy so as to achieve a dynamic sliding line during the load variations. In addition, the influence of the controller parameters on the performance of closed-loop system is investigated. It is observed that the start up response of the output voltage becomes faster with increasing value of the fractional power used in the sliding function. On the other hand, the transient response of the output voltage, caused by the step change in the load, becomes faster with decreasing the value of the fractional power. Therefore, the value of fractional power is to be chosen to make a compromise between start up and transient responses of the converter. Performance of the proposed ATSMC strategy has been tested through computer simulations and experiments. The simulation results of the proposed ATSMC strategy are compared with the conventional SMC and TSMC strategies. It is shown that the ATSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes.

  6. Nonlinear adaptive control based on fuzzy sliding mode technique and fuzzy-based compensator.

    PubMed

    Nguyen, Sy Dzung; Vo, Hoang Duy; Seo, Tae-Il

    2017-09-01

    It is difficult to efficiently control nonlinear systems in the presence of uncertainty and disturbance (UAD). One of the main reasons derives from the negative impact of the unknown features of UAD as well as the response delay of the control system on the accuracy rate in the real time of the control signal. In order to deal with this, we propose a new controller named CO-FSMC for a class of nonlinear control systems subjected to UAD, which is constituted of a fuzzy sliding mode controller (FSMC) and a fuzzy-based compensator (CO). Firstly, the FSMC and CO are designed independently, and then an adaptive fuzzy structure is discovered to combine them. Solutions for avoiding the singular cases of the fuzzy-based function approximation and reducing the calculating cost are proposed. Based on the solutions, fuzzy sliding mode technique, lumped disturbance observer and Lyapunov stability analysis, a closed-loop adaptive control law is formulated. Simulations along with a real application based on a semi-active train-car suspension are performed to fully evaluate the method. The obtained results reflected that vibration of the chassis mass is insensitive to UAD. Compared with the other fuzzy sliding mode control strategies, the CO-FSMC can provide the best control ability to reduce unwanted vibrations. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  7. Wavelet neural network control for linear ultrasonic motor drive via adaptive sliding-mode technique.

    PubMed

    Lin, Faa-Jeng; Wai, Rong-Jong; Chen, Mu-Ping

    2003-06-01

    A wavelet neural network (WNN) control system is proposed to control the moving table of a linear ultrasonic motor (LUSM) drive system to track periodic reference trajectories in this study. The design of the WNN control system is based on an adaptive sliding-mode control technique. The structure and operating principle of the LUSM are introduced, and the driving circuit of the LUSM, which is a voltage source inverter using two-inductance two capacitance (LLCC) resonant technique, is introduced. Because the dynamic characteristics and motor parameters of the LUSM are nonlinear and time varying, a WNN control system is designed based on adaptive sliding-mode control technique to achieve precision position control. In the WNN control system, a WNN is used to learn the ideal equivalent control law, and a robust controller is designed to meet the sliding condition. Moreover, the adaptive learning algorithms of the WNN and the bound estimation algorithm of the robust controller are derived from the sense of Lyapunov stability analysis. The effectiveness of the proposed WNN control system is verified by some experimental results in the presence of uncertainties.

  8. Extended observer based on adaptive second order sliding mode control for a fixed wing UAV.

    PubMed

    Castañeda, Herman; Salas-Peña, Oscar S; León-Morales, Jesús de

    2017-01-01

    This paper addresses the design of attitude and airspeed controllers for a fixed wing unmanned aerial vehicle. An adaptive second order sliding mode control is proposed for improving performance under different operating conditions and is robust in presence of external disturbances. Moreover, this control does not require the knowledge of disturbance bounds and avoids overestimation of the control gains. Furthermore, in order to implement this controller, an extended observer is designed to estimate unmeasurable states as well as external disturbances. Additionally, sufficient conditions are given to guarantee the closed-loop stability of the observer based control. Finally, using a full 6 degree of freedom model, simulation results are obtained where the performance of the proposed method is compared against active disturbance rejection based on sliding mode control.

  9. Adaptive sliding mode control design for a class of uncertain singularly perturbed nonlinear systems

    NASA Astrophysics Data System (ADS)

    Lin, Kuo-Jung

    2014-02-01

    This paper addresses adaptive sliding mode control (ASMC) of uncertain singularly perturbed nonlinear (USPN) systems with guaranteed H∞ control performance. First, we use Takagi-Sugeno (T-S) fuzzy model to construct the USPN systems. Then, the sliding surface can be determined via linear matrix inequality (LMI) design procedure. Second, we propose neural network (NN)-based ASMC design to stabilise the USPN systems. The proposed methods are based on the Lyapunov stability theorem. The adaptive law can reduce the effect of uncertainty. The proposed NN-based ASMC will stabilise the USPN systems for all ɛ ∈ (0, ɛ*]. Simulation result reveals that the proposed NN-based ASMC scheme has better convergence time compared with the fuzzy control scheme (Li, T.-H.S., & Lin, K.J. (2004). Stabilization of singularly perturbed fuzzy systems, IEEE Transactions on Fuzzy Systems, 12, 579-595.).

  10. Adaptive discrete-time sliding-mode control of nonlinear systems described by Wiener models

    NASA Astrophysics Data System (ADS)

    Salhi, Houda; Kamoun, Samira; Essounbouli, Najib; Hamzaoui, Abdelaziz

    2016-03-01

    In this paper, we propose an adaptive control scheme that can be applied to nonlinear systems with unknown parameters. The considered class of nonlinear systems is described by the block-oriented models, specifically, the Wiener models. These models consist of dynamic linear blocks in series with static nonlinear blocks. The proposed adaptive control method is based on the inverse of the nonlinear function block and on the discrete-time sliding-mode controller. The parameters adaptation are performed using a new recursive parametric estimation algorithm. This algorithm is developed using the adjustable model method and the least squares technique. A recursive least squares (RLS) algorithm is used to estimate the inverse nonlinear function. A time-varying gain is proposed, in the discrete-time sliding mode controller, to reduce the chattering problem. The stability of the closed-loop nonlinear system, with the proposed adaptive control scheme, has been proved. An application to a pH neutralisation process has been carried out and the simulation results clearly show the effectiveness of the proposed adaptive control scheme.

  11. Robust dynamic sliding-mode control using adaptive RENN for magnetic levitation system.

    PubMed

    Lin, Faa-Jeng; Chen, Syuan-Yi; Shyu, Kuo-Kai

    2009-06-01

    In this paper, a robust dynamic sliding mode control system (RDSMC) using a recurrent Elman neural network (RENN) is proposed to control the position of a levitated object of a magnetic levitation system considering the uncertainties. First, a dynamic model of the magnetic levitation system is derived. Then, a proportional-integral-derivative (PID)-type sliding-mode control system (SMC) is adopted for tracking of the reference trajectories. Moreover, a new PID-type dynamic sliding-mode control system (DSMC) is proposed to reduce the chattering phenomenon. However, due to the hardware being limited and the uncertainty bound being unknown of the switching function for the DSMC, an RDSMC is proposed to improve the control performance and further increase the robustness of the magnetic levitation system. In the RDSMC, an RENN estimator is used to estimate an unknown nonlinear function of lumped uncertainty online and replace the switching function in the hitting control of the DSMC directly. The adaptive learning algorithms that trained the parameters of the RENN online are derived using Lyapunov stability theorem. Furthermore, a robust compensator is proposed to confront the uncertainties including approximation error, optimal parameter vectors, and higher order terms in Taylor series. Finally, some experimental results of tracking the various periodic trajectories demonstrate the validity of the proposed RDSMC for practical applications.

  12. Design of adaptive fuzzy wavelet neural sliding mode controller for uncertain nonlinear systems.

    PubMed

    Shahriari kahkeshi, Maryam; Sheikholeslam, Farid; Zekri, Maryam

    2013-05-01

    This paper proposes novel adaptive fuzzy wavelet neural sliding mode controller (AFWN-SMC) for a class of uncertain nonlinear systems. The main contribution of this paper is to design smooth sliding mode control (SMC) for a class of high-order nonlinear systems while the structure of the system is unknown and no prior knowledge about uncertainty is available. The proposed scheme composed of an Adaptive Fuzzy Wavelet Neural Controller (AFWNC) to construct equivalent control term and an Adaptive Proportional-Integral (A-PI) controller for implementing switching term to provide smooth control input. Asymptotical stability of the closed loop system is guaranteed, using the Lyapunov direct method. To show the efficiency of the proposed scheme, some numerical examples are provided. To validate the results obtained by proposed approach, some other methods are adopted from the literature and applied for comparison. Simulation results show superiority and capability of the proposed controller to improve the steady state performance and transient response specifications by using less numbers of fuzzy rules and on-line adaptive parameters in comparison to other methods. Furthermore, control effort has considerably decreased and chattering phenomenon has been completely removed.

  13. Adaptive sliding mode controller based on super-twist observer for tethered satellite system

    NASA Astrophysics Data System (ADS)

    Keshtkar, Sajjad; Poznyak, Alexander

    2016-09-01

    In this work, the sliding mode control based on the super-twist observer is presented. The parameters of the controller as well as the observer are admitted to be time-varying and depending on available current measurements. In view of that, the considered controller is referred to as an adaptive one. It is shown that the deviations of the generated state estimates from real state values together with a distance of the closed-loop system trajectories to a desired sliding surface reach a μ-zone around the origin in finite time. The application of the suggested controller is illustrated for the orientation of a tethered satellite system in a required position.

  14. Adaptive Sliding Mode Control of Dynamic Systems Using Double Loop Recurrent Neural Network Structure.

    PubMed

    Fei, Juntao; Lu, Cheng

    2017-03-06

    In this paper, an adaptive sliding mode control system using a double loop recurrent neural network (DLRNN) structure is proposed for a class of nonlinear dynamic systems. A new three-layer RNN is proposed to approximate unknown dynamics with two different kinds of feedback loops where the firing weights and output signal calculated in the last step are stored and used as the feedback signals in each feedback loop. Since the new structure has combined the advantages of internal feedback NN and external feedback NN, it can acquire the internal state information while the output signal is also captured, thus the new designed DLRNN can achieve better approximation performance compared with the regular NNs without feedback loops or the regular RNNs with a single feedback loop. The new proposed DLRNN structure is employed in an equivalent controller to approximate the unknown nonlinear system dynamics, and the parameters of the DLRNN are updated online by adaptive laws to get favorable approximation performance. To investigate the effectiveness of the proposed controller, the designed adaptive sliding mode controller with the DLRNN is applied to a z-axis microelectromechanical system gyroscope to control the vibrating dynamics of the proof mass. Simulation results demonstrate that the proposed methodology can achieve good tracking property, and the comparisons of the approximation performance between radial basis function NN, RNN, and DLRNN show that the DLRNN can accurately estimate the unknown dynamics with a fast speed while the internal states of DLRNN are more stable.

  15. Adaptive Actor-Critic Design-Based Integral Sliding-Mode Control for Partially Unknown Nonlinear Systems With Input Disturbances.

    PubMed

    Fan, Quan-Yong; Yang, Guang-Hong

    2016-01-01

    This paper is concerned with the problem of integral sliding-mode control for a class of nonlinear systems with input disturbances and unknown nonlinear terms through the adaptive actor-critic (AC) control method. The main objective is to design a sliding-mode control methodology based on the adaptive dynamic programming (ADP) method, so that the closed-loop system with time-varying disturbances is stable and the nearly optimal performance of the sliding-mode dynamics can be guaranteed. In the first step, a neural network (NN)-based observer and a disturbance observer are designed to approximate the unknown nonlinear terms and estimate the input disturbances, respectively. Based on the NN approximations and disturbance estimations, the discontinuous part of the sliding-mode control is constructed to eliminate the effect of the disturbances and attain the expected equivalent sliding-mode dynamics. Then, the ADP method with AC structure is presented to learn the optimal control for the sliding-mode dynamics online. Reconstructed tuning laws are developed to guarantee the stability of the sliding-mode dynamics and the convergence of the weights of critic and actor NNs. Finally, the simulation results are presented to illustrate the effectiveness of the proposed method.

  16. An adaptive sliding mode backstepping control for the mobile manipulator with nonholonomic constraints

    NASA Astrophysics Data System (ADS)

    Chen, Naijian; Song, Fangzhen; Li, Guoping; Sun, Xuan; Ai, Changsheng

    2013-10-01

    To solve disturbances, nonlinearity, nonholonomic constraints and dynamic coupling between the platform and its mounted robot manipulator, an adaptive sliding mode controller based on the backstepping method applied to the robust trajectory tracking of the wheeled mobile manipulator is described in this article. The control algorithm rests on adopting the backstepping method to improve the global ultimate asymptotic stability and applying the sliding mode control to obtain high response and invariability to uncertainties. According to the Lyapunov stability criterion, the wheeled mobile manipulator is divided into several stabilizing subsystems, and an adaptive law is designed to estimate the general nondeterminacy, which make the controller be capable to drive the trajectory tracking error of the mobile manipulator to converge to zero even in the presence of perturbations and mathematical model errors. We compare our controller with the robust neural network based algorithm in nonholonomic constraints and uncertainties, and simulation results prove the effectivity and feasibility of the proposed method in the trajectory tracking of the wheeled mobile manipulator.

  17. Adaptive sliding mode control for six-DOF relative motion of spacecraft with input constraint

    NASA Astrophysics Data System (ADS)

    Wu, Jinjie; Liu, Kun; Han, Dapeng

    2013-06-01

    This paper addresses the synchronized control problem of relative position and attitude for spacecraft with input constraint. First, using dual quaternion, the kinematic and dynamic models of the six-degree-of-freedom relative motion of spacecraft are introduced. Second, a new adaptive sliding mode control scheme is proposed to guarantee the globally asymptotic convergence of relative motion despite the presence of control input constraint, parametric uncertainties and external disturbances. A detailed stability analysis of the resulting closed-loop system is included. Finally, simulation results are presented to illustrate the validity and effectiveness of the proposed controller, which has the following properties: (1) explicit accounting for the problem of input constraint, (2) fast convergent rate and accurate results can be obtained, (3) no chattering phenomenon is present in the control torque and control force, (4) self-adaptive regulation law is dynamically adjusted to ensure the tracking errors tend to zero asymptotically, (5) the upper bounds of unknown variables are estimated dynamically.

  18. Speed tracking and synchronization of multiple motors using ring coupling control and adaptive sliding mode control.

    PubMed

    Li, Le-Bao; Sun, Ling-Ling; Zhang, Sheng-Zhou; Yang, Qing-Quan

    2015-09-01

    A new control approach for speed tracking and synchronization of multiple motors is developed, by incorporating an adaptive sliding mode control (ASMC) technique into a ring coupling synchronization control structure. This control approach can stabilize speed tracking of each motor and synchronize its motion with other motors' motion so that speed tracking errors and synchronization errors converge to zero. Moreover, an adaptive law is exploited to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort and attenuate chattering. Performance comparisons with parallel control, relative coupling control and conventional PI control are investigated on a four-motor synchronization control system. Extensive simulation results show the effectiveness of the proposed control scheme.

  19. Distributed Adaptive Fuzzy Control for Nonlinear Multiagent Systems Via Sliding Mode Observers.

    PubMed

    Shen, Qikun; Shi, Peng; Shi, Yan

    2016-12-01

    In this paper, the problem of distributed adaptive fuzzy control is investigated for high-order uncertain nonlinear multiagent systems on directed graph with a fixed topology. It is assumed that only the outputs of each follower and its neighbors are available in the design of its distributed controllers. Equivalent output injection sliding mode observers are proposed for each follower to estimate the states of itself and its neighbors, and an observer-based distributed adaptive controller is designed for each follower to guarantee that it asymptotically synchronizes to a leader with tracking errors being semi-globally uniform ultimate bounded, in which fuzzy logic systems are utilized to approximate unknown functions. Based on algebraic graph theory and Lyapunov function approach, using Filippov-framework, the closed-loop system stability analysis is conducted. Finally, numerical simulations are provided to illustrate the effectiveness and potential of the developed design techniques.

  20. Sliding mode disturbance observer-enhanced adaptive control for the air-breathing hypersonic flight vehicle

    NASA Astrophysics Data System (ADS)

    An, Hao; Wang, Changhong; Fidan, Baris

    2017-10-01

    This paper presents a backstepping procedure to design an adaptive controller for the air-breathing hypersonic flight vehicle (AHFV) subject to external disturbances and actuator saturations. In each step, a sliding mode exact disturbance observer (SMEDO) is exploited to exactly estimate the lumped disturbance in finite time. Specific dynamics are introduced to handle the possible actuator saturations. Based on SMEDO and introduced dynamics, an adaptive control law is designed, along with the consideration on ;explosion of complexity; in backstepping design. The developed controller is equipped with fast disturbance rejection and great capability to accommodate the saturated actuators, which also lead to a wider application scope. A simulation study is provided to show the effectiveness and superiority of the proposed controller.

  1. Adaptive sliding mode dynamic controller with integrator in the loop for nonholonomic wheeled mobile robot trajectory tracking

    NASA Astrophysics Data System (ADS)

    Asif, Muhammad; Junaid Khan, Muhammad; Cai, Ning

    2014-05-01

    In this paper, novel adaptive sliding mode dynamic controller with integrator in the loop is proposed for nonholonomic wheeled mobile robot (WMR). The modified kinematics controller is used to generate kinematics velocities of WMR which are subsequently used as the input to adaptive dynamic controller. Actuator dynamics are also derived to generate actuator voltage of WMR through torque and velocity vectors. Stability of both kinematics and dynamic controller is presented using Lyapunov stability analysis. The proposed scheme is verified and validated using computer simulations for tracking the desired trajectory of WMR. The performance of proposed scheme is compared with standard backstepping kinematics controller and classical sliding mode control. In addition, the performance is further compared with standard backstepping kinematics controller with adaptive sliding mode controller without integrator. It is shown that the proposed scheme exhibits zero steady state error, fast error convergence and robustness in the presence of continuous disturbances and uncertainties.

  2. Bifurcations, chaos and adaptive backstepping sliding mode control of a power system with excitation limitation

    SciTech Connect

    Min, Fuhong Wang, Yaoda; Peng, Guangya; Wang, Enrong

    2016-08-15

    The bifurcation and Lyapunov exponent for a single-machine-infinite bus system with excitation model are carried out by varying the mechanical power, generator damping factor and the exciter gain, from which periodic motions, chaos and the divergence of system are observed respectively. From given parameters and different initial conditions, the coexisting motions are developed in power system. The dynamic behaviors in power system may switch freely between the coexisting motions, which will bring huge security menace to protection operation. Especially, the angle divergences due to the break of stable chaotic oscillation are found which causes the instability of power system. Finally, a new adaptive backstepping sliding mode controller is designed which aims to eliminate the angle divergences and make the power system run in stable orbits. Numerical simulations are illustrated to verify the effectivity of the proposed method.

  3. Decentralized adaptive sliding mode control for beam synchronization of tethered InSAR system

    NASA Astrophysics Data System (ADS)

    Zhang, Jinxiu; Zhang, Zhigang; Wu, Baolin

    2016-10-01

    Beam synchronization problem of tethered interferometric synthetic aperture radar (InSAR) is addressed in this paper. Two antennas of the system are carried by separate satellites connected through a tether to obtain a preferable baseline. A Total Zero Doppler Steering (TZDS) is implemented to mother-satellite to cancel the residual Doppler. Subsequently attitude reference trajectories for the two satellites are generated to achieve the beam synchronization and TZDS. Thereafter, a decentralized adaptive sliding mode control law is proposed to track these reference trajectories in the presence of model uncertainties and external disturbances. Finally, the stability of closed-loop system is proved by the corollary of Barbalat's Lemma. Simulation results show the proposed control law is effective to achieve beam synchronization of the system.

  4. Bifurcations, chaos and adaptive backstepping sliding mode control of a power system with excitation limitation

    NASA Astrophysics Data System (ADS)

    Min, Fuhong; Wang, Yaoda; Peng, Guangya; Wang, Enrong; Auth, Jane A.

    2016-08-01

    The bifurcation and Lyapunov exponent for a single-machine-infinite bus system with excitation model are carried out by varying the mechanical power, generator damping factor and the exciter gain, from which periodic motions, chaos and the divergence of system are observed respectively. From given parameters and different initial conditions, the coexisting motions are developed in power system. The dynamic behaviors in power system may switch freely between the coexisting motions, which will bring huge security menace to protection operation. Especially, the angle divergences due to the break of stable chaotic oscillation are found which causes the instability of power system. Finally, a new adaptive backstepping sliding mode controller is designed which aims to eliminate the angle divergences and make the power system run in stable orbits. Numerical simulations are illustrated to verify the effectivity of the proposed method.

  5. Stabilization and synchronization for a mechanical system via adaptive sliding mode control.

    PubMed

    Song, Zhankui; Sun, Kaibiao; Ling, Shuai

    2017-05-01

    In this paper, we investigate the synchronization problem of chaotic centrifugal flywheel governor with parameters uncertainty and lumped disturbances. A slave centrifugal flywheel governor system is considered as an underactuated following-system which a control input is designed to follow a master centrifugal flywheel governor system. To tackle lumped disturbances and uncertainty parameters, a novel synchronization control law is developed by employing sliding mode control strategy and Nussbaum gain technique. Adaptation updating algorithms are derived in the sense of Lyapunov stability analysis such that the lumped disturbances can be suppressed and the adverse effect caused by uncertainty parameters can be compensated. In addition, the synchronization tracking-errors are proven to converge to a small neighborhood of the origin. Finally, simulation results demonstrate the effectiveness of the proposed control scheme. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  6. Combination synchronization of time-delay chaotic system via robust adaptive sliding mode control

    NASA Astrophysics Data System (ADS)

    Khan, Ayub; Shikha

    2017-06-01

    In this paper, the methodology to achieve combination synchronization of time-delay chaotic system via robust adaptive sliding mode control is introduced. The methodology is implemented by taking identical time-delay Lorenz chaotic system. The selection of switching surface and the design of control law is also discussed, which is an important issue. By utilizing rigorous mathematical theory, sufficient condition is drawn for the stability of error dynamics based on Lyapunov stability theory. Theoretical results are supported with the numerical simulations. The complexity of this methodology is useful to strengthen the security of communication. The hidden message can be partitioned into several parts loaded in two master systems to improve the accuracy of communication.

  7. Mean deviation coupling synchronous control for multiple motors via second-order adaptive sliding mode control.

    PubMed

    Li, Lebao; Sun, Lingling; Zhang, Shengzhou

    2016-05-01

    A new mean deviation coupling synchronization control strategy is developed for multiple motor control systems, which can guarantee the synchronization performance of multiple motor control systems and reduce complexity of the control structure with the increasing number of motors. The mean deviation coupling synchronization control architecture combining second-order adaptive sliding mode control (SOASMC) approach is proposed, which can improve synchronization control precision of multiple motor control systems and make speed tracking errors, mean speed errors of each motor and speed synchronization errors converge to zero rapidly. The proposed control scheme is robustness to parameter variations and random external disturbances and can alleviate the chattering phenomena. Moreover, an adaptive law is employed to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort. Performance comparisons with master-slave control, relative coupling control, ring coupling control, conventional PI control and SMC are investigated on a four-motor synchronization control system. Extensive comparative results are given to shown the good performance of the proposed control scheme.

  8. 6-DOF robust adaptive terminal sliding mode control for spacecraft formation flying

    NASA Astrophysics Data System (ADS)

    Wang, Jianying; Sun, Zhaowei

    2012-04-01

    This paper addresses the tracking control problem of the leader-follower spacecraft formation, by which we mean that the relative motion between the leader and the follower is required to track a desired time-varying trajectory given in advance. Using dual number, the six-degree-of-freedom motion of the follower spacecraft relative to the leader spacecraft is modeled, where the coupling effect between the translational motion and the rotational one is accounted. A robust adaptive terminal sliding mode control law, including the adaptive algorithms, is proposed to ensure the finite time convergence of the relative motion tracking errors despite the presence of model uncertainties and external disturbances, based on which a modified controller is furthermore developed to solve the dual-equilibrium problem caused by dual quaternion representation. In addition, to alleviate the chattering, hyperbolic tangent function is adopted to substitute for the sign function. And by theoretical analysis, it is proved that the tracking error in such case will converge to a neighborhood of the origin in finite time. Finally, numerical simulations are performed to demonstrate the validity of the proposed approaches.

  9. A novel adaptive switching function on fault tolerable sliding mode control for uncertain stochastic systems.

    PubMed

    Zahiripour, Seyed Ali; Jalali, Ali Akbar

    2014-09-01

    A novel switching function based on an optimization strategy for the sliding mode control (SMC) method has been provided for uncertain stochastic systems subject to actuator degradation such that the closed-loop system is globally asymptotically stable with probability one. In the previous researches the focus on sliding surface has been on proportional or proportional-integral function of states. In this research, from a degree of freedom that depends on designer choice is used to meet certain objectives. In the design of the switching function, there is a parameter which the designer can regulate for specified objectives. A sliding-mode controller is synthesized to ensure the reachability of the specified switching surface, despite actuator degradation and uncertainties. Finally, the simulation results demonstrate the effectiveness of the proposed method.

  10. Adaptive Hierarchical Sliding Mode Control with Input Saturation for Attitude Regulation of Multi-satellite Tethered System

    NASA Astrophysics Data System (ADS)

    Ma, Zhiqiang; Sun, Guanghui

    2017-06-01

    This paper proposes a novel adaptive hierarchical sliding mode control for the attitude regulation of the multi-satellite inline tethered system, where the input saturation is taken into account. The governing equations for the attitude dynamics of the three-satellite inline tethered system are derived firstly by utilizing Lagrangian mechanics theory. Considering the fact that the attitude of the central satellite can be adjusted by using the simple exponential stabilization scheme, the decoupling of the central satellite and the terminal ones is presented, and in addition, the new adaptive sliding mode control law is applied to stabilize the attitude dynamics of the two terminal satellites based on the synchronization and partial contraction theory. In the adaptive hierarchical sliding mode control design, the input is modeled as saturated input due to the fact that the flywheel torque is bounded, and meanwhile, an adaptive update rate is introduced to eliminate the effect of the saturated input and the external perturbation. The proposed control scheme can be applied on the two-satellite system to achieve fixed-point rotation. Numerical results validate the effectiveness of the proposed method.

  11. Adaptive Hierarchical Sliding Mode Control with Input Saturation for Attitude Regulation of Multi-satellite Tethered System

    NASA Astrophysics Data System (ADS)

    Ma, Zhiqiang; Sun, Guanghui

    2016-11-01

    This paper proposes a novel adaptive hierarchical sliding mode control for the attitude regulation of the multi-satellite inline tethered system, where the input saturation is taken into account. The governing equations for the attitude dynamics of the three-satellite inline tethered system are derived firstly by utilizing Lagrangian mechanics theory. Considering the fact that the attitude of the central satellite can be adjusted by using the simple exponential stabilization scheme, the decoupling of the central satellite and the terminal ones is presented, and in addition, the new adaptive sliding mode control law is applied to stabilize the attitude dynamics of the two terminal satellites based on the synchronization and partial contraction theory. In the adaptive hierarchical sliding mode control design, the input is modeled as saturated input due to the fact that the flywheel torque is bounded, and meanwhile, an adaptive update rate is introduced to eliminate the effect of the saturated input and the external perturbation. The proposed control scheme can be applied on the two-satellite system to achieve fixed-point rotation. Numerical results validate the effectiveness of the proposed method.

  12. Tracking Control of a 2-DOF Arm Actuated by Pneumatic Muscle Actuators Using Adaptive Fuzzy Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Chang, Ming-Kun; Wu, Jui-Chi

    Pneumatic muscle actuators (PMAs) have the highest power/weight ratio and power/volume ratio of any actuator. Therefore, they can be used not only in the rehabilitation engineering, but also as an actuator in robots, including industrial robots and therapy robots. It is difficult to achieve excellent tracking performance using classical control methods because the compressibility of gas and the nonlinear elasticity of bladder container causes parameter variations. An adaptive fuzzy sliding mode control is developed in this study. The fuzzy sliding surface can be used to reduce fuzzy rule numbers, and the adaptive control law is used to modify fuzzy rules on-line. A model matching technique is then adopted to adjust scaling factors. The experimental results show that this control strategy can attain excellent tracking performance.

  13. Adaptive-gain fast super-twisting sliding mode fault tolerant control for a reusable launch vehicle in reentry phase.

    PubMed

    Zhang, Yao; Tang, Shengjing; Guo, Jie

    2017-09-04

    In this paper, a novel adaptive-gain fast super-twisting (AGFST) sliding mode attitude control synthesis is carried out for a reusable launch vehicle subject to actuator faults and unknown disturbances. According to the fast nonsingular terminal sliding mode surface (FNTSMS) and adaptive-gain fast super-twisting algorithm, an adaptive fault tolerant control law for the attitude stabilization is derived to protect against the actuator faults and unknown uncertainties. Firstly, a second-order nonlinear control-oriented model for the RLV is established by feedback linearization method. And on the basis a fast nonsingular terminal sliding mode (FNTSM) manifold is designed, which provides fast finite-time global convergence and avoids singularity problem as well as chattering phenomenon. Based on the merits of the standard super-twisting (ST) algorithm and fast reaching law with adaption, a novel adaptive-gain fast super-twisting (AGFST) algorithm is proposed for the finite-time fault tolerant attitude control problem of the RLV without any knowledge of the bounds of uncertainties and actuator faults. The important feature of the AGFST algorithm includes non-overestimating the values of the control gains and faster convergence speed than the standard ST algorithm. A formal proof of the finite-time stability of the closed-loop system is derived using the Lyapunov function technique. An estimation of the convergence time and accurate expression of convergence region are also provided. Finally, simulations are presented to illustrate the effectiveness and superiority of the proposed control scheme. Copyright © 2017. Published by Elsevier Ltd.

  14. Adaptive backstepping sliding mode control of flexible ball screw drives with time-varying parametric uncertainties and disturbances.

    PubMed

    Dong, Liang; Tang, Wen Cheng

    2014-01-01

    This paper presents a method to model and design servo controllers for flexible ball screw drives with dynamic variations. A mathematical model describing the structural flexibility of the ball screw drive containing time-varying uncertainties and disturbances with unknown bounds is proposed. A mode-compensating adaptive backstepping sliding mode controller is designed to suppress the vibration. The time-varying uncertainties and disturbances represented in finite-term Fourier series can be estimated by updating the Fourier coefficients through function approximation technique. Adaptive laws are obtained from Lyapunov approach to guarantee the convergence and stability of the closed loop system. The simulation results indicate that the tracking accuracy is improved considerably with the proposed scheme when the time-varying parametric uncertainties and disturbances exist. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Speed tracking control of pneumatic motor servo systems using observation-based adaptive dynamic sliding-mode control

    NASA Astrophysics Data System (ADS)

    Chen, Syuan-Yi; Gong, Sheng-Sian

    2017-09-01

    This study aims to develop an adaptive high-precision control system for controlling the speed of a vane-type air motor (VAM) pneumatic servo system. In practice, the rotor speed of a VAM depends on the input mass air flow, which can be controlled by the effective orifice area (EOA) of an electronic throttle valve (ETV). As the control variable of a second-order pneumatic system is the integral of the EOA, an observation-based adaptive dynamic sliding-mode control (ADSMC) system is proposed to derive the differential of the control variable, namely, the EOA control signal. In the ADSMC system, a proportional-integral-derivative fuzzy neural network (PIDFNN) observer is used to achieve an ideal dynamic sliding-mode control (DSMC), and a supervisor compensator is designed to eliminate the approximation error. As a result, the ADSMC incorporates the robustness of a DSMC and the online learning ability of a PIDFNN. To ensure the convergence of the tracking error, a Lyapunov-based analytical method is employed to obtain the adaptive algorithms required to tune the control parameters of the online ADSMC system. Finally, our experimental results demonstrate the precision and robustness of the ADSMC system for highly nonlinear and time-varying VAM pneumatic servo systems.

  16. A novel discrete adaptive sliding-mode-like control method for ionic polymer-metal composite manipulators

    NASA Astrophysics Data System (ADS)

    Sun, Zhiyong; Hao, Lina; Chen, Wenlin; Li, Zhi; Liu, Liqun

    2013-09-01

    Ionic polymer-metal composite (IPMC), also called artificial muscle, is an EAP material which can generate a relatively large deformation with a low driving voltage (generally less than 5 V). Like other EAP materials, IPMC possesses strong nonlinear properties, which can be described as a hybrid of back-relaxation (BR) and hysteresis characteristics, which also vary with water content, environmental temperature and even the usage consumption. Nowadays, many control approaches have been developed to tune the IPMC actuators, among which adaptive methods show a particular striking performance. To deal with IPMCs’ nonlinear problem, this paper represents a robust discrete adaptive inverse (AI) control approach, which employs an on-line identification technique based on the BR operator and Prandtl-Ishlinskii (PI) hysteresis operator hybrid model estimation method. Here the newly formed control approach is called discrete adaptive sliding-mode-like control (DASMLC) due to the similarity of its design method to that of a sliding mode controller. The weighted least mean squares (WLMS) identification method was employed to estimate the hybrid IPMC model because of its advantage of insensitivity to environmental noise. Experiments with the DASMLC approach and a conventional PID controller were carried out to compare and demonstrate the proposed controller’s better performance.

  17. Design and Experimental Evaluation of a Robust Position Controller for an Electrohydrostatic Actuator Using Adaptive Antiwindup Sliding Mode Scheme

    PubMed Central

    Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

    2013-01-01

    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. PMID:23983640

  18. Design and experimental evaluation of a robust position controller for an electrohydrostatic actuator using adaptive antiwindup sliding mode scheme.

    PubMed

    Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

    2013-01-01

    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities.

  19. Adaptive Unknown Input Estimation by Sliding Modes and Differential Neural Network Observer.

    PubMed

    Salgado, Ivan; Chairez, Isaac

    2017-08-15

    In this paper, a differential neural network (DNN) implemented as a robust observer estimates the dynamics of perturbed uncertain nonlinear systems affected by exogenous unknown inputs. In the first stage, the identification error converges into a neighborhood around the origin. Then, the second-order sliding mode supertwisting algorithm implemented as a robust exact differentiator reconstructed the unknown inputs. The approach proposed in this paper can be applied in the case of full access to the state vector (identification problem) and in the case of partial access to the state vector (estimation problem). In the second case, the nonlinear system under study must have well-defined full relative degree with respect to the unknown input. Numerical examples showed the effectiveness of the proposed algorithm. The first example tested the DNN working as an identifier into a mathematical model describing the dynamics of a spatial minisatellite. The second example (with a DNN implemented as an observer) tested the methodology of this paper over a single link flexible robot manipulator represented in a canonical (Brunovsky) form. In both examples, the mathematical models served as data generators in the testing of the neural networks. Even when not exact mathematical description of both models was used in the input estimation, the accuracy obtained with the DNN is comparable with the case of applying a high-order differentiator with complete knowledge of the plant.

  20. A novel approach for state of charge estimation based on adaptive switching gain sliding mode observer in electric vehicles

    NASA Astrophysics Data System (ADS)

    Chen, Xiaopeng; Shen, Weixiang; Cao, Zhenwei; Kapoor, Ajay

    2014-01-01

    In this paper, a novel approach for battery state of charge (SOC) estimation in electric vehicles (EVs) based on an adaptive switching gain sliding mode observer (ASGSMO) has been presented. To design the ASGSMO for the SOC estimation, the state equations based on a battery equivalent circuit model (BECM) are derived to represent dynamic behaviours of a battery. Comparing with a conventional sliding mode observer, the ASGSMO has a capability of minimising chattering levels in the SOC estimation by using the self-adjusted switching gain while maintaining the characteristics of being able to compensate modelling errors caused by the parameter variations of the BECM. Lyapunov stability theory is adopted to prove the error convergence of the ASGSMO for the SOC estimation. The lithium-polymer battery (LiPB) is utilised to conduct experiments for determining the parameters of the BECM and verifying the effectiveness of the proposed ASGSMO in various discharge current profiles including EV driving conditions in both city and suburban.

  1. Active pneumatic vibration control by using pressure and velocity measurements and adaptive fuzzy sliding-mode controller.

    PubMed

    Chen, Hung-Yi; Liang, Jin-Wei; Wu, Jia-Wei

    2013-07-02

    This paper presents an intelligent control strategy to overcome nonlinear and time-varying characteristics of a diaphragm-type pneumatic vibration isolator (PVI) system. By combining an adaptive rule with fuzzy and sliding-mode control, the method has online learning ability when it faces the system's nonlinear and time-varying behaviors during an active vibration control process. Since the proposed scheme has a simple structure, it is easy to implement. To validate the proposed scheme, a composite control which adopts both chamber pressure and payload velocity as feedback signal is implemented. During experimental investigations, sinusoidal excitation at resonance and random-like signal are input on a floor base to simulate ground vibration. Performances obtained from the proposed scheme are compared with those obtained from passive system and PID scheme to illustrate the effectiveness of the proposed intelligent control.

  2. An experimental comparison of proportional-integral, sliding mode, and robust adaptive control for piezo-actuated nanopositioning stages.

    PubMed

    Gu, Guo-Ying; Zhu, Li-Min

    2014-05-01

    This paper presents a comparative study of the proportional-integral (PI) control, sliding mode control (SMC), and robust adaptive control (RAC) for applications to piezo-actuated nanopositioning stages without the inverse hysteresis construction. For a fair comparison, the control parameters of the SMC and RAC are selected on the basis of the well-tuned parameters of the PI controller under same desired trajectories and sampling frequencies. The comparative results show that the RAC improves the tracking performance by 17 and 37 times than the PI controller in terms of the maximum tracking error e(m) and the root mean tracking error e(rms), respectively, while the RAC improves the tracking performance by 7 and 9 times than the SMC in terms of e(m) and e(rms), respectively.

  3. Active Pneumatic Vibration Control by Using Pressure and Velocity Measurements and Adaptive Fuzzy Sliding-Mode Controller

    PubMed Central

    Chen, Hung-Yi; Liang, Jin-Wei; Wu, Jia-Wei

    2013-01-01

    This paper presents an intelligent control strategy to overcome nonlinear and time-varying characteristics of a diaphragm-type pneumatic vibration isolator (PVI) system. By combining an adaptive rule with fuzzy and sliding-mode control, the method has online learning ability when it faces the system's nonlinear and time-varying behaviors during an active vibration control process. Since the proposed scheme has a simple structure, it is easy to implement. To validate the proposed scheme, a composite control which adopts both chamber pressure and payload velocity as feedback signal is implemented. During experimental investigations, sinusoidal excitation at resonance and random-like signal are input on a floor base to simulate ground vibration. Performances obtained from the proposed scheme are compared with those obtained from passive system and PID scheme to illustrate the effectiveness of the proposed intelligent control. PMID:23820746

  4. Vision-based stabilization of nonholonomic mobile robots by integrating sliding-mode control and adaptive approach

    NASA Astrophysics Data System (ADS)

    Cao, Zhengcai; Yin, Longjie; Fu, Yili

    2013-01-01

    Vision-based pose stabilization of nonholonomic mobile robots has received extensive attention. At present, most of the solutions of the problem do not take the robot dynamics into account in the controller design, so that these controllers are difficult to realize satisfactory control in practical application. Besides, many of the approaches suffer from the initial speed and torque jump which are not practical in the real world. Considering the kinematics and dynamics, a two-stage visual controller for solving the stabilization problem of a mobile robot is presented, applying the integration of adaptive control, sliding-mode control, and neural dynamics. In the first stage, an adaptive kinematic stabilization controller utilized to generate the command of velocity is developed based on Lyapunov theory. In the second stage, adopting the sliding-mode control approach, a dynamic controller with a variable speed function used to reduce the chattering is designed, which is utilized to generate the command of torque to make the actual velocity of the mobile robot asymptotically reach the desired velocity. Furthermore, to handle the speed and torque jump problems, the neural dynamics model is integrated into the above mentioned controllers. The stability of the proposed control system is analyzed by using Lyapunov theory. Finally, the simulation of the control law is implemented in perturbed case, and the results show that the control scheme can solve the stabilization problem effectively. The proposed control law can solve the speed and torque jump problems, overcome external disturbances, and provide a new solution for the vision-based stabilization of the mobile robot.

  5. Adaptive terminal sliding mode control for hypersonic flight vehicles with strictly lower convex function based nonlinear disturbance observer.

    PubMed

    Wu, Yun-Jie; Zuo, Jing-Xing; Sun, Liang-Hua

    2017-08-23

    In this paper, the altitude and velocity tracking control of a generic hypersonic flight vehicle (HFV) is considered. A novel adaptive terminal sliding mode controller (ATSMC) with strictly lower convex function based nonlinear disturbance observer (SDOB) is proposed for the longitudinal dynamics of HFV in presence of both parametric uncertainties and external disturbances. First, for the sake of enhancing the anti-interference capability, SDOB is presented to estimate and compensate the equivalent disturbances by introducing a strictly lower convex function. Next, the SDOB based ATSMC (SDOB-ATSMC) is proposed to guarantee the system outputs track the reference trajectory. Then, stability of the proposed control scheme is analyzed by the Lyapunov function method. Compared with other HFV control approaches, key novelties of SDOB-ATSMC are that a novel SDOB is proposed and drawn into the (virtual) control laws to compensate the disturbances and that several adaptive laws are used to deal with the differential explosion problem. Finally, it is illustrated by the simulation results that the new method exhibits an excellent robustness and a better disturbance rejection performance than the convention approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  6. Design of an adaptive fuzzy sliding mode control for uncertain discrete-time nonlinear systems based on noisy measurements

    NASA Astrophysics Data System (ADS)

    Yoshimura, Toshio

    2016-02-01

    This paper presents the design of an adaptive fuzzy sliding mode control (AFSMC) for uncertain discrete-time nonlinear dynamic systems. The dynamic systems are described by a discrete-time state equation with nonlinear uncertainties, and the uncertainties include the modelling errors and the external disturbances to be unknown but nonlinear with the bounded properties. The states are measured by the restriction of measurement sensors and the contamination with independent measurement noises. The nonlinear uncertainties are approximated by using the fuzzy IF-THEN rules based on the universal approximation theorem, and the approximation error is compensated by adding an adaptive complementary term to the proposed AFSMC. The fuzzy inference approach based on the extended single input rule modules is proposed to reduce the number of the fuzzy IF-THEN rules. The estimates for the un-measurable states and the adjustable parameters are obtained by using the weighted least squares estimator and its simplified one. It is proved that under some conditions the estimation errors will remain in the vicinity of zero as time increases, and the states are ultimately bounded subject to the proposed AFSMC. The effectiveness of the proposed method is indicated through the simulation experiment of a simple numerical system.

  7. Adaptive Neuro-Fuzzy Control of a Spherical Rolling Robot Using Sliding-Mode-Control-Theory-Based Online Learning Algorithm.

    PubMed

    Kayacan, Erkan; Kayacan, Erdal; Ramon, Herman; Saeys, Wouter

    2013-02-01

    As a model is only an abstraction of the real system, unmodeled dynamics, parameter variations, and disturbances can result in poor performance of a conventional controller based on this model. In such cases, a conventional controller cannot remain well tuned. This paper presents the control of a spherical rolling robot by using an adaptive neuro-fuzzy controller in combination with a sliding-mode control (SMC)-theory-based learning algorithm. The proposed control structure consists of a neuro-fuzzy network and a conventional controller which is used to guarantee the asymptotic stability of the system in a compact space. The parameter updating rules of the neuro-fuzzy system using SMC theory are derived, and the stability of the learning is proven using a Lyapunov function. The simulation results show that the control scheme with the proposed SMC-theory-based learning algorithm is able to not only eliminate the steady-state error but also improve the transient response performance of the spherical rolling robot without knowing its dynamic equations.

  8. Synchronization analysis and control of three eccentric rotors in a vibrating system using adaptive sliding mode control algorithm

    NASA Astrophysics Data System (ADS)

    Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo

    2016-05-01

    In this paper, self- and controlled synchronizations of three eccentric rotors (ERs) in line driven by induction motors rotating in the same direction in a vibrating system are investigated. The vibrating system is a typical underactuated mechanical-electromagnetic coupling system. The analysis and control of the vibrating system convert to the synchronization motion problem of three ERs. Firstly, the self-synchronization motion of three ERs is analyzed according to self-synchronization theory. The criterions of synchronization and stability of self-synchronous state are obtained by using a modified average perturbation method. The significant synchronization motion of three ERs with zero phase differences cannot be implemented according to self-synchronization theory through analysis and simulations. To implement the synchronization motion of three ERs with zero phase differences, an adaptive sliding mode control (ASMC) algorithm based on a modified master-slave control strategy is employed to design the controllers. The stability of the controllers is verified by using Lyapunov theorem. The performances of the controlled synchronization system are presented by simulations to demonstrate the effectiveness of controllers. Finally, the effects of reference speed and non-zero phase differences on the controlled system are discussed to show the strong robustness of the proposed controllers. Additionally, the dynamic responses of the vibrating system in different synchronous states are analyzed.

  9. A vehicle ABS adaptive sliding-mode control algorithm based on the vehicle velocity estimation and tyre/road friction coefficient estimations

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangwen; Xu, Yong; Pan, Ming; Ren, Fenghua

    2014-04-01

    A sliding-mode observer is designed to estimate the vehicle velocity with the measured vehicle acceleration, the wheel speeds and the braking torques. Based on the Burckhardt tyre model, the extended Kalman filter is designed to estimate the parameters of the Burckhardt model with the estimated vehicle velocity, the measured wheel speeds and the vehicle acceleration. According to the estimated parameters of the Burckhardt tyre model, the tyre/road friction coefficients and the optimal slip ratios are calculated. A vehicle adaptive sliding-mode control (SMC) algorithm is presented with the estimated vehicle velocity, the tyre/road friction coefficients and the optimal slip ratios. And the adjustment method of the sliding-mode gain factors is discussed. Based on the adaptive SMC algorithm, a vehicle's antilock braking system (ABS) control system model is built with the Simulink Toolbox. Under the single-road condition as well as the different road conditions, the performance of the vehicle ABS system is simulated with the vehicle velocity observer, the tyre/road friction coefficient estimator and the adaptive SMC algorithm. The results indicate that the estimated errors of the vehicle velocity and the tyre/road friction coefficients are acceptable and the vehicle ABS adaptive SMC algorithm is effective. So the proposed adaptive SMC algorithm can be used to control the vehicle ABS without the information of the vehicle velocity and the road conditions.

  10. Mixed H∞ and passive projective synchronization for fractional-order memristor-based neural networks with time delays via adaptive sliding mode control

    NASA Astrophysics Data System (ADS)

    Song, Shuai; Song, Xiaona; Balsera, Ines Tejado

    2017-05-01

    This paper investigates the mixed H∞ and passive projective synchronization problem for fractional-order (FO) memristor-based neural networks with time delays. Our aim is to design a controller such that, though the unavoidable phenomena of time delay and external disturbances is fully considered, the resulting closed-loop system is stable with a mixed H∞ and passive performance level. By combining sliding mode control and adaptive control methods, a novel adaptive sliding mode control strategy is designed for the synchronization of time-delayed FO dynamic networks. Via the application of FO system stability theory, the projective synchronization conditions are addressed in terms of linear matrix inequalities. Based on the conditions, a desired controller which can guarantee the stability of the closed-loop system and also ensure a mixed H∞ and passive performance level is designed. Finally, two simulation examples are given to illustrate the effectiveness of the proposed method.

  11. Adaptive super-twisting sliding mode control for a three-phase single-stage grid-connected differential boost inverter based photovoltaic system.

    PubMed

    Pati, Akshaya K; Sahoo, N C

    2017-07-01

    This paper presents an adaptive super-twisting sliding mode control (STC) along with double-loop control for voltage tracking performance of three-phase differential boost inverter and DC-link capacitor voltage regulation in grid-connected PV system. The effectiveness of the proposed control strategies are demonstrated under realistic scenarios such as variations in solar insolation, load power demand, grid voltage, and transition from grid-connected to standalone mode etc. Additional supplementary power quality control functions such as harmonic compensation, and reactive power management are also investigated with the proposed control strategy. The results are compared with conventional proportional-integral controller, and PWM sliding mode controller. The system performance is evaluated in simulation and in real-time. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Sliding mode controller with modified sliding function for DC-DC Buck Converter.

    PubMed

    Naik, B B; Mehta, A J

    2017-09-01

    This article presents design of Sliding Mode Controller with proportional integral type sliding function for DC-DC Buck Converter for the controlled power supply. The converter with conventional sliding mode controller results in a steady state error in load voltage. The proposed modified sliding function improves the steady state and dynamic performance of the Convertor and facilitates better choices of controller tuning parameters. The conditions for existence of sliding modes for proposed control scheme are derived. The stability of the closed loop system with proposed sliding mode control is proved and improvement in steady state performance is exemplified. The idea of adaptive tuning for the proposed controller to compensate load variations is outlined. The comparative study of conventional and proposed control strategy is presented. The efficacy of the proposed strategy is endowed by the simulation and experimental results. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Model-free adaptive sliding mode controller design for generalized projective synchronization of the fractional-order chaotic system via radial basis function neural networks

    NASA Astrophysics Data System (ADS)

    Wang, L. M.

    2017-09-01

    A novel model-free adaptive sliding mode strategy is proposed for a generalized projective synchronization (GPS) between two entirely unknown fractional-order chaotic systems subject to the external disturbances. To solve the difficulties from the little knowledge about the master-slave system and to overcome the bad effects of the external disturbances on the generalized projective synchronization, the radial basis function neural networks are used to approach the packaged unknown master system and the packaged unknown slave system (including the external disturbances). Consequently, based on the slide mode technology and the neural network theory, a model-free adaptive sliding mode controller is designed to guarantee asymptotic stability of the generalized projective synchronization error. The main contribution of this paper is that a control strategy is provided for the generalized projective synchronization between two entirely unknown fractional-order chaotic systems subject to the unknown external disturbances, and the proposed control strategy only requires that the master system has the same fractional orders as the slave system. Moreover, the proposed method allows us to achieve all kinds of generalized projective chaos synchronizations by turning the user-defined parameters onto the desired values. Simulation results show the effectiveness of the proposed method and the robustness of the controlled system.

  14. Active fault tolerant control based on interval type-2 fuzzy sliding mode controller and non linear adaptive observer for 3-DOF laboratory helicopter.

    PubMed

    Zeghlache, Samir; Benslimane, Tarak; Bouguerra, Abderrahmen

    2017-09-14

    In this paper, a robust controller for a three degree of freedom (3 DOF) helicopter control is proposed in presence of actuator and sensor faults. For this purpose, Interval type-2 fuzzy logic control approach (IT2FLC) and sliding mode control (SMC) technique are used to design a controller, named active fault tolerant interval type-2 Fuzzy Sliding mode controller (AFTIT2FSMC) based on non-linear adaptive observer to estimate and detect the system faults for each subsystem of the 3-DOF helicopter. The proposed control scheme allows avoiding difficult modeling, attenuating the chattering effect of the SMC, reducing the rules number of the fuzzy controller. Exponential stability of the closed loop is guaranteed by using the Lyapunov method. The simulation results show that the AFTIT2FSMC can greatly alleviate the chattering effect, providing good tracking performance, even in presence of actuator and sensor faults. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Terminal sliding mode fuzzy control based on multiple sliding surfaces for nonlinear ship autopilot systems

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Wu, Han-Song

    2010-12-01

    A terminal sliding mode fuzzy control based on multiple sliding surfaces was proposed for ship course tracking steering, which takes account of rudder characteristics and parameter uncertainty. In order to solve the problem, the controller was designed by employing the universal approximation property of fuzzy logic system, the advantage of Nussbaum function, and using multiple sliding mode control algorithm based on the recursive technique. In the last step of designing, a nonsingular terminal sliding mode was utilized to drive the last state of the system to converge in a finite period of time, and high-order sliding mode control law was designed to eliminate the chattering and make the system robust. The simulation results showed that the controller designed here could track a desired course fast and accurately. It also exhibited strong robustness peculiarly to system, and had better adaptive ability than traditional PID control algorithms.

  16. Tracking with asymptotic sliding mode and adaptive input delay effect compensation of nonlinearly perturbed delayed systems applied to traffic feedback control

    NASA Astrophysics Data System (ADS)

    Mirkin, Boris; Haddad, Jack; Shtessel, Yuri

    2016-09-01

    Asymptotical sliding mode-model reference adaptive control design for a class of systems with parametric uncertainty, unknown nonlinear perturbation and external disturbance, and with known input and state delays is proposed. To overcome the difficulty to directly predict the plant state under uncertainties, a control design is based on a developed decomposition procedure, where a 'generalised error' in conjunction with auxiliary linear dynamic blocks with adjustable gains is introduced and the sliding variable is formed on the basis of this error. The effect of such a decomposition is to pull the input delay out of first step of the design procedure. As a result, similarly to the classical Smith predictor, the adaptive control architecture based only on the lumped-delays, i.e. without conventional in such cases difficult-implemented distributed-delay blocks. Two new adaptive control schemes are proposed. A linearisation-based control design is constructed for feedback control of an urban traffic region model with uncertain dynamics. Simulation results demonstrate the effectiveness of the developed adaptive control method.

  17. An Adaptive B-Spline Neural Network and Its Application in Terminal Sliding Mode Control for a Mobile Satcom Antenna Inertially Stabilized Platform

    PubMed Central

    Zhang, Xiaolei; Zhao, Yan; Guo, Kai; Li, Gaoliang; Deng, Nianmao

    2017-01-01

    The mobile satcom antenna (MSA) enables a moving vehicle to communicate with a geostationary Earth orbit satellite. To realize continuous communication, the MSA should be aligned with the satellite in both sight and polarization all the time. Because of coupling effects, unknown disturbances, sensor noises and unmodeled dynamics existing in the system, the control system should have a strong adaptability. The significant features of terminal sliding mode control method are robustness and finite time convergence, but the robustness is related to the large switching control gain which is determined by uncertain issues and can lead to chattering phenomena. Neural networks can reduce the chattering and approximate nonlinear issues. In this work, a novel B-spline curve-based B-spline neural network (BSNN) is developed. The improved BSNN has the capability of shape changing and self-adaption. In addition, the output of the proposed BSNN is applied to approximate the nonlinear function in the system. The results of simulations and experiments are also compared with those of PID method, non-singularity fast terminal sliding mode (NFTSM) control and radial basis function (RBF) neural network-based NFTSM. It is shown that the proposed method has the best performance, with reliable control precision. PMID:28452931

  18. Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

    PubMed

    Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

    2015-09-01

    A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine.

  19. Hybrid neural network fraction integral terminal sliding mode control of an Inchworm robot manipulator

    NASA Astrophysics Data System (ADS)

    Rahmani, Mehran; Ghanbari, Ahmad; Ettefagh, Mir Mohammad

    2016-12-01

    This paper proposes a control scheme based on the fraction integral terminal sliding mode control and adaptive neural network. It deals with the system model uncertainties and the disturbances to improve the control performance of the Inchworm robot manipulator. A fraction integral terminal sliding mode control applies to the Inchworm robot manipulator to obtain the initial stability. Also, an adaptive neural network is designed to approximate the system uncertainties and unknown disturbances to reduce chattering phenomena. The weight matrix of the proposed adaptive neural network can be updated online, according to the current state error information. The stability of the proposed control method is proved by Lyapunov theory. The performance of the adaptive neural network fraction integral terminal sliding mode control is compared with three other conventional controllers such as sliding mode control, integral terminal sliding mode control and fraction integral terminal sliding mode control. Simulation results show the effectiveness of the proposed control method.

  20. Theory of sliding-mode triboelectric nanogenerators.

    PubMed

    Niu, Simiao; Liu, Ying; Wang, Sihong; Lin, Long; Zhou, Yu Sheng; Hu, Youfan; Wang, Zhong Lin

    2013-11-20

    The triboelectric nanogenerator (TENG) is a powerful approach toward new energy technology, especially for portable electronics. A theoretical model for the sliding-mode TENG is presented in this work. The finite element method was utilized to characterize the distributions of electric potential, electric field, and charges on the metal electrodes of the TENG. Based on the FEM calculation, the semi-analytical results from the interpolation method and the analytical V-Q-x relationship are built to study the sliding-mode TENG. The analytical V-Q-x equation is validated through comparison with the semi-analytical results. Furthermore, based on the analytical V-Q-x equation, dynamic output performance of sliding-mode TENG is calculated with arbitrary load resistance, and good agreement with experimental data is achieved. The theory presented here is a milestone work for in-depth understanding of the working mechanism of the sliding-mode TENG, and provides a theoretical basis for further enhancement of the sliding-mode TENG for both energy scavenging and self-powered sensor applications.

  1. Decentralized adaptive robust control based on sliding mode and nonlinear compensator for the control of ankle movement using functional electrical stimulation of agonist-antagonist muscles

    NASA Astrophysics Data System (ADS)

    Kobravi, Hamid-Reza; Erfanian, Abbas

    2009-08-01

    A decentralized control methodology is designed for the control of ankle dorsiflexion and plantarflexion in paraplegic subjects with electrical stimulation of tibialis anterior and calf muscles. Each muscle joint is considered as a subsystem and individual controllers are designed for each subsystem. Each controller operates solely on its associated subsystem, with no exchange of information between the subsystems. The interactions between the subsystems are taken as external disturbances for each isolated subsystem. In order to achieve robustness with respect to external disturbances, unmodeled dynamics, model uncertainty and time-varying properties of muscle-joint dynamics, a robust control framework is proposed which is based on the synergistic combination of an adaptive nonlinear compensator with a sliding mode control and is referred to as an adaptive robust control. Extensive simulations and experiments on healthy and paraplegic subjects were performed to demonstrate the robustness against the time-varying properties of muscle-joint dynamics, day-to-day variations, subject-to-subject variations, fast convergence, stability and tracking accuracy of the proposed method. The results indicate that the decentralized robust control provides excellent tracking control for different reference trajectories and can generate control signals to compensate the muscle fatigue and reject the external disturbance. Moreover, the controller is able to automatically regulate the interaction between agonist and antagonist muscles under different conditions of operating without any preprogrammed antagonist activities.

  2. Optimal second order sliding mode control for nonlinear uncertain systems.

    PubMed

    Das, Madhulika; Mahanta, Chitralekha

    2014-07-01

    In this paper, a chattering free optimal second order sliding mode control (OSOSMC) method is proposed to stabilize nonlinear systems affected by uncertainties. The nonlinear optimal control strategy is based on the control Lyapunov function (CLF). For ensuring robustness of the optimal controller in the presence of parametric uncertainty and external disturbances, a sliding mode control scheme is realized by combining an integral and a terminal sliding surface. The resulting second order sliding mode can effectively reduce chattering in the control input. Simulation results confirm the supremacy of the proposed optimal second order sliding mode control over some existing sliding mode controllers in controlling nonlinear systems affected by uncertainty.

  3. Terminal Sliding Modes In Nonlinear Control Systems

    NASA Technical Reports Server (NTRS)

    Venkataraman, Subramanian T.; Gulati, Sandeep

    1993-01-01

    Control systems of proposed type called "terminal controllers" offers increased precision and stability of robotic operations in presence of unknown and/or changing parameters. Systems include special computer hardware and software implementing novel control laws involving terminal sliding modes of motion: closed-loop combination of robot and terminal controller converge, in finite time, to point of stable equilibrium in abstract space of velocity and/or position coordinates applicable to particular control problem.

  4. Terminal Sliding Modes In Nonlinear Control Systems

    NASA Technical Reports Server (NTRS)

    Venkataraman, Subramanian T.; Gulati, Sandeep

    1993-01-01

    Control systems of proposed type called "terminal controllers" offers increased precision and stability of robotic operations in presence of unknown and/or changing parameters. Systems include special computer hardware and software implementing novel control laws involving terminal sliding modes of motion: closed-loop combination of robot and terminal controller converge, in finite time, to point of stable equilibrium in abstract space of velocity and/or position coordinates applicable to particular control problem.

  5. Sliding mode control of a simulated MEMS gyroscope.

    PubMed

    Batur, C; Sreeramreddy, T; Khasawneh, Q

    2006-01-01

    The microelectromechanical systems (MEMS) are penetrating more and more into measurement and control problems because of their small size, low cost, and low power consumption. The vibrating gyroscope is one of those MEMS devices that will have a significant impact on the stability control systems in transportation industry. This paper studies the design and control of a vibrating gyroscope. The device has been constructed in a Pro-E environment and its model has been simulated in the finite-element domain in order to approximate its dynamic characteristics with a lumped model. A model reference adaptive feedback controller and the sliding mode controller have been considered to guarantee the stability of the device. It is shown that the sliding mode controller of the vibrating proof mass results in a better estimate of the unknown angular velocity than that of the model reference adaptive feedback controller.

  6. Shape control of distributed parameter reflectors using sliding mode control

    NASA Astrophysics Data System (ADS)

    Andoh, Fukashi; Washington, Gregory N.; Utkin, Vadim

    2001-08-01

    Sliding mode control has become one of the most powerful control methods for variable structure systems, a set of continuous systems with an appropriate switching logic. Its robustness properties and order reduction capability have made sliding mode control one of the most efficient tools for relatively higher order nonlinear plants operating under uncertain conditions. Piezo-electric materials possess the property of creating a charge when subjected to a mechanical strain, and of generating a strain when subjected to an electric field. Piezo-electric actuators are known to have a hysteresis due to the thermal motion and Coulomb interaction of Weiss domains. Because of the thermal effect the hysteresis of piezo-electric actuators is reproducible only with some uncertainty in experiments. The robustness of sliding mode control under uncertain conditions has an advantage in handling the hysteresis of piezo-electric actuators. In this research sliding mode control is used to control the shape of one- and two-dimensionally curved adaptive reflectors with piezo-electric actuators. Four discrete linear actuators for the one-dimensionally curved reflector and eight actuators for the two-dimensionally curved reflector are assumed.

  7. Finite-time control of DC-DC buck converters via integral terminal sliding modes

    NASA Astrophysics Data System (ADS)

    Chiu, Chian-Song; Shen, Chih-Teng

    2012-05-01

    This article presents novel terminal sliding modes for finite-time output tracking control of DC-DC buck converters. Instead of using traditional singular terminal sliding mode, two integral terminal sliding modes are introduced for robust output voltage tracking of uncertain buck converters. Different from traditional sliding mode control (SMC), the proposed controller assures finite convergence time for the tracking error and integral tracking error. Furthermore, the singular problem in traditional terminal SMC is removed from this article. When considering worse modelling, adaptive integral terminal SMC is derived to guarantee finite-time convergence under more relaxed stability conditions. In addition, several experiments show better start-up performance and robustness.

  8. Interpolating sliding mode observer for a ball and beam system

    NASA Astrophysics Data System (ADS)

    Luai Hammadih, Mohammad; Hosani, Khalifa Al; Boiko, Igor

    2016-09-01

    A principle of interpolating sliding mode observer is introduced in this paper. The observer incorporates multiple linear observers through interpolation of multiple estimates, which is treated as a type of adaptation. The principle is then applied to the ball and beam system for observation of the slope of the beam from the measurement of the ball position. The linearised model of the ball and beam system using multiple linearisation points is developed. The observer dynamics implemented in Matlab/Simulink Real Time Workshop environment. Experiments conducted on the ball and beam experimental setup demonstrate excellent performance of the designed novel interpolating (adaptive) observer.

  9. Analysis and Synthesis of Memory-Based Fuzzy Sliding Mode Controllers.

    PubMed

    Zhang, Jinhui; Lin, Yujuan; Feng, Gang

    2015-12-01

    This paper addresses the sliding mode control problem for a class of Takagi-Sugeno fuzzy systems with matched uncertainties. Different from the conventional memoryless sliding surface, a memory-based sliding surface is proposed which consists of not only the current state but also the delayed state. Both robust and adaptive fuzzy sliding mode controllers are designed based on the proposed memory-based sliding surface. It is shown that the sliding surface can be reached and the closed-loop control system is asymptotically stable. Furthermore, to reduce the chattering, some continuous sliding mode controllers are also presented. Finally, the ball and beam system is used to illustrate the advantages and effectiveness of the proposed approaches. It can be seen that, with the proposed control approaches, not only can the stability be guaranteed, but also its transient performance can be improved significantly.

  10. Sliding modes of two interacting frictional interfaces

    NASA Astrophysics Data System (ADS)

    Putelat, Thibaut; Dawes, Jonathan H. P.; Willis, John R.

    2007-10-01

    In the context of rate-and-state friction, we report an extensive analysis of stability of the quasi-static frictional sliding of two parallel interfaces dividing a linear elastic solid sheared at a constant rate. One possibility for the frictional sliding is that the interfaces slip at equal rates, a steady state described as symmetric. However a steady-state friction law that is non-monotonic allows the competing possibility of an asymmetric steady state in which the interfaces slide at different rates. A rate-and-state law that delivers such behaviour and agrees with the experimental results of Heslot et al. [1994. Creep, stick-slip, and dry-friction dynamics: experiments and a heuristic model. Phys. Rev. E 49, 4973-4988] is proposed. Analytical results combined with numerical investigations performed with the continuation package A UTO and direct time integration are used to compile the complete picture of the many bifurcations that exist between the diverse steady and oscillatory sliding modes. In addition to the control parameters corresponding to the driving velocity and the stiffness of the medium, we find that the geometrical details of the steady-state friction law determine the occurrence and nature of bifurcations. Pitchfork bifurcations from the symmetric to asymmetric steady states coincide with the extrema of the friction law; Hopf bifurcations occur in the velocity weakening regime of the friction law. Torus and period-doubling bifurcations of periodic orbits also occur, and lead to complicated dynamics. We also present results of numerical computations that illustrate the complex and versatile dynamics of the two-interface system. We anticipate that the dynamics found in our model should be verifiable by experiments.

  11. Fuzzy fractional order sliding mode controller for nonlinear systems

    NASA Astrophysics Data System (ADS)

    Delavari, H.; Ghaderi, R.; Ranjbar, A.; Momani, S.

    2010-04-01

    In this paper, an intelligent robust fractional surface sliding mode control for a nonlinear system is studied. At first a sliding PD surface is designed and then, a fractional form of these networks PDα, is proposed. Fast reaching velocity into the switching hyperplane in the hitting phase and little chattering phenomena in the sliding phase is desired. To reduce the chattering phenomenon in sliding mode control (SMC), a fuzzy logic controller is used to replace the discontinuity in the signum function at the reaching phase in the sliding mode control. For the problem of determining and optimizing the parameters of fuzzy sliding mode controller (FSMC), genetic algorithm (GA) is used. Finally, the performance and the significance of the controlled system two case studies (robot manipulator and coupled tanks) are investigated under variation in system parameters and also in presence of an external disturbance. The simulation results signify performance of genetic-based fuzzy fractional sliding mode controller.

  12. Sliding Mode Control of Steerable Needles.

    PubMed

    Rucker, D Caleb; Das, Jadav; Gilbert, Hunter B; Swaney, Philip J; Miga, Michael I; Sarkar, Nilanjan; Webster, Robert J

    2013-10-01

    Steerable needles can potentially increase the accuracy of needle-based diagnosis and therapy delivery, provided they can be adequately controlled based on medical image information. We propose a novel sliding mode control law that can be used to deliver the tip of a flexible asymmetric-tipped needle to a desired point, or to track a desired trajectory within tissue. The proposed control strategy requires no a priori knowledge of model parameters, has bounded input speeds, and requires little computational resources. We show that if the standard nonholonomic model for tip-steered needles holds, then the control law will converge to desired targets in a reachable workspace, within a tolerance that can be defined by the control parameters. Experimental results validate the control law for target points and trajectory following in phantom tissue and ex vivo liver. Experiments with targets that move during insertion illustrate robustness to disturbances caused by tissue deformation.

  13. Sliding Mode Control of Steerable Needles

    PubMed Central

    Rucker, D. Caleb; Das, Jadav; Gilbert, Hunter B.; Swaney, Philip J.; Miga, Michael I.; Sarkar, Nilanjan; Webster, Robert J.

    2014-01-01

    Steerable needles can potentially increase the accuracy of needle-based diagnosis and therapy delivery, provided they can be adequately controlled based on medical image information. We propose a novel sliding mode control law that can be used to deliver the tip of a flexible asymmetric-tipped needle to a desired point, or to track a desired trajectory within tissue. The proposed control strategy requires no a priori knowledge of model parameters, has bounded input speeds, and requires little computational resources. We show that if the standard nonholonomic model for tip-steered needles holds, then the control law will converge to desired targets in a reachable workspace, within a tolerance that can be defined by the control parameters. Experimental results validate the control law for target points and trajectory following in phantom tissue and ex vivo liver. Experiments with targets that move during insertion illustrate robustness to disturbances caused by tissue deformation. PMID:25400527

  14. Optimal second order sliding mode control for linear uncertain systems.

    PubMed

    Das, Madhulika; Mahanta, Chitralekha

    2014-11-01

    In this paper an optimal second order sliding mode controller (OSOSMC) is proposed to track a linear uncertain system. The optimal controller based on the linear quadratic regulator method is designed for the nominal system. An integral sliding mode controller is combined with the optimal controller to ensure robustness of the linear system which is affected by parametric uncertainties and external disturbances. To achieve finite time convergence of the sliding mode, a nonsingular terminal sliding surface is added with the integral sliding surface giving rise to a second order sliding mode controller. The main advantage of the proposed OSOSMC is that the control input is substantially reduced and it becomes chattering free. Simulation results confirm superiority of the proposed OSOSMC over some existing.

  15. Multivariable robust adaptive sliding mode control of an industrial boiler-turbine in the presence of modeling imprecisions and external disturbances: A comparison with type-I servo controller.

    PubMed

    Ghabraei, Soheil; Moradi, Hamed; Vossoughi, Gholamreza

    2015-09-01

    To guarantee the safety and efficient performance of the power plant, a robust controller for the boiler-turbine unit is needed. In this paper, a robust adaptive sliding mode controller (RASMC) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unit, in the presence of unknown bounded uncertainties and external disturbances. To overcome the coupled nonlinearities and investigate the zero dynamics, input-output linearization is performed, and then the new decoupled inputs are derived. To tackle the uncertainties and external disturbances, appropriate adaption laws are introduced. For constructing the RASMC, suitable sliding surface is considered. To guarantee the sliding motion occurrence, appropriate control laws are constructed. Then the robustness and stability of the proposed RASMC is proved via Lyapunov stability theory. To compare the performance of the purposed RASMC with traditional control schemes, a type-I servo controller is designed. To evaluate the performance of the proposed control schemes, simulation studies on nonlinear MIMO dynamic system in the presence of high frequency bounded uncertainties and external disturbances are conducted and compared. Comparison of the results reveals the superiority of proposed RASMC over the traditional control schemes. RAMSC acts efficiently in disturbance rejection and keeping the system behavior in desirable tracking objectives, without the existence of unstable quasi-periodic solutions.

  16. Adaptive fuzzy sliding control of single-phase PV grid-connected inverter

    PubMed Central

    Zhu, Yunkai

    2017-01-01

    In this paper, an adaptive fuzzy sliding mode controller is proposed to control a two-stage single-phase photovoltaic (PV) grid-connected inverter. Two key technologies are discussed in the presented PV system. An incremental conductance method with adaptive step is adopted to track the maximum power point (MPP) by controlling the duty cycle of the controllable power switch of the boost DC-DC converter. An adaptive fuzzy sliding mode controller with an integral sliding surface is developed for the grid-connected inverter where a fuzzy system is used to approach the upper bound of the system nonlinearities. The proposed strategy has strong robustness for the sliding mode control can be designed independently and disturbances can be adaptively compensated. Simulation results of a PV grid-connected system verify the effectiveness of the proposed method, demonstrating the satisfactory robustness and performance. PMID:28797060

  17. A Sliding Mode Control with Optimized Sliding Surface for Aircraft Pitch Axis Control System

    NASA Astrophysics Data System (ADS)

    Lee, Sangchul; Kim, Kwangjin; Kim, Youdan

    A sliding mode controller with an optimized sliding surface is proposed for an aircraft control system. The quadratic type of performance index for minimizing the angle of attack and the angular rate of the aircraft in the longitudinal motion is used to design the sliding surface. For optimization of the sliding surface, a Hamilton-Jacobi-Bellman (HJB) equation is formulated and it is solved through a numerical algorithm using a Generalized HJB (GHJB) equation and the Galerkin spectral method. The solution of this equation denotes a nonlinear sliding surface, on which the trajectory of the system approximately satisfies the optimality condition. Numerical simulation is performed for a nonlinear aircraft model with an optimized sliding surface and a simple linear sliding surface. The simulation result demonstrates that the proposed controller can be effectively applied to the longitudinal maneuver of an aircraft.

  18. Synchronization of uncertain time-varying network based on sliding mode control technique

    NASA Astrophysics Data System (ADS)

    Lü, Ling; Li, Chengren; Bai, Suyuan; Li, Gang; Rong, Tingting; Gao, Yan; Yan, Zhe

    2017-09-01

    We research synchronization of uncertain time-varying network based on sliding mode control technique. The sliding mode control technique is first modified so that it can be applied to network synchronization. Further, by choosing the appropriate sliding surface, the identification law of uncertain parameter, the adaptive law of the time-varying coupling matrix element and the control input of network are designed, it is sure that the uncertain time-varying network can synchronize effectively the synchronization target. At last, we perform some numerical simulations to demonstrate the effectiveness of the proposed results.

  19. Robust sliding mode control applied to double Inverted pendulum system

    SciTech Connect

    Mahjoub, Sonia; Derbel, Nabil; Mnif, Faical

    2009-03-05

    A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.

  20. Active magnetic bearing system based on sliding mode control

    NASA Astrophysics Data System (ADS)

    Zhang, Yanhong

    2017-07-01

    A new sliding mode variable structure control algorithm suitable for active magnetic bearing is proposed, which is widely used for nonlinear control system. The model and controller is designed, simulation and experimental parts are also made, according to the switching function and the sliding mode control law. The current of electromagnet is adjusted to realize stable levitation of the rotor. The experimental result shows that the sliding mode variable structure controller is an effective way for magnetic bearing control, and the active magnetic bearing system is a highly nonlinear and advanced control method that can reduce the setting time and the cost.

  1. Sliding mode control for chaotic systems based on LMI

    NASA Astrophysics Data System (ADS)

    Wang, Hua; Han, Zheng-zhi; Xie, Qi-yue; Zhang, Wei

    2009-04-01

    This paper investigates the chaos control problem for a general class of chaotic systems. A feedback controller is established to guarantee asymptotical stability of the chaotic systems based on the sliding mode control theory. A new reaching law is introduced to solve the chattering problem that is produced by traditional sliding mode control. A dynamic compensator is designed to improve the performance of the closed-loop system in sliding mode, and its parameter is obtained from a linear matrix inequality (LMI). Simulation results for the well known Chua's circuit and Lorenz chaotic system are provided to illustrate the effectiveness of the proposed scheme.

  2. Effects of induced vibration modes on droplet sliding phenomena

    NASA Astrophysics Data System (ADS)

    Mejia, Jose Eduardo; Alvarado, Jorge; Yao, Chun-Wei; Dropwise Condensation Collaboration; Engineered Surfaces Collaboration

    2016-11-01

    An analytical and experimental investigation has been undertaken to understand the effects of induced vibration modes on droplet sliding phenomena. A mathematical model has been postulated which is capable of estimating accurately droplet sliding angles when using hydrophobic and hydrophilic surfaces. The model, which takes into account equilibrium contact angle, contact angle hysteresis, and droplet volume, has been validated using experimental data. The model has been modified to be able to estimate droplet sliding angle when different modes of vibrations are imposed on the surfaces. Experimental results to date reveal that when resonance modes of vibrations are imposed, the droplet sliding angles decrease considerably. The results also indicate that the modified model can be used effectively to relate imposed resonance frequencies to the critical sliding angle of droplets. LSAMP sponsored NSF Fellowship.

  3. Phase and speed synchronization control of four eccentric rotors driven by induction motors in a linear vibratory feeder with unknown time-varying load torques using adaptive sliding mode control algorithm

    NASA Astrophysics Data System (ADS)

    Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo

    2016-05-01

    In this paper, phase and speed synchronization control of four eccentric rotors (ERs) driven by induction motors in a linear vibratory feeder with unknown time-varying load torques is studied. Firstly, the electromechanical coupling model of the linear vibratory feeder is established by associating induction motor's model with the dynamic model of the system, which is a typical under actuated model. According to the characteristics of the linear vibratory feeder, the complex control problem of the under actuated electromechanical coupling model converts to phase and speed synchronization control of four ERs. In order to keep the four ERs operating synchronously with zero phase differences, phase and speed synchronization controllers are designed by employing adaptive sliding mode control (ASMC) algorithm via a modified master-slave structure. The stability of the controllers is proved by Lyapunov stability theorem. The proposed controllers are verified by simulation via Matlab/Simulink program and compared with the conventional sliding mode control (SMC) algorithm. The results show the proposed controllers can reject the time-varying load torques effectively and four ERs can operate synchronously with zero phase differences. Moreover, the control performance is better than the conventional SMC algorithm and the chattering phenomenon is attenuated. Furthermore, the effects of reference speed and parametric perturbations are discussed to show the strong robustness of the proposed controllers. Finally, experiments on a simple vibratory test bench are operated by using the proposed controllers and without control, respectively, to validate the effectiveness of the proposed controllers further.

  4. Second-order sliding mode control with experimental application.

    PubMed

    Eker, Ilyas

    2010-07-01

    In this article, a second-order sliding mode control (2-SMC) is proposed for second-order uncertain plants using equivalent control approach to improve the performance of control systems. A Proportional + Integral + Derivative (PID) sliding surface is used for the sliding mode. The sliding mode control law is derived using direct Lyapunov stability approach and asymptotic stability is proved theoretically. The performance of the closed-loop system is analysed through an experimental application to an electromechanical plant to show the feasibility and effectiveness of the proposed second-order sliding mode control and factors involved in the design. The second-order plant parameters are experimentally determined using input-output measured data. The results of the experimental application are presented to make a quantitative comparison with the traditional (first-order) sliding mode control (SMC) and PID control. It is demonstrated that the proposed 2-SMC system improves the performance of the closed-loop system with better tracking specifications in the case of external disturbances, better behavior of the output and faster convergence of the sliding surface while maintaining the stability.

  5. Sliding Mode Thermal Control System for Space Station Furnace Facility

    NASA Technical Reports Server (NTRS)

    Jackson Mark E.; Shtessel, Yuri B.

    1998-01-01

    The decoupled control of the nonlinear, multiinput-multioutput, and highly coupled space station furnace facility (SSFF) thermal control system is addressed. Sliding mode control theory, a subset of variable-structure control theory, is employed to increase the performance, robustness, and reliability of the SSFF's currently designed control system. This paper presents the nonlinear thermal control system description and develops the sliding mode controllers that cause the interconnected subsystems to operate in their local sliding modes, resulting in control system invariance to plant uncertainties and external and interaction disturbances. The desired decoupled flow-rate tracking is achieved by optimization of the local linear sliding mode equations. The controllers are implemented digitally and extensive simulation results are presented to show the flow-rate tracking robustness and invariance to plant uncertainties, nonlinearities, external disturbances, and variations of the system pressure supplied to the controlled subsystems.

  6. Sliding mode control application in ABWR plant pressure regulation

    SciTech Connect

    Huang, Zhengyu; Edwards, Robert M.

    2002-07-01

    A sliding mode controller is designed for an ABWR nuclear power plant turbine throttle pressure regulation. To avoid chattering problem, which is common to conventional sliding mode controllers, and estimation of uncertainties and disturbances, the recursive-form sliding mode control algorithm is developed. To apply the sliding mode control technique, the original plant's 11.-order dynamics model is first transformed to a canonical form differential equation of a relative order of 2 for turbine throttle pressure's dynamics. Simulation results show that the design objectives are achieved and the resulting controller is superior to the existing PI controller in many aspects, including settling time, overshoot/undershoot in response to setpoint step input and fluctuation amplitude in the presence of external disturbances. (authors)

  7. Integral Sliding Mode Fault-Tolerant Control for Uncertain Linear Systems Over Networks With Signals Quantization.

    PubMed

    Hao, Li-Ying; Park, Ju H; Ye, Dan

    2016-06-13

    In this paper, a new robust fault-tolerant compensation control method for uncertain linear systems over networks is proposed, where only quantized signals are assumed to be available. This approach is based on the integral sliding mode (ISM) method where two kinds of integral sliding surfaces are constructed. One is the continuous-state-dependent surface with the aim of sliding mode stability analysis and the other is the quantization-state-dependent surface, which is used for ISM controller design. A scheme that combines the adaptive ISM controller and quantization parameter adjustment strategy is then proposed. Through utilizing H∞ control analytical technique, once the system is in the sliding mode, the nature of performing disturbance attenuation and fault tolerance from the initial time can be found without requiring any fault information. Finally, the effectiveness of our proposed ISM control fault-tolerant schemes against quantization errors is demonstrated in the simulation.

  8. Second order sliding mode control for a quadrotor UAV.

    PubMed

    Zheng, En-Hui; Xiong, Jing-Jing; Luo, Ji-Liang

    2014-07-01

    A method based on second order sliding mode control (2-SMC) is proposed to design controllers for a small quadrotor UAV. For the switching sliding manifold design, the selection of the coefficients of the switching sliding manifold is in general a sophisticated issue because the coefficients are nonlinear. In this work, in order to perform the position and attitude tracking control of the quadrotor perfectly, the dynamical model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. For the former, a sliding manifold is defined by combining the position and velocity tracking errors of one state variable, i.e., the sliding manifold has two coefficients. For the latter, a sliding manifold is constructed via a linear combination of position and velocity tracking errors of two state variables, i.e., the sliding manifold has four coefficients. In order to further obtain the nonlinear coefficients of the sliding manifold, Hurwitz stability analysis is used to the solving process. In addition, the flight controllers are derived by using Lyapunov theory, which guarantees that all system state trajectories reach and stay on the sliding surfaces. Extensive simulation results are given to illustrate the effectiveness of the proposed control method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  9. Robust passive control for a class of uncertain neutral systems based on sliding mode observer.

    PubMed

    Liu, Zhen; Zhao, Lin; Kao, Yonggui; Gao, Cunchen

    2017-01-01

    The passivity-based sliding mode control (SMC) problem for a class of uncertain neutral systems with unmeasured states is investigated. Firstly, a particular non-fragile state observer is designed to generate the estimations of the system states, based upon which a novel integral-type sliding surface function is established for the control process. Secondly, a new sufficient condition for robust asymptotic stability and passivity of the resultant sliding mode dynamics (SMDs) is obtained in terms of linear matrix inequalities (LMIs). Thirdly, the finite-time reachability of the predesigned sliding surface is ensured by resorting to a novel adaptive SMC law. Finally, the validity and superiority of the scheme are justified via several examples.

  10. Sliding mode controllers for a tempered glass furnace.

    PubMed

    Almutairi, Naif B; Zribi, Mohamed

    2016-01-01

    This paper investigates the design of two sliding mode controllers (SMCs) applied to a tempered glass furnace system. The main objective of the proposed controllers is to regulate the glass plate temperature, the upper-wall temperature and the lower-wall temperature in the furnace to a common desired temperature. The first controller is a conventional sliding mode controller. The key step in the design of this controller is the introduction of a nonlinear transformation that maps the dynamic model of the tempered glass furnace into the generalized controller canonical form; this step facilitates the design of the sliding mode controller. The second controller is based on a state-dependent coefficient (SDC) factorization of the tempered glass furnace dynamic model. Using an SDC factorization, a simplified sliding mode controller is designed. The simulation results indicate that the two proposed control schemes work very well. Moreover, the robustness of the control schemes to changes in the system's parameters as well as to disturbances is investigated. In addition, a comparison of the proposed control schemes with a fuzzy PID controller is performed; the results show that the proposed SDC-based sliding mode controller gave better results.

  11. A sliding mode controller for vehicular traffic flow

    NASA Astrophysics Data System (ADS)

    Li, Yongfu; Kang, Yuhao; Yang, Bin; Peeta, Srinivas; Zhang, Li; Zheng, Taixong; Li, Yinguo

    2016-11-01

    This study proposes a sliding mode controller for vehicular traffic flow based on a car-following model to enhance the smoothness and stability of traffic flow evolution. In particular, the full velocity difference (FVD) model is used to capture the characteristics of vehicular traffic flow. The proposed sliding mode controller is designed in terms of the error between the desired space headway and the actual space headway. The stability of the controller is guaranteed using the Lyapunov technique. Numerical experiments are used to compare the performance of sliding mode control (SMC) with that of feedback control. The results illustrate the effectiveness of the proposed SMC method in terms of the distribution smoothness and stability of the space headway, velocity, and acceleration profiles. They further illustrate that the SMC strategy is superior to that of the feedback control strategy, while enabling computational efficiency that can aid in practical applications.

  12. Composite fuzzy sliding mode control of nonlinear singularly perturbed systems.

    PubMed

    Nagarale, Ravindrakumar M; Patre, B M

    2014-05-01

    This paper deals with the robust asymptotic stabilization for a class of nonlinear singularly perturbed systems using the fuzzy sliding mode control technique. In the proposed approach the original system is decomposed into two subsystems as slow and fast models by the singularly perturbed method. The composite fuzzy sliding mode controller is designed for stabilizing the full order system by combining separately designed slow and fast fuzzy sliding mode controllers. The two-time scale design approach minimizes the effect of boundary layer system on the full order system. A stability analysis allows us to provide sufficient conditions for the asymptotic stability of the full order closed-loop system. The simulation results show improved system performance of the proposed controller as compared to existing methods. The experimentation results validate the effectiveness of the proposed controller.

  13. Sliding mode controller for a photovoltaic pumping system

    NASA Astrophysics Data System (ADS)

    ElOugli, A.; Miqoi, S.; Boutouba, M.; Tidhaf, B.

    2017-03-01

    In this paper, a sliding mode control scheme (SMC) for maximum power point tracking controller for a photovoltaic pumping system, is proposed. The main goal is to maximize the flow rate for a water pump, by forcing the photovoltaic system to operate in its MPP, to obtain the maximum power that a PV system can deliver.And this, through the intermediary of a sliding mode controller to track and control the MPP by overcoming the power oscillation around the operating point, which appears in most implemented MPPT techniques. The sliding mode control approach is recognized as one of the efficient and powerful tools for nonlinear systems under uncertainty conditions.The proposed controller with photovoltaic pumping system is designed and simulated using MATLAB/SIMULINK environment. In addition, to evaluate its performances, a classical MPPT algorithm using perturb and observe (P&O) has been used for the same system to compare to our controller. Simulation results are shown.

  14. Robust sliding mode continuous control of an IM drive

    SciTech Connect

    Jezernik, K.; Hren, A.; Drevensek, D.

    1995-12-31

    A control approach for robust trajectory tracking of IM servodrive based on the variable structure systems (VSS) is described. A new discrete-time control algorithm has been developed by combining VSS and Lyapunov design. It possesses all the good properties of the sliding mode and avoids the unnecessary discontinuity of the control input, thus eliminating chattering which has been considering as serious obstacles for applications of VSS. A unified control approach for current, torque and motion control based on the discrete-time sliding mode for application in indirect vector control of an IM drive is developed. The sliding mode approach can be applied to the control of an Im drive due to the replacement of the hysteresis controller with widely used PWM technique. All the theoretical issues are verified by experiment. The experimental system consists of a transputer and a microcontroller, thus allowing parallel processing.

  15. Reusable Launch Vehicle Control in Multiple Time Scale Sliding Modes

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri

    1999-01-01

    A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. 6DOF simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. It creates possibility to operate the X-33 vehicle in an aircraft-like mode with reduced pre-launch adjustment of the control system.

  16. Reusable Launch Vehicle Control in Multiple Time Scale Sliding Modes

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri

    1999-01-01

    A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. 6DOF simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. It creates possibility to operate the X-33 vehicle in an aircraft-like mode with reduced pre-launch adjustment of the control system.

  17. Output feedback sliding mode control under networked environment

    NASA Astrophysics Data System (ADS)

    Zhang, Jinhui; Lam, James; Xia, Yuanqing

    2013-04-01

    This article considers the problem of sliding mode output feedback control for networked control systems (NCSs). The key idea is to make use of not only the current and previous measurements, but also previous inputs for the reconstruction of the state variables. Using this idea, sliding mode controllers are designed for systems with constant or time-varying network delay. The approach is not only more practical but also easy to implement. To illustrate this, the design technique is applied to an inverted pendulum system.

  18. Reusable Launch Vehicle Control In Multiple Time Scale Sliding Modes

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri; Hall, Charles; Jackson, Mark

    2000-01-01

    A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. Overall stability of a two-loop control system is addressed. An optimal control allocation algorithm is designed that allocates torque commands into end-effector deflection commands, which are executed by the actuators. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. This is a significant advancement in performance over that achieved with linear, gain scheduled control systems currently being used for launch vehicles.

  19. Decentralized sliding mode control of nonlinear flexible robots

    SciTech Connect

    Parker, G.G.; Robinett, R.D.; Segalman, D.J.; Inman, D.J.

    1994-06-01

    A technique using augmented sliding mode control for robust, real-time control of flexible multiple link robots is presented. For the purpose of controller design, the n-link, n-joint robot is subdivided into n single joint, single link subsystems. A sliding surface for each subsystem is specified so as to be globally, asymptotically stable. Each sliding surface contains rigid-body angular velocity, angular displacement and flexible body generalized velocities. The flexible body generalized accelerations are treated as disturbances during the controller design. This has the advantage of not requiring explicit equations for the flexible body motion. The result is n single input, single output controllers acting at the n joints of the robot, controlling rigid body angular displacement and providing damping for flexible body modes. Furthermore, the n controllers can be operated in parallel so that compute speed is independent of the number of links, affording real-time, robust, control.

  20. Sliding mode control: an approach to regulate nonlinear chemical processes

    PubMed

    Camacho; Smith

    2000-01-01

    A new approach for the design of sliding mode controllers based on a first-order-plus-deadtime model of the process, is developed. This approach results in a fixed structure controller with a set of tuning equations as a function of the characteristic parameters of the model. The controller performance is judged by simulations on two nonlinear chemical processes.

  1. Robust Neural Sliding Mode Control of Robot Manipulators

    NASA Astrophysics Data System (ADS)

    Hiep, Nguyen Tran; cat, Pham Thuong

    2009-03-01

    This paper proposes a robust neural sliding mode control method for robot tracking problem to overcome the noises and large uncertainties in robot dynamics. The Lyapunov direct method has been used to prove the stability of the overall system. Simulation results are given to illustrate the applicability of the proposed method

  2. Robust Neural Sliding Mode Control of Robot Manipulators

    SciTech Connect

    Nguyen Tran Hiep; Pham Thuong Cat

    2009-03-05

    This paper proposes a robust neural sliding mode control method for robot tracking problem to overcome the noises and large uncertainties in robot dynamics. The Lyapunov direct method has been used to prove the stability of the overall system. Simulation results are given to illustrate the applicability of the proposed method.

  3. Sliding Mode Control (SMC) of Robot Manipulator via Intelligent Controllers

    NASA Astrophysics Data System (ADS)

    Kapoor, Neha; Ohri, Jyoti

    2017-02-01

    Inspite of so much research, key technical problem, naming chattering of conventional, simple and robust SMC is still a challenge to the researchers and hence limits its practical application. However, newly developed soft computing based techniques can provide solution. In order to have advantages of conventional and heuristic soft computing based control techniques, in this paper various commonly used intelligent techniques, neural network, fuzzy logic and adaptive neuro fuzzy inference system (ANFIS) have been combined with sliding mode controller (SMC). For validation, proposed hybrid control schemes have been implemented for tracking a predefined trajectory by robotic manipulator, incorporating structured and unstructured uncertainties in the system. After reviewing numerous papers, all the commonly occurring uncertainties like continuous disturbance, uniform random white noise, static friction like coulomb friction and viscous friction, dynamic friction like Dhal friction and LuGre friction have been inserted in the system. Various performance indices like norm of tracking error, chattering in control input, norm of input torque, disturbance rejection, chattering rejection have been used. Comparative results show that with almost eliminated chattering the intelligent SMC controllers are found to be more efficient over simple SMC. It has also been observed from results that ANFIS based controller has the best tracking performance with the reduced burden on the system. No paper in the literature has found to have all these structured and unstructured uncertainties together for motion control of robotic manipulator.

  4. Sliding Mode Control (SMC) of Robot Manipulator via Intelligent Controllers

    NASA Astrophysics Data System (ADS)

    Kapoor, Neha; Ohri, Jyoti

    2016-06-01

    Inspite of so much research, key technical problem, naming chattering of conventional, simple and robust SMC is still a challenge to the researchers and hence limits its practical application. However, newly developed soft computing based techniques can provide solution. In order to have advantages of conventional and heuristic soft computing based control techniques, in this paper various commonly used intelligent techniques, neural network, fuzzy logic and adaptive neuro fuzzy inference system (ANFIS) have been combined with sliding mode controller (SMC). For validation, proposed hybrid control schemes have been implemented for tracking a predefined trajectory by robotic manipulator, incorporating structured and unstructured uncertainties in the system. After reviewing numerous papers, all the commonly occurring uncertainties like continuous disturbance, uniform random white noise, static friction like coulomb friction and viscous friction, dynamic friction like Dhal friction and LuGre friction have been inserted in the system. Various performance indices like norm of tracking error, chattering in control input, norm of input torque, disturbance rejection, chattering rejection have been used. Comparative results show that with almost eliminated chattering the intelligent SMC controllers are found to be more efficient over simple SMC. It has also been observed from results that ANFIS based controller has the best tracking performance with the reduced burden on the system. No paper in the literature has found to have all these structured and unstructured uncertainties together for motion control of robotic manipulator.

  5. Application of sliding mode methods to the design of reconfigurable flight control systems

    NASA Astrophysics Data System (ADS)

    Wells, Scott Russell

    Observer-based sliding mode control is investigated for application to aircraft reconfigurable flight control. A comprehensive overview of reconfigurable flight control is given, including a review of the current state-of-the-art within the subdisciplines of fault detection, parameter identification, adaptive control schemes, and dynamic control allocation. Of the adaptive control methods reviewed, sliding mode control (SMC) appears very promising due its property of invariance to matched uncertainty. An overview of sliding mode control is given and its remarkable properties are demonstrated by example. Sliding mode methods, however, are difficult to implement because unmodeled parasitic dynamics cause immediate and severe instability. This presents a challenge for all practical applications with limited bandwidth actuators. One method to deal with parasitic dynamics is the use of an asymptotic observer in the feedback path. Observer-based SMC is investigated, and a method for selecting observer gains is offered. An additional method for shaping the feedback loop using a filter is also developed. It is shown that this SMC prefilter is equivalent to a form of model reference hedging. A complete design procedure is given which takes advantage of the sliding mode boundary layer to recast the SMC as a linear control law. Frequency domain loop shaping is then used to design the sliding manifold. Finally, three aircraft applications are demonstrated. An F-18/HARV is used to demonstrate a SISO pitch rate tracking controller. It is also used to demonstrate a MIMO lateral-directional roll rate tracking controller. The last application is a full linear six degree-of-freedom advanced tailless fighter model. The observer-based SMC is seen to provide excellent tracking with superior robustness to parameter changes and actuator failures.

  6. Application of Sliding Mode Methods to the Design of Reconfigurable Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Wells, Scott R.

    2002-01-01

    Observer-based sliding mode control is investigated for application to aircraft reconfigurable flight control. A comprehensive overview of reconfigurable flight control is given, including, a review of the current state-of-the-art within the subdisciplines of fault detection, parameter identification, adaptive control schemes, and dynamic control allocation. Of the adaptive control methods reviewed, sliding mode control (SMC) appears very promising due its property of invariance to matched uncertainty. An overview of sliding mode control is given and its remarkable properties are demonstrated by example. Sliding mode methods, however, are difficult to implement because unmodeled parasitic dynamics cause immediate and severe instability. This presents a challenge for all practical applications with limited bandwidth actuators. One method to deal with parasitic dynamics is the use of an asymptotic observer in the feedback path. Observer-based SMC is investigated, and a method for selecting observer gains is offered. An additional method for shaping the feedback loop using a filter is also developed. It is shown that this SMC prefilter is equivalent to a form of model reference hedging. A complete design procedure is given which takes advantage of the sliding mode boundary layer to recast the SMC as a linear control law. Frequency domain loop shaping is then used to design the sliding manifold. Finally, three aircraft applications are demonstrated. An F-18/HARV is used to demonstrate a SISO pitch rate tracking controller. It is also used to demonstrate a MIMO lateral-directional roll rate tracking controller. The last application is a full linear six degree-of-freedom advanced tailless fighter model. The observer-based SMC is seen to provide excellent tracking with superior robustness to parameter changes and actuator failures.

  7. Sliding mode control method having terminal convergence in finite time

    NASA Technical Reports Server (NTRS)

    Venkataraman, Subramanian T. (Inventor); Gulati, Sandeep (Inventor)

    1994-01-01

    An object of this invention is to provide robust nonlinear controllers for robotic operations in unstructured environments based upon a new class of closed loop sliding control methods, sometimes denoted terminal sliders, where the new class will enforce closed-loop control convergence to equilibrium in finite time. Improved performance results from the elimination of high frequency control switching previously employed for robustness to parametric uncertainties. Improved performance also results from the dependence of terminal slider stability upon the rate of change of uncertainties over the sliding surface rather than the magnitude of the uncertainty itself for robust control. Terminal sliding mode control also yields improved convergence where convergence time is finite and is to be controlled. A further object is to apply terminal sliders to robot manipulator control and benchmark performance with the traditional computed torque control method and provide for design of control parameters.

  8. Anomaly Detection in Test Equipment via Sliding Mode Observers

    NASA Technical Reports Server (NTRS)

    Solano, Wanda M.; Drakunov, Sergey V.

    2012-01-01

    Nonlinear observers were originally developed based on the ideas of variable structure control, and for the purpose of detecting disturbances in complex systems. In this anomaly detection application, these observers were designed for estimating the distributed state of fluid flow in a pipe described by a class of advection equations. The observer algorithm uses collected data in a piping system to estimate the distributed system state (pressure and velocity along a pipe containing liquid gas propellant flow) using only boundary measurements. These estimates are then used to further estimate and localize possible anomalies such as leaks or foreign objects, and instrumentation metering problems such as incorrect flow meter orifice plate size. The observer algorithm has the following parts: a mathematical model of the fluid flow, observer control algorithm, and an anomaly identification algorithm. The main functional operation of the algorithm is in creating the sliding mode in the observer system implemented as software. Once the sliding mode starts in the system, the equivalent value of the discontinuous function in sliding mode can be obtained by filtering out the high-frequency chattering component. In control theory, "observers" are dynamic algorithms for the online estimation of the current state of a dynamic system by measurements of an output of the system. Classical linear observers can provide optimal estimates of a system state in case of uncertainty modeled by white noise. For nonlinear cases, the theory of nonlinear observers has been developed and its success is mainly due to the sliding mode approach. Using the mathematical theory of variable structure systems with sliding modes, the observer algorithm is designed in such a way that it steers the output of the model to the output of the system obtained via a variety of sensors, in spite of possible mismatches between the assumed model and actual system. The unique properties of sliding mode control

  9. Experimental sliding mode control of a flexible single link manipulator

    NASA Astrophysics Data System (ADS)

    Qian, Timothy Wei Tie

    1993-09-01

    A study was conducted to explore and develop practical controller designs for a flexible manipulator based on the variable structure (VS) system and sliding mode (SM) theory. A new control design method is first proposed based on the continuous time VSSM theory, which can significantly simplify the VS system design process. Moreover, the variables concerned can be assigned separate gains. Direct application of the VSSM control system to the flexible arm, however, has limitations due to the inherent properties of the system. To solve this problem, facilitate digital implementation, and eliminate undesirable chattering in conventional VS system control, the discrete time quasi sliding mode control (DQSMC) is developed. Two control algorithms are derived satisfying the conditions for existence of discrete time sliding hypersurfaces. It is proven that the DQSMC design is equivalent to a full state feedback with its steady state motion constrained to the sliding hypersurfaces, and that DQSMC provides a general structure unifying the three different kinds of discrete time SM control. Experimental testing of the DQSMC controller showed good results, which compared favorably to the linear quadratic Gaussian controller under the same load variations. A novel approach was then devised to realize the proposed new controller designs.

  10. Backstepping and sliding mode control hybridized for a prosthetic hand.

    PubMed

    Engeberg, Erik D; Meek, Sanford G

    2009-02-01

    Open loop and force controllers are compared experimentally with three robust parallel force-velocity controllers that are developed for a prosthetic hand. Robust sliding mode, backstepping, and hybrid sliding mode-backstepping (HSMBS) parallel force-velocity controllers are tested by ten able-bodied subjects. Results obtained with a myoelectrically controlled prosthesis indicate that all three robust controllers offer a statistically significant improvement over linear hand prosthesis control schemes. The robust controllers enable the human operators to more easily manipulate a delicate object. Bench top experiments combined with quantitative and qualitative evaluations from ten test subjects reveal the HSMBS controller to be the best choice to improve control of powered prosthetic hands.

  11. Chattering-Free Sliding Mode Control with Unmodeled Dynamics

    NASA Technical Reports Server (NTRS)

    Krupp, Don; Shtessel, Yuri B.

    1999-01-01

    Sliding mode control systems are valued for their robust accommodation of uncertainties and their ability to reject disturbances. In this paper, a design methodology is proposed to eliminate the chattering phenomenon affecting sliding mode controlled plants with input unmodeled actuator dynamics of second order or greater. The proposed controller design is based on the relative degrees of the plant and the unmodeled actuator dynamics and the ranges of the uncertainties of the plant and actuator. The controller utilizes the pass filter characteristics of the physical actuating device to provide a smoothing effect on the discontinuous control signal rather than introducing any artificial dynamics into the controller design thus eliminating chattering in the system's output response.

  12. Hybrid sliding mode control of semi-active suspension systems

    NASA Astrophysics Data System (ADS)

    Assadsangabi, Babak; Eghtesad, Mohammad; Daneshmand, Farhang; Vahdati, Nader

    2009-12-01

    In order to design a controller which can take both ride comfort and road holding into consideration, a hybrid model reference sliding mode controller (HMRSMC) is proposed. The controller includes two separate model reference sliding mode controllers (MRSMC). One of the controllers is designed so as to force the plant to follow the ideal Sky-hook model and the other is to force the plant to follow the ideal Ground-hook model; then the outputs of these two controllers are linearly combined and applied to the plant as the input. Also, since the designed controller requires a knowledge of the terrain input, this input is approximated by the unsprung mass displacement. Finally, in the simulation section of this study, the effect of the relative ratio between the two MRSMCs and the knowledge of the terrain on the performance of the controller is numerically investigated for both steady-state and transient cases.

  13. Theory of psychological adaptive modes.

    PubMed

    Lehti, Juha

    2016-05-01

    When an individual is facing a stressor and normal stress-response mechanism cannot guarantee sufficient adaptation, special emotional states, adaptive modes, are activated (for example a depressive reaction). Adaptive modes are involuntary states of mind, they are of comprehensive nature, they interfere with normal functioning, and they cannot be repressed or controlled the same way as many emotions. Their transformational nature differentiates them from other emotional states. The object of the adaptive mode is to optimize the problem-solving abilities according to the situation that has provoked the mode. Cognitions and emotions during the adaptive mode are different than in a normal mental state. These altered cognitions and emotional reactions guide the individual to use the correct coping skills in order to deal with the stressor. Successful adaptation will cause the adaptive mode to fade off since the adaptive mode is no longer necessary, and the process as a whole will lead to raised well-being. However, if the adaptation process is inadequate, then the transformation period is prolonged, and the adaptive mode will turn into a dysfunctional state. Many psychiatric disorders are such maladaptive processes. The maladaptive processes can be turned into functional ones by using adaptive skills that are used in functional adaptive processes.

  14. Glucose level regulation via integral high-order sliding modes.

    PubMed

    Dorel, Lela

    2011-04-01

    Diabetes is a condition in which the body either does not produce enough insulin, or does not properly respond to it. This causes the glucose level in blood to increase. An algorithm based on Integral High-Order Sliding Mode technique is proposed, which keeps the normal blood glucose level automatically releasing insulin into the blood. The system is highly insensitive to inevitable parametric and model uncertainties, measurement noises and small delays.

  15. Sliding Mode Control Applied to Reconfigurable Flight Control Design

    NASA Technical Reports Server (NTRS)

    Hess, R. A.; Wells, S. R.; Bacon, Barton (Technical Monitor)

    2002-01-01

    Sliding mode control is applied to the design of a flight control system capable of operating with limited bandwidth actuators and in the presence of significant damage to the airframe and/or control effector actuators. Although inherently robust, sliding mode control algorithms have been hampered by their sensitivity to the effects of parasitic unmodeled dynamics, such as those associated with actuators and structural modes. It is known that asymptotic observers can alleviate this sensitivity while still allowing the system to exhibit significant robustness. This approach is demonstrated. The selection of the sliding manifold as well as the interpretation of the linear design that results after introduction of a boundary layer is accomplished in the frequency domain. The design technique is exercised on a pitch-axis controller for a simple short-period model of the High Angle of Attack F-18 vehicle via computer simulation. Stability and performance is compared to that of a system incorporating a controller designed by classical loop-shaping techniques.

  16. Robust Stabilization of T-S Fuzzy Stochastic Descriptor Systems via Integral Sliding Modes.

    PubMed

    Li, Jinghao; Zhang, Qingling; Yan, Xing-Gang; Spurgeon, Sarah K

    2017-09-19

    This paper addresses the robust stabilization problem for T-S fuzzy stochastic descriptor systems using an integral sliding mode control paradigm. A classical integral sliding mode control scheme and a nonparallel distributed compensation (Non-PDC) integral sliding mode control scheme are presented. It is shown that two restrictive assumptions previously adopted developing sliding mode controllers for Takagi-Sugeno (T-S) fuzzy stochastic systems are not required with the proposed framework. A unified framework for sliding mode control of T-S fuzzy systems is formulated. The proposed Non-PDC integral sliding mode control scheme encompasses existing schemes when the previously imposed assumptions hold. Stability of the sliding motion is analyzed and the sliding mode controller is parameterized in terms of the solutions of a set of linear matrix inequalities which facilitates design. The methodology is applied to an inverted pendulum model to validate the effectiveness of the results presented.

  17. Nanolubrication of sliding components in adaptive optics used in microprojectors

    NASA Astrophysics Data System (ADS)

    Bhushan, Bharat; Lee, Hyungoo; Chaparala, Satish C.; Bhatia, Vikram

    2010-10-01

    Integrated microprojectors are being developed to project a large image on any surface chosen by the users. For a laser-based microprojector, a piezo-electric based adaptive optics unit is adopted in the green laser architecture. The operation of this unit depends on stick-slip motion between the sliding components. Nanolubrication of adaptive optics sliding components is needed to reduce wear and for smooth operation. In this study, a methodology to measure lubricant thickness distribution with a nanoscale resolution is developed. Friction, adhesion, and wear mechanisms of lubricant on the sliding components are studied. Effect of actual composite components, scan direction, scale effect, temperature, and humidity to correlate AFM data with the microscale device performance is studied.

  18. Multi-input sliding mode control of nonlinear uncertain affine systems

    NASA Astrophysics Data System (ADS)

    Bartolini, Giorgio; Punta, Elisabetta; Zolezzi, Tullio

    2011-05-01

    In the extension to multi-input nonlinear uncertain systems of the sliding mode methodology, a crucial role is played by the matrix pre-multiplying the control in the dynamic equation of the sliding output. If this matrix is perfectly known and invertible, it is possible to transform a multi-input sliding mode control problem in an almost decoupled set of single-input problems. If this matrix is uncertain then nothing can be done in general, and the investigation is oriented to find conditions ensuring the feasibility of control strategies in a progressively more general set of uncertain matrices. In the case of uncertain and constant matrices, it is possible, in principle, to manage the case in which the matrix in question is invertible. The corresponding adaptive or switching strategy suffers from the curse of dimensionality of the so-called unmixing set. In this article the case of time- and state-varying uncertain matrix is dealt with. A more general class of such a matrices for which there is, at least locally, a solution of the problem is found. The introduction of artificial integrators in the output channel (the integral sliding mode control methodology) allows the practical implementation of the control law without requiring the a priori knowledge of parameters featured by the solution of a relevant nonlinear Lyapunov equation.

  19. Multi-mode sliding mode control for precision linear stage based on fixed or floating stator.

    PubMed

    Fang, Jiwen; Long, Zhili; Wang, Michael Yu; Zhang, Lufan; Dai, Xufei

    2016-02-01

    This paper presents the control performance of a linear motion stage driven by Voice Coil Motor (VCM). Unlike the conventional VCM, the stator of this VCM is regulated, which means it can be adjusted as a floating-stator or fixed-stator. A Multi-Mode Sliding Mode Control (MMSMC), including a conventional Sliding Mode Control (SMC) and an Integral Sliding Mode Control (ISMC), is designed to control the linear motion stage. The control is switched between SMC and IMSC based on the error threshold. To eliminate the chattering, a smooth function is adopted instead of a signum function. The experimental results with the floating stator show that the positioning accuracy and tracking performance of the linear motion stage are improved with the MMSMC approach.

  20. Multi-mode sliding mode control for precision linear stage based on fixed or floating stator

    NASA Astrophysics Data System (ADS)

    Fang, Jiwen; Long, Zhili; Wang, Michael Yu; Zhang, Lufan; Dai, Xufei

    2016-02-01

    This paper presents the control performance of a linear motion stage driven by Voice Coil Motor (VCM). Unlike the conventional VCM, the stator of this VCM is regulated, which means it can be adjusted as a floating-stator or fixed-stator. A Multi-Mode Sliding Mode Control (MMSMC), including a conventional Sliding Mode Control (SMC) and an Integral Sliding Mode Control (ISMC), is designed to control the linear motion stage. The control is switched between SMC and IMSC based on the error threshold. To eliminate the chattering, a smooth function is adopted instead of a signum function. The experimental results with the floating stator show that the positioning accuracy and tracking performance of the linear motion stage are improved with the MMSMC approach.

  1. Sliding Mode Control of the X-33 Vehicle in Launch Mode

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri; Jackson, Mark; Hall, Charles; Krupp, Don; Hendrix, N. Douglas

    1998-01-01

    The "nested" structure of the control system for the X33 vehicle in launch mode is developed. Employing backstopping concepts, the outer loop (guidance) and the Inner loop (rates) continuous sliding mode controllers are designed. Simulations of the 3-DOF model of the X33 launch vehicle showed an accurate, robust, de-coupled tracking performance.

  2. Passivity-based sliding mode control for a polytopic stochastic differential inclusion system.

    PubMed

    Liu, Leipo; Fu, Zhumu; Song, Xiaona

    2013-11-01

    Passivity-based sliding mode control for a polytopic stochastic differential inclusion (PSDI) system is considered. A control law is designed such that the reachability of sliding motion is guaranteed. Moreover, sufficient conditions for mean square asymptotic stability and passivity of sliding mode dynamics are obtained by linear matrix inequalities (LMIs). Finally, two examples are given to illustrate the effectiveness of the proposed method.

  3. Control of nonlinear systems using terminal sliding modes

    NASA Technical Reports Server (NTRS)

    Venkataraman, S. T.; Gulati, S.

    1992-01-01

    The development of an approach to control synthesis for robust robot operations in unstructured environments is discussed. To enhance control performance with full model information, the authors introduce the notion of terminal convergence and develop control laws based on a class of sliding modes, denoted as terminal sliders. They demonstrate that terminal sliders provide robustness to parametric uncertainty without having to resort to high-frequency control switching, as in the case of conventional sliders. It is shown that the proposed method leads to greater guaranteed precision in all control cases discussed.

  4. Sliding Mode Control of a Slewing Flexible Beam

    NASA Technical Reports Server (NTRS)

    Wilson, David G.; Parker, Gordon G.; Starr, Gregory P.; Robinett, Rush D., III

    1997-01-01

    An output feedback sliding mode controller (SMC) is proposed to minimize the effects of vibrations of slewing flexible manipulators. A spline trajectory is used to generate ideal position and velocity commands. Constrained nonlinear optimization techniques are used to both calibrate nonlinear models and determine optimized gains to produce a rest-to-rest, residual vibration-free maneuver. Vibration-free maneuvers are important for current and future NASA space missions. This study required the development of the nonlinear dynamic system equations of motion; robust control law design; numerical implementation; system identification; and verification using the Sandia National Laboratories flexible robot testbed. Results are shown for a slewing flexible beam.

  5. Disturbance observer based sliding mode control of active suspension systems

    NASA Astrophysics Data System (ADS)

    Deshpande, Vaijayanti S.; Mohan, B.; Shendge, P. D.; Phadke, S. B.

    2014-05-01

    In this paper, a novel scheme to reduce the acceleration of the sprung mass, used in combination with sliding mode control, is proposed. The proposed scheme estimates the effects of the uncertain, nonlinear spring and damper, load variation and the unknown road disturbance. The controller needs the states of sprung mass only, obviating the need to measure the states of the unsprung mass. The ultimate boundedness of the overall suspension system is proved. The efficacy of the method is verified through simulations for three different types of road profiles and load variation and the scheme is validated on an experimental setup. The results are compared with passive suspension system.

  6. Sliding Mode Control for Trajectory Tracking of Intelligent Vehicle

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Ma, Rong; Zhang, Yanrong; Zhao, Chengzhi

    The intelligent vehicle is a complex non-linear system of various machines, sensors and computers, of which the controller design for trajectory tracking is one of the key techniques for intelligent vehicles. For the high qualities of robustness, accuracy and rigid time limitation of high-speed autonomous navigation intelligent vehicle, this paper is about the design of a sliding mode controller, based on the structures and motion model. It realizes that the intelligent vehicle can track random trajectory through controlling the linear velocity and the angular velocity. Through the simulation experiment using Matlab it is showing the effectiveness and reliability of the designed algorithms.

  7. Simulation and design of fuzzy sliding-mode controller for ship heading-tracking

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Wu, Hansong

    2011-03-01

    In considering the characteristic of a rudder, the maneuvers of a ship were described by an unmatched uncertain nonlinear mathematic model with unknown virtual control coefficient and parameter uncertainties. In order to solve the uncertainties in the ship heading control, specifically the controller singular and paramount re-estimation problem, a new multiple sliding-mode adaptive fuzzy control algorithm was proposed by combining Nussbaum gain technology, the approximation property of fuzzy logic systems, and a multiple sliding-mode control algorithm. Based on the Lyapunov function, it was proven in theory that the controller made all signals in the nonlinear system of unmatched uncertain ship motion uniformly bounded, with tracking errors converging to zero. Simulation results show that the demonstrated controller design can track a desired course fast and accurately. It also exhibits strong robustness peculiarity in relation to system uncertainties and disturbances.

  8. Sliding mode control of electromagnetic tethered satellite formation

    NASA Astrophysics Data System (ADS)

    Hallaj, Mohammad Amin Alandi; Assadian, Nima

    2016-08-01

    This paper investigates the control of tethered satellite formation actuated by electromagnetic dipoles and reaction wheels using the robust sliding mode control technique. Generating electromagnetic forces and moments by electric current coils provides an attractive control actuation alternative for tethered satellite system due to the advantages of no propellant consumption and no obligatory rotational motion. Based on a dumbbell model of tethered satellite in which the flexibility and mass of the tether is neglected, the equations of motion in Cartesian coordinate are derived. In this model, the J2 perturbation is taken into account. The far-field and mid-field models of electromagnetic forces and moments of two satellites on each other and the effect of the Earth's magnetic field are presented. A robust sliding mode controller is designed for precise trajectory tracking purposes and to deal with the electromagnetic force and moment uncertainties and external disturbances due to the Earth's gravitational and magnetic fields inaccuracy. Numerical simulation results are presented to validate the effectiveness of the developed controller and its superiority over the linear controller.

  9. Design of sliding mode control for a class of uncertain switched systems

    NASA Astrophysics Data System (ADS)

    Liu, Yonghui; Jia, Tinggang; Niu, Yugang; Zou, Yuanyuan

    2015-04-01

    This paper considers the problem of sliding mode control for a class of uncertain switched systems with parameter uncertainties and external disturbances. A key feature of the controlled system is that each subsystem is not required to share the same input channel, which was usually assumed in some existing works. By means of a weighted sum of the input matrix, a common sliding surface is designed in this work. It is shown that the reachability of the sliding surface can be ensured by the present sliding mode controller. Moreover, the sliding motion on the specified sliding surface is asymptotically stable under the proposed switching signal dependent on the state and time. Additionally, the above results are further extended to the case that the system states are unavailable. Both the sliding surface and sliding mode controller are designed by utilising state-observer. Finally, numerical simulation examples are given to illustrate the effectiveness of the present method.

  10. Robust current control-based generalized predictive control with sliding mode disturbance compensation for PMSM drives.

    PubMed

    Liu, Xudong; Zhang, Chenghui; Li, Ke; Zhang, Qi

    2017-09-06

    This paper addresses the current control of permanent magnet synchronous motor (PMSM) for electric drives with model uncertainties and disturbances. A generalized predictive current control method combined with sliding mode disturbance compensation is proposed to satisfy the requirement of fast response and strong robustness. Firstly, according to the generalized predictive control (GPC) theory based on the continuous time model, a predictive current control method is presented without considering the disturbance, which is convenient to be realized in the digital controller. In fact, it's difficult to derive the exact motor model and parameters in the practical system. Thus, a sliding mode disturbance compensation controller is studied to improve the adaptiveness and robustness of the control system. The designed controller attempts to combine the merits of both predictive control and sliding mode control, meanwhile, the controller parameters are easy to be adjusted. Lastly, the proposed controller is tested on an interior PMSM by simulation and experiment, and the results indicate that it has good performance in both current tracking and disturbance rejection. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  11. Controlling chaos based on a novel intelligent integral terminal sliding mode control in a rod-type plasma torch

    NASA Astrophysics Data System (ADS)

    Safa, Khari; Zahra, Rahmani; Behrooz, Rezaie

    2016-05-01

    An integral terminal sliding mode controller is proposed in order to control chaos in a rod-type plasma torch system. In this method, a new sliding surface is defined based on a combination of the conventional sliding surface in terminal sliding mode control and a nonlinear function of the integral of the system states. It is assumed that the dynamics of a chaotic system are unknown and also the system is exposed to disturbance and unstructured uncertainty. To achieve a chattering-free and high-speed response for such an unknown system, an adaptive neuro-fuzzy inference system is utilized in the next step to approximate the unknown part of the nonlinear dynamics. Then, the proposed integral terminal sliding mode controller stabilizes the approximated system based on Lyapunov’s stability theory. In addition, a Bee algorithm is used to select the coefficients of integral terminal sliding mode controller to improve the performance of the proposed method. Simulation results demonstrate the improvement in the response speed, chattering rejection, transient response, and robustness against uncertainties.

  12. Flexible Modes Control Using Sliding Mode Observers: Application to Ares I

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.; Hall, Charles E.; Baev, Simon; Orr, Jeb S.

    2010-01-01

    The launch vehicle dynamics affected by bending and sloshing modes are considered. Attitude measurement data that are corrupted by flexible modes could yield instability of the vehicle dynamics. Flexible body and sloshing modes are reconstructed by sliding mode observers. The resultant estimates are used to remove the undesirable dynamics from the measurements, and the direct effects of sloshing and bending modes on the launch vehicle are compensated by means of a controller that is designed without taking the bending and sloshing modes into account. A linearized mathematical model of Ares I launch vehicle was derived based on FRACTAL, a linear model developed by NASA/MSFC. The compensated vehicle dynamics with a simple PID controller were studied for the launch vehicle model that included two bending modes, two slosh modes and actuator dynamics. A simulation study demonstrated stable and accurate performance of the flight control system with the augmented simple PID controller without the use of traditional linear bending filters.

  13. Frequency-Shaped Sliding Mode Control for Rudder Roll Damping System of Robotic Boat

    NASA Astrophysics Data System (ADS)

    Bao, Xinping; Yu, Zhenyu; Nonami, Kenzo

    In this paper, a robotic boat model of combined yaw and roll rate is obtained by a system identification approach. The identified system is designed with frequency-shaped sliding mode control. The control scheme is composed of a sliding mode observer and a sliding mode controller. The stability and reachability of the switching function are proved by Lyapunov theory. Computer simulations and experiment carried out at INAGE offshore show that successful course keeping and roll reduction results are achieved.

  14. Sliding Mode Control of a Thermal Mixing Process

    NASA Technical Reports Server (NTRS)

    Richter, Hanz; Figueroa, Fernando

    2004-01-01

    In this paper we consider the robust control of a thermal mixer using multivariable Sliding Mode Control (SMC). The mixer consists of a mixing chamber, hot and cold fluid valves, and an exit valve. The commanded positions of the three valves are the available control inputs, while the controlled variables are total mass flow rate, chamber pressure and the density of the mixture inside the chamber. Unsteady thermodynamics and linear valve models are used in deriving a 5th order nonlinear system with three inputs and three outputs, An SMC controller is designed to achieve robust output tracking in the presence of unknown energy losses between the chamber and the environment. The usefulness of the technique is illustrated with a simulation.

  15. Multicell actuator based on a sliding mode control

    NASA Astrophysics Data System (ADS)

    Béthoux, O.; Barbot, J.-P.; Hilairet, M.

    2008-08-01

    This paper deals with reliability of motor drive systems. It focuses on the switching power converter which is the weakest drive part. It investigates a new architecture which provides intrinsic redundancy. The method used in this fault switch detection and diagnosis is based on a sliding mode observer. The original aspect of this new approach is that the observer influences the control algorithm in order to rule out or accept the possibility of the device failure. This leads to the right decision which induces the rebuilding of the converter topology. This fault tolerant control strategy assures continuous operation even though one switch failure occurs. This article has been submitted as part of “IET Colloquium on Reliability in Electromagnetic Systems”, 24 and 25 May 2007, Paris

  16. A new optimal sliding mode controller design using scalar sign function.

    PubMed

    Singla, Mithun; Shieh, Leang-San; Song, Gangbing; Xie, Linbo; Zhang, Yongpeng

    2014-03-01

    This paper presents a new optimal sliding mode controller using the scalar sign function method. A smooth, continuous-time scalar sign function is used to replace the discontinuous switching function in the design of a sliding mode controller. The proposed sliding mode controller is designed using an optimal Linear Quadratic Regulator (LQR) approach. The sliding surface of the system is designed using stable eigenvectors and the scalar sign function. Controller simulations are compared with another existing optimal sliding mode controller. To test the effectiveness of the proposed controller, the controller is implemented on an aluminum beam with piezoceramic sensor and actuator for vibration control. This paper includes the control design and stability analysis of the new optimal sliding mode controller, followed by simulation and experimental results. The simulation and experimental results show that the proposed approach is very effective. © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  17. Improved robustness and performance of discrete time sliding mode control systems.

    PubMed

    Chakrabarty, Sohom; Bartoszewicz, Andrzej

    2016-11-01

    This paper presents a theoretical analysis along with simulations to show that increased robustness can be achieved for discrete time sliding mode control systems by choosing the sliding variable, or the output, to be of relative degree two instead of relative degree one. In other words it successfully reduces the ultimate bound of the sliding variable compared to the ultimate bound for standard discrete time sliding mode control systems. It is also found out that for such a selection of relative degree two output of the discrete time system, the reduced order system during sliding becomes finite time stable in absence of disturbance. With disturbance, it becomes finite time ultimately bounded.

  18. Robust fault tolerant control based on sliding mode method for uncertain linear systems with quantization.

    PubMed

    Hao, Li-Ying; Yang, Guang-Hong

    2013-09-01

    This paper is concerned with the problem of robust fault-tolerant compensation control problem for uncertain linear systems subject to both state and input signal quantization. By incorporating novel matrix full-rank factorization technique with sliding surface design successfully, the total failure of certain actuators can be coped with, under a special actuator redundancy assumption. In order to compensate for quantization errors, an adjustment range of quantization sensitivity for a dynamic uniform quantizer is given through the flexible choices of design parameters. Comparing with the existing results, the derived inequality condition leads to the fault tolerance ability stronger and much wider scope of applicability. With a static adjustment policy of quantization sensitivity, an adaptive sliding mode controller is then designed to maintain the sliding mode, where the gain of the nonlinear unit vector term is updated automatically to compensate for the effects of actuator faults, quantization errors, exogenous disturbances and parameter uncertainties without the need for a fault detection and isolation (FDI) mechanism. Finally, the effectiveness of the proposed design method is illustrated via a model of a rocket fairing structural-acoustic.

  19. Finite-Time Attitude Tracking Control for Spacecraft Using Terminal Sliding Mode and Chebyshev Neural Network.

    PubMed

    An-Min Zou; Kumar, K D; Zeng-Guang Hou; Xi Liu

    2011-08-01

    A finite-time attitude tracking control scheme is proposed for spacecraft using terminal sliding mode and Chebyshev neural network (NN) (CNN). The four-parameter representations (quaternion) are used to describe the spacecraft attitude for global representation without singularities. The attitude state (i.e., attitude and velocity) error dynamics is transformed to a double integrator dynamics with a constraint on the spacecraft attitude. With consideration of this constraint, a novel terminal sliding manifold is proposed for the spacecraft. In order to guarantee that the output of the NN used in the controller is bounded by the corresponding bound of the approximated unknown function, a switch function is applied to generate a switching between the adaptive NN control and the robust controller. Meanwhile, a CNN, whose basis functions are implemented using only desired signals, is introduced to approximate the desired nonlinear function and bounded external disturbances online, and the robust term based on the hyperbolic tangent function is applied to counteract NN approximation errors in the adaptive neural control scheme. Most importantly, the finite-time stability in both the reaching phase and the sliding phase can be guaranteed by a Lyapunov-based approach. Finally, numerical simulations on the attitude tracking control of spacecraft in the presence of an unknown mass moment of inertia matrix, bounded external disturbances, and control input constraints are presented to demonstrate the performance of the proposed controller.

  20. Sliding mode control of magnetic suspensions for precision pointing and tracking applications

    NASA Technical Reports Server (NTRS)

    Misovec, Kathleen M.; Flynn, Frederick J.; Johnson, Bruce G.; Hedrick, J. Karl

    1991-01-01

    A recently developed nonlinear control method, sliding mode control, is examined as a means of advancing the achievable performance of space-based precision pointing and tracking systems that use nonlinear magnetic actuators. Analytic results indicate that sliding mode control improves performance compared to linear control approaches. In order to realize these performance improvements, precise knowledge of the plant is required. Additionally, the interaction of an estimating scheme and the sliding mode controller has not been fully examined in the literature. Estimation schemes were designed for use with this sliding mode controller that do not seriously degrade system performance. The authors designed and built a laboratory testbed to determine the feasibility of utilizing sliding mode control in these types of applications. Using this testbed, experimental verification of the authors' analyses is ongoing.

  1. Sliding mode observer based incipient sensor fault detection with application to high-speed railway traction device.

    PubMed

    Zhang, Kangkang; Jiang, Bin; Yan, Xing-Gang; Mao, Zehui

    2016-07-01

    This paper considers incipient sensor fault detection issue for a class of nonlinear systems with "observer unmatched" uncertainties. A particular fault detection sliding mode observer is designed for the augmented system formed by the original system and incipient sensor faults. The designed parameters are obtained using LMI and line filter techniques to guarantee that the generated residuals are robust to uncertainties and that sliding motion is not destroyed by faults. Then, three levels of novel adaptive thresholds are proposed based on the reduced order sliding mode dynamics, which effectively improve incipient sensor faults detectability. Case study of on the traction system in China Railway High-speed is presented to demonstrate the effectiveness of the proposed incipient senor faults detection schemes.

  2. Projective synchronization of nonidentical fractional-order neural networks based on sliding mode controller.

    PubMed

    Ding, Zhixia; Shen, Yi

    2016-04-01

    This paper investigates global projective synchronization of nonidentical fractional-order neural networks (FNNs) based on sliding mode control technique. We firstly construct a fractional-order integral sliding surface. Then, according to the sliding mode control theory, we design a sliding mode controller to guarantee the occurrence of the sliding motion. Based on fractional Lyapunov direct methods, system trajectories are driven to the proposed sliding surface and remain on it evermore, and some novel criteria are obtained to realize global projective synchronization of nonidentical FNNs. As the special cases, some sufficient conditions are given to ensure projective synchronization of identical FNNs, complete synchronization of nonidentical FNNs and anti-synchronization of nonidentical FNNs. Finally, one numerical example is given to demonstrate the effectiveness of the obtained results.

  3. Certifiable higher order sliding mode control: Practical stability margins approach

    NASA Astrophysics Data System (ADS)

    Panathula, Chandrasekhara Bharath

    The Higher Order Sliding Mode (HOSM) controllers are well known for their robustness/insensitivity to bounded perturbations and for handling any given arbitrary relative degree system. The HOSM controller is to be certified for robustness to unmodeled dynamics, before deploying the controller for practical applications. Phase Margin (PM) and Gain Margin ( GM) are the classical characteristics used in linear systems to quantify the linear controller robustness to unmodeled dynamics, and certain values of these margins are required to certify the controller. These conventional margins (PM and GM) are extended to Practical Stability Phase Margin (PSPM) and Practical Stability Gain Margin (PSGM) in this dissertation, and are used to quantify the HOSM control robustness to unmodeled dynamics, presiding the tool to close the gap for HOSM control certification. The proposed robustness metrics ( PSPM and PSGM) are identified by developing tools/algorithms based on Describing Function-Harmonic Balance method. In order for the HOSM controller to achieve the prescribed values on robustness metrics ( PSPM and PSGM), the HOSM controller is cascaded with a linear compensator. A case study of the application of the proposed metrics (PSPM and PSGM) for the certification of F-16 aircraft HOSM attitude control robustness to cascade unmodeled dynamics is presented. In addition, several simulation examples are presented to verify and to validate the proposed methodology.

  4. Functional Based Adaptive and Fuzzy Sliding Controller for Non-Autonomous Active Suspension System

    NASA Astrophysics Data System (ADS)

    Huang, Shiuh-Jer; Chen, Hung-Yi

    In this paper, an adaptive sliding controller is developed for controlling a vehicle active suspension system. The functional approximation technique is employed to substitute the unknown non-autonomous functions of the suspension system and release the model-based requirement of sliding mode control algorithm. In order to improve the control performance and reduce the implementation problem, a fuzzy strategy with online learning ability is added to compensate the functional approximation error. The update laws of the functional approximation coefficients and the fuzzy tuning parameters are derived from the Lyapunov theorem to guarantee the system stability. The proposed controller is implemented on a quarter-car hydraulic actuating active suspension system test-rig. The experimental results show that the proposed controller suppresses the oscillation amplitude of the suspension system effectively.

  5. Output Feedback Integral Sliding Mode Control for Uncertain Systems with Bounded L2 Performance

    NASA Astrophysics Data System (ADS)

    Chang, Jeang-Lin; Ting, Huan-Chan

    This paper presents an output feedback sliding mode control algorithm for linear MIMO systems with mismatched parameter uncertainties along with disturbances and matched nonlinear perturbations. A scheme of the output-dependent integral sliding surface is proposed and a control law is then designed to satisfy the reaching and sliding condition. Through utilizing H∞ control analytical technique, once the system is in the sliding mode, the proposed algorithm can guarantee robust stabilization and sustain the nature of performing disturbance attenuation in terms of an algebraic Riccati equation. Finally, the feasibility of our proposed algorithm is illustrated using a numerical example.

  6. Designing for Damage: Robust Flight Control Design using Sliding Mode Techniques

    NASA Technical Reports Server (NTRS)

    Vetter, T. K.; Wells, S. R.; Hess, Ronald A.; Bacon, Barton (Technical Monitor); Davidson, John (Technical Monitor)

    2002-01-01

    A brief review of sliding model control is undertaken, with particular emphasis upon the effects of neglected parasitic dynamics. Sliding model control design is interpreted in the frequency domain. The inclusion of asymptotic observers and control 'hedging' is shown to reduce the effects of neglected parasitic dynamics. An investigation into the application of observer-based sliding mode control to the robust longitudinal control of a highly unstable is described. The sliding mode controller is shown to exhibit stability and performance robustness superior to that of a classical loop-shaped design when significant changes in vehicle and actuator dynamics are employed to model airframe damage.

  7. The stability control of fractional order unified chaotic system with sliding mode control theory

    NASA Astrophysics Data System (ADS)

    Qi, Dong-Lian; Yang, Jie; Zhang, Jian-Liang

    2010-10-01

    This paper studies the stability of the fractional order unified chaotic system with sliding mode control theory. The sliding manifold is constructed by the definition of fractional order derivative and integral for the fractional order unified chaotic system. By the existing proof of sliding manifold, the sliding mode controller is designed. To improve the convergence rate, the equivalent controller includes two parts: the continuous part and switching part. With Gronwall's inequality and the boundness of chaotic attractor, the finite stabilization of the fractional order unified chaotic system is proved, and the controlling parameters can be obtained. Simulation results are made to verify the effectiveness of this method.

  8. Second-Order Consensus in Multiagent Systems via Distributed Sliding Mode Control.

    PubMed

    Yu, Wenwu; Wang, He; Cheng, Fei; Yu, Xinghuo; Wen, Guanghui

    2016-11-22

    In this paper, the new decoupled distributed sliding-mode control (DSMC) is first proposed for second-order consensus in multiagent systems, which finally solves the fundamental unknown problem for sliding-mode control (SMC) design of coupled networked systems. A distributed full-order sliding-mode surface is designed based on the homogeneity with dilation for reaching second-order consensus in multiagent systems, under which the sliding-mode states are decoupled. Then, the SMC is applied to the decoupled sliding-mode states to reach their origin in finite time, which is the sliding-mode surface. The states of agents can first reach the designed sliding-mode surface in finite time and then move to the second-order consensus state along the surface in finite time as well. The DSMC designed in this paper can eliminate the influence of singularity problems and weaken the influence of chattering, which is still very difficult in the SMC systems. In addition, DSMC proposes a general decoupling framework for designing SMC in networked multiagent systems. Simulations are presented to verify the theoretical results in this paper.

  9. Adaptive fuzzy predictive sliding control of uncertain nonlinear systems with bound-known input delay.

    PubMed

    Khazaee, Mostafa; Markazi, Amir H D; Omidi, Ehsan

    2015-11-01

    In this paper, a new Adaptive Fuzzy Predictive Sliding Mode Control (AFP-SMC) is presented for nonlinear systems with uncertain dynamics and unknown input delay. The control unit consists of a fuzzy inference system to approximate the ideal linearization control, together with a switching strategy to compensate for the estimation errors. Also, an adaptive fuzzy predictor is used to estimate the future values of the system states to compensate for the time delay. The adaptation laws are used to tune the controller and predictor parameters, which guarantee the stability based on a Lyapunov-Krasovskii functional. To evaluate the method effectiveness, the simulation and experiment on an overhead crane system are presented. According to the obtained results, AFP-SMC can effectively control the uncertain nonlinear systems, subject to input delays of known bound. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  10. Stabilization and tracking control of X-Z inverted pendulum with sliding-mode control.

    PubMed

    Wang, Jia-Jun

    2012-11-01

    X-Z inverted pendulum is a new kind of inverted pendulum which can move with the combination of the vertical and horizontal forces. Through a new transformation, the X-Z inverted pendulum is decomposed into three simple models. Based on the simple models, sliding-mode control is applied to stabilization and tracking control of the inverted pendulum. The performance of the sliding mode control is compared with that of the PID control. Simulation results show that the design scheme of sliding-mode control is effective for the stabilization and tracking control of the X-Z inverted pendulum.

  11. Neural Feedback Passivity of Unknown Nonlinear Systems via Sliding Mode Technique.

    PubMed

    Yu, Wen

    2015-07-01

    Passivity method is very effective to analyze large-scale nonlinear systems with strong nonlinearities. However, when most parts of the nonlinear system are unknown, the published neural passivity methods are not suitable for feedback stability. In this brief, we propose a novel sliding mode learning algorithm and sliding mode feedback passivity control. We prove that for a wide class of unknown nonlinear systems, this neural sliding mode control can passify and stabilize them. This passivity method is validated with a simulation and real experiment tests.

  12. Sliding mode pulse-width modulation technique for direct torque controlled induction motor drive

    NASA Astrophysics Data System (ADS)

    Bounadja, M.; Belarbi, A. W.; Belmadani, B.

    2010-05-01

    This paper presents a novel pulse-width modulation technique based sliding mode approach for direct torque control of an induction machine drive. Methodology begins with a sliding mode control of machine's torque and stator flux to generate the reference voltage vector and to reduce parameters sensitivity. Then, the switching control of the three-phase inverter is developed using sliding mode concept to make the system tracking reference voltage inputs. The main features of the proposed methodologies are the high tracking accuracy and the much easier implementation compared to the space vector modulation. Simulations are carried out to confirm the effectiveness of proposed control algorithms.

  13. Trajectory tracking control of omnidirectional wheeled mobile manipulators: robust neural network-based sliding mode approach.

    PubMed

    Xu, Dong; Zhao, Dongbin; Yi, Jianqiang; Tan, Xiangmin

    2009-06-01

    This paper addresses the robust trajectory tracking problem for a redundantly actuated omnidirectional mobile manipulator in the presence of uncertainties and disturbances. The development of control algorithms is based on sliding mode control (SMC) technique. First, a dynamic model is derived based on the practical omnidirectional mobile manipulator system. Then, a SMC scheme, based on the fixed large upper boundedness of the system dynamics (FLUBSMC), is designed to ensure trajectory tracking of the closed-loop system. However, the FLUBSMC scheme has inherent deficiency, which needs computing the upper boundedness of the system dynamics, and may cause high noise amplification and high control cost, particularly for the complex dynamics of the omnidirectional mobile manipulator system. Therefore, a robust neural network (NN)-based sliding mode controller (NNSMC), which uses an NN to identify the unstructured system dynamics directly, is further proposed to overcome the disadvantages of FLUBSMC and reduce the online computing burden of conventional NN adaptive controllers. Using learning ability of NN, NNSMC can coordinately control the omnidirectional mobile platform and the mounted manipulator with different dynamics effectively. The stability of the closed-loop system, the convergence of the NN weight-updating process, and the boundedness of the NN weight estimation errors are all strictly guaranteed. Then, in order to accelerate the NN learning efficiency, a partitioned NN structure is applied. Finally, simulation examples are given to demonstrate the proposed NNSMC approach can guarantee the whole system's convergence to the desired manifold with prescribed performance.

  14. Motorized CPM/CAM physiotherapy device with sliding-mode Fuzzy Neural Network control loop.

    PubMed

    Ho, Hung-Jung; Chen, Tien-Chi

    2009-11-01

    Continuous passive motion (CPM) and controllable active motion (CAM) physiotherapy devices promote rehabilitation of damaged joints. This paper presents a computerized CPM/CAM system that obviates the need for mechanical resistance devices such as springs. The system is controlled by a computer which performs sliding-mode Fuzzy Neural Network (FNN) calculations online. CAM-type resistance force is generated by the active performance of an electric motor which is controlled so as to oppose the motion of the patient's leg. A force sensor under the patient's foot on the device pedal provides data for feedback in a sliding-mode FNN control loop built around the motor. Via an active impedance control feedback system, the controller drives the motor to behave similarly to a damped spring by generating and controlling the amplitude and direction of the pedal force in relation to the patient's leg. Experiments demonstrate the high sensitivity and speed of the device. The PC-based feedback nature of the control loop means that sophisticated auto-adaptable CPM/CAM custom-designed physiotherapy becomes possible. The computer base also allows extensive data recording, data analysis and network-connected remote patient monitoring.

  15. A new fuzzy sliding mode controller for vibration control systems using integrated-structure smart dampers

    NASA Astrophysics Data System (ADS)

    Dzung Nguyen, Sy; Kim, Wanho; Park, Jhinha; Choi, Seung-Bok

    2017-04-01

    Vibration control systems using smart dampers (SmDs) such as magnetorheological and electrorheological dampers (MRD and ERD), which are classified as the integrated structure-SmD control systems (ISSmDCSs), have been actively researched and widely used. This work proposes a new controller for a class of ISSmDCSs in which high accuracy of SmD models as well as increment of control ability to deal with uncertainty and time delay are to be expected. In order to achieve this goal, two formualtion steps are required; a non-parametric SmD model based on an adaptive neuro-fuzzy inference system (ANFIS) and a novel fuzzy sliding mode controller (FSMC) which can weaken the model error of the ISSmDCSs and hence provide enhanced vibration control performances. As for the formulation of the proposed controller, first, an ANFIS controller is desgned to identify SmDs using the improved control algorithm named improved establishing neuro-fuzzy system (establishing neuro-fuzzy system). Second, a new control law for the FSMC is designed via Lyapunov stability analysis. An application to a semi-active MRD vehicle suspension system is then undertaken to illustrate and evaluate the effectiveness of the proposed control method. It is demonstrated through an experimental realization that the FSMC proposed in this work shows superior vibration control performance of the vehicle suspension compared to other surveyed controller which have similar structures to the FSMC, such as fuzzy logic and sliding mode control.

  16. Sliding mode output feedback control based on tracking error observer with disturbance estimator.

    PubMed

    Xiao, Lingfei; Zhu, Yue

    2014-07-01

    For a class of systems who suffers from disturbances, an original output feedback sliding mode control method is presented based on a novel tracking error observer with disturbance estimator. The mathematical models of the systems are not required to be with high accuracy, and the disturbances can be vanishing or nonvanishing, while the bounds of disturbances are unknown. By constructing a differential sliding surface and employing reaching law approach, a sliding mode controller is obtained. On the basis of an extended disturbance estimator, a creative tracking error observer is produced. By using the observation of tracking error and the estimation of disturbance, the sliding mode controller is implementable. It is proved that the disturbance estimation error and tracking observation error are bounded, the sliding surface is reachable and the closed-loop system is robustly stable. The simulations on a servomotor positioning system and a five-degree-of-freedom active magnetic bearings system verify the effect of the proposed method.

  17. Sliding Mode Control for Discrete-Time Systems With Markovian Packet Dropouts.

    PubMed

    Song, Heran; Chen, Shih-Chi; Yam, Yeung

    2016-07-09

    This paper presents the design of a sliding mode controller for networked control systems subject to successive Markovian packet dropouts. This paper adopts the Gilbert-Elliott channel model to describe the temporal correlation among packet losses, and proposes an update scheme to select the assumed available states for use in a sliding mode control law. A technique used in the theory of discrete-time Markov jump linear systems is applied to tackle the effect of the packet losses. This involves introducing a couple of Lyapunov functions dependent on the indicator functions of the instantaneous packet loss, and proving that the sliding mode controller is able to drive the system state trajectories into the neighborhood of the designed integral sliding surface in mean-square sense given that the corresponding Lyapunov inequalities are satisfied. The system is guaranteed thereafter to remain inside the neighborhood of the sliding surface. Simulated case studies are presented to illustrate the effectiveness of the control law.

  18. A fuzzy logic sliding mode controlled electronic differential for a direct wheel drive EV

    NASA Astrophysics Data System (ADS)

    Ozkop, Emre; Altas, Ismail H.; Okumus, H. Ibrahim; Sharaf, Adel M.

    2015-11-01

    In this study, a direct wheel drive electric vehicle based on an electronic differential system with a fuzzy logic sliding mode controller (FLSMC) is studied. The conventional sliding surface is modified using a fuzzy rule base to obtain fuzzy dynamic sliding surfaces by changing its slopes using the global error and its derivative in a fuzzy logic inference system. The controller is compared with proportional-integral-derivative (PID) and sliding mode controllers (SMCs), which are usually preferred to be used in industry. The proposed controller provides robustness and flexibility to direct wheel drive electric vehicles. The fuzzy logic sliding mode controller, electronic differential system and the overall electrical vehicle mechanism are modelled and digitally simulated by using the Matlab software. Simulation results show that the system with FLSMC has better efficiency and performance compared to those of PID and SMCs.

  19. A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

    PubMed

    Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

    2016-03-01

    Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results.

  20. Adaptive Batch Mode Active Learning.

    PubMed

    Chakraborty, Shayok; Balasubramanian, Vineeth; Panchanathan, Sethuraman

    2015-08-01

    Active learning techniques have gained popularity to reduce human effort in labeling data instances for inducing a classifier. When faced with large amounts of unlabeled data, such algorithms automatically identify the exemplar and representative instances to be selected for manual annotation. More recently, there have been attempts toward a batch mode form of active learning, where a batch of data points is simultaneously selected from an unlabeled set. Real-world applications require adaptive approaches for batch selection in active learning, depending on the complexity of the data stream in question. However, the existing work in this field has primarily focused on static or heuristic batch size selection. In this paper, we propose two novel optimization-based frameworks for adaptive batch mode active learning (BMAL), where the batch size as well as the selection criteria are combined in a single formulation. We exploit gradient-descent-based optimization strategies as well as properties of submodular functions to derive the adaptive BMAL algorithms. The solution procedures have the same computational complexity as existing state-of-the-art static BMAL techniques. Our empirical results on the widely used VidTIMIT and the mobile biometric (MOBIO) data sets portray the efficacy of the proposed frameworks and also certify the potential of these approaches in being used for real-world biometric recognition applications.

  1. Discrete sliding mode control for robust tracking of higher order delay time systems with experimental application.

    PubMed

    Khandekar, A A; Malwatkar, G M; Patre, B M

    2013-01-01

    In this paper, a discrete time sliding mode controller (DSMC) is proposed for higher order plus delay time (HOPDT) processes. A sliding mode surface is selected as a function of system states and error and the tuning parameters of sliding mode controller are determined using dominant pole placement strategy. The condition for the existence of stable sliding mode is obtained by using Lyapunov function. The proposed method is applicable to HOPDT processes with oscillatory and integrating behavior, open loop instability or non-minimum phase characteristics and works satisfactory under the effect of parametric uncertainty. The method does not require reduced order model and provides simple way to design the controllers. The simulation and experimentation results show that the proposed method ensures desired tracking dynamics.

  2. Finite time control for MIMO nonlinear system based on higher-order sliding mode.

    PubMed

    Liu, Xiangjie; Han, Yaozhen

    2014-11-01

    Considering a class of MIMO uncertain nonlinear system, a novel finite time stable control algorithm is proposed based on higher-order sliding mode concept. The higher-order sliding mode control problem of MIMO nonlinear system is firstly transformed into finite time stability problem of multivariable system. Then continuous control law, which can guarantee finite time stabilization of nominal integral chain system, is employed. The second-order sliding mode is used to overcome the system uncertainties. High frequency chattering phenomenon of sliding mode is greatly weakened, and the arbitrarily fast convergence is reached. The finite time stability is proved based on the quadratic form Lyapunov function. Examples concerning the triple integral chain system with uncertainty and the hovercraft trajectory tracking are simulated respectively to verify the effectiveness and the robustness of the proposed algorithm.

  3. Optimal integral sliding mode control scheme based on pseudospectral method for robotic manipulators

    NASA Astrophysics Data System (ADS)

    Liu, Rongjie; Li, Shihua

    2014-06-01

    For a multi-input multi-output nonlinear system, an optimal integral sliding mode control scheme based on pseudospectral method is proposed in this paper. And the controller is applied on rigid robotic manipulators with constraints. First, a general form of integral sliding mode is designed with the aim of restraining disturbance. Then, pseudospectral method is adopted to deal with constrained optimal control problem. In consideration of the benefits of both methods, an optimal integral sliding mode controller is given, which is based on the combination of integral sliding mode and pseudospectral method. The stability analysis shows that the controller can guarantee stability of robotic manipulator system. Simulations show the effectiveness of proposed method.

  4. An Application of Chaotic Chua's System for Secure Chaotic Communication Based on Sliding Mode observer

    NASA Astrophysics Data System (ADS)

    Kemih, K.; Halimi, M.; Ghanes, M.; Zhang, G.

    2011-12-01

    In this paper, we study the design and implementation of analog secure communication systems via synchronized chaotic Chua's circuit with sliding mode observer. For this, we adopt an approach based on an inclusion of the message in the transmitter and in the receiver; we use a sliding mode observer with un-known input in order to recover the information. Finally, an analog electronic circuit with Multisim software is designed to physically realize the complete system (transmitter-receiver).

  5. Simulation and Research of Control-System for PMSM Based on Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Baofeng, Lv; Guoxiang, Zhang

    In this paper, permanent magnet synchronous motor rotor flux oriented control strategy is studied, for the key issues of vector control is to observe the rotor flux, the control system is given based on sliding mode observer, and the sliding mode rotor flux observer is designed, with MATLAB/SIMULINK simulation, the results of simulation show that the system with wide speed range, has a good dynamic and static performance.

  6. Terminal sliding mode tracking control for a class of SISO uncertain nonlinear systems.

    PubMed

    Chen, Mou; Wu, Qing-Xian; Cui, Rong-Xin

    2013-03-01

    In this paper, the terminal sliding mode tracking control is proposed for the uncertain single-input and single-output (SISO) nonlinear system with unknown external disturbance. For the unmeasured disturbance of nonlinear systems, terminal sliding mode disturbance observer is presented. The developed disturbance observer can guarantee the disturbance approximation error to converge to zero in the finite time. Based on the output of designed disturbance observer, the terminal sliding mode tracking control is presented for uncertain SISO nonlinear systems. Subsequently, terminal sliding mode tracking control is developed using disturbance observer technique for the uncertain SISO nonlinear system with control singularity and unknown non-symmetric input saturation. The effects of the control singularity and unknown input saturation are combined with the external disturbance which is approximated using the disturbance observer. Under the proposed terminal sliding mode tracking control techniques, the finite time convergence of all closed-loop signals are guaranteed via Lyapunov analysis. Numerical simulation results are given to illustrate the effectiveness of the proposed terminal sliding mode tracking control.

  7. Minimum sliding mode error feedback control for fault tolerant reconfigurable satellite formations with J2 perturbations

    NASA Astrophysics Data System (ADS)

    Cao, Lu; Chen, Xiaoqian; Misra, Arun K.

    2014-03-01

    Minimum Sliding Mode Error Feedback Control (MSMEFC) is proposed to improve the control precision of spacecraft formations based on the conventional sliding mode control theory. This paper proposes a new approach to estimate and offset the system model errors, which include various kinds of uncertainties and disturbances, as well as smoothes out the effect of nonlinear switching control terms. To facilitate the analysis, the concept of equivalent control error is introduced, which is the key to the utilization of MSMEFC. A cost function is formulated on the basis of the principle of minimum sliding mode error; then the equivalent control error is estimated and fed back to the conventional sliding mode control. It is shown that the sliding mode after the MSMEFC will approximate to the ideal sliding mode, resulting in improved control performance and quality. The new methodology is applied to spacecraft formation flying. It guarantees global asymptotic convergence of the relative tracking error in the presence of J2 perturbations. In addition, some fault tolerant situations such as thruster failure for a period of time, thruster degradation and so on, are also considered to verify the effectiveness of MSMEFC. Numerical simulations are performed to demonstrate the efficacy of the proposed methodology to maintain and reconfigure the satellite formation with the existence of initial offsets and J2 perturbation effects, even in the fault-tolerant cases.

  8. Projective synchronization of uncertain scale-free network based on modified sliding mode control technique

    NASA Astrophysics Data System (ADS)

    Li, Chengren; Lü, Ling; Zhao, Guannan; Li, Gang; Tian, Jing; Gu, Jiajia; Wang, Zhouyang

    2017-05-01

    We modify sliding mode control technique from the synchronization of a single dynamic system to the synchronization of complex network. Projective synchronization of uncertain scale-free network is investigated based on modified sliding mode control technique. Further, the sliding surfaces, the identification laws of uncertain parameters and the control inputs are designed, and the condition of realizing projective synchronization of uncertain scale-free network is obtained. Finally, the Logistic systems with chaotic behavior are taken as nodes to constitute the scale-free network and the synchronization target. The simulation results show that the synchronization mechanism is effective.

  9. Robust adaptive synchronization of Rossler and Chen chaotic systems via slide technique

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Shi, Songjiao

    2003-05-01

    This Letter considers the robust adaptive synchronization problem of Rossler and Chen chaotic systems with different time-varying unknown parameters. When system's unknown parameters vary in bound intervals and the bounds of intervals are unknown, a robust adaptive controller is designed. In order to increase the robustness of the closed loop systems, the key idea is that a sliding mode type of controller is employed. Besides, instead of the estimate values of systems' unknown parameters being taken as updating object, a new updating object is introduced in constructing controller. The proposed controller can make the states of Rossler and Chen chaotic systems globally asymptotically robustly synchronized. Simulation results are given to show the effectiveness of the proposed method.

  10. Sliding mode control of outbreaks of emerging infectious diseases.

    PubMed

    Xiao, Yanni; Xu, Xiaxia; Tang, Sanyi

    2012-10-01

    This paper proposes and analyzes a mathematical model of an infectious disease system with a piecewise control function concerning threshold policy for disease management strategy. The proposed models extend the classic models by including a piecewise incidence rate to represent control or precautionary measures being triggered once the number of infected individuals exceeds a threshold level. The long-term behaviour of the proposed non-smooth system under this strategy consists of the so-called sliding motion-a very rapid switching between application and interruption of the control action. Model solutions ultimately approach either one of two endemic states for two structures or the sliding equilibrium on the switching surface, depending on the threshold level. Our findings suggest that proper combinations of threshold densities and control intensities based on threshold policy can either preclude outbreaks or lead the number of infected to a previously chosen level.

  11. Universal fuzzy integral sliding-mode controllers for stochastic nonlinear systems.

    PubMed

    Gao, Qing; Liu, Lu; Feng, Gang; Wang, Yong

    2014-12-01

    In this paper, the universal integral sliding-mode controller problem for the general stochastic nonlinear systems modeled by Itô type stochastic differential equations is investigated. One of the main contributions is that a novel dynamic integral sliding mode control (DISMC) scheme is developed for stochastic nonlinear systems based on their stochastic T-S fuzzy approximation models. The key advantage of the proposed DISMC scheme is that two very restrictive assumptions in most existing ISMC approaches to stochastic fuzzy systems have been removed. Based on the stochastic Lyapunov theory, it is shown that the closed-loop control system trajectories are kept on the integral sliding surface almost surely since the initial time, and moreover, the stochastic stability of the sliding motion can be guaranteed in terms of linear matrix inequalities. Another main contribution is that the results of universal fuzzy integral sliding-mode controllers for two classes of stochastic nonlinear systems, along with constructive procedures to obtain the universal fuzzy integral sliding-mode controllers, are provided, respectively. Simulation results from an inverted pendulum example are presented to illustrate the advantages and effectiveness of the proposed approaches.

  12. High-vacuum adhesion and friction properties of sliding contact-mode micromachines

    NASA Astrophysics Data System (ADS)

    Xiang, H.; Komvopoulos, K.

    2013-07-01

    The evolution of adhesion and friction in contact-mode micromachines operated in high vacuum was studied by tracking changes in the adhesive pressure, interfacial shear strength, and static coefficient of friction with accumulating sliding cycles. Low adhesion and high static friction observed during the initial stage of sliding were followed by monotonically intensifying adhesion and decreasing friction until reaching an equilibrium stage at steady-state sliding. This trend revealed the existence of two friction regimes in which asperity deformation and adhesion were the dominant friction mechanisms. Scanning electron microscopy and atomic force microscopy observations indicated that sliding resulted in physical and chemical surface changes. The evolution of the adhesion and friction properties with sliding cycles is attributed to the increase of both the real contact area and the work of adhesion due to nanoscale surface smoothening and the removal of contaminant adsorbents, respectively.

  13. Semi-active sliding mode control of vehicle suspension with magneto-rheological damper

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Wang, Enrong; Zhang, Ning; Min, Fuhong; Subash, Rakheja; Su, Chunyi

    2015-01-01

    The vehicle semi-active suspension with magneto-rheological damper(MRD) has been a hot topic since this decade, in which the robust control synthesis considering load variation is a challenging task. In this paper, a new semi-active controller based upon the inverse model and sliding mode control (SMC) strategies is proposed for the quarter-vehicle suspension with the magneto-rheological (MR) damper, wherein an ideal skyhook suspension is employed as the control reference model and the vehicle sprung mass is considered as an uncertain parameter. According to the asymptotical stability of SMC, the dynamic errors between the plant and reference systems are used to derive the control damping force acquired by the MR quarter-vehicle suspension system. The proposed modified Bouc-wen hysteretic force-velocity ( F- v) model and its inverse model of MR damper, as well as the proposed continuous modulation (CM) filtering algorithm without phase shift are employed to convert the control damping force into the direct drive current of the MR damper. Moreover, the proposed semi-active sliding mode controller (SSMC)-based MR quarter-vehicle suspension is systematically evaluated through comparing the time and frequency domain responses of the sprung and unsprung mass displacement accelerations, suspension travel and the tire dynamic force with those of the passive quarter-vehicle suspension, under three kinds of varied amplitude harmonic, rounded pulse and real-road measured random excitations. The evaluation results illustrate that the proposed SSMC can greatly suppress the vehicle suspension vibration due to uncertainty of the load, and thus improve the ride comfort and handling safety. The study establishes a solid theoretical foundation as the universal control scheme for the adaptive semi-active control of the MR full-vehicle suspension decoupled into four MR quarter-vehicle sub-suspension systems.

  14. Microgravity Isolation Control System Design Via High-Order Sliding Mode Control

    NASA Technical Reports Server (NTRS)

    Shkolnikov, Ilya; Shtessel, Yuri; Whorton, Mark S.; Jackson, Mark

    2000-01-01

    Vibration isolation control system design for a microgravity experiment mount is considered. The controller design based on dynamic sliding manifold (DSM) technique is proposed to attenuate the accelerations transmitted to an isolated experiment mount either from a vibrating base or directly generated by the experiment, as well as to stabilize the internal dynamics of this nonminimum phase plant. An auxiliary DSM is employed to maintain the high-order sliding mode on the primary sliding manifold in the presence of uncertain actuator dynamics of second order. The primary DSM is designed for the closed-loop system in sliding mode to be a filter with given characteristics with respect to the input external disturbances.

  15. Finite-time control for nonlinear spacecraft attitude based on terminal sliding mode technique.

    PubMed

    Song, Zhankui; Li, Hongxing; Sun, Kaibiao

    2014-01-01

    In this paper, a fast terminal sliding mode control (FTSMC) scheme with double closed loops is proposed for the spacecraft attitude control. The FTSMC laws are included both in an inner control loop and an outer control loop. Firstly, a fast terminal sliding surface (FTSS) is constructed, which can drive the inner loop tracking-error and the outer loop tracking-error on the FTSS to converge to zero in finite time. Secondly, FTSMC strategy is designed by using Lyaponov's method for ensuring the occurrence of the sliding motion in finite time, which can hold the character of fast transient response and improve the tracking accuracy. It is proved that FTSMC can guarantee the convergence of tracking-error in both approaching and sliding mode surface. Finally, simulation results demonstrate the effectiveness of the proposed control scheme.

  16. Dynamic output feedback sliding mode control for uncertain mechanical systems without velocity measurements.

    PubMed

    Chang, Jeang-Lin

    2010-04-01

    For MIMO mechanical systems using position measurements only, this paper presents a dynamic output feedback sliding mode control algorithm in which an additional dynamics is introduced into the design of the sliding surface. Although the system has the mismatched uncertainty and external disturbance, once the system is in the sliding mode, the proposed method can guarantee robust stabilization and sustain the nature of performing disturbance attenuation through utilizing H(infinity) control analytical technique. A controller is then designed to drive the system to the sliding surface in a finite time and stay on it thereafter. Finally, a numerical example is explained for demonstrating the applicability of the proposed scheme. Copyright 2009 ISA. Published by Elsevier Ltd. All rights reserved.

  17. Global Sliding Mode Control for the Bank-to-Turn of Hypersonic Glide Vehicle

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Yu, Y. F.; Yan, P. P.; Fan, Y. H.; Guo, X. W.

    2017-03-01

    The technology of Bank-to-Turn has been recognized as an attractive direction due to their significance for the control of hypersonic glide vehicle. Strong coupling existing among pitch, yaw and roll channel was a great challenge for banking to turn, and thus a novel global sliding mode controller was designed for hypersonic glider in this paper. Considering the coupling among channels as interference, we can use invariance principle of sliding mode motion to realize the decoupling control. The global sliding mode control system could eliminate the stage of reaching, which can lead to the realization of whole systematic process decoupling control. When the global sliding mode factor was designed, a minimum norm pole assignment method of the sliding mode matrix was introduced to improve the robustness of the system. The method of continuity of symbolic function was adopted to overcome the chatter, which furtherly modify the transient performance of the system. The simulation results show that this method has good performance of three channel decoupling control and guidance command tracking. And it can meet the requirements of the dynamic performance of the system.

  18. Second-order sliding mode control for DFIG-based wind turbines fault ride-through capability enhancement.

    PubMed

    Benbouzid, Mohamed; Beltran, Brice; Amirat, Yassine; Yao, Gang; Han, Jingang; Mangel, Hervé

    2014-05-01

    This paper deals with the fault ride-through capability assessment of a doubly fed induction generator-based wind turbine using a high-order sliding mode control. Indeed, it has been recently suggested that sliding mode control is a solution of choice to the fault ride-through problem. In this context, this paper proposes a second-order sliding mode as an improved solution that handle the classical sliding mode chattering problem. Indeed, the main and attractive features of high-order sliding modes are robustness against external disturbances, the grids faults in particular, and chattering-free behavior (no extra mechanical stress on the wind turbine drive train). Simulations using the NREL FAST code on a 1.5-MW wind turbine are carried out to evaluate ride-through performance of the proposed high-order sliding mode control strategy in case of grid frequency variations and unbalanced voltage sags.

  19. Cytopathology whole slide images and adaptive tutorials for postgraduate pathology trainees: a randomized crossover trial.

    PubMed

    Van Es, Simone L; Kumar, Rakesh K; Pryor, Wendy M; Salisbury, Elizabeth L; Velan, Gary M

    2015-09-01

    To determine whether cytopathology whole slide images and virtual microscopy adaptive tutorials aid learning by postgraduate trainees, we designed a randomized crossover trial to evaluate the quantitative and qualitative impact of whole slide images and virtual microscopy adaptive tutorials compared with traditional glass slide and textbook methods of learning cytopathology. Forty-three anatomical pathology registrars were recruited from Australia, New Zealand, and Malaysia. Online assessments were used to determine efficacy, whereas user experience and perceptions of efficiency were evaluated using online Likert scales and open-ended questions. Outcomes of online assessments indicated that, with respect to performance, learning with whole slide images and virtual microscopy adaptive tutorials was equivalent to using traditional methods. High-impact learning, efficiency, and equity of learning from virtual microscopy adaptive tutorials were strong themes identified in open-ended responses. Participants raised concern about the lack of z-axis capability in the cytopathology whole slide images, suggesting that delivery of z-stacked whole slide images online may be important for future educational development. In this trial, learning cytopathology with whole slide images and virtual microscopy adaptive tutorials was found to be as effective as and perceived as more efficient than learning from glass slides and textbooks. The use of whole slide images and virtual microscopy adaptive tutorials has the potential to provide equitable access to effective learning from teaching material of consistently high quality. It also has broader implications for continuing professional development and maintenance of competence and quality assurance in specialist practice. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Advanced Interval Type-2 Fuzzy Sliding Mode Control for Robot Manipulator.

    PubMed

    Hwang, Ji-Hwan; Kang, Young-Chang; Park, Jong-Wook; Kim, Dong W

    2017-01-01

    In this paper, advanced interval type-2 fuzzy sliding mode control (AIT2FSMC) for robot manipulator is proposed. The proposed AIT2FSMC is a combination of interval type-2 fuzzy system and sliding mode control. For resembling a feedback linearization (FL) control law, interval type-2 fuzzy system is designed. For compensating the approximation error between the FL control law and interval type-2 fuzzy system, sliding mode controller is designed, respectively. The tuning algorithms are derived in the sense of Lyapunov stability theorem. Two-link rigid robot manipulator with nonlinearity is used to test and the simulation results are presented to show the effectiveness of the proposed method that can control unknown system well.

  1. Sliding mode control for multi-agent systems under a time-varying topology

    NASA Astrophysics Data System (ADS)

    Dong, Lijing; Chai, Senchun; Zhang, Baihai; Kiong Nguang, Sing

    2016-07-01

    This paper addresses the tracking problem of a class of multi-agent systems under uncertain communication environments which has been modelled by a finite number of constant Laplacian matrices together with their corresponding scheduling functions. Sliding mode control method is applied to solve this nonlinear tracking problem under a time-varying topology. The controller of each tracking agent has been designed by using only its own and neighbours' information. Sufficient conditions for the existence of a sliding mode control tracking strategy have been provided by the solvability of linear matrix inequalities. At the end of this work, numerical simulations are employed to demonstrate the effectiveness of the proposed sliding mode control tracking strategy.

  2. Sliding-mode control design for nonlinear systems using probability density function shaping.

    PubMed

    Liu, Yu; Wang, Hong; Hou, Chaohuan

    2014-02-01

    In this paper, we propose a sliding-mode-based stochastic distribution control algorithm for nonlinear systems, where the sliding-mode controller is designed to stabilize the stochastic system and stochastic distribution control tries to shape the sliding surface as close as possible to the desired probability density function. Kullback-Leibler divergence is introduced to the stochastic distribution control, and the parameter of the stochastic distribution controller is updated at each sample interval rather than using a batch mode. It is shown that the estimated weight vector will converge to its ideal value and the system will be asymptotically stable under the rank-condition, which is much weaker than the persistent excitation condition. The effectiveness of the proposed algorithm is illustrated by simulation.

  3. Advanced Interval Type-2 Fuzzy Sliding Mode Control for Robot Manipulator

    PubMed Central

    Hwang, Ji-Hwan; Kang, Young-Chang

    2017-01-01

    In this paper, advanced interval type-2 fuzzy sliding mode control (AIT2FSMC) for robot manipulator is proposed. The proposed AIT2FSMC is a combination of interval type-2 fuzzy system and sliding mode control. For resembling a feedback linearization (FL) control law, interval type-2 fuzzy system is designed. For compensating the approximation error between the FL control law and interval type-2 fuzzy system, sliding mode controller is designed, respectively. The tuning algorithms are derived in the sense of Lyapunov stability theorem. Two-link rigid robot manipulator with nonlinearity is used to test and the simulation results are presented to show the effectiveness of the proposed method that can control unknown system well. PMID:28280505

  4. Self-Tuning Sliding Mode Controller—Program Control for Process and Mechanical System—

    NASA Astrophysics Data System (ADS)

    Sakamoto, Noriaki; Komiyama, Daigo; Kubota, Masakazu

    Sliding mode control is a well-known technique to guarantee robustness in the presence of uncertainties of modeling, parameter variations, and external disturbances. The sliding mode control law is based on the knowledge of controlled system and the norm (or maximum value, etc.) of uncertainties. However, the modeling work is difficult, and the cost of it is expensive. So, this paper proposes the self-tuning sliding mode controller that calculates the control input (manipulated variable) only by using the desired value and the state variable without requiring the system parameter, the input parameter and the size of the disturbance. Various experiments, which are the temperature control of aluminum and wood-ceramics, the level control of the water tank, and the position control of the shape memory alloy in the program control (time-scheduled control), show the validity and utility of the proposed controller.

  5. Disturbance observer based sliding mode control of nonlinear mismatched uncertain systems

    NASA Astrophysics Data System (ADS)

    Ginoya, Divyesh; Shendge, P. D.; Phadke, S. B.

    2015-09-01

    This paper presents a new design of multiple-surface sliding mode control for a class of nonlinear uncertain systems with mismatched uncertainties and disturbances. In the method of multiple-surface sliding mode control, it is required to compensate for the derivatives of the virtual inputs which gives rise to the so-called problem of 'explosion of terms'. In this paper a disturbance observer based multiple-surface sliding mode control is proposed to estimate the uncertainties as well as the derivative of the virtual inputs to overcome this problem. The practical stability of the overall system is proved. The effectiveness of the proposed control strategy is illustrated via simulation of a benchmark problem and comparison with other control strategies. The proposed scheme is validated by implementing it on a serial flexible joint manipulator in the laboratory.

  6. Nonlinear integral sliding mode control design of photovoltaic pumping system: Real time implementation.

    PubMed

    Chihi, Asma; Ben Azza, Hechmi; Jemli, Mohamed; Sellami, Anis

    2017-09-01

    The aim of this paper is to provide high performance control of pumping system. The proposed method is designed by an indirect field oriented control based on Sliding Mode (SM) technique. The first contribution of this work is to design modified switching surfaces which presented by adding an integral action to the considered controlled variables. Then, in order to prevent the chattering phenomenon, modified nonlinear component is developed. The SM concept and a Lyapunov function are combined to compute the Sliding Mode Control (SMC) gains. Besides, the motor performance is validated by numeric simulations and real time implementation using a dSpace system with DS1104 controller board. Also, to show the effectiveness of the proposed approach, the obtained results are compared with other techniques such as conventional PI, Proportional Sliding Mode (PSM) and backstepping controls. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  7. Discrete-time sliding mode control for uncertain systems with state and input delays

    NASA Astrophysics Data System (ADS)

    Pai, Ming-Chang

    2010-12-01

    This article presents a discrete-time sliding mode control method for the robust stabilisation of linear uncertain multi-input discrete-time systems with state and input delays. The systems are assumed to have structured mismatched time-varying parameter uncertainties. A specified switching surface is proposed and a sliding mode controller is derived to ensure the existence of the quasi-sliding mode. Based on the improved Lyapunov function and linear matrix inequality technique, delay-independent sufficient conditions for the design of a stable switching surface are given and the stability of the overall closed-loop system is guaranteed. Neither chattering phenomenon will occur nor the knowledge of upper bound of uncertainties is required. Finally, simulation results demonstrate the efficacy of the proposed control methodology.

  8. Robust sliding mode control for fractional-order chaotic economical system with parameter uncertainty and external disturbance

    NASA Astrophysics Data System (ADS)

    Zhou, Ke; Wang, Zhi-Hui; Gao, Li-Ke; Sun, Yue; Ma, Tie-Dong

    2015-03-01

    This paper presents a modified sliding mode control for fractional-order chaotic economical systems with parameter uncertainty and external disturbance. By constructing the suitable sliding mode surface with fractional-order integral, the effective sliding mode controller is designed to realize the asymptotical stability of fractional-order chaotic economical systems. Comparing with the existing results, the main results in this paper are more practical and rigorous. Simulation results show the effectiveness and feasibility of the proposed sliding mode control method. Project supported by the National Natural Science Foundation of China (Grant Nos. 51207173 and 51277192).

  9. Unknown Input and Sensor Fault Estimation Using Sliding-Mode Observers

    SciTech Connect

    Kalsi, Karanjit; Hui, Stefen; Zak, Stanislaw

    2011-06-29

    Sliding-mode observers are used to construct unknown input estimators. Then, these unknown input estimators are combined with sensor fault estimation schemes into one architecture that employs two sliding-mode observers for simultaneously estimating the plant’s actuator faults (part of the unknown input) and detecting sensor faults. Closed form expressions are presented for the estimates of unknown inputs and sensor faults. A benchmark example of a controlled inverted pendulum system from the literature is utilized in the simulation study. The study shows that the observers analyzed in this paper generate good estimates of the unknown input and sensor faults signals in noisy environments for nonlinear plants.

  10. Dynamic optimal sliding-mode control for six-DOF follow-up robust tracking of active satellite

    NASA Astrophysics Data System (ADS)

    Yuankai, Li; Zhongliang, Jing; Shiqiang, Hu

    2011-09-01

    This paper presents a six-DOF follow-up tracking scheme for active target satellite tracking. The scheme is mainly composed of a robust tracking algorithm and a six-DOF follow-up control law. Firstly, a relative motion model using osculating reference orbit (ORO) is built and applied to the redundant adaptive robust extended Kalman filter (RAREKF) to form an ORO-based robust method as the tracking algorithm. Then, a dynamic optimal sliding-mode control (DOSMC) with dynamic optimal sliding surface (DOSS) is proposed to design the six-DOF follow-up control of both relative orbit and chaser attitude. The scheme structure is also discussed in the paper. Three cases are simulated to illustrate the advantage of ORO-based RAREKF and DOSMC and to verify the effectiveness of the presented follow-up tracking scheme.

  11. Integral backstepping sliding mode control for underactuated systems: swing-up and stabilization of the Cart-Pendulum System.

    PubMed

    Adhikary, Nabanita; Mahanta, Chitralekha

    2013-11-01

    In this paper an integral backstepping sliding mode controller is proposed for controlling underactuated systems. A feedback control law is designed based on backstepping algorithm and a sliding surface is introduced in the final stage of the algorithm. The backstepping algorithm makes the controller immune to matched and mismatched uncertainties and the sliding mode control provides robustness. The proposed controller ensures asymptotic stability. The effectiveness of the proposed controller is compared against a coupled sliding mode controller for swing-up and stabilization of the Cart-Pendulum System. Simulation results show that the proposed integral backstepping sliding mode controller is able to reject both matched and mismatched uncertainties with a chattering free control law, while utilizing less control effort than the sliding mode controller.

  12. Sliding Mode Control of the X-33 with an Engine Failure

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.; Hall, Charles E.

    2000-01-01

    Ascent flight control of the X-3 is performed using two XRS-2200 linear aerospike engines. in addition to aerosurfaces. The baseline control algorithms are PID with gain scheduling. Flight control using an innovative method. Sliding Mode Control. is presented for nominal and engine failed modes of flight. An easy to implement, robust controller. requiring no reconfiguration or gain scheduling is demonstrated through high fidelity flight simulations. The proposed sliding mode controller utilizes a two-loop structure and provides robust. de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of engine failure, bounded external disturbances (wind gusts) and uncertain matrix of inertia. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues. Conditions that restrict engine failures to robustness domain of the sliding mode controller are derived. Overall stability of a two-loop flight control system is assessed. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in the presence of external disturbances and vehicle inertia uncertainties, as well as the single engine failed case. The designed robust controller will significantly reduce the time and cost associated with flying new trajectory profiles or orbits, with new payloads, and with modified vehicles

  13. Fractional order sliding mode control for tethered satellite deployment with disturbances

    NASA Astrophysics Data System (ADS)

    Kang, Junjie; Zhu, Zheng H.; Wang, Wei; Li, Aijun; Wang, Changqing

    2017-01-01

    This paper proposes a fractional order sliding mode control for the deployment of tethered space systems with the consideration of uncertainty of external disturbances and unmodeled system dynamics. The proposed fractional order sliding mode control consists of two sub-sliding manifolds that are defined separately for the actuated and unactuated states. This, in turn, generates a control scheme to make all states move toward to the desired states. The stability analysis of the proposed control law indicates not only all states converge to the desired states at equilibrium but also disturbances caused by the uncertainty can be suppressed satisfactorily. Parametric studies are conducted to investigate the influences of fractional order and sub-sliding manifold of unactuated states on the performance of the proposed control law. The performance is compared with the sliding mode, PD and fractional order PD control laws for a baseline scenario of tether deployment. The proposed control law performs better than others in the settling time and the maximum pitch angle control in the presence of unwanted disturbances. Effectiveness and robustness of the proposed control law are demonstrated by computer simulations.

  14. Vibration suppression in flexible structures via the sliding-mode control approach

    NASA Technical Reports Server (NTRS)

    Drakunov, S.; Oezguener, Uemit

    1994-01-01

    Sliding mode control became very popular recently because it makes the closed loop system highly insensitive to external disturbances and parameter variations. Sliding algorithms for flexible structures have been used previously, but these were based on finite-dimensional models. An extension of this approach for differential-difference systems is obtained. That makes if possible to apply sliding-mode control algorithms to the variety of nondispersive flexible structures which can be described as differential-difference systems. The main idea of using this technique for dispersive structures is to reduce the order of the controlled part of the system by applying an integral transformation. We can say that transformation 'absorbs' the dispersive properties of the flexible structure as the controlled part becomes dispersive.

  15. Robust stabilization of underactuated nonlinear systems: A fast terminal sliding mode approach.

    PubMed

    Khan, Qudrat; Akmeliawati, Rini; Bhatti, Aamer Iqbal; Khan, Mahmood Ashraf

    2017-01-01

    This paper presents a fast terminal sliding mode based control design strategy for a class of uncertain underactuated nonlinear systems. Strategically, this development encompasses those electro-mechanical underactuated systems which can be transformed into the so-called regular form. The novelty of the proposed technique lies in the hierarchical development of a fast terminal sliding attractor design for the considered class. Having established sliding mode along the designed manifold, the close loop dynamics become finite time stable which, consequently, result in high precision. In addition, the adverse effects of the chattering phenomenon are reduced via strong reachability condition and the robustness of the system against uncertainties is confirmed theoretically. A simulation as well as experimental study of an inverted pendulum is presented to demonstrate the applicability of the proposed technique.

  16. Dynamic Sliding Mode Autopilot for Nonlinear Non-Minimum Phase Flight Vehicle

    NASA Astrophysics Data System (ADS)

    Bahrami, Mohsen; Ebrahimi, Behrouz; Roshanian, Jafar

    Design and synthesis of a nonlinear non-minimum phase supersonic flight vehicle longitudinal dynamics control for g commands output tracking are presented. The non-minimum nature of the resulting input/output pair necessitates using a modified switching manifold in sliding mode control theory. The dynamic sliding manifold is designed to compensate for unstable internal dynamics of the system associated with coupling between the moment generating actuators and aerodynamic forces on the flight vehicle. The method is simple to implement in practical applications and enables the sliding mode control design to exhibit the desired dynamic properties during the entire output-tracking process independent of matched perturbations and accommodates unmatched perturbations. Simulation results are presented to demonstrate the performance, robustness, and stability of the autopilot.

  17. Smith predictor based-sliding mode controller for integrating processes with elevated deadtime.

    PubMed

    Camacho, Oscar; De la Cruz, Francisco

    2004-04-01

    An approach to control integrating processes with elevated deadtime using a Smith predictor sliding mode controller is presented. A PID sliding surface and an integrating first-order plus deadtime model have been used to synthesize the controller. Since the performance of existing controllers with a Smith predictor decrease in the presence of modeling errors, this paper presents a simple approach to combining the Smith predictor with the sliding mode concept, which is a proven, simple, and robust procedure. The proposed scheme has a set of tuning equations as a function of the characteristic parameters of the model. For implementation of our proposed approach, computer based industrial controllers that execute PID algorithms can be used. The performance and robustness of the proposed controller are compared with the Matausek-Micić scheme for linear systems using simulations.

  18. A sliding mode control proposal for open-loop unstable processes.

    PubMed

    Rojas, Rubén; Camacho, Oscar; González, Luis

    2004-04-01

    This papers presents a sliding mode controller based on a first-order-plus-dead-time model of the process for controlling open-loop unstable systems. The proposed controller has a simple and fixed structure with a set of tuning equations as a function of the desired performance. Both linear and nonlinear models were used to study the controller performance by computer simulations.

  19. RCMAC hybrid control for MIMO uncertain nonlinear systems using sliding-mode technology.

    PubMed

    Lin, Chih-Min; Chen, Li-Yang; Chen, Chiu-Hsiung

    2007-05-01

    A hybrid control system, integrating principal and compensation controllers, is developed for multiple-input-multiple-output (MIMO) uncertain nonlinear systems. This hybrid control system is based on sliding-mode technique and uses a recurrent cerebellar model articulation controller (RCMAC) as an uncertainty observer. The principal controller containing an RCMAC uncertainty observer is the main controller, and the compensation controller is a compensator for the approximation error of the system uncertainty. In addition, in order to relax the requirement of approximation error bound, an estimation law is derived to estimate the error bound. The Taylor linearization technique is employed to increase the learning ability of RCMAC and the adaptive laws of the control system are derived based on Lyapunov stability theorem and Barbalat's lemma so that the asymptotical stability of the system can be guaranteed. Finally, the proposed design method is applied to control a biped robot. Simulation results demonstrate the effectiveness of the proposed control scheme for the MIMO uncertain nonlinear system.

  20. Sliding mode control for a three phase multicellular inverter dedicated to renewable energy systems

    NASA Astrophysics Data System (ADS)

    Hemici, K.; Zegaoui, A.; Djahbar, A.; Bokhtache, A. Aissa; Kessaissia, F. Z.; Allouache, H.; Mahmoudi, M. O.; Aillerie, M.

    2017-02-01

    In this paper, Sliding Mode controller has been sized to control multi-cell converters configured as a three-phase multicellular inverter. Unlike traditional inverters, multicellular inverters have the following advantages: lower switching frequency, high number of output levels, and less voltage constraints on the power switch. Significant performances are provided with this structure, which is constituted with flying capacitors. The main purpose of this paper is to present the model and generate commutation sliding-surfaces based on a Lyapunov function. The performed simulations point the efficiency of the proposed strategy with a three-phase multicellular inverters and allow to assess the performances and the robustness of the synthesized controller.

  1. Uncertainty Quantification for Robust Control of Wind Turbines using Sliding Mode Observer

    NASA Astrophysics Data System (ADS)

    Schulte, Horst

    2016-09-01

    A new quantification method of uncertain models for robust wind turbine control using sliding-mode techniques is presented with the objective to improve active load mitigation. This approach is based on the so-called equivalent output injection signal, which corresponds to the average behavior of the discontinuous switching term, establishing and maintaining a motion on a so-called sliding surface. The injection signal is directly evaluated to obtain estimates of the uncertainty bounds of external disturbances and parameter uncertainties. The applicability of the proposed method is illustrated by the quantification of a four degree-of-freedom model of the NREL 5MW reference turbine containing uncertainties.

  2. Model-based Sliding Mode Controller of Anti-lock Braking System

    NASA Astrophysics Data System (ADS)

    Zheng, Lin; Luo, Yue-Gang; Kang, Jing; Shi, Zhan-Qun

    2016-05-01

    The anti-lock braking system (ABS) used in automobiles is used to prevent wheel from lockup and to maintain the steering ability and stability. The sliding mode controller is able to control nonlinear system steadily. In this research, a one-wheel dynamic model with ABS control is built up using model-based method. Using the sliding model controller, the simulation results by using Matlab/Simulink show qualified data compared with optimal slip rate. By using this method, the ABS brake efficiency is improved efficiently.

  3. X33 Reusable Launch Vehicle Control on Sliding Modes: Concepts for a Control System Development

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.

    1998-01-01

    Control of the X33 reusable launch vehicle is considered. The launch control problem consists of automatic tracking of the launch trajectory which is assumed to be optimally precalculated. It requires development of a reliable, robust control algorithm that can automatically adjust to some changes in mission specifications (mass of payload, target orbit) and the operating environment (atmospheric perturbations, interconnection perturbations from the other subsystems of the vehicle, thrust deficiencies, failure scenarios). One of the effective control strategies successfully applied in nonlinear systems is the Sliding Mode Control. The main advantage of the Sliding Mode Control is that the system's state response in the sliding surface remains insensitive to certain parameter variations, nonlinearities and disturbances. Employing the time scaling concept, a new two (three)-loop structure of the control system for the X33 launch vehicle was developed. Smoothed sliding mode controllers were designed to robustly enforce the given closed-loop dynamics. Simulations of the 3-DOF model of the X33 launch vehicle with the table-look-up models for Euler angle reference profiles and disturbance torque profiles showed a very accurate, robust tracking performance.

  4. Sliding-Mode Control Applied for Robust Control of a Highly Unstable Aircraft

    NASA Technical Reports Server (NTRS)

    Vetter, Travis Kenneth

    2002-01-01

    An investigation into the application of an observer based sliding mode controller for robust control of a highly unstable aircraft and methods of compensating for actuator dynamics is performed. After a brief overview of some reconfigurable controllers, sliding mode control (SMC) is selected because of its invariance properties and lack of need for parameter identification. SMC is reviewed and issues with parasitic dynamics, which cause system instability, are addressed. Utilizing sliding manifold boundary layers, the nonlinear control is converted to a linear control and sliding manifold design is performed in the frequency domain. An additional feedback form of model reference hedging is employed which is similar to a prefilter and has large benefits to system performance. The effects of inclusion of actuator dynamics into the designed plant is heavily investigated. Multiple Simulink models of the full longitudinal dynamics and wing deflection modes of the forward swept aero elastic vehicle (FSAV) are constructed. Additionally a linear state space models to analyze effects from various system parameters. The FSAV has a pole at +7 rad/sec and is non-minimum phase. The use of 'model actuators' in the feedback path, and varying there design, is heavily investigated for the resulting effects on plant robustness and tolerance to actuator failure. The use of redundant actuators is also explored and improved robustness is shown. All models are simulated with severe failure and excellent tracking, and task dependent handling qualities, and low pilot induced oscillation tendency is shown.

  5. Time-varying sliding-coefficient-based decoupled terminal sliding-mode control for a class of fourth-order systems.

    PubMed

    Bayramoglu, Husnu; Komurcugil, Hasan

    2014-07-01

    A time-varying sliding-coefficient-based decoupled terminal sliding mode control strategy is presented for a class of fourth-order systems. First, the fourth-order system is decoupled into two second-order subsystems. The sliding surface of each subsystem was designed by utilizing time-varying coefficients. Then, the control target of one subsystem to another subsystem was embedded. Thereafter, a terminal sliding mode control method was utilized to make both subsystems converge to their equilibrium points in finite time. The simulation results on the inverted pendulum system demonstrate that the proposed method exhibits a considerable improvement in terms of a faster dynamic response and lower IAE and ITAE values as compared with the existing decoupled control methods.

  6. Classical and higher-order sliding mode attitude control for launch vehicle systems

    NASA Astrophysics Data System (ADS)

    Stott, James Edward, Jr.

    In determining flight controls for launch vehicle systems, several things must be taken into account. Launch vehicle systems can be expendable or reusable, carry crew or cargo, etc. Each of these launch vehicles maneuvers through a wide range of flight conditions and different mission profiles. Crewed vehicles must adhere to human rating requirements which limit the angular rates. Reusable launch vehicle systems must take into account actuator saturation during entry. Wind disturbances and plant uncertainties are major perturbations to the nominal state of any launch vehicle. An ideal controller is one that is robust enough to handle these uncertainties and external disturbances with limited control authority. One major challenge that exists in the design of these vehicles is the updating of old autopilot technology to new robust designs while also taking into account the different type of launch vehicle system employed. Sliding mode control algorithms that are inherently robust to external disturbances and plant uncertainties are very good candidates for improving the robustness and accuracy of the flight control systems. This dissertation focuses on systematically studying and developing a 'toolbox' of classical and higher-order sliding mode attitude control algorithms for different types of launch vehicle systems operating in uncertain conditions, including model uncertainties, actuator malfunctions, and external perturbations such as wind gusts. The developed toolbox comprises of time-varying sliding variables, classical and higher-order sliding mode attitude control algorithms, and observer techniques that yield novel sliding mode attitude control architectures. The proposed control toolbox allows achieving even higher standards of performance, reliability, safety, operability, and cost for launch vehicles over the current state of the art. Case studies include controlling the X-33 and SLV-X Launch Vehicles studied under NASA's Space Launch Initiative (SLI

  7. Two-Link Flexible Manipulator Control Using Sliding Mode Control Based Linear Matrix Inequality

    NASA Astrophysics Data System (ADS)

    Zulfatman; Marzuki, Mohammad; Alif Mardiyah, Nur

    2017-04-01

    Two-link flexible manipulator is a manipulator robot which at least one of its arms is made of lightweight material and not rigid. Flexible robot manipulator has some advantages over the rigid robot manipulator, such as lighter, requires less power and costs, and to result greater payload. However, suitable control algorithm to maintain the two-link flexible robot manipulator in accurate positioning is very challenging. In this study, sliding mode control (SMC) was employed as robust control algorithm due to its insensitivity on the system parameter variations and the presence of disturbances when the system states are sliding on a sliding surface. SMC algorithm was combined with linear matrix inequality (LMI), which aims to reduce the effects of chattering coming from the oscillation of the state during sliding on the sliding surface. Stability of the control algorithm is guaranteed by Lyapunov function candidate. Based on simulation works, SMC based LMI resulted in better performance improvements despite the disturbances with significant chattering reduction. This was evident from the decline of the sum of squared tracking error (SSTE) and the sum of squared of control input (SSCI) indexes respectively 25.4% and 19.4%.

  8. Adaptive braking by Ase1 prevents overlapping microtubules from sliding completely apart.

    PubMed

    Braun, Marcus; Lansky, Zdenek; Fink, Gero; Ruhnow, Felix; Diez, Stefan; Janson, Marcel E

    2011-09-04

    Short regions of overlap between ends of antiparallel microtubules are central elements within bipolar microtubule arrays. Although their formation requires motors, recent in vitro studies demonstrated that stable overlaps cannot be generated by molecular motors alone. Motors either slide microtubules along each other until complete separation or, in the presence of opposing motors, generate oscillatory movements. Here, we show that Ase1, a member of the conserved MAP65/PRC1 family of microtubule-bundling proteins, enables the formation of stable antiparallel overlaps through adaptive braking of Kinesin-14-driven microtubule-microtubule sliding. As overlapping microtubules start to slide apart, Ase1 molecules become compacted in the shrinking overlap and the sliding velocity gradually decreases in a dose-dependent manner. Compaction is driven by moving microtubule ends that act as barriers to Ase1 diffusion. Quantitative modelling showed that the molecular off-rate of Ase1 is sufficiently low to enable persistent overlap stabilization over tens of minutes. The finding of adaptive braking demonstrates that sliding can be slowed down locally to stabilize overlaps at the centre of bipolar arrays, whereas sliding proceeds elsewhere to enable network self-organization.

  9. Event-triggered sliding mode control for a class of nonlinear systems

    NASA Astrophysics Data System (ADS)

    Behera, Abhisek K.; Bandyopadhyay, Bijnan

    2016-09-01

    Event-triggering strategy is one of the real-time control implementation techniques which aims at achieving minimum resource utilisation while ensuring the satisfactory performance of the closed-loop system. In this paper, we address the problem of robust stabilisation for a class of nonlinear systems subject to external disturbances using sliding mode control (SMC) by event-triggering scheme. An event-triggering scheme is developed for SMC to ensure the sliding trajectory remains confined in the vicinity of sliding manifold. The event-triggered SMC brings the sliding mode in the system and thus the steady-state trajectories of the system also remain bounded within a predesigned region in the presence of disturbances. The design of event parameters is also given considering the practical constraints on control execution. We show that the next triggering instant is larger than its immediate past triggering instant by a given positive constant. The analysis is also presented with taking delay into account in the control updates. An upper bound for delay is calculated to ensure stability of the system. It is shown that with delay steady-state bound of the system is increased than that of the case without delay. However, the system trajectories remain bounded in the case of delay, so stability is ensured. The performance of this event-triggered SMC is demonstrated through a numerical simulation.

  10. Adaptive mode control in few mode fibers and its applications

    NASA Astrophysics Data System (ADS)

    Ashry, Islam; Lu, Peng; Xu, Yong

    2016-10-01

    With the development of mode-division-multiplexing (MDM), few mode fibers (FMFs) have found a wide range of applications in optical sensing and communications. However, how to precisely control the mode composition of optical signals in FMFs remains a difficult challenge. In this paper, we present an adaptive mode control method that can selectively excite the linearly polarized (LP) mode within the FMF. The method is based on using optical pulses reflected by a fiber Bragg grating (FBG) for wavefront optimization. Two potential applications are discussed. First, we theoretically demonstrate the feasibility of large scale multiplexing of absorption based fiber optical sensors. Second, we discuss the possibility of using mode dependent loss to reconstruct the spatial distributions of absorptive chemicals diffused within a FMF.

  11. A novel guidance law using fast terminal sliding mode control with impact angle constraints.

    PubMed

    Sun, Lianghua; Wang, Weihong; Yi, Ran; Xiong, Shaofeng

    2016-09-01

    This paper is concerned with the question of, for a missile interception with impact angle constraints, how to design a guidance law. Firstly, missile interception with impact angle constraints is modeled; secondly, a novel guidance law using fast terminal sliding mode control based on extended state observer is proposed to optimize the trajectory and time of interception; finally, for stationary targets, constant velocity targets and maneuvering targets, the guidance law and the stability of the closed loop system is analyzed and the stability of the closed loop system is analyzed, respectively. Simulation results show that when missile and target are on a collision course, the novel guidance law using fast terminal sliding mode control with extended state observer has more optimized trajectory and effectively reduces the time of interception which has a great significance in modern warfare. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Observation and sliding mode observer for nonlinear fractional-order system with unknown input.

    PubMed

    Djeghali, Nadia; Djennoune, Said; Bettayeb, Maamar; Ghanes, Malek; Barbot, Jean-Pierre

    2016-07-01

    The main purpose of this paper is twofold. First, the observability and the left invertibility properties and the observable canonical form for nonlinear fractional-order systems are introduced. By using a transformation, we show that these properties can be deduced from an equivalent nonlinear integer-order system. Second, a step by step sliding mode observer for fault detection and estimation in nonlinear fractional-order systems is proposed. Starting with a chained fractional-order integrators form, a step by step first-order sliding mode observer is designed. The finite time convergence of the observer is established by using Lyapunov stability theory. A numerical example is given to illustrate the performance of the proposed approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Terminal Sliding Mode-Based Consensus Tracking Control for Networked Uncertain Mechanical Systems on Digraphs.

    PubMed

    Chen, Gang; Song, Yongduan; Guan, Yanfeng

    2016-12-29

    This brief investigates the finite-time consensus tracking control problem for networked uncertain mechanical systems on digraphs. A new terminal sliding-mode-based cooperative control scheme is developed to guarantee that the tracking errors converge to an arbitrarily small bound around zero in finite time. All the networked systems can have different dynamics and all the dynamics are unknown. A neural network is used at each node to approximate the local unknown dynamics. The control schemes are implemented in a fully distributed manner. The proposed control method eliminates some limitations in the existing terminal sliding-mode-based consensus control methods and extends the existing analysis methods to the case of directed graphs. Simulation results on networked robot manipulators are provided to show the effectiveness of the proposed control algorithms.

  14. Smooth integral sliding mode controller for the position control of Stewart platform.

    PubMed

    Kumar P, Ramesh; Chalanga, Asif; Bandyopadhyay, B

    2015-09-01

    This paper proposes the application of a new algorithm for the position control of a Stewart platform. The conventional integral sliding mode controller is a combination of nominal control and discontinuous feedback control hence the overall control is discontinuous in nature. The discontinuity in the feedback control is undesirable for practical applications due to chattering which causes the wear and tear of the mechanical actuators. In this paper the existing integral sliding mode control law for systems with matched disturbances is modified by replacing the discontinuous part by a continuous modified twisting control. This proposed controller is continuous in nature due to the combinations of two continuous controls. The desired position of the platform has been achieved using the proposed controller even in the presence of matched disturbances. The effectiveness of the proposed controller has been proved with the simulation results.

  15. Implementation of fuzzy-sliding mode based control of a grid connected photovoltaic system.

    PubMed

    Menadi, Abdelkrim; Abdeddaim, Sabrina; Ghamri, Ahmed; Betka, Achour

    2015-09-01

    The present work describes an optimal operation of a small scale photovoltaic system connected to a micro-grid, based on both sliding mode and fuzzy logic control. Real time implementation is done through a dSPACE 1104 single board, controlling a boost chopper on the PV array side and a voltage source inverter (VSI) on the grid side. The sliding mode controller tracks permanently the maximum power of the PV array regardless of atmospheric condition variations, while The fuzzy logic controller (FLC) regulates the DC-link voltage, and ensures via current control of the VSI a quasi-total transit of the extracted PV power to the grid under a unity power factor operation. Simulation results, carried out via Matlab-Simulink package were approved through experiment, showing the effectiveness of the proposed control techniques. Copyright © 2015. Published by Elsevier Ltd.

  16. High-order sliding mode observers and integral backstepping sensorless control of IPMS motor

    NASA Astrophysics Data System (ADS)

    Hamida, M. A.; De Leon, J.; Glumineau, A.

    2014-10-01

    This paper presents a robust high-order sliding mode interconnected observer and an integral backstepping controller for a sensorless interior permanent magnet synchronous motor. To limit the chattering phenomenon on the observed state, a super twisting algorithm is combined with an interconnected observer to design a new high-order sliding mode observer which will be used for multiple-input multiple-output systems. The proposed observer is used to estimate in finite time the rotor position, the speed and the stator resistance. Moreover, a robust nonlinear controller based on the backstepping algorithm is designed where integral actions are introduced step by step. This controller allows to track a desired reference which is computed by using a maximum-torque-per-ampere strategy. Simulation results are shown to illustrate the performance of the proposed scheme by using significant trajectories including the zero speed and under parametric uncertainties.

  17. Biomolecular implementation of a quasi sliding mode feedback controller based on DNA strand displacement reactions.

    PubMed

    Sawlekar, Rucha; Montefusco, Francesco; Kulkarni, Vishwesh; Bates, Declan G

    2015-08-01

    A fundamental aim of synthetic biology is to achieve the capability to design and implement robust embedded biomolecular feedback control circuits. An approach to realize this objective is to use abstract chemical reaction networks (CRNs) as a programming language for the design of complex circuits and networks. Here, we employ this approach to facilitate the implementation of a class of nonlinear feedback controllers based on sliding mode control theory. We show how a set of two-step irreversible reactions with ultrasensitive response dynamics can provide a biomolecular implementation of a nonlinear quasi sliding mode (QSM) controller. We implement our controller in closed-loop with a prototype of a biological pathway and demonstrate that the nonlinear QSM controller outperforms a traditional linear controller by facilitating faster tracking response dynamics without introducing overshoots in the transient response.

  18. Smooth sliding mode control with a disturbance observer for a virtual axis parallel mechanism

    NASA Astrophysics Data System (ADS)

    Jiang, Daogen; Wang, Zhenhua; Wang, Zhenqi; Zhang, Xiaotong

    2013-10-01

    The control charactics of the virtual axis parallel mechanism is nonlinear and strong coupling as well as uncertainty. To achieve the goal of decoupling and inhibition of various uncertaities, this paper proposes the algorithm of smooth sliding mode control with a disturbance observer.In order to decline the inherent trembling of the sliding mode control, the paper uses the nonlinear power function such as fal(s,α , δ) in the approaching law decision. Also it uses the PVT interpolation strategy in the joint-space trajectory planning to ensure the stability of the mechanism movement, which is based on the mechnical kinematics models. Simulation of the trajectory tracing shows that the algorithm can improve the robust performance of the parameter perturbation and certain interferance, which achives the aim of the accurate steady-state performance and the good dynamic tracing performance.

  19. Position synchronised control of multiple robotic manipulators based on integral sliding mode

    NASA Astrophysics Data System (ADS)

    Zhao, Dongya; Zhu, Quanmin

    2014-03-01

    In this study, a new position synchronised control algorithm is developed for multiple robotic manipulator systems. In the merit of system synchronisation and integral sliding mode control, the proposed approach can stabilise position tracking of each robotic manipulator while coordinating its motion with the other manipulators. With the integral sliding mode, the proposed approach has insensitiveness against the lumped system uncertainty within the entire process of operation. Further, a perturbation estimator is proposed to reduce chattering effect. The corresponding stability analysis is presented to lay a foundation for theoretical understanding to the underlying issues as well as safely operating real systems. An illustrative example is bench tested to validate the effectiveness of the proposed approach.

  20. High-order sliding mode control for sensorless trajectory tracking of a PMSM

    NASA Astrophysics Data System (ADS)

    Delpoux, R.; Floquet, T.

    2014-10-01

    The paper presents a new sensorless approach for permanent magnet synchronous motor. Current sensors are assumed available, but position and velocity sensors are not. Based on the electrical equations, sliding mode observers are designed to estimate the back-electro motive force (EMF) of the motor. These estimations are used to reconstruct the position and the velocity. From this estimation, a robust sliding mode control is developed which ensures the position tracking of the motor. A new reference frame is used that presents advantages similar to the standard (d - q) frame, but without the need for a position sensor. The efficiency of the algorithm is shown through experimental results. The approach is potentially applicable to other types of synchronous motors as well.

  1. Stabilization of a Quadrotor With Uncertain Suspended Load Using Sliding Mode Control

    SciTech Connect

    Zhou, Xu; Liu, Rui; Zhang, Jiucai; Zhang, Xiaoli

    2016-08-21

    The stability and trajectory control of a quadrotor carrying a suspended load with a fixed known mass has been extensively studied in recent years. However, the load mass is not always known beforehand in practical applications. This mass uncertainty brings uncertain disturbances to the quadrotor system, causing existing controllers to have a worse performance or to be collapsed. To improve the quadrotor's stability in this situation, we investigate the impacts of the uncertain load mass on the quadrotor. By comparing the simulation results of two controllers -- the proportional-derivative (PD) controller and the sliding mode controller (SMC) driven by a sliding mode disturbance of observer (SMDO), the quadrotor's performance is verified to be worse as the uncertainty increases. The simulation results also show a controller with stronger robustness against disturbances is better for practical applications.

  2. Sliding mode control of the space nuclear reactor system TOPAZ II

    SciTech Connect

    Shtessel, Y.B.; Wyant, F.J.

    1996-03-01

    The Automatic Control System (ACS) of the space nuclear reactor power system TOPAZ II that generates electricity from nuclear heat using in-core thermionic converters is considered. Sliding Mode Control Technique was applied to the reactor system controller design in order to provide the robust high accuracy following of a neutron (thermal) power reference profile in a start up regime and a payload electric power (current) reference profile following in an operation regime. Extensive simulations of the TOPAZ II reactor system with the designed sliding mode controllers showed improved accuracy and robustness of the reactor system performances in a start up regime and in an electric power supply regime as well. {copyright} {ital 1996 American Institute of Physics.}

  3. Analysis and design of sliding mode controller gains for boost power factor corrector.

    PubMed

    Kessal, Abdelhalim; Rahmani, Lazhar

    2013-09-01

    This paper presents a systematic procedure to compute the gains of sliding mode controller based on an optimization scheme. This controller is oriented to drive an AC-DC converter operating in continuous mode with power factor near unity, and in order to improve static and dynamic performances with large variations of reference voltage and load. This study shows the great influence of the controller gains on the global performances of the system. Hence, a methodology for choosing the gains is detailed. The sliding surface used in this study contains two state variables, input current and output voltage; the advantage of this surface is getting reactions against various disturbances-at the power source, the reference of the output, or the value of the load. The controller is experimentally confirmed for steady-state performance and transient response.

  4. Output feedback sliding mode control for a linear multi-compartment lung mechanics system

    NASA Astrophysics Data System (ADS)

    Hou, Saing Paul; Meskin, Nader; Haddad, Wassim M.

    2014-10-01

    In this paper, we develop a sliding mode control architecture to control lung volume and minute ventilation in the presence of modelling system uncertainties. Since the applied input pressure to the lungs is, in general, nonnegative and cannot be arbitrarily large, as not to damage the lungs, a sliding mode control with bounded nonnegative control inputs is proposed. The controller only uses output information (i.e., the total volume of the lungs) and automatically adjusts the applied input pressure so that the system is able to track a given reference signal in the presence of parameter uncertainty (i.e., modelling uncertainty of the lung resistances and lung compliances) and system disturbances. Controllers for both matched and unmatched uncertainties are presented. Specifically, a Lyapunov-based approach is presented for the stability analysis of the system and the proposed control framework is applied to a two-compartment lung model to show the efficacy of the proposed control method.

  5. Discrete sliding mode controller with reaching phase elimination for TITO systems.

    PubMed

    Hajare, V D; Khandekar, A A; Patre, B M

    2017-01-01

    Sliding mode control (SMC) is emerged as a powerful robust controller for the process control application. However, it does not posses robustness properties during reaching phase and suffers from chattering, which is undesirable. In this paper, a chatter free discrete sliding mode controller (DSMC) with reaching phase elimination is proposed. The issue of existence of reaching phase due to physical constraints such as saturation of actuating devices is also addressed. The two-input-two-output (TITO) system is decoupled into two single-input-single-output (SISO) systems using ideal decoupler. The DSMCs are separately designed for two decoupled SISO systems. The stability is ensured via Lyapunov approach. Simulation study and experimentation on real life interacting two tank liquid level system are included to demonstrate effectiveness and applicability of the proposed controller. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  6. Sliding mode control with self-tuning law for uncertain nonlinear systems.

    PubMed

    Kuo, Tzu-Chun; Huang, Ying-Jeh; Chang, Shin-Hung

    2008-04-01

    A robust sliding mode control that follows a self-tuning law for nonlinear systems possessing uncertain parameters is proposed. The adjustable control gain and a bipolar sigmoid function are on-line tuned to force the tracking error to approach zero. Control system stability is ensured using the Lyapunov method. Both simulation and experimental application of a planetary gear type inverted pendulum control system verify the effectiveness of the developed approach.

  7. Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems.

    PubMed

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; Huang, Yi-Shan; Zhao, Kai-Hui

    2015-05-11

    This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

  8. Singularity-free integral-augmented sliding mode control for combined energy and attitude control system

    NASA Astrophysics Data System (ADS)

    Eshghi, Samira; Varatharajoo, Renuganth

    2017-01-01

    A combined energy and attitude control system (CEACS) is a synergized system in which flywheels are used as attitude control actuators and simultaneously as a power storage system. This paper, a subsequent to previous research on CEACS, addresses the attitude-tracking problem. Integral Augmented Sliding Mode Control with Boundary-Layer (IASMC-BL), a locally asymptotically stable controller, is developed to provide a robust and accurate solution for the CEACS's attitude-tracking problem. The controller alleviates the chattering phenomenon associated with the sliding mode using a boundary-layer technique. Simultaneously, it reduces the steady-state error using an integral action. This paper highlights the uncertainty of inertia matrix as a contributing factor to singularity problem. The inversion of the uncertain inertia matrix in simulation of a spacecraft dynamics is also identified as a leading factor to a singular situation. Therefore, an avoidance strategy is proposed in this paper to guarantee a singular-free dynamics behavior in faces of the uncertainties. This maiden work attempts to employ the singularity-free Integral Augmented Sliding Mode Control with Boundary-Layer (IASMC-BL) to provide a robust, accurate and nonsingular attitude-tracking solution for CEACS.

  9. Decoupled thermal control for space station furnace facility using sliding mode techniques

    SciTech Connect

    Jackson, M.E.; Shtessel, Y.B.

    1996-03-01

    The Space Station Furnace Facility (SSFF) provides the necessary core systems to operate various material processing furnaces. The Thermal Control System (TCS) is defined as one of the core systems and its function is to collect excess heat from furnaces and to provide precise cold temperature control of components and of certain furnace zones. Physical interconnection of parallel thermal control subsystems through a common pump implies the description of the whole TCS by coupled nonlinear differential equations in flow and pressure. The paper formulates the system equations and develops the sliding mode controllers that cause the interconnected subsystems to operate in the local sliding modes, resulting in control system invariance to interaction disturbances. The desired de-coupled flow rate profile tracking is achieved by optimization of the local linear sliding mode equations. Extensive digital simulation results are presented to show the flow rate tracking robustness and invariance to plant nonlinearities and variations of the pump pressure supplied to the controlled subsystems. {copyright} {ital 1996 American Institute of Physics.}

  10. Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems

    PubMed Central

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; Huang, Yi-Shan; Zhao, Kai-Hui

    2015-01-01

    This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method. PMID:25970258

  11. Flight Control Design for an Autonomous Rotorcraft Using Pseudo-Sliding Mode Control and Waypoint Navigation

    NASA Astrophysics Data System (ADS)

    Mallory, Nicolas Joseph

    The design of robust automated flight control systems for aircraft of varying size and complexity is a topic of continuing interest for both military and civilian industries. By merging the benefits of robustness from sliding mode control (SMC) with the familiarity and transparency of design tradeoff offered by frequency domain approaches, this thesis presents pseudo-sliding mode control as a viable option for designing automated flight control systems for complex six degree-of-freedom aircraft. The infinite frequency control switching of SMC is replaced, by necessity, with control inputs that are continuous in nature. An introduction to SMC theory is presented, followed by a detailed design of a pseudo-sliding mode control and automated flight control system for a six degree-of-freedom model of a Hughes OH6 helicopter. This model is then controlled through three different waypoint missions that demonstrate the stability of the system and the aircraft's ability to follow certain maneuvers despite time delays, large changes in model parameters and vehicle dynamics, actuator dynamics, sensor noise, and atmospheric disturbances.

  12. Observer-based robust finite time H∞ sliding mode control for Markovian switching systems with mode-dependent time-varying delay and incomplete transition rate.

    PubMed

    Gao, Lijun; Jiang, Xiaoxiao; Wang, Dandan

    2016-03-01

    This paper investigates the problem of robust finite time H∞ sliding mode control for a class of Markovian switching systems. The system is subjected to the mode-dependent time-varying delay, partly unknown transition rate and unmeasurable state. The main difficulty is that, a sliding mode surface cannot be designed based on the unknown transition rate and unmeasurable state directly. To overcome this obstacle, the set of modes is firstly divided into two subsets standing for known transition rate subset and unknown one, based on which a state observer is established. A component robust finite-time sliding mode controller is also designed to cope with the effect of partially unknown transition rate. It is illustrated that the reachability, finite-time stability, finite-time boundedness, finite-time H∞ state feedback stabilization of sliding mode dynamics can be ensured despite the unknown transition rate. Finally, the simulation results verify the effectiveness of robust finite time control problem.

  13. RTDS implementation of an improved sliding mode based inverter controller for PV system.

    PubMed

    Islam, Gazi; Muyeen, S M; Al-Durra, Ahmed; Hasanien, Hany M

    2016-05-01

    This paper proposes a novel approach for testing dynamics and control aspects of a large scale photovoltaic (PV) system in real time along with resolving design hindrances of controller parameters using Real Time Digital Simulator (RTDS). In general, the harmonic profile of a fast controller has wide distribution due to the large bandwidth of the controller. The major contribution of this paper is that the proposed control strategy gives an improved voltage harmonic profile and distribute it more around the switching frequency along with fast transient response; filter design, thus, becomes easier. The implementation of a control strategy with high bandwidth in small time steps of Real Time Digital Simulator (RTDS) is not straight forward. This paper shows a good methodology for the practitioners to implement such control scheme in RTDS. As a part of the industrial process, the controller parameters are optimized using particle swarm optimization (PSO) technique to improve the low voltage ride through (LVRT) performance under network disturbance. The response surface methodology (RSM) is well adapted to build analytical models for recovery time (Rt), maximum percentage overshoot (MPOS), settling time (Ts), and steady state error (Ess) of the voltage profile immediate after inverter under disturbance. A systematic approach of controller parameter optimization is detailed. The transient performance of the PSO based optimization method applied to the proposed sliding mode controlled PV inverter is compared with the results from genetic algorithm (GA) based optimization technique. The reported real time implementation challenges and controller optimization procedure are applicable to other control applications in the field of renewable and distributed generation systems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Finite-time synchronization for second-order nonlinear multi-agent system via pinning exponent sliding mode control.

    PubMed

    Hou, Huazhou; Zhang, Qingling

    2016-11-01

    In this paper we investigate the finite-time synchronization for second-order multi-agent system via pinning exponent sliding mode control. Firstly, for the nonlinear multi-agent system, differential mean value theorem is employed to transfer the nonlinear system into linear system, then, by pinning only one node in the system with novel exponent sliding mode control, we can achieve synchronization in finite time. Secondly, considering the 3-DOF helicopter system with nonlinear dynamics and disturbances, the novel exponent sliding mode control protocol is applied to only one node to achieve the synchronization. Finally, the simulation results show the effectiveness and the advantages of the proposed method.

  15. Intelligent nonsingular terminal sliding-mode control using MIMO Elman neural network for piezo-flexural nanopositioning stage.

    PubMed

    Lin, Faa-Jeng; Lee, Shih-Yang; Chou, Po-Huan

    2012-12-01

    The objective of this study is to develop an intelligent nonsingular terminal sliding-mode control (INTSMC) system using an Elman neural network (ENN) for the threedimensional motion control of a piezo-flexural nanopositioning stage (PFNS). First, the dynamic model of the PFNS is derived in detail. Then, to achieve robust, accurate trajectory-tracking performance, a nonsingular terminal sliding-mode control (NTSMC) system is proposed for the tracking of the reference contours. The steady-state response of the control system can be improved effectively because of the addition of the nonsingularity in the NTSMC. Moreover, to relax the requirements of the bounds and discard the switching function in NTSMC, an INTSMC system using a multi-input-multioutput (MIMO) ENN estimator is proposed to improve the control performance and robustness of the PFNS. The ENN estimator is proposed to estimate the hysteresis phenomenon and lumped uncertainty, including the system parameters and external disturbance of the PFNS online. Furthermore, the adaptive learning algorithms for the training of the parameters of the ENN online are derived using the Lyapunov stability theorem. In addition, two robust compensators are proposed to confront the minimum reconstructed errors in INTSMC. Finally, some experimental results for the tracking of various contours are given to demonstrate the validity of the proposed INTSMC system for PFNS.

  16. A new design of robust H∞ sliding mode control for uncertain stochastic T-S fuzzy time-delay systems.

    PubMed

    Gao, Qing; Feng, Gang; Xi, Zhiyu; Wang, Yong; Qiu, Jianbin

    2014-09-01

    In this paper, a novel dynamic sliding mode control scheme is proposed for a class of uncertain stochastic nonlinear time-delay systems represented by Takagi-Sugeno fuzzy models. The key advantage of the proposed scheme is that two very restrictive assumptions in most existing sliding mode control approaches for stochastic fuzzy systems have been removed. It is shown that the closed-loop control system trajectories can be driven onto the sliding surface in finite time almost certainly. It is also shown that the stochastic stability of the resulting sliding motion can be guaranteed in terms of linear matrix inequalities; moreover, the sliding-mode controller can be obtained simultaneously. Simulation results illustrating the advantages and effectiveness of the proposed approaches are also provided.

  17. Sliding mode control for a class of nonlinear discrete-time networked systems with multiple stochastic communication delays

    NASA Astrophysics Data System (ADS)

    Ma, Lifeng; Wang, Zidong; Niu, Yugang; Bo, Yumimg; Guo, Zhi

    2011-04-01

    In this article, a sliding mode control problem is studied for a class of uncertain nonlinear networked systems with multiple communication delays. A sequence of stochastic variables obeying Bernoulli distribution is applied in the system model to describe the randomly occurring communication delays. The discrete-time system considered is also subject to parameter uncertainties and state-dependent stochastic disturbances. A novel discrete switching function is proposed to facilitate the sliding mode controller design. The sufficient conditions are derived by means of the linear matrix inequality (LMI) approach. It is shown that the system dynamics in the specified sliding surface is robustly exponentially stable in the mean square if two LMIs with an equality constraint are feasible. A discrete-time SMC controller is designed that is capable of guaranteeing the discrete-time sliding-mode reaching condition of the specified sliding surface. Finally, a simulation example is given to show the effectiveness of the proposed method.

  18. An Adaptive Supervisory Sliding Fuzzy Cerebellar Model Articulation Controller for Sensorless Vector-Controlled Induction Motor Drive Systems

    PubMed Central

    Wang, Shun-Yuan; Tseng, Chwan-Lu; Lin, Shou-Chuang; Chiu, Chun-Jung; Chou, Jen-Hsiang

    2015-01-01

    This paper presents the implementation of an adaptive supervisory sliding fuzzy cerebellar model articulation controller (FCMAC) in the speed sensorless vector control of an induction motor (IM) drive system. The proposed adaptive supervisory sliding FCMAC comprised a supervisory controller, integral sliding surface, and an adaptive FCMAC. The integral sliding surface was employed to eliminate steady-state errors and enhance the responsiveness of the system. The adaptive FCMAC incorporated an FCMAC with a compensating controller to perform a desired control action. The proposed controller was derived using the Lyapunov approach, which guarantees learning-error convergence. The implementation of three intelligent control schemes—the adaptive supervisory sliding FCMAC, adaptive sliding FCMAC, and adaptive sliding CMAC—were experimentally investigated under various conditions in a realistic sensorless vector-controlled IM drive system. The root mean square error (RMSE) was used as a performance index to evaluate the experimental results of each control scheme. The analysis results indicated that the proposed adaptive supervisory sliding FCMAC substantially improved the system performance compared with the other control schemes. PMID:25815450

  19. An adaptive supervisory sliding fuzzy cerebellar model articulation controller for sensorless vector-controlled induction motor drive systems.

    PubMed

    Wang, Shun-Yuan; Tseng, Chwan-Lu; Lin, Shou-Chuang; Chiu, Chun-Jung; Chou, Jen-Hsiang

    2015-03-25

    This paper presents the implementation of an adaptive supervisory sliding fuzzy cerebellar model articulation controller (FCMAC) in the speed sensorless vector control of an induction motor (IM) drive system. The proposed adaptive supervisory sliding FCMAC comprised a supervisory controller, integral sliding surface, and an adaptive FCMAC. The integral sliding surface was employed to eliminate steady-state errors and enhance the responsiveness of the system. The adaptive FCMAC incorporated an FCMAC with a compensating controller to perform a desired control action. The proposed controller was derived using the Lyapunov approach, which guarantees learning-error convergence. The implementation of three intelligent control schemes--the adaptive supervisory sliding FCMAC, adaptive sliding FCMAC, and adaptive sliding CMAC--were experimentally investigated under various conditions in a realistic sensorless vector-controlled IM drive system. The root mean square error (RMSE) was used as a performance index to evaluate the experimental results of each control scheme. The analysis results indicated that the proposed adaptive supervisory sliding FCMAC substantially improved the system performance compared with the other control schemes.

  20. Sliding-mode control of single input multiple output DC-DC converter

    NASA Astrophysics Data System (ADS)

    Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

    2016-10-01

    Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

  1. Sliding-mode control of single input multiple output DC-DC converter.

    PubMed

    Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

    2016-10-01

    Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

  2. Time-scaling based sliding mode control for Neuromuscular Electrical Stimulation under uncertain relative degrees.

    PubMed

    Oliveira, Tiago Roux; Costa, Luiz Rennó; Catunda, João Marcos Yamasaki; Pino, Alexandre Visintainer; Barbosa, William; Souza, Márcio Nogueira de

    2017-06-01

    This paper addresses the application of the sliding mode approach to control the arm movements by artificial recruitment of muscles using Neuromuscular Electrical Stimulation (NMES). Such a technique allows the activation of motor nerves using surface electrodes. The goal of the proposed control system is to move the upper limbs of subjects through electrical stimulation to achieve a desired elbow angular displacement. Since the human neuro-motor system has individual characteristics, being time-varying, nonlinear and subject to uncertainties, the use of advanced robust control schemes may represent a better solution than classical Proportional-Integral (PI) controllers and model-based approaches, being simpler than more sophisticated strategies using fuzzy logic or neural networks usually applied in this control problem. The objective is the introduction of a new time-scaling base sliding mode control (SMC) strategy for NMES and its experimental evaluation. The main qualitative advantages of the proposed controller via time-scaling procedure are its independence of the knowledge of the plant relative degree and the design/tuning simplicity. The developed sliding mode strategy allows for chattering alleviation due to the impact of the integrator in smoothing the control signal. In addition, no differentiator is applied to construct the sliding surface. The stability analysis of the closed-loop system is also carried out by using singular perturbation methods. Experimental results are conducted with healthy volunteers as well as stroke patients. Quantitative results show a reduction of 45% in terms of root mean square (RMS) error (from 5.9° to [Formula: see text] ) in comparison with PI control scheme, which is similar to that obtained in the literature. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Sliding mode based fault detection, reconstruction and fault tolerant control scheme for motor systems.

    PubMed

    Mekki, Hemza; Benzineb, Omar; Boukhetala, Djamel; Tadjine, Mohamed; Benbouzid, Mohamed

    2015-07-01

    The fault-tolerant control problem belongs to the domain of complex control systems in which inter-control-disciplinary information and expertise are required. This paper proposes an improved faults detection, reconstruction and fault-tolerant control (FTC) scheme for motor systems (MS) with typical faults. For this purpose, a sliding mode controller (SMC) with an integral sliding surface is adopted. This controller can make the output of system to track the desired position reference signal in finite-time and obtain a better dynamic response and anti-disturbance performance. But this controller cannot deal directly with total system failures. However an appropriate combination of the adopted SMC and sliding mode observer (SMO), later it is designed to on-line detect and reconstruct the faults and also to give a sensorless control strategy which can achieve tolerance to a wide class of total additive failures. The closed-loop stability is proved, using the Lyapunov stability theory. Simulation results in healthy and faulty conditions confirm the reliability of the suggested framework.

  4. Hysteresis-reduced dynamic displacement control of piezoceramic stack actuators using model predictive sliding mode control

    NASA Astrophysics Data System (ADS)

    Kim, Byeongil; Washington, Gregory N.; Yoon, Hwan-Sik

    2012-05-01

    Currently, piezoelectric actuators are being used in many applications from precision positioning control to active vibration control of large space structures. They can take the form of a solid-state device and are conveniently controlled by a voltage input. In spite of their relative ease of control, positioning accuracy and actuator longevity can be compromised by the hysteresis. Thus, the primary objective of this research is to minimize the hysteretic effect of a piezoelectric actuator in order to obtain a near linear relationship between the input voltage and the output displacement. The reduction of the hysteresis is accomplished by a newly developed control methodology named model predictive sliding mode control. A nonlinear energy-based hysteresis model is developed for a piezoelectric stack actuator and model predictive sliding mode control is applied to force the system state to reach a sliding surface in an optimal manner and track the reference signal accurately thereafter. To validate this new approach, simulations and experiments are conducted and the results highlight significantly improved hysteresis reduction in the displacement control of the piezoelectric stack actuator.

  5. Variable speed wind turbine control by discrete-time sliding mode approach.

    PubMed

    Torchani, Borhen; Sellami, Anis; Garcia, Germain

    2016-05-01

    The aim of this paper is to propose a new design variable speed wind turbine control by discrete-time sliding mode approach. This methodology is designed for linear saturated system. The saturation constraint is reported on inputs vector. To this end, the back stepping design procedure is followed to construct a suitable sliding manifold that guarantees the attainment of a stabilization control objective. It is well known that the mechanisms are investigated in term of the most proposed assumptions to deal with the damping, shaft stiffness and inertia effect of the gear. The objectives are to synthesize robust controllers that maximize the energy extracted from wind, while reducing mechanical loads and rotor speed tracking combined with an electromagnetic torque. Simulation results of the proposed scheme are presented.

  6. Second-order integral sliding-mode control with experimental application.

    PubMed

    Furat, Murat; Eker, İlyas

    2014-09-01

    In the present study, a second-order sliding-mode controller is proposed for single-input single-output (SISO) uncertain real systems. The proposed controller successively overcomes the variations caused by the uncertainties and external load disturbances although an approximate model of the system is used in the design procedure. An integral type sliding surface is used and the stability and robustness properties of the proposed controller are proved by means of Lyapunov stability theorem. The chattering phenomenon is significantly reduced adopting the switching gain with the known parameters of the system. Thus, the proposed controller is suitable for long-term application to the real systems. The performance of the proposed control scheme is validated by a real system experiments and the results are compared with the similar controllers presented in the literature.

  7. Sliding-mode control for semi-active suspension with actuator dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Bo-Chiuan; Shiu, Yu-Hua; Hsieh, Feng-Chi

    2011-02-01

    A sliding-mode controller (SMC) is proposed for semi-active suspensions to achieve ride comfort and handling performance simultaneously. First, a nonlinear quarter-car model of Macpherson strut suspension is established in Matlab/Simulink. Constrained damper force and actuator dynamics are considered for the damper model. System identification is applied to the nonlinear model for obtaining the linear model parameters. Kalman filter is designed based on the linear model and the actuator dynamics to estimate the state responses required for SMC. The sliding surface consists of tyre deflection and sprung mass acceleration. The proposed SMC is evaluated using the nonlinear model for both time and frequency domain responses. Robustness due to the increased sprung mass and deteriorated suspension is also investigated in this paper. Preliminary simulation results show improved ride comfort without sacrificing the road holding performance.

  8. MIMO Sliding Mode Control for a Tailless Fighter Aircraft, An Alternative to Reconfigurable Architectures

    NASA Technical Reports Server (NTRS)

    Wells, S. R.; Hess, R. A.

    2002-01-01

    A frequency-domain procedure for the design of sliding mode controllers for multi-input, multi-output (MIMO) systems is presented. The methodology accommodates the effects of parasitic dynamics such as those introduced by unmodeled actuators through the introduction of multiple asymptotic observers and model reference hedging. The design procedure includes a frequency domain approach to specify the sliding manifold, the observer eigenvalues, and the hedge model. The procedure is applied to the development of a flight control system for a linear model of the Innovative Control Effector (ICE) fighter aircraft. The stability and performance robustness of the resulting design is demonstrated through the introduction of significant degradation in the control effector actuators and variation in vehicle dynamics.

  9. Sensorless control of ship propulsion interior permanent magnet synchronous motor based on a new sliding mode observer.

    PubMed

    Ren, Jun-Jie; Liu, Yan-Cheng; Wang, Ning; Liu, Si-Yuan

    2015-01-01

    This paper proposes a sensorless speed control strategy for ship propulsion interior permanent magnet synchronous motor (IPMSM) based on a new sliding-mode observer (SMO). In the SMO the low-pass filter and the method of arc-tangent calculation of extended electromotive force (EMF) or phase-locked loop (PLL) technique are not used. The calculation of the rotor speed is deduced from the Lyapunov function stability analysis. In order to reduce system chattering, sigmoid functions with switching gains being adaptively updated by fuzzy logic systems are innovatively incorporated into the SMO. Finally, simulation results for a 4.088 MW ship propulsion IPMSM and experimental results from a 7.5 kW IPMSM drive are provided to verify the effectiveness of the proposed SMO method.

  10. Sliding-mode control of a six-phase series/parallel connected two induction motors drive.

    PubMed

    Abjadi, Navid R

    2014-11-01

    In this paper, a parallel configuration is proposed for two quasi six-phase induction motors (QIMs) to feed them from a single six-phase voltage source inverter (VSI). A direct torque control (DTC) based on input-output feedback linearization (IOFL) combined with sliding mode (SM) control is used for each QIM in stationary reference frame. In addition, an adaptive scheme is employed to solve the motor resistances mismatching problem. The effectiveness and capability of the proposed method are shown by practical results obtained for two QIMs in series/parallel connections supplied from a single VSI. The decoupling control of QIMs and the feasibility of their torque and flux control are investigated. Moreover, a complete comparison between series and parallel connections of two QIMs is given.

  11. Darkfield adapter for whole slide imaging: adapting a darkfield internal reflection illumination system to extend WSI applications.

    PubMed

    Kawano, Yoshihiro; Higgins, Christopher; Yamamoto, Yasuhito; Nyhus, Julie; Bernard, Amy; Dong, Hong-Wei; Karten, Harvey J; Schilling, Tobias

    2013-01-01

    We present a new method for whole slide darkfield imaging. Whole Slide Imaging (WSI), also sometimes called virtual slide or virtual microscopy technology, produces images that simultaneously provide high resolution and a wide field of observation that can encompass the entire section, extending far beyond any single field of view. For example, a brain slice can be imaged so that both overall morphology and individual neuronal detail can be seen. We extended the capabilities of traditional whole slide systems and developed a prototype system for darkfield internal reflection illumination (DIRI). Our darkfield system uses an ultra-thin light-emitting diode (LED) light source to illuminate slide specimens from the edge of the slide. We used a new type of side illumination, a variation on the internal reflection method, to illuminate the specimen and create a darkfield image. This system has four main advantages over traditional darkfield: (1) no oil condenser is required for high resolution imaging (2) there is less scatter from dust and dirt on the slide specimen (3) there is less halo, providing a more natural darkfield contrast image, and (4) the motorized system produces darkfield, brightfield and fluorescence images. The WSI method sometimes allows us to image using fewer stains. For instance, diaminobenzidine (DAB) and fluorescent staining are helpful tools for observing protein localization and volume in tissues. However, these methods usually require counter-staining in order to visualize tissue structure, limiting the accuracy of localization of labeled cells within the complex multiple regions of typical neurohistological preparations. Darkfield imaging works on the basis of light scattering from refractive index mismatches in the sample. It is a label-free method of producing contrast in a sample. We propose that adapting darkfield imaging to WSI is very useful, particularly when researchers require additional structural information without the use of

  12. Darkfield Adapter for Whole Slide Imaging: Adapting a Darkfield Internal Reflection Illumination System to Extend WSI Applications

    PubMed Central

    Kawano, Yoshihiro; Higgins, Christopher; Yamamoto, Yasuhito; Nyhus, Julie; Bernard, Amy; Dong, Hong-Wei; Karten, Harvey J.; Schilling, Tobias

    2013-01-01

    We present a new method for whole slide darkfield imaging. Whole Slide Imaging (WSI), also sometimes called virtual slide or virtual microscopy technology, produces images that simultaneously provide high resolution and a wide field of observation that can encompass the entire section, extending far beyond any single field of view. For example, a brain slice can be imaged so that both overall morphology and individual neuronal detail can be seen. We extended the capabilities of traditional whole slide systems and developed a prototype system for darkfield internal reflection illumination (DIRI). Our darkfield system uses an ultra-thin light-emitting diode (LED) light source to illuminate slide specimens from the edge of the slide. We used a new type of side illumination, a variation on the internal reflection method, to illuminate the specimen and create a darkfield image. This system has four main advantages over traditional darkfield: (1) no oil condenser is required for high resolution imaging (2) there is less scatter from dust and dirt on the slide specimen (3) there is less halo, providing a more natural darkfield contrast image, and (4) the motorized system produces darkfield, brightfield and fluorescence images. The WSI method sometimes allows us to image using fewer stains. For instance, diaminobenzidine (DAB) and fluorescent staining are helpful tools for observing protein localization and volume in tissues. However, these methods usually require counter-staining in order to visualize tissue structure, limiting the accuracy of localization of labeled cells within the complex multiple regions of typical neurohistological preparations. Darkfield imaging works on the basis of light scattering from refractive index mismatches in the sample. It is a label-free method of producing contrast in a sample. We propose that adapting darkfield imaging to WSI is very useful, particularly when researchers require additional structural information without the use of

  13. A swarm intelligence-based tuning method for the Sliding Mode Generalized Predictive Control.

    PubMed

    Oliveira, J B; Boaventura-Cunha, J; Moura Oliveira, P B; Freire, H

    2014-09-01

    This work presents an automatic tuning method for the discontinuous component of the Sliding Mode Generalized Predictive Controller (SMGPC) subject to constraints. The strategy employs Particle Swarm Optimization (PSO) to minimize a second aggregated cost function. The continuous component is obtained by the standard procedure, by Quadratic Programming (QP), thus yielding an online dual optimization scheme. Simulations and performance indexes for common process models in industry, such as nonminimum phase and time delayed systems, result in a better performance, improving robustness and tracking accuracy.

  14. Hybrid force-velocity sliding mode control of a prosthetic hand.

    PubMed

    Engeberg, Erik D; Meek, Sanford G; Minor, Mark A

    2008-05-01

    Four different methods of hand prosthesis control are developed and examined experimentally. Open-loop control is shown to offer the least sensitivity when manipulating objects. Force feedback substantially improves upon open-loop control. However, it is shown that the inclusion of velocity and/or position feedback in a hybrid force-velocity control scheme can further improve the functionality of hand prostheses. Experimental results indicate that the sliding mode controller with force, position, and velocity feedback is less prone to unwanted force overshoot when initially grasping objects than the other controllers.

  15. A modified integral sliding mode control to lateral stabilisation of 4-wheel independent drive electric vehicles

    NASA Astrophysics Data System (ADS)

    Alipour, Hasan; Bagher Bannae Sharifian, Mohammad; Sabahi, Mehran

    2014-12-01

    This paper presents a novel sliding mode controller (SMC) and its application in the lateral stability control of a 4-wheel independent drive electric vehicle. The structure of the SMC is modified and online-tuned to ensure vehicle system stability, and to track the desired vehicle motion references when an in-wheel motor fault happens. The proposed controller is faster, more accurate, more robust, and with smaller chattering than common SMCs chatter. The effectiveness of the introduced approach is investigated through conducted simulations in the CARSIM and MATLAB software environments.

  16. Drag-based composite super-twisting sliding mode control law design for Mars entry guidance

    NASA Astrophysics Data System (ADS)

    Zhao, Zhenhua; Yang, Jun; Li, Shihua; Guo, Lei

    2016-06-01

    In this paper, the drag-based trajectory tracking guidance problem is investigated for Mars entry vehicle subject to uncertainties. A composite super twisting sliding mode control method based on finite-time disturbance observer is proposed for guidance law design. The proposed controller not only eliminates the effects of matched and mismatched disturbances due to uncertainties of atmospheric models and vehicle aerodynamics but also guarantees the continuity of control action. Numerical simulations are carried out on the basis of Mars Science Laboratory mission, where the results show that the proposed methods can improve the Mars entry guidance precision as compared with some existing guidance methods including PID and ADRC.

  17. Sensorless sliding mode observer for a five-phase permanent magnet synchronous motor drive.

    PubMed

    Hosseyni, Anissa; Trabelsi, Ramzi; Mimouni, Med Faouzi; Iqbal, Atif; Alammari, Rashid

    2015-09-01

    This paper deals with the sensorless vector controlled five-phase permanent magnet synchronous motor (PMSM) drive based on a sliding mode observer (SMO). The observer is designed considering the back electromotive force (EMF) of five-phase permanent magnet synchronous motor. The SMO structure and design are illustrated. Stability of the proposed observer is demonstrated using Lyapunov stability criteria. The proposed strategy is asymptotically stable in the context of Lyapunov theory. Simulated results on a five-phase PMSM drive are displayed to validate the feasibility and the effectiveness of the proposed control strategy.

  18. Nonlinear H ∞ control of a Quadrotor (UAV), using high order sliding mode disturbance estimator

    NASA Astrophysics Data System (ADS)

    Kerma, Mokhtar; Mokhtari, Abdellah; Abdelaziz, Benallegue; Orlov, Yuri

    2012-12-01

    A nonlinear H ∞ output feedback controller is proposed and coupled to a high-order sliding mode estimator to regulate an UAV in the presence of the unmatched perturbations. The plant to be controlled is a Quadrotor helicopter described by nonlinear dynamics with plant uncertainties due to the variations of inertia moments and payload operation. A robust state estimation is considered under model uncertainties as well as external/measurement disturbances. Performance issues of the controller are illustrated in a simulation study made for an UAV prototype.

  19. Synchronizing chaotic dynamics with uncertainties based on a sliding mode control design.

    PubMed

    Yang, Tao; Shao, Hui He

    2002-04-01

    The synchronization of two chaotic systems with uncertainties is studied in this paper. A feedback controller is provided based on a sliding mode control design. A kind of extended state observer is used to compensate for the systems' uncertainties, such as the structure difference or parameter mismatching, using only the available synchronizing error. Then the feedback controller becomes physically realizable based on the states of the observer, and can be used to synchronize two continuous chaotic systems. Illustrative examples of the synchronization of Duffing and Van der Pol oscillators as well as two Lorenz systems with parameter mismatching are proposed to show the effectiveness of this method.

  20. Large motion tracking control for thrust magnetic bearings with fuzzy logic, sliding mode, and direct linearization

    NASA Astrophysics Data System (ADS)

    Minihan, T. P.; Lei, S.; Sun, G.; Palazzolo, A.; Kascak, A. F.; Calvert, T.

    2003-06-01

    Conventional use of magnetic bearings relies on a zero reference to keep the rotor centered in the radial and axial axes. This paper compares different control methods developed for the alternate control task of tracking an axial dynamic target. Controllers based on fuzzy logic, sliding mode, and direct linearization were designed to meet this task. Performance criteria, such as maximum axial displacement, minimum phase lag and I2R power losses were compared for each controller. The large motion, tracking problem for a rotor has utility in applications where dynamic seal clearances are required. This has a variety of potential applications in turbo-machinery, such as active stall control.

  1. Robust Sliding Mode Control Based on GA Optimization and CMAC Compensation for Lower Limb Exoskeleton.

    PubMed

    Long, Yi; Du, Zhi-Jiang; Wang, Wei-Dong; Dong, Wei

    2016-01-01

    A lower limb assistive exoskeleton is designed to help operators walk or carry payloads. The exoskeleton is required to shadow human motion intent accurately and compliantly to prevent incoordination. If the user's intention is estimated accurately, a precise position control strategy will improve collaboration between the user and the exoskeleton. In this paper, a hybrid position control scheme, combining sliding mode control (SMC) with a cerebellar model articulation controller (CMAC) neural network, is proposed to control the exoskeleton to react appropriately to human motion intent. A genetic algorithm (GA) is utilized to determine the optimal sliding surface and the sliding control law to improve performance of SMC. The proposed control strategy (SMC_GA_CMAC) is compared with three other types of approaches, that is, conventional SMC without optimization, optimal SMC with GA (SMC_GA), and SMC with CMAC compensation (SMC_CMAC), all of which are employed to track the desired joint angular position which is deduced from Clinical Gait Analysis (CGA) data. Position tracking performance is investigated with cosimulation using ADAMS and MATLAB/SIMULINK in two cases, of which the first case is without disturbances while the second case is with a bounded disturbance. The cosimulation results show the effectiveness of the proposed control strategy which can be employed in similar exoskeleton systems.

  2. Robust Sliding Mode Control Based on GA Optimization and CMAC Compensation for Lower Limb Exoskeleton

    PubMed Central

    Long, Yi; Du, Zhi-jiang; Wang, Wei-dong; Dong, Wei

    2016-01-01

    A lower limb assistive exoskeleton is designed to help operators walk or carry payloads. The exoskeleton is required to shadow human motion intent accurately and compliantly to prevent incoordination. If the user's intention is estimated accurately, a precise position control strategy will improve collaboration between the user and the exoskeleton. In this paper, a hybrid position control scheme, combining sliding mode control (SMC) with a cerebellar model articulation controller (CMAC) neural network, is proposed to control the exoskeleton to react appropriately to human motion intent. A genetic algorithm (GA) is utilized to determine the optimal sliding surface and the sliding control law to improve performance of SMC. The proposed control strategy (SMC_GA_CMAC) is compared with three other types of approaches, that is, conventional SMC without optimization, optimal SMC with GA (SMC_GA), and SMC with CMAC compensation (SMC_CMAC), all of which are employed to track the desired joint angular position which is deduced from Clinical Gait Analysis (CGA) data. Position tracking performance is investigated with cosimulation using ADAMS and MATLAB/SIMULINK in two cases, of which the first case is without disturbances while the second case is with a bounded disturbance. The cosimulation results show the effectiveness of the proposed control strategy which can be employed in similar exoskeleton systems. PMID:27069353

  3. Second-order sliding mode control of a 2D torsional MEMS micromirror with sidewall electrodes

    NASA Astrophysics Data System (ADS)

    Chen, H.; Sun, W. J.; Sun, Z. D.; Yeow, J. T. W.

    2013-01-01

    A second-order sliding mode control (2-SMC) scheme with a proportional integral derivative (PID) sliding surface, to achieve enhanced transient response, accurate positioning and precise tracking performance of a 2-degree-of-freedom (2D) torsional MEMS micromirror with sidewall electrodes, is developed in this paper. The PID sliding surface is chosen to achieve a zero steady-state error of the closed-loop system. The 2-SMC is able to reduce the chattering phenomena, which comprises of an equivalent control and switching control to dominate model uncertainty and external disturbances leading to an enhanced performance of the controlled system. Finite-time convergence of the closed-loop system in the presence of bounded parameter uncertainties and external disturbances is guaranteed through Lyapunov stability analysis. The proposed 2-SMC is programmed in a LABVIEW environment and implemented based on National Instrument (NI) field-programmable gate array hardware to verify the effectiveness and robustness. The experimental results of set-point regulation and sinusoidal trajectory tacking demonstrate that the closed-loop system with the proposed control scheme significantly improves the transient performance, accurate positioning and trajectory tracking with robustness against external disturbance. The 95% settling time is shortened from 70 to 3 ms for the X-axis and from 60 to 3 ms for the Y-axis respectively, the overshoots and steady-state errors are eliminated in both axes, and less than 5% maximum positioning error is achieved in the presence of external disturbance.

  4. Sliding Mode Control of a Class of Uncertain Nonlinear Time-Delay Systems Using LMI and TS Recurrent Fuzzy Neural Network

    NASA Astrophysics Data System (ADS)

    Chiang, Tung-Sheng; Chiu, Chian-Song

    This paper proposes the sliding mode control using LMI techniques and adaptive recurrent fuzzy neural network (RFNN) for a class of uncertain nonlinear time-delay systems. First, a novel TS recurrent fuzzy neural network (TS-RFNN) is developed to provide more flexible and powerful compensation of system uncertainty. Then, the TS-RFNN based sliding model control is proposed for uncertain time-delay systems. In detail, sliding surface design is derived to cope with the non-Isidori-Bynes canonical form of dynamics, unknown delay time, and mismatched uncertainties. Based on the Lyapunov-Krasoviskii method, the asymptotic stability condition of the sliding motion is formulated into solving a Linear Matrix Inequality (LMI) problem which is independent on the time-varying delay. Furthermore, the input coupling uncertainty is also taken into our consideration. The overall controlled system achieves asymptotic stability even if considering poor modeling. The contributions include: i) asymptotic sliding surface is designed from solving a simple and legible delay-independent LMI; and ii) the TS-RFNN is more realizable (due to fewer fuzzy rules being used). Finally, simulation results demonstrate the validity of the proposed control scheme.

  5. Direct Torque Control of a Small Wind Turbine with a Sliding-Mode Speed Controller

    NASA Astrophysics Data System (ADS)

    Sri Lal Senanayaka, Jagath; Karimi, Hamid Reza; Robbersmyr, Kjell G.

    2016-09-01

    In this paper. the method of direct torque control in the presence of a sliding-mode speed controller is proposed for a small wind turbine being used in water heating applications. This concept and control system design can be expanded to grid connected or off-grid applications. Direct torque control of electrical machines has shown several advantages including very fast dynamics torque control over field-oriented control. Moreover. the torque and flux controllers in the direct torque control algorithms are based on hvsteretic controllers which are nonlinear. In the presence of a sliding-mode speed control. a nonlinear control system can be constructed which is matched for AC/DC conversion of the converter that gives fast responses with low overshoots. The main control objectives of the proposed small wind turbine can be maximum power point tracking and soft-stall power control. This small wind turbine consists of permanent magnet synchronous generator and external wind speed. and rotor speed measurements are not required for the system. However. a sensor is needed to detect the rated wind speed overpass events to activate proper speed references for the wind turbine. Based on the low-cost design requirement of small wind turbines. an available wind speed sensor can be modified. or a new sensor can be designed to get the required measurement. The simulation results will be provided to illustrate the excellent performance of the closed-loop control system in entire wind speed range (4-25 m/s).

  6. A sliding mode-based starling-like controller for implantable rotary blood pumps.

    PubMed

    Bakouri, Mohsen A; Salamonsen, Robert F; Savkin, Andrey V; AlOmari, Abdul-Hakeem H; Lim, Einly; Lovell, Nigel H

    2014-07-01

    Clinically adequate implementation of physiological control of a rotary left ventricular assist device requires a sophisticated technique such as the recently proposed method based on the Frank-Starling mechanism. In this mechanism, the stroke volume of the heart increases in response to an increase in the volume of blood filling the left ventricle at the end of diastole. To emulate this process, changes in pump speed need to automatically regulate pump flow to ensure that the combined output of the left ventricle and pump match the output of the right ventricle across changing cardiovascular states. In this approach, we exploit the linear relationship between estimated mean pump flow (Q ̅ est) and pump flow pulsatility (PIQp) in a tracking control algorithm based on sliding mode control. The immediate response of the controller was assessed using a lumped parameter model of the cardiovascular system (CVS) and pump from which could be extracted both Q ̅ est and PIQp. Two different perturbations from the resting state in the presence of left ventricular failure were tested. The first was blood loss requiring a reduction in pump flow to match the reduced output from the right ventricle and to avoid the complication of ventricular suction. The second was exercise, requiring an increase in pump flow. The sliding mode controller induced the required changes in Qp within approximately five heart beats in the blood loss simulation and eight heart beats in the exercise simulation without clinically significant transients or steady-state errors.

  7. Analytical impact time and angle guidance via time-varying sliding mode technique.

    PubMed

    Zhao, Yao; Sheng, Yongzhi; Liu, Xiangdong

    2016-05-01

    To concretely provide a feasible solution for homing missiles with the precise impact time and angle, this paper develops a novel guidance law, based on the nonlinear engagement dynamics. The guidance law is firstly designed with the prior assumption of a stationary target, followed by the practical extension to a moving target scenario. The time-varying sliding mode (TVSM) technique is applied to fulfill the terminal constraints, in which a specific TVSM surface is constructed with two unknown coefficients. One is tuned to meet the impact time requirement and the other one is targeted with a global sliding mode, so that the impact angle constraint as well as the zero miss distance can be satisfied. Because the proposed law possesses three guidance gain as design parameters, the intercept trajectory can be shaped according to the operational conditions and missile׳s capability. To improve the tolerance of initial heading errors and broaden the application, a new frame of reference is also introduced. Furthermore, the analytical solutions of the flight trajectory, heading angle and acceleration command can be totally expressed for the prediction and offline parameter selection by solving a first-order linear differential equation. Numerical simulation results for various scenarios validate the effectiveness of the proposed guidance law and demonstrate the accuracy of the analytic solutions.

  8. Output Feedback Fractional-Order Nonsingular Terminal Sliding Mode Control of Underwater Remotely Operated Vehicles

    PubMed Central

    Chen, Jiawang; Gu, Linyi

    2014-01-01

    For the 4-DOF (degrees of freedom) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC) technique is introduced in light of the equivalent output injection sliding mode observer (SMO) and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time. PMID:24983004

  9. Output feedback fractional-order nonsingular terminal sliding mode control of underwater remotely operated vehicles.

    PubMed

    Wang, Yaoyao; Chen, Jiawang; Gu, Linyi

    2014-01-01

    For the 4-DOF (degrees of freedom) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC) technique is introduced in light of the equivalent output injection sliding mode observer (SMO) and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time.

  10. Robust In-Flight Sensor Fault Diagnostics for Aircraft Engine Based on Sliding Mode Observers

    PubMed Central

    Chang, Xiaodong; Huang, Jinquan; Lu, Feng

    2017-01-01

    For a sensor fault diagnostic system of aircraft engines, the health performance degradation is an inevitable interference that cannot be neglected. To address this issue, this paper investigates an integrated on-line sensor fault diagnostic scheme for a commercial aircraft engine based on a sliding mode observer (SMO). In this approach, one sliding mode observer is designed for engine health performance tracking, and another for sensor fault reconstruction. Both observers are employed in in-flight applications. The results of the former SMO are analyzed for post-flight updating the baseline model of the latter. This idea is practical and feasible since the updating process does not require the algorithm to be regulated or redesigned, so that ground-based intervention is avoided, and the update process is implemented in an economical and efficient way. With this setup, the robustness of the proposed scheme to the health degradation is much enhanced and the latter SMO is able to fulfill sensor fault reconstruction over the course of the engine life. The proposed sensor fault diagnostic system is applied to a nonlinear simulation of a commercial aircraft engine, and its effectiveness is evaluated in several fault scenarios. PMID:28398255

  11. Robust In-Flight Sensor Fault Diagnostics for Aircraft Engine Based on Sliding Mode Observers.

    PubMed

    Chang, Xiaodong; Huang, Jinquan; Lu, Feng

    2017-04-11

    For a sensor fault diagnostic system of aircraft engines, the health performance degradation is an inevitable interference that cannot be neglected. To address this issue, this paper investigates an integrated on-line sensor fault diagnostic scheme for a commercial aircraft engine based on a sliding mode observer (SMO). In this approach, one sliding mode observer is designed for engine health performance tracking, and another for sensor fault reconstruction. Both observers are employed in in-flight applications. The results of the former SMO are analyzed for post-flight updating the baseline model of the latter. This idea is practical and feasible since the updating process does not require the algorithm to be regulated or redesigned, so that ground-based intervention is avoided, and the update process is implemented in an economical and efficient way. With this setup, the robustness of the proposed scheme to the health degradation is much enhanced and the latter SMO is able to fulfill sensor fault reconstruction over the course of the engine life. The proposed sensor fault diagnostic system is applied to a nonlinear simulation of a commercial aircraft engine, and its effectiveness is evaluated in several fault scenarios.

  12. Two modified discrete PID-based sliding mode controllers for piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Cao, Y.; Chen, X. B.

    2014-01-01

    Hysteresis is a nonlinear effect that can result in the degraded performance of piezoelectric actuators (PEAs). To counteract the effect, several control methods have been developed and reported in the literature. One promising method for compensation is the use of a proportional-integral-derivative (PID)-based sliding mode control (SMC), in which the PEA hysteresis is treated as an unknown disturbance to the PEA input. If the hysteresis can be modelled or partially modelled, the integration of the hysteresis models into the control schemes may lead to further improved performance. On this philosophy, this paper presents the development of two modified discrete PID-based sliding mode controllers (PID-SMCs) for the PEAs, namely an inversion-based PID-SMC and a disturbance-observer (DOB)-based PID-SMC, in which the PEA hysteresis is predicted or partially predicted through the use of existing models for the PEA hysteresis. Experiments were performed to verify the effectiveness of the proposed control schemes. The results were compared to those of the nominal PID-SMC. By employing the inversion hysteresis and the DOB, the PEA performance was greatly improved.

  13. Dynamic fast terminal sliding mode control of a shape memory alloy actuated system

    NASA Astrophysics Data System (ADS)

    Marathe, Meeshawn S.; Srinivasan, S. M.

    2016-04-01

    In this paper we address the chattering phenomenon which is a common drawback associated with the normal Sliding Mode Control (SMC) law for a basic shape memory alloy (SMA) actuated system. A new method has been proposed to counter this effect by combining the concepts of Fast Terminal SMC and Dynamic controller. A phenomenological model is developed for the SMA which incorporates a piecewise linear hysteresis behavior. This model is used for both open loop as well as closed loop simulations for a linear motion control system. Based on this model, a dynamic terminal sliding mode control law is derived and applied to the system. A normal SMC law with saturation function which is known to reduce chattering is compared with the proposed control law for its effectiveness to curb the issue of chattering versus its ability to faithfully track a desired trajectory. Numerical Simulations indicate that the proposed law is able to reduce the chattering effect sufficiently and at par with the control technique involving saturation function.

  14. Robust fuzzy neural network sliding mode control scheme for IPMSM drives

    NASA Astrophysics Data System (ADS)

    Leu, V. Q.; Mwasilu, F.; Choi, H. H.; Lee, J.; Jung, J. W.

    2014-07-01

    This article proposes a robust fuzzy neural network sliding mode control (FNNSMC) law for interior permanent magnet synchronous motor (IPMSM) drives. The proposed control strategy not only guarantees accurate and fast command speed tracking but also it ensures the robustness to system uncertainties and sudden speed and load changes. The proposed speed controller encompasses three control terms: a decoupling control term which compensates for nonlinear coupling factors using nominal parameters, a fuzzy neural network (FNN) control term which approximates the ideal control components and a sliding mode control (SMC) term which is proposed to compensate for the errors of that approximation. Next, an online FNN training methodology, which is developed using the Lyapunov stability theorem and the gradient descent method, is proposed to enhance the learning capability of the FNN. Moreover, the maximum torque per ampere (MTPA) control is incorporated to maximise the torque generation in the constant torque region and increase the efficiency of the IPMSM drives. To verify the effectiveness of the proposed robust FNNSMC, simulations and experiments are performed by using MATLAB/Simulink platform and a TI TMS320F28335 DSP on a prototype IPMSM drive setup, respectively. Finally, the simulated and experimental results indicate that the proposed design scheme can achieve much better control performances (e.g. more rapid transient response and smaller steady-state error) when compared to the conventional SMC method, especially in the case that there exist system uncertainties.

  15. Inverse optimal sliding mode control of spacecraft with coupled translation and attitude dynamics

    NASA Astrophysics Data System (ADS)

    Pukdeboon, Chutiphon

    2015-10-01

    This paper proposes two robust inverse optimal control schemes for spacecraft with coupled translation and attitude dynamics in the presence of external disturbances. For the first controller, an inverse optimal control law is designed based on Sontag-type formula and the control Lyapunov function. Then a robust inverse optimal position and attitude controller is designed by using a new second-order integral sliding mode control method to combine a sliding mode control with the derived inverse optimal control. The global asymptotic stability of the proposed control law is proved by using the second method of Lyapunov. For the other control law, a nonlinear H∞ inverse optimal controller for spacecraft position and attitude tracking motion is developed to achieve the design conditions of controller gains that the control law becomes suboptimal H∞ state feedback control. The ultimate boundedness of system state is proved by using the Lyapunov stability theory. Both developed robust inverse optimal controllers can minimise a performance index and ensure the stability of the closed-loop system and external disturbance attenuation. An example of position and attitude tracking manoeuvres is presented and simulation results are included to show the performance of the proposed controllers.

  16. Dynamic boundary layer based neural network quasi-sliding mode control for soft touching down on asteroid

    NASA Astrophysics Data System (ADS)

    Liu, Xiaosong; Shan, Zebiao; Li, Yuanchun

    2017-04-01

    Pinpoint landing is a critical step in some asteroid exploring missions. This paper is concerned with the descent trajectory control for soft touching down on a small irregularly-shaped asteroid. A dynamic boundary layer based neural network quasi-sliding mode control law is proposed to track a desired descending path. The asteroid's gravitational acceleration acting on the spacecraft is described by the polyhedron method. Considering the presence of input constraint and unmodeled acceleration, the dynamic equation of relative motion is presented first. The desired descending path is planned using cubic polynomial method, and a collision detection algorithm is designed. To perform trajectory tracking, a neural network sliding mode control law is given first, where the sliding mode control is used to ensure the convergence of system states. Two radial basis function neural networks (RBFNNs) are respectively used as an approximator for the unmodeled term and a compensator for the difference between the actual control input with magnitude constraint and nominal control. To improve the chattering induced by the traditional sliding mode control and guarantee the reachability of the system, a specific saturation function with dynamic boundary layer is proposed to replace the sign function in the preceding control law. Through the Lyapunov approach, the reachability condition of the control system is given. The improved control law can guarantee the system state move within a gradually shrinking quasi-sliding mode band. Numerical simulation results demonstrate the effectiveness of the proposed control strategy.

  17. On the synthesis of sliding mode controller for the autopilot design of free flight system

    NASA Astrophysics Data System (ADS)

    Devika K., B.; Thomas, Susy

    2017-01-01

    Today's rapid growth in air transportation demand leads to the problem of congestion in air traffic routes. In recent years, free flight concept is widely discussed as the solution to this problem. Free flight is a decentralized method of air traffic management, in which each aircraft has the freedom to self optimize its own route. Conflict detection and its subsequent resolution are the major challenges in the realization of this concept. Today's modern navigation and surveillance equipment can ensure accurate conflict predictions. Once a conflict is detected, it should be avoided through suitable conflict avoidance maneuvers. An autopilot capable of initiating these conflict free maneuvers should be a necessary part of any aircraft in free flight to ensure conflict avoided flight. Controller design based on Sliding Mode Control (SMC) strategy is presented in this paper for the purpose of free flight autopilot implementation. Since SMC has the inherent property of robustness in sliding mode, it can ensure a highly efficient autopilot design. Conventional and reaching law approaches of SMC design are considered here for controller design. Conventional SMC technique usually exhibits an unacceptable phenomenon, viz., chattering. Reaching law approaches for SMC design are being investigated here so as to identify an appropriate strategy that can ensure near chattering free operation. Considering typical free flight conflict avoidance modes of operation, the performance of all the considered SMC strategies are compared through simulation studies. The comparison is based on their ability to reduce chattering and the effectiveness in ensuring quick conflict resolution maneuvers, so that an efficient controller for free flight autopilot system can be recommended.

  18. Regulation of Blood Glucose Concentration in Type 1 Diabetics Using Single Order Sliding Mode Control Combined with Fuzzy On-line Tunable Gain, a Simulation Study.

    PubMed

    Dinani, Soudabeh Taghian; Zekri, Maryam; Kamali, Marzieh

    2015-01-01

    Diabetes is considered as a global affecting disease with an increasing contribution to both mortality rate and cost damage in the society. Therefore, tight control of blood glucose levels has gained significant attention over the decades. This paper proposes a method for blood glucose level regulation in type 1 diabetics. The control strategy is based on combining the fuzzy logic theory and single order sliding mode control (SOSMC) to improve the properties of sliding mode control method and to alleviate its drawbacks. The aim of the proposed controller that is called SOSMC combined with fuzzy on-line tunable gain is to tune the gain of the controller adaptively. This merit causes a less amount of control effort, which is the rate of insulin delivered to the patient body. As a result, this method can decline the risk of hypoglycemia, a lethal phenomenon in regulating blood glucose level in diabetics caused by a low blood glucose level. Moreover, it attenuates the chattering observed in SOSMC significantly. It is worth noting that in this approach, a mathematical model called minimal model is applied instead of the intravenously infused insulin-blood glucose dynamics. The simulation results demonstrate a good performance of the proposed controller in meal disturbance rejection and robustness against parameter changes. In addition, this method is compared to fuzzy high-order sliding mode control (FHOSMC) and the superiority of the new method compared to FHOSMC is shown in the results.

  19. Decoupling control based on terminal sliding mode and wavelet network for the speed and tension system of reversible cold strip rolling mill

    NASA Astrophysics Data System (ADS)

    Fang, Yiming; Liu, Le; Li, Jianxiong; Xu, Yanze

    2015-08-01

    To weaken the nonlinear coupling influences among the variables in the speed and tension system of reversible cold strip rolling mill, a novel dynamic decoupling control strategy is proposed based on nonsingular fast terminal sliding mode (NFTSM) and wavelet neural network (WNN). First, nonlinear disturbance observers are developed to counteract the mismatched uncertainties, and then input/output dynamic decoupling and linearisation for the speed and tension nonlinear coupling system are realised by utilising the inverse system theory. Second, nonsingular fast terminal sliding mode controller (NFTSMC) for each pseudo linear subsystem is presented based on backstepping and two-power reaching law, so as to improve the global convergence speed and robust stability of the system. Third, adaptive WNNs are used to approximate the uncertain items of the system, so as to improve the control precision of the speed and tension of reversible cold strip rolling mill. Theoretical analyses show that the NFTSMs satisfy reachability condition, the system error variables can converge to equilibrium point in finite time, and the resulting closed-loop system is globally asymptotically stable. Finally, simulation research is carried out on the speed and tension system of a 1422 mm reversible cold strip rolling mill by using the actual data, and results show the superiority of the proposed control strategy in comparison with the strategies of cascade PI, linear sliding mode control and internal model control.

  20. Regulation of Blood Glucose Concentration in Type 1 Diabetics Using Single Order Sliding Mode Control Combined with Fuzzy On-line Tunable Gain, a Simulation Study

    PubMed Central

    Dinani, Soudabeh Taghian; Zekri, Maryam; Kamali, Marzieh

    2015-01-01

    Diabetes is considered as a global affecting disease with an increasing contribution to both mortality rate and cost damage in the society. Therefore, tight control of blood glucose levels has gained significant attention over the decades. This paper proposes a method for blood glucose level regulation in type 1 diabetics. The control strategy is based on combining the fuzzy logic theory and single order sliding mode control (SOSMC) to improve the properties of sliding mode control method and to alleviate its drawbacks. The aim of the proposed controller that is called SOSMC combined with fuzzy on-line tunable gain is to tune the gain of the controller adaptively. This merit causes a less amount of control effort, which is the rate of insulin delivered to the patient body. As a result, this method can decline the risk of hypoglycemia, a lethal phenomenon in regulating blood glucose level in diabetics caused by a low blood glucose level. Moreover, it attenuates the chattering observed in SOSMC significantly. It is worth noting that in this approach, a mathematical model called minimal model is applied instead of the intravenously infused insulin–blood glucose dynamics. The simulation results demonstrate a good performance of the proposed controller in meal disturbance rejection and robustness against parameter changes. In addition, this method is compared to fuzzy high-order sliding mode control (FHOSMC) and the superiority of the new method compared to FHOSMC is shown in the results. PMID:26284169

  1. Fuzzy fast terminal sliding mode vibration control of a two-connected flexible plate using laser sensors

    NASA Astrophysics Data System (ADS)

    Qiu, Zhi-cheng; Zhang, Si-ma

    2016-10-01

    A kind of non-contact vibration measurement method for a two-connected flexible piezoelectric plate using laser sensors is proposed. Decoupling of the bending and torsional vibration on measurement and driving control is carried out via using two laser displacement sensors and piezoelectric actuators. The fuzzy fast terminal sliding mode controller (FFTSMC) is investigated to suppress both the larger and the smaller amplitude vibrations quickly. In order to alleviate the chattering phenomenon and enhance the control effect, the fuzzy logic adaptive algorithm is used to adjust the switching control gain for softening the signum function adaptively. To verify the non-contact measurement method and the designed controller, the experimental setup is built up. Experiments on active vibration control using the designed FFTSMC are conducted, compared with the classical proportional derivative (PD) control algorithm. The experimental identification results demonstrate that the laser displacement sensors can detect the low-frequency bending and torsional vibration effectively, after using the decoupling method. Furthermore, the designed FFTSMC can suppress both bending and torsional vibration more quickly than the designed PD controller owing to the adjustment of the switching control gains and the softening factors, especially for the small amplitude residual vibrations.

  2. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    NASA Astrophysics Data System (ADS)

    Hu, Qinglei

    2010-09-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input voltage of the reaction wheel is derived to control the orientation of the spacecraft, incorporating the L 2-gain performance criterion constraint. The resulting closed-loop system is proven to be uniformly ultimately bounded stability and the effect of the external disturbance on both attitude quaternion and angular velocity can be attenuated to the prescribed level as well. In addition, an adaptive version of the control law is designed for adapting the unknown upper bounds of the lumped disturbance such that the limitation of knowing the bound of the disturbance in advance is released. For actively suppressing the induced vibration, strain rate feedback control method is also investigated by using piezoelectric materials as additional sensors and actuators bonded on the surface of the flexible appendages. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance and uncertainty.

  3. Fractional order sliding-mode control based on parameters auto-tuning for velocity control of permanent magnet synchronous motor.

    PubMed

    Zhang, BiTao; Pi, YouGuo; Luo, Ying

    2012-09-01

    A fractional order sliding mode control (FROSMC) scheme based on parameters auto-tuning for the velocity control of permanent magnet synchronous motor (PMSM) is proposed in this paper. The control law of the proposed F(R)OSMC scheme is designed according to Lyapunov stability theorem. Based on the property of transferring energy with adjustable type in F(R)OSMC, this paper analyzes the chattering phenomenon in classic sliding mode control (SMC) is attenuated with F(R)OSMC system. A fuzzy logic inference scheme (FLIS) is utilized to obtain the gain of switching control. Simulations and experiments demonstrate that the proposed FROSMC not only achieve better control performance with smaller chatting than that with integer order sliding mode control, but also is robust to external load disturbance and parameter variations.

  4. Least square based sliding mode control for a quad-rotor helicopter and energy saving by chattering reduction

    NASA Astrophysics Data System (ADS)

    Sumantri, Bambang; Uchiyama, Naoki; Sano, Shigenori

    2016-01-01

    In this paper, a new control structure for a quad-rotor helicopter that employs the least squares method is introduced. This proposed algorithm solves the overdetermined problem of the control input for the translational motion of a quad-rotor helicopter. The algorithm allows all six degrees of freedom to be considered to calculate the control input. The sliding mode controller is applied to achieve robust tracking and stabilization. A saturation function is designed around a boundary layer to reduce the chattering phenomenon that is a common problem in sliding mode control. In order to improve the tracking performance, an integral sliding surface is designed. An energy saving effect because of chattering reduction is also evaluated. First, the dynamics of the quad-rotor helicopter is derived by the Newton-Euler formulation for a rigid body. Second, a constant plus proportional reaching law is introduced to increase the reaching rate of the sliding mode controller. Global stability of the proposed control strategy is guaranteed based on the Lyapunov's stability theory. Finally, the robustness and effectiveness of the proposed control system are demonstrated experimentally under wind gusts, and are compared with a regular sliding mode controller, a proportional-differential controller, and a proportional-integral-differential controller.

  5. Design of a chatter-free terminal sliding mode controller for nonlinear fractional-order dynamical systems

    NASA Astrophysics Data System (ADS)

    Pourmahmood Aghababa, Mohammad

    2013-10-01

    This paper investigates the problem of robust control of nonlinear fractional-order dynamical systems in the presence of uncertainties. First, a novel switching surface is proposed and its finite-time stability to the origin is proved. Subsequently, using the sliding mode theory, a robust fractional control law is proposed to ensure the existence of the sliding motion in finite time. We use a fractional Lyapunov stability theory to prove the stability of the system in a given finite time. In order to avoid the chattering, which is inherent in conventional sliding mode controllers, we transfer the sign function of the control input into the fractional derivative of the control signal. The proposed chattering-free sliding mode technique is then applied for stabilisation of a broad class of three-dimensional fractional-order chaotic systems via a single variable driving control input. Simulation results reveal that the proposed fractional sliding mode controller works well for chaos control of fractional-order hyperchaotic Chen, chaotic Lorenz and chaotic Arneodo systems with no-chatter control inputs.

  6. Reusable Launch Vehicle Attitude Control Using a Time-Varying Sliding Mode Control Technique

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.; Zhu, J. Jim; Daniels, Dan; Jackson, Scott (Technical Monitor)

    2002-01-01

    In this paper we present a time-varying sliding mode control (TVSMC) technique for reusable launch vehicle (RLV) attitude control in ascent and entry flight phases. In ascent flight the guidance commands Euler roll, pitch and yaw angles, and in entry flight it commands the aerodynamic angles of bank, attack and sideslip. The controller employs a body rate inner loop and the attitude outer loop, which are separated in time-scale by the singular perturbation principle. The novelty of the TVSMC is that both the sliding surface and the boundary layer dynamics can be varied in real time using the PD-eigenvalue assignment technique. This salient feature is used to cope with control command saturation and integrator windup in the presence of severe disturbance or control effector failure, which enhances the robustness and fault tolerance of the controller. The TV-SMC ascent and descent designs are currently being tested with high fidelity, 6-DOF dispersion simulations. The test results will be presented in the final version of this paper.

  7. Sliding mode based trajectory linearization control for hypersonic reentry vehicle via extended disturbance observer.

    PubMed

    Xingling, Shao; Honglun, Wang

    2014-11-01

    This paper proposes a novel hybrid control framework by combing observer-based sliding mode control (SMC) with trajectory linearization control (TLC) for hypersonic reentry vehicle (HRV) attitude tracking problem. First, fewer control consumption is achieved using nonlinear tracking differentiator (TD) in the attitude loop. Second, a novel SMC that employs extended disturbance observer (EDO) to counteract the effect of uncertainties using a new sliding surface which includes the estimation error is integrated to address the tracking error stabilization issues in the attitude and angular rate loop, respectively. In addition, new results associated with EDO are examined in terms of dynamic response and noise-tolerant performance, as well as estimation accuracy. The key feature of the proposed compound control approach is that chattering free tracking performance with high accuracy can be ensured for HRV in the presence of multiple uncertainties under control constraints. Based on finite time convergence stability theory, the stability of the resulting closed-loop system is well established. Also, comparisons and extensive simulation results are presented to demonstrate the effectiveness of the control strategy.

  8. Design and implementation of a novel sliding mode sensing architecture for capacitive MEMS accelerometers

    NASA Astrophysics Data System (ADS)

    Sarraf, E. H.; Cousins, B.; Cretu, E.; Mirabbasi, S.

    2011-11-01

    We propose novel feedback control and sensing schemes based on sliding mode control (SMC) for closed-loop micro-accelerometers as alternative digital control architectures to sigma-delta (ΣΔ) approaches. The under-damped micro-device has been designed in Coventorware, fabricated in SOIMUMPs (25 µm thick structural layer) technology and experimentally characterized using a Polytec MSA-500 (micro-system analyzer) equipment. To verify the system architecture robustness, the application of SMC is extended to an over-damped accelerometer model. In either case, the SMC demonstrates the repositioning of the proof mass to null position; however, the over-damped model exhibits shorter transition time (15 ms for 1g acceleration) due to the increased damping. In addition to that, we extend the usage of SMC beyond the classical actuation problem to a novel sensing problem where we demonstrate the extraction of the external acceleration measurement from the switching behavior along the sliding surface. An optimized fixed-point implementation is targeted on a field-programmable gate array (FPGA) using rapid prototyping methodology, where the new proposed method has been compared for reference with a control scheme that employs a ΣΔ modulator. The SMC-based architecture is advantageous in terms of hardware complexity, and the control of the number of degrees of freedom required by an inertial measurement unit can be accommodated on a low-cost FPGA device. SMC offers a sound theoretical framework for the nonlinear control of inertial sensors.

  9. Sliding mode coordination control for multiagent systems with underactuated agent dynamics

    NASA Astrophysics Data System (ADS)

    Ghasemi, Masood; Nersesov, Sergey G.; Clayton, Garrett; Ashrafiuon, Hashem

    2014-12-01

    In this paper, we develop a new integrated coordinated control and obstacle avoidance approach for a general class of underactuated agents. We use graph-theoretic notions to characterise communication topology in the network of underactuated agents as determined by the information flow directions and captured by the graph Laplacian matrix. Obstacle avoidance is achieved by surrounding the stationary as well as moving obstacles by elliptical or other convex shapes that serve as stable periodic solutions to planar systems of ordinary differential equations and using transient trajectories of those systems to navigate the agents around the obstacles. Decentralised controllers for individual agents are designed using sliding mode control approach and are only based on data communicated from the neighbouring agents. We demonstrate the efficacy of our theoretical approach using an example of a system of wheeled mobile robots that reach and maintain a desired formation. Finally, we validate our results experimentally.

  10. Continuous high order sliding mode controller design for a flexible air-breathing hypersonic vehicle.

    PubMed

    Wang, Jie; Zong, Qun; Su, Rui; Tian, Bailing

    2014-05-01

    This paper investigates the problem of tracking control with uncertainties for a flexible air-breathing hypersonic vehicle (FAHV). In order to overcome the analytical intractability of this model, an Input-Output linearization model is constructed for the purpose of feedback control design. Then, the continuous finite time convergence high order sliding mode controller is designed for the Input-Output linearization model without uncertainties. In addition, a nonlinear disturbance observer is applied to estimate the uncertainties in order to compensate the controller and disturbance suppression, where disturbance observer and controller synthesis design is obtained. Finally, the synthesis of controller and disturbance observer is used to achieve the tracking for the velocity and altitude of the FAHV and simulations are presented to illustrate the effectiveness of the control strategies.

  11. Fault tolerant control based on interval type-2 fuzzy sliding mode controller for coaxial trirotor aircraft.

    PubMed

    Zeghlache, Samir; Kara, Kamel; Saigaa, Djamel

    2015-11-01

    In this paper, a robust controller for a Six Degrees of Freedom (6 DOF) coaxial trirotor helicopter control is proposed in presence of defects in the system. A control strategy based on the coupling of the interval type-2 fuzzy logic control and sliding mode control technique are used to design a controller. The main purpose of this work is to eliminate the chattering phenomenon and guaranteeing the stability and the robustness of the system. In order to achieve this goal, interval type-2 fuzzy logic control has been used to generate the discontinuous control signal. The simulation results have shown that the proposed control strategy can greatly alleviate the chattering effect, and perform good reference tracking in presence of defects in the system.

  12. Impedance Control of the Rehabilitation Robot Based on Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Zhou, Jiawang; Zhou, Zude; Ai, Qingsong

    As an auxiliary treatment, the 6-DOF parallel robot plays an important role in lower limb rehabilitation. In order to improve the efficiency and flexibility of the lower limb rehabilitation training, this paper studies the impedance controller based on the position control. A nonsingular terminal sliding mode control is developed to ensure the trajectory tracking precision and in contrast to traditional PID control strategy in the inner position loop, the system will be more stable. The stability of the system is proved by Lyapunov function to guarantee the convergence of the control errors. Simulation results validate the effectiveness of the target impedance model and show that the parallel robot can adjust gait trajectory online according to the human-machine interaction force to meet the gait request of patients, and changing the impedance parameters can meet the demands of different stages of rehabilitation training.

  13. Experimental Study of Flexible Plate Vibration Control by Using Two-Loop Sliding Mode Control Strategy

    NASA Astrophysics Data System (ADS)

    Yang, Jingyu; Lin, Jiahui; Liu, Yuejun; Yang, Kang; Zhou, Lanwei; Chen, Guoping

    2016-06-01

    It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.

  14. A fuzzy neural network sliding mode controller for vibration suppression in robotically assisted minimally invasive surgery.

    PubMed

    Sang, Hongqiang; Yang, Chenghao; Liu, Fen; Yun, Jintian; Jin, Guoguang

    2016-12-01

    It is very important for robotically assisted minimally invasive surgery to achieve a high-precision and smooth motion control. However, the surgical instrument tip will exhibit vibration caused by nonlinear friction and unmodeled dynamics, especially when the surgical robot system is attempting low-speed, fine motion. A fuzzy neural network sliding mode controller (FNNSMC) is proposed to suppress vibration of the surgical robotic system. Nonlinear friction and modeling uncertainties are compensated by a Stribeck model, a radial basis function (RBF) neural network and a fuzzy system, respectively. Simulations and experiments were performed on a 3 degree-of-freedom (DOF) minimally invasive surgical robot. The results demonstrate that the FNNSMC is effective and can suppress vibrations at the surgical instrument tip. The proposed FNNSMC can provide a robust performance and suppress the vibrations at the surgical instrument tip, which can enhance the quality and security of surgical procedures. Copyright © 2016 John Wiley & Sons, Ltd.

  15. Designing a robust minimum variance controller using discrete slide mode controller approach.

    PubMed

    Alipouri, Yousef; Poshtan, Javad

    2013-03-01

    Designing minimum variance controllers (MVC) for nonlinear systems is confronted with many difficulties. The methods able to identify MIMO nonlinear systems are scarce. Harsh control signals produced by MVC are among other disadvantages of this controller. Besides, MVC is not a robust controller. In this article, the Vector ARX (VARX) model is used for simultaneously modeling the system and disturbance in order to tackle these disadvantages. For ensuring the robustness of the control loop, the discrete slide mode controller design approach is used in designing MVC and generalized MVC (GMVC). The proposed method for controller design is tested on a nonlinear experimental Four-Tank benchmark process and is compared with nonlinear MVCs designed by neural networks. In spite of the simplicity of designing GMVCs for the VARX models with uncertainty, the results show that the proposed method is accurate and implementable.

  16. A Global Sliding-Mode Control Scheme with Adjustable Robustness for A Linear Variable Reluctance Motor

    NASA Astrophysics Data System (ADS)

    Lin, Jin-Yuan; Lu, Yu-Sheng; Chen, Jian-Shiang

    A novel global sliding-mode control (GSMC) scheme with adjustable robustness is presented in this article. The proposed scheme offers a switching function together with unperturbed system dynamics to weigh the contribution from SMC such that all of the closed-loop poles can be located within predefined regions to provide design flexibility, and the robustness of system can thus be adjusted. By this scheme, the maximal control effort and chattering level can be reduced according to designer's specifications directly. Since the switching function can initially be made to equal to zero, the adjustable performance during the entire response can be guaranteed, and the reaching condition is thus lifted. The efficacy of this scheme is demonstrated via successful implementation on a linear variable reluctance motor (LVRM) servo system. Both simulation and experimental studies further demonstrate its feasibility and effectiveness.

  17. State of charge estimation of lithium-ion batteries using fractional order sliding mode observer.

    PubMed

    Zhong, Qishui; Zhong, Fuli; Cheng, Jun; Li, Hui; Zhong, Shouming

    2017-01-01

    This paper presents a state of charge (SOC) estimation method based on fractional order sliding mode observer (SMO) for lithium-ion batteries. A fractional order RC equivalent circuit model (FORCECM) is firstly constructed to describe the charging and discharging dynamic characteristics of the battery. Then, based on the differential equations of the FORCECM, fractional order SMOs for SOC, polarization voltage and terminal voltage estimation are designed. After that, convergence of the proposed observers is analyzed by Lyapunov's stability theory method. The framework of the designed observer system is simple and easy to implement. The SMOs can overcome the uncertainties of parameters, modeling and measurement errors, and present good robustness. Simulation results show that the presented estimation method is effective, and the designed observers have good performance.

  18. A reduced-order nonlinear sliding mode observer for vehicle slip angle and tyre forces

    NASA Astrophysics Data System (ADS)

    Chen, Yuhang; Ji, Yunfeng; Guo, Konghui

    2014-12-01

    In this paper, a reduced-order sliding mode observer (RO-SMO) is developed for vehicle state estimation. Several improvements are achieved in this paper. First, the reference model accuracy is improved by considering vehicle load transfers and using a precise nonlinear tyre model 'UniTire'. Second, without the reference model accuracy degraded, the computing burden of the state observer is decreased by a reduced-order approach. Third, nonlinear system damping is integrated into the SMO to speed convergence and reduce chattering. The proposed RO-SMO is evaluated through simulation and experiments based on an in-wheel motor electric vehicle. The results show that the proposed observer accurately predicts the vehicle states.

  19. Higher order sliding mode control of laser pointing for orbital debris mitigation

    NASA Astrophysics Data System (ADS)

    Palosz, Arthur

    This thesis explores the use of a space-based laser to clean up small orbital debris from near Earth space. This system's challenge is to quickly and precisely aim the laser beam at very small (<1cm) and distant (<10km) moving orbital debris in the presence of parametric uncertainties and external disturbances. A mathematical model is derived for the debris position sensors, a Fast Steering Mirror (FSM), and a telescope which are used to track the orbital debris and then point and focus the laser beam onto the orbital debris. A Kalman Filter (KF) is designed to accurately track the orbital debris and generate a command signal for the controller. A second order Super Twisting Sliding Mode Controller (2-SMC) is designed to follow the command signal generated by the KF and to overcome the parametric uncertainties and external disturbances. The performance of the system is validated with a computer simulation created in MATLAB and Simulink.

  20. An improved sliding mode control method for omnidirectional mobile robots based on motion characteristics

    NASA Astrophysics Data System (ADS)

    Leng, Chuntao; Cao, Qixin; Lo, Charles

    2010-01-01

    An improved sliding mode control (SMC) method for omni-directional mobile robots (OMRs) is proposed in this paper. Due to the motion characteristics of OMRs, the driving torque acting on each axis while the robot moves in different directions is distinct. Accordingly, a novel concept of anisotropy characteristics for OMRs is proposed here. In order to achieve a coordinated motion in a multi-axis system such as an OMR, the anisotropy characteristics are introduced into SMC system to coordinate the driving torque. The improved motion control method can guarantee that each driving wheel will reach the target speed with proper driving torque. Owing to the advantage of SMC, the control system of OMRs is insensitive to parametric vibration and external disturbances. To validate the performance of the improved motion control method, experiments have been carried out.

  1. An improved sliding mode control method for omnidirectional mobile robots based on motion characteristics

    NASA Astrophysics Data System (ADS)

    Leng, Chuntao; Cao, Qixin; Lo, Charles

    2009-12-01

    An improved sliding mode control (SMC) method for omni-directional mobile robots (OMRs) is proposed in this paper. Due to the motion characteristics of OMRs, the driving torque acting on each axis while the robot moves in different directions is distinct. Accordingly, a novel concept of anisotropy characteristics for OMRs is proposed here. In order to achieve a coordinated motion in a multi-axis system such as an OMR, the anisotropy characteristics are introduced into SMC system to coordinate the driving torque. The improved motion control method can guarantee that each driving wheel will reach the target speed with proper driving torque. Owing to the advantage of SMC, the control system of OMRs is insensitive to parametric vibration and external disturbances. To validate the performance of the improved motion control method, experiments have been carried out.

  2. Robotic Implementation of Realistic Reaching Motion Using a Sliding Mode/Operational Space Controller

    NASA Astrophysics Data System (ADS)

    Spiers, Adam; Herrmann, Guido; Melhuish, Chris; Pipe, Tony; Lenz, Alexander

    It has been shown that a task-level controller with minimal-effort posture control produces human-like motion in simulation. This control approach is based on the dynamic model of a human skeletal system superimposed with realistic muscle like actuators whose effort is minimised. In practical application, there is often a degree of error between the dynamic model of a system used for controller derivation and the actual dynamics of the system. We present a practical application of the task-level control framework with simplified posture control in order to produce life-like and compliant reaching motions for a redundant task. The addition of a sliding mode controller improves performance of the physical robot by compensating for unknown parametric and dynamic disturbances without compromising the human-like posture.

  3. Experimental Study of Flexible Plate Vibration Control by Using Two-Loop Sliding Mode Control Strategy

    NASA Astrophysics Data System (ADS)

    Yang, Jingyu; Lin, Jiahui; Liu, Yuejun; Yang, Kang; Zhou, Lanwei; Chen, Guoping

    2017-08-01

    It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.

  4. Equivalent Neural Network Optimal Coefficients Using Forgetting Factor with Sliding Modes

    PubMed Central

    2016-01-01

    The Artificial Neural Network (ANN) concept is familiar in methods whose task is, for example, the identification or approximation of the outputs of complex systems difficult to model. In general, the objective is to determine online the adequate parameters to reach a better point-to-point convergence rate, so that this paper presents the parameter estimation for an equivalent ANN (EANN), obtaining a recursive identification for a stochastic system, firstly, with constant parameters and, secondly, with nonstationary output system conditions. Therefore, in the last estimation, the parameters also have stochastic properties, making the traditional approximation methods not adequate due to their losing of convergence rate. In order to give a solution to this problematic, we propose a nonconstant exponential forgetting factor (NCEFF) with sliding modes, obtaining in almost all points an exponential convergence rate decreasing. Theoretical results of both identification stages are performed using MATLAB® and compared, observing improvement when the new proposal for nonstationary output conditions is applied. PMID:28058045

  5. Equivalent Neural Network Optimal Coefficients Using Forgetting Factor with Sliding Modes.

    PubMed

    Aguilar Cruz, Karen Alicia; Medel Juárez, José de Jesús; Urbieta Parrazales, Romeo

    2016-01-01

    The Artificial Neural Network (ANN) concept is familiar in methods whose task is, for example, the identification or approximation of the outputs of complex systems difficult to model. In general, the objective is to determine online the adequate parameters to reach a better point-to-point convergence rate, so that this paper presents the parameter estimation for an equivalent ANN (EANN), obtaining a recursive identification for a stochastic system, firstly, with constant parameters and, secondly, with nonstationary output system conditions. Therefore, in the last estimation, the parameters also have stochastic properties, making the traditional approximation methods not adequate due to their losing of convergence rate. In order to give a solution to this problematic, we propose a nonconstant exponential forgetting factor (NCEFF) with sliding modes, obtaining in almost all points an exponential convergence rate decreasing. Theoretical results of both identification stages are performed using MATLAB® and compared, observing improvement when the new proposal for nonstationary output conditions is applied.

  6. Application of nonlinear sliding mode control to ultrasound contrast agent microbubbles.

    PubMed

    Carroll, James M; Lauderbaugh, Leal K; Calvisi, Michael L

    2013-07-01

    A sliding mode control system is developed and applied to a spherical model of a contrast agent microbubble that simulates its radial response to ultrasound. The model uses a compressible form of the Rayleigh-Plesset equation combined with a thin-shell model. A nonlinear control law for the second-order model is derived and used to design and simulate the controller. The effect of the controller on the contrast agent response is investigated for various control scenarios. This work demonstrates the feasibility of using a nonlinear control system to modulate the dynamic response of ultrasound contrast agents, but highlights the need for improved feedback mechanisms and control input methods. Possible applications of the nonlinear control system to contrast agents illustrated in this work include radius stabilization in the presence of an acoustic wave, radial growth and subsequent collapse, and generation of periodic radial oscillations while a contrast agent is within an acoustic forcing regime known to cause a chaotic response.

  7. Cellular modes of adaptation to environmental changes

    NASA Astrophysics Data System (ADS)

    Huckle, William R.

    2001-10-01

    Eukaryotic cells are remarkably adaptable entities. Whether embedded in solid tissues or freely suspended in blood or other fluids, cells principally exist in an aqueous environment but maintain a hydrophobic barrier, the plasma membrane, across which changes in the environment are detected. Utilizing specialized macromolecular components, cells can sense changes in temperature, hydrostatic pressure, oxygen tension, shear, shape, osmolarity, pH, electrical potential, electromagnetic radiation, and the concentrations of specific chemical compounds. Modes of response are equally varied, ranging from rapid secretion of stored substances to irreversible functional differentiation to self-destruction. Recent research has elucidated many of the enzymatic and genetic programs that accomplish these adaptations and suggests novel targets for therapeutic intervention.

  8. Reducing False Negative Reads in RFID Data Streams Using an Adaptive Sliding-Window Approach

    PubMed Central

    Massawe, Libe Valentine; Kinyua, Johnson D. M.; Vermaak, Herman

    2012-01-01

    Unreliability of the data streams generated by RFID readers is among the primary factors which limit the widespread adoption of the RFID technology. RFID data cleaning is, therefore, an essential task in the RFID middleware systems in order to reduce reading errors, and to allow these data streams to be used to make a correct interpretation and analysis of the physical world they are representing. In this paper we propose an adaptive sliding-window based approach called WSTD which is capable of efficiently coping with both environmental variation and tag dynamics. Our experimental results demonstrate the efficacy of the proposed approach. PMID:22666027

  9. Adaptive Control of Flexible Structures Using Residual Mode Filters

    NASA Technical Reports Server (NTRS)

    Balas, Mark J.; Frost, Susan

    2010-01-01

    Flexible structures containing a large number of modes can benefit from adaptive control techniques which are well suited to applications that have unknown modeling parameters and poorly known operating conditions. In this paper, we focus on a direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend our adaptive control theory to accommodate troublesome modal subsystems of a plant that might inhibit the adaptive controller. In some cases the plant does not satisfy the requirements of Almost Strict Positive Realness. Instead, there maybe be a modal subsystem that inhibits this property. This section will present new results for our adaptive control theory. We will modify the adaptive controller with a Residual Mode Filter (RMF) to compensate for the troublesome modal subsystem, or the Q modes. Here we present the theory for adaptive controllers modified by RMFs, with attention to the issue of disturbances propagating through the Q modes. We apply the theoretical results to a flexible structure example to illustrate the behavior with and without the residual mode filter. We have proposed a modified adaptive controller with a residual mode filter. The RMF is used to accommodate troublesome modes in the system that might otherwise inhibit the adaptive controller, in particular the ASPR condition. This new theory accounts for leakage of the disturbance term into the Q modes. A simple three-mode example shows that the RMF can restore stability to an otherwise unstable adaptively controlled system. This is done without modifying the adaptive controller design.

  10. Adaptive stochastic resonance method for impact signal detection based on sliding window

    NASA Astrophysics Data System (ADS)

    Li, Jimeng; Chen, Xuefeng; He, Zhengjia

    2013-04-01

    Aiming at solving the existing sharp problems in impact signal detection by using stochastic resonance (SR) in the fault diagnosis of rotating machinery, such as the measurement index selection of SR and the detection of impact signal with different impact amplitudes, the present study proposes an adaptive SR method for impact signal detection based on sliding window by analyzing the SR characteristics of impact signal. This method can not only achieve the optimal selection of system parameters by means of weighted kurtosis index constructed through using kurtosis index and correlation coefficient, but also achieve the detection of weak impact signal through the algorithm of data segmentation based on sliding window, even though the differences between different impact amplitudes are great. The algorithm flow of adaptive SR method is given and effectiveness of the method has been verified by the contrastive results between the proposed method and the traditional SR method of simulation experiments. Finally, the proposed method has been applied to a gearbox fault diagnosis in a hot strip finishing mill in which two local faults located on the pinion are obtained successfully. Therefore, it can be concluded that the proposed method is of great practical value in engineering.

  11. Sliding mode control based impact angle control guidance considering the seeker׳s field-of-view constraint.

    PubMed

    Wang, Xingliang; Zhang, Youan; Wu, Huali

    2016-03-01

    The problem of impact angle control guidance for a field-of-view constrained missile against non-maneuvering or maneuvering targets is solved by using the sliding mode control theory. The existing impact angle control guidance laws with field-of-view constraint are only applicable against stationary targets and most of them suffer abrupt-jumping of guidance command due to the application of additional guidance mode switching logic. In this paper, the field-of-view constraint is handled without using any additional switching logic. In particular, a novel time-varying sliding surface is first designed to achieve zero miss distance and zero impact angle error without violating the field-of-view constraint during the sliding mode phase. Then a control integral barrier Lyapunov function is used to design the reaching law so that the sliding mode can be reached within finite time and the field-of-view constraint is not violated during the reaching phase as well. A nonlinear extended state observer is constructed to estimate the disturbance caused by unknown target maneuver, and the undesirable chattering is alleviated effectively by using the estimation as a compensation item in the guidance law. The performance of the proposed guidance law is illustrated with simulations.

  12. Cytopathology whole slide images and virtual microscopy adaptive tutorials: A software pilot

    PubMed Central

    Van Es, Simone L.; Pryor, Wendy M.; Belinson, Zack; Salisbury, Elizabeth L.; Velan, Gary M.

    2015-01-01

    Background: The constant growth in the body of knowledge in medicine requires pathologists and pathology trainees to engage in continuing education. Providing them with equitable access to efficient and effective forms of education in pathology (especially in remote and rural settings) is important, but challenging. Methods: We developed three pilot cytopathology virtual microscopy adaptive tutorials (VMATs) to explore a novel adaptive E-learning platform (AeLP) which can incorporate whole slide images for pathology education. We collected user feedback to further develop this educational material and to subsequently deploy randomized trials in both pathology specialist trainee and also medical student cohorts. Cytopathology whole slide images were first acquired then novel VMATs teaching cytopathology were created using the AeLP, an intelligent tutoring system developed by Smart Sparrow. The pilot was run for Australian pathologists and trainees through the education section of Royal College of Pathologists of Australasia website over a period of 9 months. Feedback on the usability, impact on learning and any technical issues was obtained using 5-point Likert scale items and open-ended feedback in online questionnaires. Results: A total of 181 pathologists and pathology trainees anonymously attempted the three adaptive tutorials, a smaller proportion of whom went on to provide feedback at the end of each tutorial. VMATs were perceived as effective and efficient E-learning tools for pathology education. User feedback was positive. There were no significant technical issues. Conclusion: During this pilot, the user feedback on the educational content and interface and the lack of technical issues were helpful. Large scale trials of similar online cytopathology adaptive tutorials were planned for the future. PMID:26605119

  13. Cytopathology whole slide images and adaptive tutorials for senior medical students: a randomized crossover trial.

    PubMed

    Van Es, Simone L; Kumar, Rakesh K; Pryor, Wendy M; Salisbury, Elizabeth L; Velan, Gary M

    2016-01-08

    Diagnostic cytopathology is an essential part of clinical decision-making. However, due to a combination of factors including curriculum reform and shortage of pathologists to teach introductory cytopathology, this area of pathology receives little or no formal attention in most medical school curricula. We have previously described the successful use of efficient and effective digital learning resources, including whole slide images (WSI) and virtual microscopy adaptive tutorials (VMATs), to teach cytopathology to pathology specialist trainees - a group that had prior exposure to cytopathology in their day to day practice. Consequently, in the current study we attempted to demonstrate the efficiency and efficacy of this eLearning resource in a cohort of senior medical students that was completely naïve to the subject matter (cytopathology). We evaluated both the quantitative and qualitative impact of these digital educational materials for learning cytopathology compared with existing resources (e-textbooks and online atlases). The senior medical students were recruited from The University of New South Wales Australia for a randomized cross-over trial. Online assessments, administered after each arm of the trial, contained questions which related directly to a whole slide image. Two categories of questions in the assessments (focusing on either diagnosis or identification of cellular features) were utilized to determine efficacy. User experience and perceptions of efficiency were evaluated using online questionnaires containing Likert scale items and open-ended questions. For this cohort of senior medical students, virtual microscopy adaptive tutorials (VMATs) proved to be at least as effective as existing digital resources for learning cytopathology. Importantly, virtual microscopy adaptive tutorials had superior efficacy in facilitating accurate diagnosis on whole slide images. Student perceptions of VMATs were positive, particularly regarding the immediate

  14. Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

    NASA Astrophysics Data System (ADS)

    Keum, Jung-Hoon; Ra, Sung-Woong

    2009-12-01

    Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

  15. Global fast dynamic terminal sliding mode control for a quadrotor UAV.

    PubMed

    Xiong, Jing-Jing; Zhang, Guo-Bao

    2017-01-01

    A control method based on global fast dynamic terminal sliding mode control (TSMC) technique is proposed to design the flight controller for performing the finite-time position and attitude tracking control of a small quadrotor UAV. Firstly, the dynamic model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. Secondly, the dynamic flight controllers of the quadrotor are formulated based on global fast dynamic TSMC, which is able to guarantee that the position and velocity tracking errors of all system state variables converge to zero in finite-time. Moreover, the global fast dynamic TSMC is also able to eliminate the chattering phenomenon caused by the switching control action and realize the high precision performance. In addition, the stabilities of two subsystems are demonstrated by Lyapunov theory, respectively. Lastly, the simulation results are given to illustrate the effectiveness and robustness of the proposed control method in the presence of external disturbances. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  16. A coordinated MIMO control design for a power plant using improved sliding mode controller.

    PubMed

    Ataei, Mohammad; Hooshmand, Rahmat-Allah; Samani, Siavash Golmohammadi

    2014-03-01

    For the participation of the steam power plants in regulating the network frequency, boilers and turbines should be co-ordinately controlled in addition to the base load productions. Lack of coordinated control over boiler-turbine may lead to instability; oscillation in producing power and boiler parameters; reduction in the reliability of the unit; and inflicting thermodynamic tension on devices. This paper proposes a boiler-turbine coordinated multivariable control system based on improved sliding mode controller (ISMC). The system controls two main boiler-turbine parameters i.e., the turbine revolution and superheated steam pressure of the boiler output. For this purpose, a comprehensive model of the system including complete and exact description of the subsystems is extracted. The parameters of this model are determined according to our case study that is the 320MW unit of Islam-Abad power plant in Isfahan/Iran. The ISMC method is simulated on the power plant and its performance is compared with the related real PI (proportional-integral) controllers which have been used in this unit. The simulation results show the capability of the proposed controller system in controlling local network frequency and superheated steam pressure in the presence of load variations and disturbances of boiler.

  17. Development of a sliding mode control model for quiet upright stance.

    PubMed

    Zhang, Hongbo; Nussbaum, Maury A; Agnew, Michael J

    2016-02-01

    Human upright stance appears maintained or controlled intermittently, through some combination of passive and active ankle torques, respectively representing intrinsic and contractile contributions of the ankle musculature. Several intermittent postural control models have been proposed, though it has been challenging to accurately represent actual kinematics and kinetics and to separately estimate passive and active ankle torque components. Here, a simplified single-segment, 2D (sagittal plane) sliding mode control model was developed for application to track kinematics and kinetics during upright stance. The model was implemented and evaluated using previous experimental data consisting of whole body angular kinematics and ankle torques. Tracking errors for the whole-body center-of-mass (COM) angle and angular velocity, as well as ankle torque, were all within ∼10% of experimental values, though tracking performance for COM angular acceleration was substantially poorer. The model also enabled separate estimates of the contributions of passive and active ankle torques, with overall contributions estimated here to be 96% and 4% of the total ankle torque, respectively. Such a model may have future utility in understanding human postural control, though additional work is needed, such as expanding the model to multiple segments and to three dimensions.

  18. A Double-Wing Chaotic System Based on Ion Migration Memristor and Its Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Min, Guoqi; Duan, Shukai; Wang, Lidan

    The ion migration memristor is a nonlinear element with memory function and nanoscale size, it is considered as a potential candidate to reduce system power consumption and circuit size. When it works as the nonlinear part of the chaotic system, rich nonlinear curves will be produced, and at the same time, the complexity of chaotic systems and the randomness of signals will be enhanced. So in this paper, by Matlab numerical simulation, a new double-wing chaotic system based on an ion migration memristor is designed. In reality, there are many systems interfered inevitably by random noise, so in this paper the random bounded noises are also considered. The power spectrum, Lyapunov exponent spectrum, Poincaré map and bifurcation diagram are used to investigate its complex dynamic characteristics. Then, a SPICE-based analog circuit is presented to verify the feasibility of the system, for which the simulation results are consistent with the numerical simulation. Finally, the sliding mode variable structure control is applied to overcome the shortcomings of traditional control method, so that the chaotic orbits can be controlled to any fixed points or periodic orbits, and this provides an insight into chaos control in power electronics systems.

  19. Wiener sliding-mode control for artificial pancreas: a new nonlinear approach to glucose regulation.

    PubMed

    Abu-Rmileh, Amjad; Garcia-Gabin, Winston

    2012-08-01

    Type 1 diabetic patients need insulin therapy to keep their blood glucose close to normal. In this paper an attempt is made to show how nonlinear control-oriented model may be used to improve the performance of closed-loop control of blood glucose in diabetic patients. The nonlinear Wiener model is used as a novel modeling approach to be applied to the glucose control problem. The identified Wiener model is used in the design of a robust nonlinear sliding mode control strategy. Two configurations of the nonlinear controller are tested and compared to a controller designed with a linear model. The controllers are designed in a Smith predictor structure to reduce the effect of system time delay. To improve the meal compensation features, the controllers are provided with a simple feedforward controller to inject an insulin bolus at meal time. Different simulation scenarios have been used to evaluate the proposed controllers. The obtained results show that the new approach outperforms the linear control scheme, and regulates the glucose level within safe limits in the presence of measurement and modeling errors, meal uncertainty and patient variations.

  20. Robust tracking control of an IPMC actuator using nonsingular terminal sliding mode

    NASA Astrophysics Data System (ADS)

    Khawwaf, Jasim; Zheng, Jinchuan; Lu, Renquan; Al-Ghanimi, Ali; Kazem, Bahaa I.; Man, Zhihong

    2017-09-01

    Ionic polymer metal composite (IPMC) is a highly innovative material that has recently gained attention in many fields such as medical, biomimetic, and micro/nano underwater applications. The main characteristic of IPMC lies in its ability to achieve a large deflection under a fairly low driving voltage. Moreover, its agile, light weight, noiseless and flexible features render it well suited for certain specific applications. Like other smart materials, such as piezoelectric ceramics, IPMC could be used in actuators or sensors. In this paper, we study the application of IPMC as an actuator for underwater use. The goal is to develop a robust feedback controller for the IPMC actuator to track a desired reference whilst dealing with the uncertainties due to the inherent actuator nonlinearity, external disturbance or the variations of working environment. To this end, we first present a nominal model of the IPMC actuator through experimental identification. Next, a nonsingular terminal sliding mode controller is proposed. Lastly, experimental studies are conducted to verify the tracking accuracy and robustness of the designed controller.

  1. Sliding Mode Pulsed Averaging IC Drivers for High Brightness Light Emitting Diodes

    SciTech Connect

    Dr. Anatoly Shteynberg, PhD

    2006-08-17

    This project developed new Light Emitting Diode (LED) driver ICs associated with specific (uniquely operated) switching power supplies that optimize performance for High Brightness LEDs (HB-LEDs). The drivers utilize a digital control core with a newly developed nonlinear, hysteretic/sliding mode controller with mixed-signal processing. The drivers are flexible enough to allow both traditional microprocessor interface as well as other options such as “on the fly” adjustment of color and brightness. Some other unique features of the newly developed drivers include • AC Power Factor Correction; • High power efficiency; • Substantially fewer external components should be required, leading to substantial reduction of Bill of Materials (BOM). Thus, the LED drivers developed in this research : optimize LED performance by increasing power efficiency and power factor. Perhaps more remarkably, the LED drivers provide this improved performance at substantially reduced costs compared to the present LED power electronic driver circuits. Since one of the barriers to market penetration for HB-LEDs (in particular “white” light LEDs) is cost/lumen, this research makes important contributions in helping the advancement of SSL consumer acceptance and usage.

  2. State observer-based sliding mode control for semi-active hydro-pneumatic suspension

    NASA Astrophysics Data System (ADS)

    Ren, Hongbin; Chen, Sizhong; Zhao, Yuzhuang; Liu, Gang; Yang, Lin

    2016-02-01

    This paper proposes an improved virtual reference model for semi-active suspension to coordinate the vehicle ride comfort and handling stability. The reference model combines the virtues of sky-hook with ground-hook control logic, and the hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high-speed condition. Suspension state observer based on unscented Kalman filter is designed. A sliding mode controller (SMC) is developed to track the states of the reference model. The stability of the SMC strategy is proven by means of Lyapunov function taking into account the nonlinear damper characteristics and sprung mass variation of the vehicle. Finally, the performance of the controller is demonstrated under three typical working conditions: the random road excitation, speed bump road and sharp acceleration and braking. The simulation results indicated that, compared with the traditional passive suspension, the proposed control algorithm can offer a better coordination between vehicle ride comfort and handling stability. This approach provides a viable alternative to costlier active suspension control systems for commercial vehicles.

  3. LQ optimal and reaching law-based sliding modes for inventory management systems

    NASA Astrophysics Data System (ADS)

    Ignaciuk, Przemysław; Bartoszewicz, Andrzej

    2012-01-01

    In this article, the theory of discrete sliding-mode control is used to design new supply strategies for periodic-review inventory systems. In the considered systems, the stock used to fulfil an unknown, time-varying demand can be replenished from a single supply source or from multiple suppliers procuring orders with different delays. The proposed strategies guarantee that demand is always entirely satisfied from the on-hand stock (yielding the maximum service level), and the warehouse capacity is not exceeded (which eliminates the cost of emergency storage). In contrast to the classical, stochastic approaches, in this article, we focus on optimising the inventory system dynamics. The parameters of the first control strategy are selected by minimising a quadratic cost functional. Next, it is shown how the system dynamical performance can be improved by applying the concept of a reaching law with the appropriately adjusted reaching phase. The stable, nonoscillatory behaviour of the closed-loop system is demonstrated and the properties of the designed controllers are discussed and strictly proved.

  4. Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore Costa Rica

    NASA Astrophysics Data System (ADS)

    Steeb, P.; Krause, S.; Linke, P.; Hensen, C.; Dale, A. W.; Nuzzo, M.; Treude, T.

    2014-11-01

    Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane reaching the seafloor at cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at Quepos Slide site; a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m-2 d-1, with only 1 to 2.5% of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed Sediment-F low-Through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within 150-170 days. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

  5. Design and implementation of a new modified sliding mode controller for grid-connected inverter to controlling the voltage and frequency.

    PubMed

    Ghanbarian, Mohammad Mehdi; Nayeripour, Majid; Rajaei, Amirhossein; Mansouri, Mohammad Mahdi

    2016-03-01

    As the output power of a microgrid with renewable energy sources should be regulated based on the grid conditions, using robust controllers to share and balance the power in order to regulate the voltage and frequency of microgrid is critical. Therefore a proper control system is necessary for updating the reference signals and determining the proportion of each inverter in the microgrid control. This paper proposes a new adaptive method which is robust while the conditions are changing. This controller is based on a modified sliding mode controller which provides adapting conditions in linear and nonlinear loads. The performance of the proposed method is validated by representing the simulation results and experimental lab results.

  6. FAT-based adaptive sliding control for flexible arms: Theory and experiments

    NASA Astrophysics Data System (ADS)

    Haung, An-Chyau; Liao, Kuo-Kai

    2006-11-01

    An adaptive sliding controller is proposed in this paper for flexible arms containing time-varying uncertainties with unknown bounds based on function approximation technique (FAT). The uncertainties are firstly represented by finite linear combinations of orthonormal basis with some unknown constant weighting vectors. Output error dynamics can thus be derived as a stable first-order filter driven by parameter error vectors. Appropriate update laws for the weighting vectors are selected using the Lyapunov method so that asymptotic convergence of the output error can be proved as long as a sufficient number of basis functions are used. Effects of the approximation error on system performance are also investigated in this paper. Both computer simulation and experimental results confirm the feasibility of the proposed control strategy.

  7. A new fractional-order sliding mode controller via a nonlinear disturbance observer for a class of dynamical systems with mismatched disturbances.

    PubMed

    Pashaei, Shabnam; Badamchizadeh, Mohammadali

    2016-07-01

    This paper investigates the stabilization and disturbance rejection for a class of fractional-order nonlinear dynamical systems with mismatched disturbances. To fulfill this purpose a new fractional-order sliding mode control (FOSMC) based on a nonlinear disturbance observer is proposed. In order to design the suitable fractional-order sliding mode controller, a proper switching surface is introduced. Afterward, by using the sliding mode theory and Lyapunov stability theory, a robust fractional-order control law via a nonlinear disturbance observer is proposed to assure the existence of the sliding motion in finite time. The proposed fractional-order sliding mode controller exposes better control performance, ensures fast and robust stability of the closed-loop system, eliminates the disturbances and diminishes the chattering problem. Finally, the effectiveness of the proposed fractional-order controller is depicted via numerical simulation results of practical example and is compared with some other controllers.

  8. Adaptive sliding control of non-autonomous active suspension systems with time-varying loadings

    NASA Astrophysics Data System (ADS)

    Chen, Po-Chang; Huang, An-Chyau

    2005-04-01

    An adaptive sliding controller is proposed in this paper for controlling a non-autonomous quarter-car suspension system with time-varying loadings. The bound of the car-body loading is assumed to be available. Then, the reference coordinate is placed at the static position under the nominal loading so that the system dynamic equation is derived. Due to spring nonlinearities, the system property becomes asymmetric after coordinate transformation. Besides, in practical cases, system parameters are not easy to be obtained precisely for controller design. Therefore, in this paper, system uncertainties are lumped into two unknown time-varying functions. Since the variation bound of one of the unknown functions is not available, conventional adaptive schemes and robust designs are not applicable. To deal with this problem, the function approximation technique is employed to represent the unknown function as a finite combination of basis functions. The Lyapunov direct method can thus be used to find adaptive laws for updating coefficients in the approximating series and to prove stability of the closed-loop system. Since the position and velocity measurements of the unsprung mass are lumped into the unknown function, there is no need to install sensors on the axle and wheel assembly in the actual implementation. Simulation results are presented to show the performance of the proposed strategy.

  9. Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines.

    PubMed

    Ebrahimkhani, Sadegh

    2016-07-01

    Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme.

  10. Chaos suppression of Fractional order Willamowski-Rössler Chemical system and its synchronization using Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Rajagopal, Karthikeyan; Karthikeyan, Anitha

    2016-09-01

    Most of the Real systems shows chaotic behavior when they approach complex states. Especially in physical and chemical systems these behaviors define the character of the system. The control of these chaotic behaviors is of very high practical importance and hence mathematical models of these chaotic systems proves vital in deciding the control structures. One such model of chemical reactors is the Willamowski-Rössler system (WR). In this paper we derive a fractional order sliding mode control scheme where the states of the WR system are driven back to the defined equilibrium points. We have also synchronized master and slave fractional order WR system using sliding mode control. As the entire control law is defined in fractional order, we derived a new methodology to prove the stability of the controller. The numerical simulation and analysis are achieved with LabVIEW.

  11. A frequency independent approximation and a sliding mode control scheme for a system of a micro-cantilever beam.

    PubMed

    Vagia, Marialena

    2012-03-01

    In the present article, a sliding mode controller is proposed for a micro-cantilever beam (μCB) with fringing and squeezed film damping effects. The narrow micro-cantilever beam can move via the application of an external electrically induced force. The introduction of the squeezed film parameters results in a frequency-dependent nonlinear system. Particular attention, has been paid, in order to approximate the frequency dependent μCB model, with a valid, frequency independent one, that would be incorporated in the design of a robust sliding mode controller. The suggested control technique enables compact realization of a robust controller tolerant in device characteristics' variations, nonlinearities and types of inherent instabilities. Robustness of the proposed control scheme against disturbances is proved by Lyapunov's second method. In addition, bifurcation analysis is carried on the beam's nonlinear model, and numerous simulation test cases are presented in order to test the suggested modeling and control techniques.

  12. Direct power control of DFIG wind turbine systems based on an intelligent proportional-integral sliding mode control.

    PubMed

    Li, Shanzhi; Wang, Haoping; Tian, Yang; Aitouch, Abdel; Klein, John

    2016-09-01

    This paper presents an intelligent proportional-integral sliding mode control (iPISMC) for direct power control of variable speed-constant frequency wind turbine system. This approach deals with optimal power production (in the maximum power point tracking sense) under several disturbance factors such as turbulent wind. This controller is made of two sub-components: (i) an intelligent proportional-integral module for online disturbance compensation and (ii) a sliding mode module for circumventing disturbance estimation errors. This iPISMC method has been tested on FAST/Simulink platform of a 5MW wind turbine system. The obtained results demonstrate that the proposed iPISMC method outperforms the classical PI and intelligent proportional-integral control (iPI) in terms of both active power and response time. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Feedback attitude sliding mode regulation control of spacecraft using arm motion

    NASA Astrophysics Data System (ADS)

    Shi, Ye; Liang, Bin; Xu, Dong; Wang, Xueqian; Xu, Wenfu

    2013-09-01

    The problem of spacecraft attitude regulation based on the reaction of arm motion has attracted extensive attentions from both engineering and academic fields. Most of the solutions of the manipulator’s motion tracking problem just achieve asymptotical stabilization performance, so that these controllers cannot realize precise attitude regulation because of the existence of non-holonomic constraints. Thus, sliding mode control algorithms are adopted to stabilize the tracking error with zero transient process. Due to the switching effects of the variable structure controller, once the tracking error reaches the designed hyper-plane, it will be restricted to this plane permanently even with the existence of external disturbances. Thus, precise attitude regulation can be achieved. Furthermore, taking the non-zero initial tracking errors and chattering phenomenon into consideration, saturation functions are used to replace sign functions to smooth the control torques. The relations between the upper bounds of tracking errors and the controller parameters are derived to reveal physical characteristic of the controller. Mathematical models of free-floating space manipulator are established and simulations are conducted in the end. The results show that the spacecraft’s attitude can be regulated to the position as desired by using the proposed algorithm, the steady state error is 0.000 2 rad. In addition, the joint tracking trajectory is smooth, the joint tracking errors converges to zero quickly with a satisfactory continuous joint control input. The proposed research provides a feasible solution for spacecraft attitude regulation by using arm motion, and improves the precision of the spacecraft attitude regulation.

  14. Nonlinear Fractional Sliding Mode Controller Based on Reduced Order FNPK Model for Output Power Control of Nuclear Research Reactors

    NASA Astrophysics Data System (ADS)

    Davijani, Nafiseh Zare; Jahanfarnia, Gholamreza; Abharian, Amir Esmaeili

    2017-01-01

    One of the most important issues with respect to nuclear reactors is power control. In this study, we designed a fractional-order sliding mode controller based on a nonlinear fractional-order model of the reactor system in order to track the reference power trajectory and overcome uncertainties and external disturbances. Since not all of the variables in an operating reactor are measurable or specified in the control law, we propose a reduced-order fractional neutron point kinetic (ROFNPK) model based on measurable variables. In the design, we assume the differences between the approximated model and the real system is limited. We use the obtained model in the controller design process and use the Lyapunov method to perform a stability analysis of the closed-loop system. We simulate the proposed reduced-order fractional-order sliding mode controller (ROFOSMC) using Matlab/Simulink, and its performance is compared with that of a reduced order integer-order sliding mode controller (ROIOSMC). Our simulation results indicate an acceptable performance of the proposed approach in tracking the reference power trajectory with respect to ROIOSMC because of faster response of control effort signal and the smaller tracking error. Moreover, the results illustrate the capability of the controller in rejection of the disturbance and the noise signals and the robustness of controller against uncertainty.

  15. Backstepping sliding mode tracking control of a vane-type air motor X-Y table motion system.

    PubMed

    Lu, Chia-Hua; Hwang, Yean-Ren; Shen, Yu-Ta

    2011-04-01

    Air motors are increasingly being used in pneumatic related industries because of their advantages of low operating cost and low maintenance. The DSP controller and the backstepping sliding mode control method were utilized in this study to control an X-Y pneumatic table for tracking trajectory. Due to the effects of the compressibility of air, friction between the motor and ball screw table and the dead-zone effect caused by the proportional valve, the system will yield different responses even with the same inlet pressure and will chatter at low speed. Hence under certain conditions, this method of backstepping sliding mode control can be applied to achieve better results than with the PID controller, such as for tracking circle error and tracking error of the two axes. According to the results, a steady-state error of 0.5 μm can be achieved. The proposed method of backstepping sliding mode control can accomplish accurate tracking circle trajectory performance, offering an improvement in the tracking error of more than 50% over that of the PID controller.

  16. Sliding mode fault detection and fault-tolerant control of smart dampers in semi-active control of building structures

    NASA Astrophysics Data System (ADS)

    Yeganeh Fallah, Arash; Taghikhany, Touraj

    2015-12-01

    Recent decades have witnessed much interest in the application of active and semi-active control strategies for seismic protection of civil infrastructures. However, the reliability of these systems is still in doubt as there remains the possibility of malfunctioning of their critical components (i.e. actuators and sensors) during an earthquake. This paper focuses on the application of the sliding mode method due to the inherent robustness of its fault detection observer and fault-tolerant control. The robust sliding mode observer estimates the state of the system and reconstructs the actuators’ faults which are used for calculating a fault distribution matrix. Then the fault-tolerant sliding mode controller reconfigures itself by the fault distribution matrix and accommodates the fault effect on the system. Numerical simulation of a three-story structure with magneto-rheological dampers demonstrates the effectiveness of the proposed fault-tolerant control system. It was shown that the fault-tolerant control system maintains the performance of the structure at an acceptable level in the post-fault case.

  17. Adaptive control of waveguide modes using a directional coupler.

    PubMed

    Lu, Peng; Shipton, Matthew; Wang, Anbo; Xu, Yong

    2014-08-25

    Using adaptive optics (AO) and a directional coupler, we demonstrate adaptive control of linearly polarized (LP) modes in a two mode fiber. The AO feedback is provided by the coupling ratio of the directional coupler, and does not depend on the spatial profiles of optical field distributions. As a proof of concept demonstration, this work confirms the feasibility of using AO and all fiber devices to control the waveguide modes in a multimode network in a quasi-distributed manner.

  18. Adaptive Control Using Residual Mode Filters Applied to Wind Turbines

    NASA Technical Reports Server (NTRS)

    Frost, Susan A.; Balas, Mark J.

    2011-01-01

    Many dynamic systems containing a large number of modes can benefit from adaptive control techniques, which are well suited to applications that have unknown parameters and poorly known operating conditions. In this paper, we focus on a model reference direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend this adaptive control theory to accommodate problematic modal subsystems of a plant that inhibit the adaptive controller by causing the open-loop plant to be non-minimum phase. We will augment the adaptive controller using a Residual Mode Filter (RMF) to compensate for problematic modal subsystems, thereby allowing the system to satisfy the requirements for the adaptive controller to have guaranteed convergence and bounded gains. We apply these theoretical results to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine that has minimum phase zeros.

  19. Robust nonlinear generalised predictive control for a class of uncertain nonlinear systems via an integral sliding mode approach

    NASA Astrophysics Data System (ADS)

    Errouissi, Rachid; Yang, Jun; Chen, Wen-Hua; Al-Durra, Ahmed

    2016-08-01

    In this paper, a robust nonlinear generalised predictive control (GPC) method is proposed by combining an integral sliding mode approach. The composite controller can guarantee zero steady-state error for a class of uncertain nonlinear systems in the presence of both matched and unmatched disturbances. Indeed, it is well known that the traditional GPC based on Taylor series expansion cannot completely reject unknown disturbance and achieve offset-free tracking performance. To deal with this problem, the existing approaches are enhanced by avoiding the use of the disturbance observer and modifying the gain function of the nonlinear integral sliding surface. This modified strategy appears to be more capable of achieving both the disturbance rejection and the nominal prescribed specifications for matched disturbance. Simulation results demonstrate the effectiveness of the proposed approach.

  20. A fault-tolerant attitude control system for a satellite based on fuzzy global sliding mode control algorithm

    NASA Astrophysics Data System (ADS)

    Liang, Jinjin; Dong, Chaoyang; Wang, Qing

    2008-10-01

    The structures and missions of modern satellites are very complicated, so the reliability of satellites is becoming increasingly important. This paper proposed a fault-tolerant attitude control system for a satellite based on Fuzzy Global Sliding Mode Control (FGSMC) algorithm. We designed a controller for the nonlinear model of a satellite. By designing a global sliding surface, this controller can ensure that the response of the system has global robustness against the uncertainties of system and external disturbances. In this paper attitude control is performed by four reaction flywheels. The attitude control system distributed the three control torques to the four reaction flywheels according to the distribution matrix. We deduced the formula to calculate the distribution matrix. Paper proved the stability of the designed control law, and simulated the attitude control system. The simulation results show that the attitude control law has high accuracy and robustness.

  1. Unwinding forward and sliding back: an intermittent unwinding mode of the BLM helicase

    PubMed Central

    Wang, Shuang; Qin, Wei; Li, Jing-Hua; Lu, Ying; Lu, Ke-Yu; Nong, Da-Guan; Dou, Shuo-Xing; Xu, Chun-Hua; Xi, Xu-Guang; Li, Ming

    2015-01-01

    There are lines of evidence that the Bloom syndrome helicase, BLM, catalyzes regression of stalled replication forks and disrupts displacement loops (D-loops) formed during homologous recombination (HR). Here we constructed a forked DNA with a 3′ single-stranded gap and a 5′ double-stranded handle to partly mimic a stalled DNA fork and used magnetic tweezers to study BLM-catalyzed unwinding of the forked DNA. We have directly observed that the BLM helicase may slide on the opposite strand for some distance after duplex unwinding at different forces. For DNA construct with a long hairpin, progressive unwinding of the hairpin is frequently interrupted by strand switching and backward sliding of the enzyme. Quantitative study of the uninterrupted unwinding length (time) has revealed a two-state-transition mechanism for strand-switching during the unwinding process. Mutational studies revealed that the RQC domain plays an important role in stabilizing the helicase/DNA interaction during both DNA unwinding and backward sliding of BLM. Especially, Lys1125 in the RQC domain, a highly conserved amino acid among RecQ helicases, may be involved in the backward sliding activity. We have also directly observed the in vitro pathway that BLM disrupts the mimic stalled replication fork. These results may shed new light on the mechanisms for BLM in DNA repair and homologous recombination. PMID:25765643

  2. Unwinding forward and sliding back: an intermittent unwinding mode of the BLM helicase.

    PubMed

    Wang, Shuang; Qin, Wei; Li, Jing-Hua; Lu, Ying; Lu, Ke-Yu; Nong, Da-Guan; Dou, Shuo-Xing; Xu, Chun-Hua; Xi, Xu-Guang; Li, Ming

    2015-04-20

    There are lines of evidence that the Bloom syndrome helicase, BLM, catalyzes regression of stalled replication forks and disrupts displacement loops (D-loops) formed during homologous recombination (HR). Here we constructed a forked DNA with a 3' single-stranded gap and a 5' double-stranded handle to partly mimic a stalled DNA fork and used magnetic tweezers to study BLM-catalyzed unwinding of the forked DNA. We have directly observed that the BLM helicase may slide on the opposite strand for some distance after duplex unwinding at different forces. For DNA construct with a long hairpin, progressive unwinding of the hairpin is frequently interrupted by strand switching and backward sliding of the enzyme. Quantitative study of the uninterrupted unwinding length (time) has revealed a two-state-transition mechanism for strand-switching during the unwinding process. Mutational studies revealed that the RQC domain plays an important role in stabilizing the helicase/DNA interaction during both DNA unwinding and backward sliding of BLM. Especially, Lys1125 in the RQC domain, a highly conserved amino acid among RecQ helicases, may be involved in the backward sliding activity. We have also directly observed the in vitro pathway that BLM disrupts the mimic stalled replication fork. These results may shed new light on the mechanisms for BLM in DNA repair and homologous recombination.

  3. Maximum power point tracking algorithm based on sliding mode and fuzzy logic for photovoltaic sources under variable environmental conditions

    NASA Astrophysics Data System (ADS)

    Atik, L.; Petit, P.; Sawicki, J. P.; Ternifi, Z. T.; Bachir, G.; Della, M.; Aillerie, M.

    2017-02-01

    Solar panels have a nonlinear voltage-current characteristic, with a distinct maximum power point (MPP), which depends on the environmental factors, such as temperature and irradiation. In order to continuously harvest maximum power from the solar panels, they have to operate at their MPP despite the inevitable changes in the environment. Various methods for maximum power point tracking (MPPT) were developed and finally implemented in solar power electronic controllers to increase the efficiency in the electricity production originate from renewables. In this paper we compare using Matlab tools Simulink, two different MPP tracking methods, which are, fuzzy logic control (FL) and sliding mode control (SMC), considering their efficiency in solar energy production.

  4. Real-time crankshaft angular speed tracking and indicated torque estimation via optimized Luenberger sliding mode observer

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Tan, R.; Zheng, T. X.; Zhou, T. L.; Han, W. M.; Wang, Y. J.

    2017-03-01

    The interest in engine indicated torque estimation plays an important role in the automotive industry. In this study, an optimized Luenberger sliding mode observer is proposed based on easily available crankshaft angular speed of a four-cylinder spark ignition (SI) engine. Especially, the new observer is applied to track crankshaft angular speed and estimate engine indicated torque in New European Drive Cycle (NEDC). Convergence is proven through Lyapunov stability theory. The experimental results show that the proposed estimated technique can effectively track speed and has a higher accuracy in steady state.

  5. INDIRECT INTELLIGENT SLIDING MODE CONTROL OF A SHAPE MEMORY ALLOY ACTUATED FLEXIBLE BEAM USING HYSTERETIC RECURRENT NEURAL NETWORKS

    PubMed Central

    Hannen, Jennifer C.; Crews, John H.; Buckner, Gregory D.

    2012-01-01

    This paper introduces an indirect intelligent sliding mode controller (IISMC) for shape memory alloy (SMA) actuators, specifically a flexible beam deflected by a single offset SMA tendon. The controller manipulates applied voltage, which alters SMA tendon temperature to track reference bending angles. A hysteretic recurrent neural network (HRNN) captures the nonlinear, hysteretic relationship between SMA temperature and bending angle. The variable structure control strategy provides robustness to model uncertainties and parameter variations, while effectively compensating for system nonlinearities, achieving superior tracking compared to an optimized PI controller. PMID:22962538

  6. Robust tracking control of a unicycle-type wheeled mobile manipulator using a hybrid sliding mode fuzzy neural network

    NASA Astrophysics Data System (ADS)

    Cheng, Meng-Bi; Su, Wu-Chung; Tsai, Ching-Chih

    2012-03-01

    This article presents a robust tracking controller for an uncertain mobile manipulator system. A rigid robotic arm is mounted on a wheeled mobile platform whose motion is subject to nonholonomic constraints. The sliding mode control (SMC) method is associated with the fuzzy neural network (FNN) to constitute a robust control scheme to cope with three types of system uncertainties; namely, external disturbances, modelling errors, and strong couplings in between the mobile platform and the onboard arm subsystems. All parameter adjustment rules for the proposed controller are derived from the Lyapunov theory such that the tracking error dynamics and the FNN weighting updates are ensured to be stable with uniform ultimate boundedness (UUB).

  7. A sliding-mode approach to the simultaneous shape and attitude control of flexible space structures with uncertain dynamics

    NASA Astrophysics Data System (ADS)

    Dodds, S. J.; Senior, M.

    1993-09-01

    A new sliding-mode approach is applied to the simultaneous shape and attitude control of large space structures, such as an antenna reflector whose shape is to be accurately preserved. Arrangements of collocated sensors and continuous actuators are catered for. The control system is able to maintain a specified closed-loop transient performance over a wide range of dynamics parameters. This property enables the system to continue to operate satisfactorily after the occurrence of sensor and actuator failures, thereby greatly enhancing the system reliability. It also enables the control system to be designed without the need to derive a detailed dynamics model.

  8. Free-flying dynamics and control of an astronaut assistant robot based on fuzzy sliding mode algorithm

    NASA Astrophysics Data System (ADS)

    Gao, Qing; Liu, Jinguo; Tian, Tongtong; Li, Yangmin

    2017-09-01

    Space robots can perform some tasks in harsh environment as assistants of astronauts or substitutions of astronauts. Taking the limited working time and the arduous task of the astronauts in the space station into account, an astronaut assistant robot (AAR-2) applied in the space station is proposed and designed in this paper. The AAR-2 is achieved with some improvements on the basis of AAR-1 which was designed before. It can exploit its position and attitude sensors and control system to free flight or hover in the space cabin. And it also has a definite environmental awareness and artificial intelligence to complete some specified tasks under the control of astronauts or autonomously. In this paper, it mainly analyzes and controls the 6-DOF motion of the AAR-2. Firstly, the system configuration of AAR-2 is specifically described, and the movement principles are analyzed. Secondly, according to the physical model of the AAR-2, the Newton - Euler equation is applied in the preparation of space dynamics model of 6-DOF motion. Then, according to the mathematical model's characteristics which are nonlinear and strong coupling, a dual closed loop position and attitude controller based on fuzzy sliding mode control is proposed and designed. Finally, simulation experiments are appropriate to provide for AAR-2 control system by using Matlab/Simulink. From the simulation results it can be observed that the designed fuzzy sliding mode controller can control the 6-DOF motion of AAR-2 quickly and precisely.

  9. Finite Time Fault Tolerant Control for Robot Manipulators Using Time Delay Estimation and Continuous Nonsingular Fast Terminal Sliding Mode Control.

    PubMed

    Van, Mien; Ge, Shuzhi Sam; Ren, Hongliang

    2016-04-28

    In this paper, a novel finite time fault tolerant control (FTC) is proposed for uncertain robot manipulators with actuator faults. First, a finite time passive FTC (PFTC) based on a robust nonsingular fast terminal sliding mode control (NFTSMC) is investigated. Be analyzed for addressing the disadvantages of the PFTC, an AFTC are then investigated by combining NFTSMC with a simple fault diagnosis scheme. In this scheme, an online fault estimation algorithm based on time delay estimation (TDE) is proposed to approximate actuator faults. The estimated fault information is used to detect, isolate, and accommodate the effect of the faults in the system. Then, a robust AFTC law is established by combining the obtained fault information and a robust NFTSMC. Finally, a high-order sliding mode (HOSM) control based on super-twisting algorithm is employed to eliminate the chattering. In comparison to the PFTC and other state-of-the-art approaches, the proposed AFTC scheme possess several advantages such as high precision, strong robustness, no singularity, less chattering, and fast finite-time convergence due to the combined NFTSMC and HOSM control, and requires no prior knowledge of the fault due to TDE-based fault estimation. Finally, simulation results are obtained to verify the effectiveness of the proposed strategy.

  10. A new adjustable gains for second order sliding mode control of saturated DFIG-based wind turbine

    NASA Astrophysics Data System (ADS)

    Bounadja, E.; Djahbar, A.; Taleb, R.; Boudjema, Z.

    2017-02-01

    The control of Doubly-Fed induction generator (DFIG), used in wind energy conversion, has been given a great deal of interest. Frequently, this control has been dealt with ignoring the magnetic saturation effect in the DFIG model. The aim of the present work is twofold: firstly, the magnetic saturation effect is accounted in the control design model; secondly, a new second order sliding mode control scheme using adjustable-gains (AG-SOSMC) is proposed to control the DFIG via its rotor side converter. This scheme allows the independent control of the generated active and reactive power. Conventionally, the second order sliding mode control (SOSMC) applied to the DFIG, utilize the super-twisting algorithm with fixed gains. In the proposed AG-SOSMC, a simple means by which the controller can adjust its behavior is used. For that, a linear function is used to represent the variation in gain as a function of the absolute value of the discrepancy between the reference rotor current and its measured value. The transient DFIG speed response using the aforementioned characteristic is compared with the one determined by using the conventional SOSMC controller with fixed gains. Simulation results show, accurate dynamic performances, quicker transient response and more accurate control are achieved for different operating conditions.

  11. Nonlinear torque and air-to-fuel ratio control of spark ignition engines using neuro-sliding mode techniques.

    PubMed

    Huang, Ting; Javaherian, Hossein; Liu, Derong

    2011-06-01

    This paper presents a new approach for the calibration and control of spark ignition engines using a combination of neural networks and sliding mode control technique. Two parallel neural networks are utilized to realize a neuro-sliding mode control (NSLMC) for self-learning control of automotive engines. The equivalent control and the corrective control terms are the outputs of the neural networks. Instead of using error backpropagation algorithm, the network weights of equivalent control are updated using the Levenberg-Marquardt algorithm. Moreover, a new approach is utilized to update the gain of corrective control. Both modifications of the NSLMC are aimed at improving the transient performance and speed of convergence. Using the data from a test vehicle with a V8 engine, we built neural network models for the engine torque (TRQ) and the air-to-fuel ratio (AFR) dynamics and developed NSLMC controllers to achieve tracking control. The goal of TRQ control and AFR control is to track the commanded values under various operating conditions. From simulation studies, the feasibility and efficiency of the approach are illustrated. For both control problems, excellent tracking performance has been achieved.

  12. Switching sliding mode force tracking control of piezoelectric-hydraulic pump-based friction element actuation systems for automotive transmissions

    NASA Astrophysics Data System (ADS)

    Kim, Gi-Woo; Wang, K. W.

    2009-08-01

    In this study, a nonlinear sliding-mode controller is designed for force tracking of a piezoelectric-hydraulic pump (PHP)-based actuation system, which is developed to replace the current electro-hydraulic actuation systems for automatic transmission (AT) friction elements, such as band brakes or clutches. By utilizing the PHP, one can eliminate the various hydraulic components (oil pump, regulating valve and control valve) in current ATs and achieve a simpler configuration with more efficient operation. With the derived governing equation of motion of the PHP-based actuation system integrated with the friction element (band brake), a switching control law is synthesized based on the sliding-mode theory. To evaluate the effectiveness of the proposed control law, its force tracking performance for the engagement of a friction element during an AT 1\\to 2 up-shift is examined experimentally. It is shown that one can successfully track the desired force trajectory for AT shift control with small tracking error. This study demonstrates the potential of the PHP as a new controllable actuation system for AT friction elements.

  13. Implementation of a sliding-mode-based position sensorless drive for high-speed micro permanent-magnet synchronous motors.

    PubMed

    Chi, Wen-Chun; Cheng, Ming-Yang

    2014-03-01

    Due to issues such as limited space, it is difficult if it is not impossible to employ a position sensor in the drive control of high-speed micro PMSMs. In order to alleviate this problem, this paper analyzes and implements a simple and robust position sensorless field-oriented control method of high-speed micro PMSMs based on the sliding-mode observer. In particular, the angular position and velocity of the rotor of the high-speed micro PMSM are estimated using the sliding-mode observer. This observer is able to accurately estimate rotor position in the low speed region and guarantee fast convergence of the observer in the high speed region. The proposed position sensorless control method is suitable for electric dental handpiece motor drives where a wide speed range operation is essential. The proposed sensorless FOC method is implemented using a cost-effective 16-bit microcontroller and tested in a prototype electric dental handpiece motor. Several experiments are performed to verify the effectiveness of the proposed method.

  14. Haptic adaptation to slant: No transfer between exploration modes

    PubMed Central

    van Dam, Loes C. J.; Plaisier, Myrthe A.; Glowania, Catharina; Ernst, Marc O.

    2016-01-01

    Human touch is an inherently active sense: to estimate an object’s shape humans often move their hand across its surface. This way the object is sampled both in a serial (sampling different parts of the object across time) and parallel fashion (sampling using different parts of the hand simultaneously). Both the serial (moving a single finger) and parallel (static contact with the entire hand) exploration modes provide reliable and similar global shape information, suggesting the possibility that this information is shared early in the sensory cortex. In contrast, we here show the opposite. Using an adaptation-and-transfer paradigm, a change in haptic perception was induced by slant-adaptation using either the serial or parallel exploration mode. A unified shape-based coding would predict that this would equally affect perception using other exploration modes. However, we found that adaptation-induced perceptual changes did not transfer between exploration modes. Instead, serial and parallel exploration components adapted simultaneously, but to different kinaesthetic aspects of exploration behaviour rather than object-shape per se. These results indicate that a potential combination of information from different exploration modes can only occur at down-stream cortical processing stages, at which adaptation is no longer effective. PMID:27698392

  15. A new robust control scheme using second order sliding mode and fuzzy logic of a DFIM supplied by two five-level SVPWM inverters

    NASA Astrophysics Data System (ADS)

    Boudjema, Zinelaabidine; Taleb, Rachid; Bounadja, Elhadj

    2017-02-01

    Traditional filed oriented control strategy including proportional-integral (PI) regulator for the speed drive of the doubly fed induction motor (DFIM) have some drawbacks such as parameter tuning complications, mediocre dynamic performances and reduced robustness. Therefore, based on the analysis of the mathematical model of a DFIM supplied by two five-level SVPWM inverters, this paper proposes a new robust control scheme based on super twisting sliding mode and fuzzy logic. The conventional sliding mode control (SMC) has vast chattering effect on the electromagnetic torque developed by the DFIM. In order to resolve this problem, a second order sliding mode technique based on super twisting algorithm and fuzzy logic functions is employed. The validity of the employed approach was tested by using Matlab/Simulink software. Interesting simulation results were obtained and remarkable advantages of the proposed control scheme were exposed including simple design of the control system, reduced chattering as well as the other advantages.

  16. Rotor Current Control of DFIG for Improving Fault Ride - Through Using a Novel Sliding Mode Control Approach

    NASA Astrophysics Data System (ADS)

    Cai, Guowei; Liu, Cheng; Yang, Deyou

    2013-11-01

    The doubly fed induction generators (DFIG) have been recognized as the dominant technology used in wind power generation systems with the rapid development of wind power. However, continuous operation of DFIG may cause a serious wind turbine generators tripping accident, due to destructive over-current in the rotor winding which is caused by the power system fault or inefficient fault ride-through (FRT) strategy. A new rotor current control scheme in the rotor-side converter (RSC) ispresented to enhance FRT capacities of grid-connected DFIG. Due to the strongly nonlinear nature of DFIG and insensitive to DFIG parameter's variations, a novel sliding mode controller was designed. The controller combines extended state observer (ESO) with sliding model variable structure control theory. The simulation is carried out to verify the effectiveness of the proposed control approach under various types of grid disturbances. It is shown that the proposed controller provides enhanced transient features than the classic proportional-integral control. The proposed control method can effectively reduce over-current in the RSC, and the transient pulse value of electromagnetic torque is too large under power grid fault.

  17. Discrete-Time Integral Sliding Mode Control with Disturbances Compensation and Reduced Chattering for Pv Grid-Connected Inverter

    NASA Astrophysics Data System (ADS)

    Meo, Santolo; Sorrentino, Vincenzo

    2015-03-01

    In the paper a new discrete-time integral sliding mode control (DISMC) with disturbances compensation and reduced chattering for grid-connected inverter is proposed for active and reactive power regulation. Differently by many SMC proposed in literature that have a time-continuous formulation in spite have been implemented with digital processor, the proposed DISMC is fully formulated in discrete-time, taking into account the effects introduced by a microprocessor-based implementation. As will be demonstrated such approach consents to reduce the chattering about the sliding manifold within a boundary layer of O(T2) thickness instead of O(T) (being T the sampling period of the control algorithm). Moreover it introduces a correction of the control vector which eliminates the influence of modeling error and external disturbances improving stability and robustness of the controlled system. Constant converter switching frequency is achieved by using space vector modulation, which eases the design of the ac harmonic filter. In the paper, after a detailed formalization of the proposed control algorithm, several numerical and experimental results on a three-phase grid-connected inverter prototype are shown, proving the effectiveness of the control strategy.

  18. Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control.

    PubMed

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2016-08-25

    Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved.

  19. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

    PubMed

    Zhao, Bo; Li, Chenghao; Liu, Derong; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations.

  20. High-order sliding-mode control for blood glucose regulation in the presence of uncertain dynamics.

    PubMed

    Hernández, Ana Gabriela Gallardo; Fridman, Leonid; Leder, Ron; Andrade, Sergio Islas; Monsalve, Cristina Revilla; Shtessel, Yuri; Levant, Arie

    2011-01-01

    The success of blood glucose automatic regulation depends on the robustness of the control algorithm used. It is a difficult task to perform due to the complexity of the glucose-insulin regulation system. The variety of model existing reflects the great amount of phenomena involved in the process, and the inter-patient variability of the parameters represent another challenge. In this research a High-Order Sliding-Mode Control is proposed. It is applied to two well known models, Bergman Minimal Model, and Sorensen Model, to test its robustness with respect to uncertain dynamics, and patients' parameter variability. The controller designed based on the simulations is tested with the specific Bergman Minimal Model of a diabetic patient whose parameters were identified from an in vivo assay. To minimize the insulin infusion rate, and avoid the hypoglycemia risk, the glucose target is a dynamical profile.

  1. Parameter estimation and interval type-2 fuzzy sliding mode control of a z-axis MEMS gyroscope.

    PubMed

    Fazlyab, Mahyar; Pedram, Maysam Zamani; Salarieh, Hassan; Alasty, Aria

    2013-11-01

    This paper reports a hybrid intelligent controller for application in single axis MEMS vibratory gyroscopes. First, unknown parameters of a micro gyroscope including unknown time varying angular velocity are estimated online via normalized continuous time least mean squares algorithm. Then, an additional interval type-2 fuzzy sliding mode control is incorporated in order to match the resonant frequencies and to compensate for undesired mechanical couplings. The main advantage of this control strategy is its robustness to parameters uncertainty, external disturbance and measurement noise. Consistent estimation of parameters is guaranteed and stability of the closed-loop system is proved via the Lyapunov stability theorem. Finally, numerical simulation is done in order to validate the effectiveness of the proposed method, both for a constant and time-varying angular rate.

  2. Online fault detection of permanent magnet demagnetization for IPMSMs by nonsingular fast terminal-sliding-mode observer.

    PubMed

    Zhao, Kai-Hui; Chen, Te-Fang; Zhang, Chang-Fan; He, Jing; Huang, Gang

    2014-12-05

    To prevent irreversible demagnetization of a permanent magnet (PM) for interior permanent magnet synchronous motors (IPMSMs) by flux-weakening control, a robust PM flux-linkage nonsingular fast terminal-sliding-mode observer (NFTSMO) is proposed to detect demagnetization faults. First, the IPMSM mathematical model of demagnetization is presented. Second, the construction of the NFTSMO to estimate PM demagnetization faults in IPMSM is described, and a proof of observer stability is given. The fault decision criteria and fault-processing method are also presented. Finally, the proposed scheme was simulated using MATLAB/Simulink and implemented on the RT-LAB platform. A number of robustness tests have been carried out. The scheme shows good performance in spite of speed fluctuations, torque ripples and the uncertainties of stator resistance.

  3. Sliding mode control of dissolved oxygen in an integrated nitrogen removal process in a sequencing batch reactor (SBR).

    PubMed

    Muñoz, C; Young, H; Antileo, C; Bornhardt, C

    2009-01-01

    This paper presents a sliding mode controller (SMC) for dissolved oxygen (DO) in an integrated nitrogen removal process carried out in a suspended biomass sequencing batch reactor (SBR). The SMC performance was compared against an auto-tuning PI controller with parameters adjusted at the beginning of the batch cycle. A method for cancelling the slow DO sensor dynamics was implemented by using a first order model of the sensor. Tests in a lab-scale reactor showed that the SMC offers a better disturbance rejection capability than the auto-tuning PI controller, furthermore providing reasonable performance in a wide range of operation. Thus, SMC becomes an effective robust nonlinear tool to the DO control in this process, being also simple from a computational point of view, allowing its implementation in devices such as industrial programmable logic controllers (PLCs).

  4. Continuous higher-order sliding mode control with time-varying gain for a class of uncertain nonlinear systems.

    PubMed

    Han, Yaozhen; Liu, Xiangjie

    2016-05-01

    This paper presents a continuous higher-order sliding mode (HOSM) control scheme with time-varying gain for a class of uncertain nonlinear systems. The proposed controller is derived from the concept of geometric homogeneity and super-twisting algorithm, and includes two parts, the first part of which achieves smooth finite time stabilization of pure integrator chains. The second part conquers the twice differentiable uncertainty and realizes system robustness by employing super-twisting algorithm. Particularly, time-varying switching control gain is constructed to reduce the switching control action magnitude to the minimum possible value while keeping the property of finite time convergence. Examples concerning the perturbed triple integrator chains and excitation control for single-machine infinite bus power system are simulated respectively to demonstrate the effectiveness and applicability of the proposed approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  5. Online Fault Detection of Permanent Magnet Demagnetization for IPMSMs by Nonsingular Fast Terminal-Sliding-Mode Observer

    PubMed Central

    Zhao, Kai-Hui; Chen, Te-Fang; Zhang, Chang-Fan; He, Jing; Huang, Gang

    2014-01-01

    To prevent irreversible demagnetization of a permanent magnet (PM) for interior permanent magnet synchronous motors (IPMSMs) by flux-weakening control, a robust PM flux-linkage nonsingular fast terminal-sliding-mode observer (NFTSMO) is proposed to detect demagnetization faults. First, the IPMSM mathematical model of demagnetization is presented. Second, the construction of the NFTSMO to estimate PM demagnetization faults in IPMSM is described, and a proof of observer stability is given. The fault decision criteria and fault-processing method are also presented. Finally, the proposed scheme was simulated using MATLAB/Simulink and implemented on the RT-LAB platform. A number of robustness tests have been carried out. The scheme shows good performance in spite of speed fluctuations, torque ripples and the uncertainties of stator resistance. PMID:25490582

  6. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure

    PubMed Central

    Zhao, Bo; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations. PMID:26181826

  7. Real-time networked control of an industrial robot manipulator via discrete-time second-order sliding modes

    NASA Astrophysics Data System (ADS)

    Massimiliano Capisani, Luca; Facchinetti, Tullio; Ferrara, Antonella

    2010-08-01

    This article presents the networked control of a robotic anthropomorphic manipulator based on a second-order sliding mode technique, where the control objective is to track a desired trajectory for the manipulator. The adopted control scheme allows an easy and effective distribution of the control algorithm over two networked machines. While the predictability of real-time tasks execution is achieved by the Soft Hard Real-Time Kernel (S.Ha.R.K.) real-time operating system, the communication is established via a standard Ethernet network. The performances of the control system are evaluated under different experimental system configurations using, to perform the experiments, a COMAU SMART3-S2 industrial robot, and the results are analysed to put into evidence the robustness of the proposed approach against possible network delays, packet losses and unmodelled effects.

  8. Posture and Vibration Control Based on Virtual Suspension Model Using Sliding Mode Control for Six-Legged Walking Robot

    NASA Astrophysics Data System (ADS)

    Huang, Qingjiu; Fukuhara, Yasuyuki; Chen, Xuedong

    In this paper, we proposed a robust control method based on the virtual suspension model for keeping the posture stability and decreasing the tiny vibration of the robot body when it is walking on irregular terrain. Firstly, we developed a six-legged walking robot for this study based on stable theory of wave gaits and CAD dynamic model. Secondly, in order to keep the posture stability of body when robot walks, we designed a virtual suspension model with one degree of freedom, which has virtual spring and damper, for the direction of the center of gravity, the pitch angle, and the roll angle of body respectively. And then, in order to decrease the tiny vibration of body when robot walks, we proposed an active suspension control by using sliding mode control based on a virtual suspension model. These proposed methods are discussed using the walking experimental results of the developed six-legged walking robot.

  9. Robust Sensor Faults Reconstruction for a Class of Uncertain Linear Systems Using a Sliding Mode Observer: An LMI Approach

    SciTech Connect

    Iskander, Boulaabi; Faycal, Ben Hmida; Moncef, Gossa; Anis, Sellami

    2009-03-05

    This paper presents a design method of a Sliding Mode Observer (SMO) for robust sensor faults reconstruction of systems with matched uncertainty. This class of uncertainty requires a known upper bound. The basic idea is to use the H{sub {infinity}} concept to design the observer, which minimizes the effect of the uncertainty on the reconstruction of the sensor faults. Specifically, we applied the equivalent output error injection concept from previous work in Fault Detection and Isolation (FDI) scheme. Then, these two problems of design and reconstruction can be expressed and numerically formulate via Linear Matrix Inequalities (LMIs) optimization. Finally, a numerical example is given to illustrate the validity and the applicability of the proposed approach.

  10. Robust Sensor Faults Reconstruction for a Class of Uncertain Linear Systems Using a Sliding Mode Observer: An LMI Approach

    NASA Astrophysics Data System (ADS)

    Iskander, Boulaabi; Anis, Sellami; Fayçal, Ben Hmida; Moncef, Gossa

    2009-03-01

    This paper presents a design method of a Sliding Mode Observer (SMO) for robust sensor faults reconstruction of systems with matched uncertainty. This class of uncertainty requires a known upper bound. The basic idea is to use the H∞ concept to design the observer, which minimizes the effect of the uncertainty on the reconstruction of the sensor faults. Specifically, we applied the equivalent output error injection concept from previous work in Fault Detection and Isolation (FDI) scheme. Then, these two problems of design and reconstruction can be expressed and numerically formulate via Linear Matrix Inequalities (LMIs) optimization. Finally, a numerical example is given to illustrate the validity and the applicability of the proposed approach.

  11. Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control

    PubMed Central

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2016-01-01

    Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved. PMID:27571081

  12. Design and Investigation of a Dive Plane Sliding Mode Compensator for an Autonomous Underwater Vehicle

    DTIC Science & Technology

    1989-09-01

    CP1*CP2)/(-UX) 1/SLIDING SURFACE COEFFICIENT T-10: 0. 1:150.J; IETA -6.0; GA3 --O.035; GA4--UX; GA5---0.7; GA6---O.03; GA7-S2; GA8-S3; GA9-IETA; GA1O=1...GA1m(GA6-S3*UX)/(- GA3 ); GA2-(GA5+S2)/(- GA3 ); INPUT( : ,1)100*ONES(T); INPUT( :,2)-0.*ONES(T); Y-SIM(T,INPUT); PLOT(T,Y(:,1),’UPPER LEFT XLABEL/TIME...0.7;0.03;0J; AHAT-[LA1+LA2iLA3 ;LA1*LA2+LA2*LA3+LA1*LA3;L..L*LA2*LA3]; KC=INV( (N*W)’ )*(AHAT-ABAR); GA1=-1 .4; GA2=-0 .06; GA3 =-2*UX; GA4-KC(3,1) ; GA5

  13. Comparative Performance Analysis of Sliding Mode and Q-Controller Algorithms for Buck Converter

    NASA Astrophysics Data System (ADS)

    Pati, Nivedita

    2017-08-01

    The switched mode dc-dc converters are some of the simplest power electronic circuits which have received an increasing deal of interest in many areas due to their high efficiency and small size. These converters are non-linear and time-variant in nature; hence the analysis, control and stabilization are the main factors that need to be considered. Many control methodology are used for control of switch mode dc-dc converters but the optimum one is always in demand. This paper presents the linearization of the Buck converter model and a comparison between a linear and non-linear control algorithms for better output voltage regulation along with robustness to change in input voltage and load parameters. The computer –aided design software tool Matlab/Simulink is used for the simulations and the results are presented.

  14. Residual mode filters and adaptive control in large space structures

    NASA Technical Reports Server (NTRS)

    Davidson, Roger A.; Balas, Mark J.

    1989-01-01

    One of the most difficult problems in controlling large systems and structures is compensating for the destructive interaction which can occur between the reduced-order model (ROM) of the plant, which is used by the controller, and the unmodeled dynamics of the plant, often called the residual modes. The problem is more significant in the case of large space structures because their naturally light damping and high performance requirements lead to more frequent, destructive residual mode interaction (RMI). Using the design/compensation technique of residual mode filters (RMF's), effective compensation of RMI can be accomplished in a straightforward manner when using linear controllers. The use of RMF's has been shown to be effective for a variety of large structures, including a space-based laser and infinite dimensional systems. However, the dynamics of space structures is often uncertain and may even change over time due to on-orbit erosion from space debris and corrosive chemicals in the upper atmosphere. In this case, adaptive control can be extremely beneficial in meeting the performance requirements of the structure. Adaptive control for large structures is also based on ROM's and so destructive RMI may occur. Unfortunately, adaptive control is inherently nonlinear, and therefore the known results of RMF's cannot be applied. The purpose is to present the results of new research showing the effects of RMI when using adaptive control and the work which will hopefully lead to RMF compensation of this problem.

  15. An Adaptive Classification Strategy for Reliable Locomotion Mode Recognition.

    PubMed

    Liu, Ming; Zhang, Fan; Huang, He Helen

    2017-09-04

    Algorithms for locomotion mode recognition (LMR) based on surface electromyography and mechanical sensors have recently been developed and could be used for the neural control of powered prosthetic legs. However, the variations in input signals, caused by physical changes at the sensor interface and human physiological changes, may threaten the reliability of these algorithms. This study aimed to investigate the effectiveness of applying adaptive pattern classifiers for LMR. Three adaptive classifiers, i.e., entropy-based adaptation (EBA), LearnIng From Testing data (LIFT), and Transductive Support Vector Machine (TSVM), were compared and offline evaluated using data collected from two able-bodied subjects and one transfemoral amputee. The offline analysis indicated that the adaptive classifier could effectively maintain or restore the performance of the LMR algorithm when gradual signal variations occurred. EBA and LIFT were recommended because of their better performance and higher computational efficiency. Finally, the EBA was implemented for real-time human-in-the-loop prosthesis control. The online evaluation showed that the applied EBA effectively adapted to changes in input signals across sessions and yielded more reliable prosthesis control over time, compared with the LMR without adaptation. The developed novel adaptive strategy may further enhance the reliability of neurally-controlled prosthetic legs.

  16. Type-1 and Type-2 Fuzzy Logic and Sliding-Mode Based Speed Control of Direct Torque and Flux Control Induction Motor Drives - A Comparative Study

    NASA Astrophysics Data System (ADS)

    Ramesh, Tejavathu; Panda, A. K.; Kumar, S. Shiva

    2013-08-01

    In this research study, the performance of direct torque and flux control induction motor drive (IMD) is presented using five different speed control techniques. The performance of IMD mainly depends on the design of speed controller. The PI speed controller requires precise mathematical model, continuous and appropriate gain values. Therefore, adaptive control based speed controller is desirable to achieve high-performance drive. The sliding-mode speed controller (SMSC) is developed to achieve continuous control of motor speed and torque. Furthermore, the type-1 fuzzy logic speed controller (T1FLSC), type-1 fuzzy SMSC and a new type-2 fuzzy logic speed controller are designed to obtain high performance, dynamic tracking behaviour, speed accuracy and also robustness to parameter variations. The performance of each control technique has been tested for its robustness to parameter uncertainties and load disturbances. The detailed comparison of different control schemes are carried out in a MATALB/Simulink environment at different speed operating conditions, such as, forward and reversal motoring under no-load, load and sudden change in speed.

  17. Adaptive control of waveguide modes in a two-mode-fiber

    PubMed Central

    Lu, Peng; Shipton, Matthew; Wang, Anbo; Soker, Shay; Xu, Yong

    2014-01-01

    We experimentally demonstrate an adaptive-optics-based approach that allows selective excitation of waveguide modes and their mixtures in a two-mode fiber (TMF). A phase-only spatial light modulator is used for wavefront control, using feedback signals provided by the correlation between the experimentally measured field distribution and the desired mode profiles. Experimental results show the optical field within the TMF can be shaped to be pure linearly polarized (LP) modes or their combinations. Analysis shows selective mode excitation can be achieved using only 5 × 5 independent phase blocks. With proper feedback signals, this method should enable one to precisely control the optical field within any multimode fiber or other types of waveguides in real time. PMID:24663587

  18. Adaptive feedback control of wall modes in tokamaks

    NASA Astrophysics Data System (ADS)

    Sun, Zhipeng

    The goal of this study is to stabilize the resistive wall modes (RWM) in tokamaks with adaptive stochastic feedback control. This is the first ever attempt at adaptive stochastic feedback optimal control of RWM in tokamaks. Both adaptive optimal state feedback and adaptive output feedback control have been studied. The adaptive optimal state feedback control design successfully stabilizes a slowly time-evolving RWM in a tokamak in a time scale of 4 times the inverse of the growth rate of the RWM. The stabilized system output for the time-invariant model is twice the system noise level. For the time-varying model, it is several times larger than the time-invariant case. The adaptive stochastic output feedback can also stabilize the slowly time-evolving RWM. It can do this in a time about 3 times that of the inverse of the growth rate of the RWM. The stabilized system output is twice as large as that of the state feedback case. In order to avoid the bottleneck encountered in the various sequential computations with big matrices in the feedback algorithms, neural network control has been proposed. It has been used to implement the adaptive stochastic output feedback control. It can stabilize the RWM instability in a time of 3 times the inverse of the growth rate of the RWM. The stabilized wall modes have the steady state output similar to the output feedback case. The developed algorithms, state feedback, output feedback, neural network control, can be readily applied to other plasma instabilities.

  19. Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

    NASA Astrophysics Data System (ADS)

    Steeb, P.; Krause, S.; Linke, P.; Hensen, C.; Dale, A. W.; Nuzzo, M.; Treude, T.

    2015-11-01

    Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore of Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane migrating through the sediments of cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at the Quepos Slide site, a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m-2 d-1, with only 1 to 2.5 % of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed sediment-flow-through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within ca. 170 d. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

  20. Symmetric caging formation for convex polygonal object transportation by multiple mobile robots based on fuzzy sliding mode control.

    PubMed

    Dai, Yanyan; Kim, YoonGu; Wee, SungGil; Lee, DongHa; Lee, SukGyu

    2016-01-01

    In this paper, the problem of object caging and transporting is considered for multiple mobile robots. With the consideration of minimizing the number of robots and decreasing the rotation of the object, the proper points are calculated and assigned to the multiple mobile robots to allow them to form a symmetric caging formation. The caging formation guarantees that all of the Euclidean distances between any two adjacent robots are smaller than the minimal width of the polygonal object so that the object cannot escape. In order to avoid collision among robots, the parameter of the robots radius is utilized to design the caging formation, and the A⁎ algorithm is used so that mobile robots can move to the proper points. In order to avoid obstacles, the robots and the object are regarded as a rigid body to apply artificial potential field method. The fuzzy sliding mode control method is applied for tracking control of the nonholonomic mobile robots. Finally, the simulation and experimental results show that multiple mobile robots are able to cage and transport the polygonal object to the goal position, avoiding obstacles.

  1. Design of Linear DC Motor Two-degree-of-freedom Positioning System using Model Reference type Sliding Mode Controller

    NASA Astrophysics Data System (ADS)

    Urushihara, Shiro; Kamano, Takuya; Yura, Satoshi; Yasuno, Takashi; Suzuki, Takayuki

    One of fundamental problems in the factory automation is how to obtain linear motion. Linear motors produce directly the linear motion force without a motion-transform mechanism. Linear d.c. motors (LDMs) have excellent performance and controllability. However, the dynamics of small-sized LDMs is adversely affected by the dead-band due to the friction between brushes and commutators. In this paper, it is described that the design of the two-degree-of-freedom positioning system with a LDM using model reference type sliding mode controller (SMC). The proposed positioning system consists of a fixed gain feedforward controller and a SMC used as a feedback controller. The objective of the SMC is to repress the influence of nonlinear characteristics (the dead-band and parameter variations etc.). The tracking performance can be improved as the fixed gain feedforward controller makes a dynamic inverse system in the feedforward path. The effectiveness of the proposed system for improvement of the tracking performance is demonstrated by experimental results.

  2. Fault-tolerant control of electric vehicles with in-wheel motors using actuator-grouping sliding mode controllers

    NASA Astrophysics Data System (ADS)

    Li, Boyuan; Du, Haiping; Li, Weihua

    2016-05-01

    Although electric vehicles with in-wheel motors have been regarded as one of the promising vehicle architectures in recent years, the probability of in-wheel motor fault is still a crucial issue due to the system complexity and large number of control actuators. In this study, a modified sliding mode control (SMC) is applied to achieve fault-tolerant control of electric vehicles with four-wheel-independent-steering (4WIS) and four-wheel-independent-driving (4WID). Unlike in traditional SMC, in this approach the steering geometry is re-arranged according to the location of faulty wheels in the modified SMC. Three SMC control laws for longitudinal velocity control, lateral velocity control and yaw rate control are designed based on specific vehicle motion scenarios. In addition the actuator-grouping SMC method is proposed so that driving actuators are grouped and each group of actuators can be used to achieve the specific control target, which avoids the strong coupling effect between each control target. Simulation results prove that the proposed modified SMC can achieve good vehicle dynamics control performance in normal driving and large steering angle turning scenarios. In addition, the proposed actuator-grouping SMC can solve the coupling effect of different control targets and the control performance is improved.

  3. A Sliding-Mode Triboelectric Nanogenerator with Chemical Group Grated Structure by Shadow Mask Reactive Ion Etching.

    PubMed

    Shang, Wanyu; Gu, Guang Qin; Yang, Feng; Zhao, Lei; Cheng, Gang; Du, Zu-Liang; Wang, Zhong Lin

    2017-08-25

    The sliding-mode triboelectric nanogenerator (S-TENG) with grated structure has important applications in energy harvest and active sensors; however its concavo-convex structure leads to large frictional resistance and abrasion. Here, we developed a S-TENG with a chemical group grated structure (S-TENG-CGG), in which the triboelectric layer's triboelectric potential has a positive-negative alternating charged structure. The triboelectric layer of the S-TENG-CGG was fabricated through a reactive ion etching process with a metal shadow mask with grated structure. In the etched region, the nylon film, originally positively charged as in friction with stainless steel, gained opposite triboelectric potential and became negatively charged because of the change of surface functional groups. The output signals of the S-TENG-CGG are alternating and the frequency is determined by both the segment numbers and the moving speed. The applications of the S-TENG-CGG in the charging capacitor and driving calculator are demonstrated. In the S-TENG-CGG, since there is no concavo-convex structure, the frictional resistance and abrasion are largely reduced, which enhances its performances in better stability and longer working time.

  4. Nonlinear observation of internal states of fuel cell cathode utilizing a high-order sliding-mode algorithm

    NASA Astrophysics Data System (ADS)

    Xu, Liangfei; Hu, Junming; Cheng, Siliang; Fang, Chuan; Li, Jianqiu; Ouyang, Minggao; Lehnert, Werner

    2017-07-01

    A scheme for designing a second-order sliding-mode (SOSM) observer that estimates critical internal states on the cathode side of a polymer electrolyte membrane (PEM) fuel cell system is presented. A nonlinear, isothermal dynamic model for the cathode side and a membrane electrolyte assembly are first described. A nonlinear observer topology based on an SOSM algorithm is then introduced, and equations for the SOSM observer deduced. Online calculation of the inverse matrix produces numerical errors, so a modified matrix is introduced to eliminate the negative effects of these on the observer. The simulation results indicate that the SOSM observer performs well for the gas partial pressures and air stoichiometry. The estimation results follow the simulated values in the model with relative errors within ± 2% at stable status. Large errors occur during the fast dynamic processes (<1 s). Moreover, the nonlinear observer shows good robustness against variations in the initial values of the internal states, but less robustness against variations in system parameters. The partial pressures are more sensitive than the air stoichiometry to system parameters. Finally, the order of effects of parameter uncertainties on the estimation results is outlined and analyzed.

  5. Controller-structure interaction compensation using adaptive residual mode filters

    NASA Technical Reports Server (NTRS)

    Davidson, Roger A.; Balas, Mark J.

    1990-01-01

    It is not feasible to construct controllers for large space structures or large scale systems (LSS's) which are of the same order as the structures. The complexity of the dynamics of these systems is such that full knowledge of its behavior cannot by processed by today's controller design methods. The controller for system performance of such a system is therefore based on a much smaller reduced-order model (ROM). Unfortunately, the interaction between the LSS and the ROM-based controller can produce instabilities in the closed-loop system due to the unmodeled dynamics of the LSS. Residual mode filters (RMF's) allow the systematic removal of these instabilities in a matter which does not require a redesign of the controller. In addition RMF's have a strong theoretical basis. As simple first- or second-order filters, the RMF CSI compensation technique is at once modular, simple and highly effective. RMF compensation requires knowledge of the dynamics of the system modes which resulted in the previous closed-loop instabilities (the residual modes), but this information is sometimes known imperfectly. An adaptive, self-tuning RMF design, which compensates for uncertainty in the frequency of the residual mode, has been simulated using continuous-time and discrete-time models of a flexible robot manipulator. Work has also been completed on the discrete-time experimental implementation on the Martin Marietta flexible robot manipulator experiment. This paper will present the results of that work on adaptive, self-tuning RMF's, and will clearly show the advantage of this adaptive compensation technique for controller-structure interaction (CSI) instabilities in actively-controlled LSS's.

  6. Imaging and suppression of Lamb modes using adaptive beamforming

    NASA Astrophysics Data System (ADS)

    Engholm, Marcus; Stepinski, Tadeusz; Olofsson, Tomas

    2011-08-01

    Lamb waves have proven to be very useful for plate inspection because large areas of a plate can be covered from a fixed position. This capability makes them suitable for both inspection and structural health monitoring (SHM) applications. During the last decade, research on the use of active arrays in combination with beamforming techniques has shown that a fixed array can be used to perform omni-directional monitoring of a plate structure. The dispersion and multiple propagating modes are issues that need to be addressed when working with Lamb waves. Previous work has mainly focused on conventional, delay-and-sum (DAS) beamforming, while reducing the effects of multiple modes through frequency selectivity and transducer design. The paper describes an adaptive beamforming technique using a minimum variance distortionless response beamforming (MVBF) approach for spatial Lamb wave filtering with multiple-transmitter-multiple-receiver arrays. Dispersion is compensated for by using theoretically calculated dispersion curves. Simulations are used for evaluating the performance of the technique for suppression of interfering Lamb modes, both with and without the presence of mode conversion using different array configurations. A simple simulation model of the plate is used to compare the performance of different sizes of active arrays. An aluminum plate with artificial defects is used for the experimental evaluation. The results show that the MVBF approach performs a lot better in terms of resolution and suppression of interfering modes than the widely used standard beamformer.

  7. Motion-compensated wavelet video coding using adaptive mode selection

    NASA Astrophysics Data System (ADS)

    Zhai, Fan; Pappas, Thrasyvoulos N.

    2004-01-01

    A motion-compensated wavelet video coder is presented that uses adaptive mode selection (AMS) for each macroblock (MB). The block-based motion estimation is performed in the spatial domain, and an embedded zerotree wavelet coder (EZW) is employed to encode the residue frame. In contrast to other motion-compensated wavelet video coders, where all the MBs are forced to be in INTER mode, we construct the residue frame by combining the prediction residual of the INTER MBs with the coding residual of the INTRA and INTER_ENCODE MBs. Different from INTER MBs that are not coded, the INTRA and INTER_ENCODE MBs are encoded separately by a DCT coder. By adaptively selecting the quantizers of the INTRA and INTER_ENCODE coded MBs, our goal is to equalize the characteristics of the residue frame in order to improve the overall coding efficiency of the wavelet coder. The mode selection is based on the variance of the MB, the variance of the prediction error, and the variance of the neighboring MBs' residual. Simulations show that the proposed motion-compensated wavelet video coder achieves a gain of around 0.7-0.8dB PSNR over MPEG-2 TM5, and a comparable PSNR to other 2D motion-compensated wavelet-based video codecs. It also provides potential visual quality improvement.

  8. A non-saturated sliding-mode control of shaft deflection for magnetically suspended momentum wheel with coupled disturbance and saturated amplifier

    NASA Astrophysics Data System (ADS)

    Han, Chao; Wang, Xinwei; Yu, Yuanjin; Yang, Zhaohua

    2017-10-01

    The magnetically suspended momentum wheel (MSMW) expands its fresh functions through deflecting the rotary shaft. An improved nonsingular terminal sliding-mode control (NTSMC) method is proposed to achieve high precision tracking of shaft deflection for the MSMW under coupled disturbance and saturated amplifier. A novel structure designed for this MSMW is introduced initially. Its magnetic torque model and coupled disturbance are analyzed, and a tracking error dynamic model is established. Then a NTSMC method is applied to shaft tracking control. As the saturation of amplifier influences tracking performances, an improved NTSMC is designed to deal with saturation problem. Finally, several simulations are performed to validate the effectiveness of the proposed method. The results indicate the proposed method improves the tracking precision and velocity compared with the conventional integral sliding-mode method, and solves the saturation problem compared with existing NTSMC method.

  9. Observer-based higher order sliding mode control of power factor in three-phase AC/DC converter for hybrid electric vehicle applications

    NASA Astrophysics Data System (ADS)

    Liu, Jianxing; Laghrouche, Salah; Wack, Maxime

    2014-06-01

    In this paper, a full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control. The AC/DC converters are used for charging the battery and super-capacitor in hybrid electric vehicles from the utility. The proposed control forces the input currents to track the desired values, which can control the output voltage while keeping the power factor close to one. Super-twisting sliding mode observer is employed to estimate the input currents and load resistance only from the measurement of output voltage. Lyapunov analysis shows the asymptotic convergence of the closed-loop system to zero. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.

  10. Adaptive Localization of Focus Point Regions via Random Patch Probabilistic Density from Whole-Slide, Ki-67-Stained Brain Tumor Tissue

    PubMed Central

    Alomari, Yazan M.; MdZin, Reena Rahayu

    2015-01-01

    Analysis of whole-slide tissue for digital pathology images has been clinically approved to provide a second opinion to pathologists. Localization of focus points from Ki-67-stained histopathology whole-slide tissue microscopic images is considered the first step in the process of proliferation rate estimation. Pathologists use eye pooling or eagle-view techniques to localize the highly stained cell-concentrated regions from the whole slide under microscope, which is called focus-point regions. This procedure leads to a high variety of interpersonal observations and time consuming, tedious work and causes inaccurate findings. The localization of focus-point regions can be addressed as a clustering problem. This paper aims to automate the localization of focus-point regions from whole-slide images using the random patch probabilistic density method. Unlike other clustering methods, random patch probabilistic density method can adaptively localize focus-point regions without predetermining the number of clusters. The proposed method was compared with the k-means and fuzzy c-means clustering methods. Our proposed method achieves a good performance, when the results were evaluated by three expert pathologists. The proposed method achieves an average false-positive rate of 0.84% for the focus-point region localization error. Moreover, regarding RPPD used to localize tissue from whole-slide images, 228 whole-slide images have been tested; 97.3% localization accuracy was achieved. PMID:25793010

  11. Adaptive localization of focus point regions via random patch probabilistic density from whole-slide, Ki-67-stained brain tumor tissue.

    PubMed

    Alomari, Yazan M; Sheikh Abdullah, Siti Norul Huda; MdZin, Reena Rahayu; Omar, Khairuddin

    2015-01-01

    Analysis of whole-slide tissue for digital pathology images has been clinically approved to provide a second opinion to pathologists. Localization of focus points from Ki-67-stained histopathology whole-slide tissue microscopic images is considered the first step in the process of proliferation rate estimation. Pathologists use eye pooling or eagle-view techniques to localize the highly stained cell-concentrated regions from the whole slide under microscope, which is called focus-point regions. This procedure leads to a high variety of interpersonal observations and time consuming, tedious work and causes inaccurate findings. The localization of focus-point regions can be addressed as a clustering problem. This paper aims to automate the localization of focus-point regions from whole-slide images using the random patch probabilistic density method. Unlike other clustering methods, random patch probabilistic density method can adaptively localize focus-point regions without predetermining the number of clusters. The proposed method was compared with the k-means and fuzzy c-means clustering methods. Our proposed method achieves a good performance, when the results were evaluated by three expert pathologists. The proposed method achieves an average false-positive rate of 0.84% for the focus-point region localization error. Moreover, regarding RPPD used to localize tissue from whole-slide images, 228 whole-slide images have been tested; 97.3% localization accuracy was achieved.

  12. Fully automatic control of paraplegic FES pedaling using higher-order sliding mode and fuzzy logic control.

    PubMed

    Farhoud, Aidin; Erfanian, Abbas

    2014-05-01

    In this paper, a fully automatic robust control strategy is proposed for control of paraplegic pedaling using functional electrical stimulation (FES). The method is based on higher-order sliding mode (HOSM) control and fuzzy logic control. In FES, the strength of muscle contraction can be altered either by varying the pulse width (PW) or by the pulse amplitude (PA) of the stimulation signal. The proposed control strategy regulates simultaneously both PA and PW (i.e., PA/PW modulation). A HOSM controller is designed for regulating the PW and a fuzzy logic controller for the PA. The proposed control scheme is free-model and does not require any offline training phase and subject-specific information. Simulation studies on a virtual patient and experiments on three paraplegic subjects demonstrate good tracking performance and robustness of the proposed control strategy against muscle fatigue and external disturbances during FES-induced pedaling. The results of simulation studies show that the power and cadence tracking errors are 5.4% and 4.8%, respectively. The experimental results indicate that the proposed controller can improve pedaling system efficacy and increase the endurance of FES pedaling. The average of power tracking error over three paraplegic subjects is 7.4±1.4% using PA/PW modulation, while the tracking error is 10.2±1.2% when PW modulation is used. The subjects could pedal for 15 min with about 4.1% power loss at the end of experiment using proposed control strategy, while the power loss is 14.3% using PW modulation. The controller could adjust the stimulation intensity to compensate the muscle fatigue during long period of FES pedaling.

  13. SMA actuator material model with self-sensing and sliding-mode control; experiment and multibody dynamics model

    NASA Astrophysics Data System (ADS)

    Lambert, Tyler Ross; Gurley, Austin; Beale, David

    2017-03-01

    Shape memory alloys (SMA) can be used to create actuators that are simple, high strength, and inexpensive. These benefits come at the cost of low electrical efficiency, moderate lifetime, and complex mechanical behavior that makes them difficult to design into new applications and products. To improve the integration of SMA actuators—in particular thin SMA wires heated by passing electric current through them—into modern mechanical applications, we have created tools for modeling SMA mechanical and thermal behavior in dynamic systems and under feedback controls. Thermo-electro-mechanical constitutive models are implemented in a multibody dynamics software where they are easily applied to an actuator emplaced in a multibody dynamic system. Mechanical behavior is modeled with 1D constitutive equations. The material state determines the electrical resistivity of the material which drives ohmic heating, while thermal cooling is based on a heat transfer analysis of thin cylinders. These models contain states which are very difficult to measure experimentally (such as crystal phase fraction) and thus provide insight into the material behavior and design that experimental results cannot offer. This thermomechanical model is used in conjunction with sliding mode control—historically difficult to simulate in numerically integrated models—to develop a working ball-on-a-beam setup in which the ball position is controlled via current passed through an SMA wire and with application of an original self-sensing method. The constitutive model is developed in the multibody dynamics software MSC ADAMS and validated through the simulation of the same system.

  14. Nonlinear mode decomposition: a noise-robust, adaptive decomposition method.

    PubMed

    Iatsenko, Dmytro; McClintock, Peter V E; Stefanovska, Aneta

    2015-09-01

    The signals emanating from complex systems are usually composed of a mixture of different oscillations which, for a reliable analysis, should be separated from each other and from the inevitable background of noise. Here we introduce an adaptive decomposition tool-nonlinear mode decomposition (NMD)-which decomposes a given signal into a set of physically meaningful oscillations for any wave form, simultaneously removing the noise. NMD is based on the powerful combination of time-frequency analysis techniques-which, together with the adaptive choice of their parameters, make it extremely noise robust-and surrogate data tests used to identify interdependent oscillations and to distinguish deterministic from random activity. We illustrate the application of NMD to both simulated and real signals and demonstrate its qualitative and quantitative superiority over other approaches, such as (ensemble) empirical mode decomposition, Karhunen-Loève expansion, and independent component analysis. We point out that NMD is likely to be applicable and useful in many different areas of research, such as geophysics, finance, and the life sciences. The necessary matlab codes for running NMD are freely available for download.

  15. Nonlinear mode decomposition: A noise-robust, adaptive decomposition method

    NASA Astrophysics Data System (ADS)

    Iatsenko, Dmytro; McClintock, Peter V. E.; Stefanovska, Aneta

    2015-09-01

    The signals emanating from complex systems are usually composed of a mixture of different oscillations which, for a reliable analysis, should be separated from each other and from the inevitable background of noise. Here we introduce an adaptive decomposition tool—nonlinear mode decomposition (NMD)—which decomposes a given signal into a set of physically meaningful oscillations for any wave form, simultaneously removing the noise. NMD is based on the powerful combination of time-frequency analysis techniques—which, together with the adaptive choice of their parameters, make it extremely noise robust—and surrogate data tests used to identify interdependent oscillations and to distinguish deterministic from random activity. We illustrate the application of NMD to both simulated and real signals and demonstrate its qualitative and quantitative superiority over other approaches, such as (ensemble) empirical mode decomposition, Karhunen-Loève expansion, and independent component analysis. We point out that NMD is likely to be applicable and useful in many different areas of research, such as geophysics, finance, and the life sciences. The necessary matlab codes for running NMD are freely available for download.

  16. Adaptive chromosomal divergence driven by mixed geographic mode of evolution.

    PubMed

    Feder, Jeffrey L; Gejji, Richard; Powell, Thomas H Q; Nosil, Patrik

    2011-08-01

    Chromosomal inversions are ubiquitous in nature and of great significance for understanding adaptation and speciation. Inversions were the first markers used to investigate the genetic structure of natural populations, leading to the concept of coadapted gene complexes and theories concerning founder effects and genetic drift in small populations. However, we still lack elements of a general theory accounting for the origins and distribution of inversions in nature. Here, we use computer simulations to show that a "mixed geographic mode" of evolution involving allopatric separation of populations followed by secondary contact and gene flow generates chromosomal divergence by natural selection under wider conditions than previous hypotheses. This occurs because inversions arising in allopatry contain a full complement of locally adapted genes. Once gene flow ensues, reduced recombination within inversions keeps these favorable genotypic combinations intact, resulting in inverted genomic regions being favored over collinear regions. This process allows inversions to establish to high frequencies. Our model can account for several classic patterns in the geographic distribution of inversions and highlights how selection on standing genetic variation allows rapid chromosomal evolution without the waiting time for new mutations. As inversion differences often separate closely related taxa, mixed modes of divergence could be common. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

  17. Adapted G-mode Clustering Method applied to Asteroid Taxonomy

    NASA Astrophysics Data System (ADS)

    Hasselmann, Pedro H.; Carvano, Jorge M.; Lazzaro, D.

    2013-11-01

    The original G-mode was a clustering method developed by A. I. Gavrishin in the late 60's for geochemical classification of rocks, but was also applied to asteroid photometry, cosmic rays, lunar sample and planetary science spectroscopy data. In this work, we used an adapted version to classify the asteroid photometry from SDSS Moving Objects Catalog. The method works by identifying normal distributions in a multidimensional space of variables. The identification starts by locating a set of points with smallest mutual distance in the sample, which is a problem when data is not planar. Here we present a modified version of the G-mode algorithm, which was previously written in FORTRAN 77, in Python 2.7 and using NumPy, SciPy and Matplotlib packages. The NumPy was used for array and matrix manipulation and Matplotlib for plot control. The Scipy had a import role in speeding up G-mode, Scipy.spatial.distance.mahalanobis was chosen as distance estimator and Numpy.histogramdd was applied to find the initial seeds from which clusters are going to evolve. Scipy was also used to quickly produce dendrograms showing the distances among clusters. Finally, results for Asteroids Taxonomy and tests for different sample sizes and implementations are presented.

  18. Sliding-mode and proportional-derivative-type motion control with radial basis function neural network based estimators for wheeled vehicles

    NASA Astrophysics Data System (ADS)

    Pamosoaji, Anugrah K.; Thuong Cat, Pham; Hong, Keum-Shik

    2014-12-01

    An obstacle avoidance problem of rear-steered wheeled vehicles in consideration of the presence of uncertainties is addressed. Modelling errors and additional uncertainties are taken into consideration. Controller designs for driving and steering motors are designed. A proportional-derivative-type driving motor controller and a sliding-mode steering controller combined with radial basis function neural network (RBFNN) based estimators are proposed. The convergence properties of the RBFNN-based estimators are proven by the Stone-Weierstrass theorem. The stability of the proposed control law is proven using Lyapunov stability analysis. The obstacle avoidance strategy utilising the sliding surface adjustment to an existing navigation method is presented. It is concluded that the driving velocity and steering-angle performances of the proposed control system are satisfactory.

  19. Adaptive frequency-domain equalization for the transmission of the fundamental mode in a few-mode fiber.

    PubMed

    Bai, Neng; Xia, Cen; Li, Guifang

    2012-10-08

    We propose and experimentally demonstrate single-carrier adaptive frequency-domain equalization (SC-FDE) to mitigate multipath interference (MPI) for the transmission of the fundamental mode in a few-mode fiber. The FDE approach reduces computational complexity significantly compared to the time-domain equalization (TDE) approach while maintaining the same performance. Both FDE and TDE methods are evaluated by simulating long-haul fundamental-mode transmission using a few-mode fiber. For the fundamental mode operation, the required tap length of the equalizer depends on the differential mode group delay (DMGD) of a single span rather than DMGD of the entire link.

  20. Adaptive lesion formation using dual mode ultrasound array system

    NASA Astrophysics Data System (ADS)

    Liu, Dalong; Casper, Andrew; Haritonova, Alyona; Ebbini, Emad S.

    2017-03-01

    We present the results from an ultrasound-guided focused ultrasound platform designed to perform real-time monitoring and control of lesion formation. Real-time signal processing of echogenicity changes during lesion formation allows for identification of signature events indicative of tissue damage. The detection of these events triggers the cessation or the reduction of the exposure (intensity and/or time) to prevent overexposure. A dual mode ultrasound array (DMUA) is used for forming single- and multiple-focus patterns in a variety of tissues. The DMUA approach allows for inherent registration between the therapeutic and imaging coordinate systems providing instantaneous, spatially-accurate feedback on lesion formation dynamics. The beamformed RF data has been shown to have high sensitivity and specificity to tissue changes during lesion formation, including in vivo. In particular, the beamformed echo data from the DMUA is very sensitive to cavitation activity in response to HIFU in a variety of modes, e.g. boiling cavitation. This form of feedback is characterized by sudden increase in echogenicity that could occur within milliseconds of the application of HIFU (see http://youtu.be/No2wh-ceTLs for an example). The real-time beamforming and signal processing allowing the adaptive control of lesion formation is enabled by a high performance GPU platform (response time within 10 msec). We present results from a series of experiments in bovine cardiac tissue demonstrating the robustness and increased speed of volumetric lesion formation for a range of clinically-relevant exposures. Gross histology demonstrate clearly that adaptive lesion formation results in tissue damage consistent with the size of the focal spot and the raster scan in 3 dimensions. In contrast, uncontrolled volumetric lesions exhibit significant pre-focal buildup due to excessive exposure from multiple full-exposure HIFU shots. Stopping or reducing the HIFU exposure upon the detection of such an

  1. Vibration control of a ship engine system using high-load magnetorheological mounts associated with a new indirect fuzzy sliding mode controller

    NASA Astrophysics Data System (ADS)

    Phu, Do Xuan; Choi, Seung-Bok

    2015-02-01

    In this work, a new high-load magnetorheological (MR) fluid mount system is devised and applied to control vibration in a ship engine. In the investigation of vibration-control performance, a new modified indirect fuzzy sliding mode controller is formulated and realized. The design of the proposed MR mount is based on the flow mode of MR fluid, and it includes two separated coils for generating a magnetic field. An optimization process is carried out to achieve maximal damping force under certain design constraints, such as the allowable height of the mount. As an actuating smart fluid, a new plate-like iron-particle-based MR fluid is used, instead of the conventional spherical iron-particle-based MR fluid. After evaluating the field-dependent yield stress of the MR fluid, the field-dependent damping force required to control unwanted vibration in the ship engine is determined. Subsequently, an appropriate-sized MR mount is manufactured and its damping characteristics are evaluated. After confirming the sufficient damping force level of the manufactured MR mount, a medium-sized ship engine mount system consisting of eight MR mounts is established, and its dynamic governing equations are derived. A new modified indirect fuzzy sliding mode controller is then formulated and applied to the engine mount system. The displacement and velocity responses show that the unwanted vibrations of the ship engine system can be effectively controlled in both the axial and radial directions by applying the proposed control methodology.

  2. Nonlinear and chaos control of a micro-electro-mechanical system by using second-order fast terminal sliding mode control

    NASA Astrophysics Data System (ADS)

    Zhankui, Song; Sun, Kaibiao

    2013-09-01

    In this paper, a novel second-order fast terminal sliding mode control (SFTSMC) scheme is proposed to suppress the chaotic motion of a micro-mechanical resonator with system uncertainty and external disturbance. To obtain a better disturbance rejection property, a fuzzy logic system is introduced to estimate the upper boundary of the sum of system uncertainty and external disturbance. Moreover, we employ the finite-time technique to obtain the properties of fast response and high precision. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.

  3. GLACIER SLIDING,

    DTIC Science & Technology

    The theory of the sliding of glaciers presented in earlier papers has been generalized (1) by taking into account the resistance to sliding offered...bed at the downstream side of an obstacle. The sliding velocities and controlling obstacle sizes which are found from the generalized theory are...magnitude smaller in thickness than the height of the controlling obstacles can cause an appreciable increase in the sliding velocity. The generalized

  4. Full-order sliding mode control of uncertain chaos in a permanent magnet synchronous motor based on a fuzzy extended state observer

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Nan, Yu-Rong; Zheng, Heng-Huo; Ren, Xue-Mei

    2015-11-01

    A full-order sliding mode control based on a fuzzy extended state observer is proposed to control the uncertain chaos in the permanent magnet synchronous motor. Through a simple coordinate transformation, the chaotic PMSM model is transformed into the Brunovsky canonical form, which is more suitable for the controller design. Based on the fuzzy control theory, a fuzzy extended state observer is developed to estimate the unknown states and uncertainties, and the restriction that all the system states should be completely measurable is avoided. Thereafter, a full-order sliding mode controller is designed to ensure the convergence of all system states without any chattering problem. Comparative simulations show the effectiveness and superior performance of the proposed control method. Project supported by the National Natural Science Foundation of China (Grant Nos. 61403343 and 61433003), the Scientific Research Foundation of Education Department of Zhejiang Province, China (Grant No. Y201329260), and the Natural Science Foundation of Zhejiang University of Technology, China (Grant No. 1301103053408).

  5. Improved Re-Configurable Sliding Mode Controller for Reusable Launch Vehicle of Second Generation Addressing Aerodynamic Surface Failures and Thrust Deficiencies

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.

    2002-01-01

    In this report we present a time-varying sliding mode control (TV-SMC) technique for reusable launch vehicle (RLV) attitude control in ascent and entry flight phases. In ascent flight the guidance commands Euler roll, pitch and yaw angles, and in entry flight it commands the aerodynamic angles of bank, attack and sideslip. The controller employs a body rate inner loop and the attitude outer loop, which are separated in time-scale by the singular perturbation principle. The novelty of the TVSMC is that both the sliding surface and the boundary layer dynamics can be varied in real time using the PD-eigenvalue assignment technique. This salient feature is used to cope with control command saturation and integrator windup in the presence of severe disturbance or control effector failure, which enhances the robustness and fault tolerance of the controller. The TV-SMC is developed and tuned up for the X-33 sub-orbital technology demonstration vehicle in launch and re-entry modes. A variety of nominal, dispersion and failure scenarios have tested via high fidelity 6DOF simulations using MAVERIC/SLIM simulation software.

  6. Fabric evolution of quartz-gouge from stable sliding to stick-slip and implications for fault slip mode

    NASA Astrophysics Data System (ADS)

    Scuderi, Marco; Collettini, Cristiano; Viti, Cecilia; Tinti, Elisa; Marone, Chris

    2017-04-01

    Numerous laboratory studies have documented the mechanisms that control the earthquake nucleation phase, when fault slip velocity is slow (<0.001 cm/s), or the earthquake dynamic phase when fault slips at high velocities (>1 cm/s). Although these studies are fundamental to characterize specific phases of the seismic cycle, they are not able of capturing the entire evolution of fabric and mechanical data from stable sliding to stick-slip. Here we report on laboratory experiments that illuminate the mechanisms controlling the transition from stable sliding (v= 0.001 cm/s) to dynamic stick-slip (v > 1 cm/s), by altering the elastic stiffness of the loading system (k) to match the critical rheologic stiffness of the fault gouge (kc). In particular we observe that the stiffness ratio, K = kc/k, controls the transition from slow-and-silent (K = 0.9, slip velocity 0.01 cm/s, stress drop 0.5 MPa, slip duration 0.5 s) to fast-and-audible (K = 0.5, slip velocity 3 cm/s, stress drop 2.4 MPa, slip duration 0.003 s) slip events. Microstructural observations show that with accumulated strain, deformation localizes along sharp shear planes consisting of nano-metric grains, which favour the development of frictional instabilities. Once this fabric is established, for the tested boundary conditions (normal stress 13-35 MPa), fault fabric does not change significantly with slip velocity, and fault slip behaviour is mainly controlled by the interplay between fault rheological properties and the stiffness of the loading system. As applied to tectonic faults, our results suggest that a single fault segment can experience a spectrum of fault slip behaviour depending on the evolution of fault rock frictional properties and elastic conditions of the loading system.

  7. Testing and analysis of dual-mode adaptive landing gear, taxi mode test system for YF-12A

    NASA Technical Reports Server (NTRS)

    Gamon, M. A.

    1979-01-01

    The effectiveness of a dual mode adaptive landing gear system in reducing the dynamic response of an airplane during ground taxiing was studied. The dynamic taxi tests of the YF-12A research airplane are presented. A digital computer program which simulated the test conditions is discussed. The dual mode system as tested provides dynamic taxi response reductions of 25 percent at the cg and 30 to 45 percent at the cockpit.

  8. Robust pre-specified time synchronization of chaotic systems by employing time-varying switching surfaces in the sliding mode control scheme

    NASA Astrophysics Data System (ADS)

    Khanzadeh, Alireza; Pourgholi, Mahdi

    2016-08-01

    In the conventional chaos synchronization methods, the time at which two chaotic systems are synchronized, is usually unknown and depends on initial conditions. In this work based on Lyapunov stability theory a sliding mode controller with time-varying switching surfaces is proposed to achieve chaos synchronization at a pre-specified time for the first time. The proposed controller is able to synchronize chaotic systems precisely at any time when we want. Moreover, by choosing the time-varying switching surfaces in a way that the reaching phase is eliminated, the synchronization becomes robust to uncertainties and exogenous disturbances. Simulation results are presented to show the effectiveness of the proposed method of stabilizing and synchronizing chaotic systems with complete robustness to uncertainty and disturbances exactly at a pre-specified time.

  9. Multi-Objective Sliding Mode Control on Vehicle Cornering Stability with Variable Gear Ratio Actuator-Based Active Front Steering Systems.

    PubMed

    Ma, Xinbo; Wong, Pak Kin; Zhao, Jing; Xie, Zhengchao

    2016-12-28

    Active front steering (AFS) is an emerging technology to improve the vehicle cornering stability by introducing an additional small steering angle to the driver's input. This paper proposes an AFS system with a variable gear ratio steering (VGRS) actuator which is controlled by using the sliding mode control (SMC) strategy to improve the cornering stability of vehicles. In the design of an AFS system, different sensors are considered to measure the vehicle state, and the mechanism of the AFS system is also modelled in detail. Moreover, in order to improve the cornering stability of vehicles, two dependent objectives, namely sideslip angle and yaw rate, are considered together in the design of SMC strategy. By evaluating the cornering performance, Sine with Dwell and accident avoidance tests are conducted, and the simulation results indicate that the proposed SMC strategy is capable of improving the cornering stability of vehicles in practice.

  10. Multi-Objective Sliding Mode Control on Vehicle Cornering Stability with Variable Gear Ratio Actuator-Based Active Front Steering Systems

    PubMed Central

    Ma, Xinbo; Wong, Pak Kin; Zhao, Jing; Xie, Zhengchao

    2016-01-01

    Active front steering (AFS) is an emerging technology to improve the vehicle cornering stability by introducing an additional small steering angle to the driver’s input. This paper proposes an AFS system with a variable gear ratio steering (VGRS) actuator which is controlled by using the sliding mode control (SMC) strategy to improve the cornering stability of vehicles. In the design of an AFS system, different sensors are considered to measure the vehicle state, and the mechanism of the AFS system is also modelled in detail. Moreover, in order to improve the cornering stability of vehicles, two dependent objectives, namely sideslip angle and yaw rate, are considered together in the design of SMC strategy. By evaluating the cornering performance, Sine with Dwell and accident avoidance tests are conducted, and the simulation results indicate that the proposed SMC strategy is capable of improving the cornering stability of vehicles in practice. PMID:28036037

  11. Adaptive Control of Linear Modal Systems Using Residual Mode Filters and a Simple Disturbance Estimator

    NASA Technical Reports Server (NTRS)

    Balas, Mark; Frost, Susan

    2012-01-01

    Flexible structures containing a large number of modes can benefit from adaptive control techniques which are well suited to applications that have unknown modeling parameters and poorly known operating conditions. In this paper, we focus on a direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend our adaptive control theory to accommodate troublesome modal subsystems of a plant that might inhibit the adaptive controller. In some cases the plant does not satisfy the requirements of Almost Strict Positive Realness. Instead, there maybe be a modal subsystem that inhibits this property. This section will present new results for our adaptive control theory. We will modify the adaptive controller with a Residual Mode Filter (RMF) to compensate for the troublesome modal subsystem, or the Q modes. Here we present the theory for adaptive controllers modified by RMFs, with attention to the issue of disturbances propagating through the Q modes. We apply the theoretical results to a flexible structure example to illustrate the behavior with and without the residual mode filter.

  12. RAB-plate versus sliding hip screw for unstable trochanteric hip fractures: stability of the fixation and modes of failure--radiographic analysis of 218 fractures.

    PubMed

    Buciuto, R; Hammer, R

    2001-03-01

    The sliding hip screw has gained considerable acceptance in the treatment of unstable trochanteric fractures. However, the new type of 120 degrees fixed angle blade-plate with a buttress rod (RAB-plate) showed encouraging clinical results. The purpose of this study was to assess stability of fixation and analyze modes of failure in unstable trochanteric hip fractures treated with these devices. A retrospective radiographic review of 218 unstable fractures was performed. Linear and angular displacements of the major fragments and implant migration into the femoral head during healing were assessed. Additionally, adequacy of the reduction and the location of the implant within the femoral head as predictors of fixation failure were evaluated. The postreduction neck-shaft angle was maintained in the majority of the fractures in both groups. However, there was a significantly higher incidence of varus angulation by 10 degrees or more by the completion of healing among fractures treated with the sliding hip screw (p = 0.04). There was no statistically significant difference in vertical migration of the device into the femoral head between the implants used (p = 0.3). There was a significant relationship between failure of the fixation and varus reduction (p = 0.04) as well as screw/neck angle deviation more than 20 degrees in the lateral projection (p = 0.005) or if the implant was in a superior or posterior position (p = 0.02). The RAB-plate provided a more stable fixation, especially with regard to maintained postoperative alignment. However, positive predictors for fixation failure were identical for both devices. Here, the screw/neck angle deviation has had the strongest significance for prediction of fixation failure.

  13. All-Atom Calculation of the Normal Modes of Bacteriorhodopsin Using a Sliding Block Iterative Diagonalization Method.

    PubMed

    Kaledin, Alexey L; Kaledin, Martina; Bowman, Joel M

    2006-01-01

    Conventional normal-mode analysis of molecular vibrations requires computation and storage of the Hessian matrix. For a typical biological system such storage can reach several gigabytes posing difficulties for straightforward implementation. In this work we discuss an iterative block method to carry out full diagonalization of the Hessian while only storing a few vectors in memory. The iterative approach is based on the conjugate gradient formulation of the Davidson algorithm for simultaneous optimization of L roots, where in our case 10 < L < 300. The procedure is modified further by automatically adding a new vector into the search space for each locked (converged) root and keeping the new vector orthogonal to the eigenvectors previously determined. The higher excited states are then converged with the orthonormality constraint to the locked roots by applying a projector which is carried out using a read-rewind step done once per iteration. This allows for convergence of as many roots as desired without increasing the computer memory. The required Hessian-vector products are calculated on the fly as follows, Kp = dgp/dt, where K is the mass weighted Hessian, and gp is the gradient along p. The method has been implemented into the TINKER suite of molecular design codes. Preliminary results are presented for the normal modes of bacteriorhodopsin (bR) up to 300 cm(-)(1) and for the high frequency range between 2840 and 3680 cm(-)(1). There is evidence of a highly localized, noncollective mode at ∼1.4 cm(-)(1), caused by long-range interactions acting between the cytoplasmic and extracellular domains of bR.

  14. Method for Adapting to Rough Terrain Based on Environmental Modes for Biped Robots

    NASA Astrophysics Data System (ADS)

    Ohashi, Eijiro; Sato, Tomoya; Ohnishi, Kouhei

    This paper describes a method for adapting to rough terrain for biped robots. The robots obtain information of reaction force from the ground by sensors located at each corner of rectangular soles. From the sensor information, environmental modes are extracted. The environmental modes consist of four modes: heaving, rolling, pitching, and twisting, which represent contact states between the ground and the soles. On the basis of the twisting mode, the robot detects the unevenness of the ground, makes contact with the uneven ground stably with three corners of the sole, and modifies the trajectory to continue stable walking. The validity of the proposed method is confirmed by experimental results.

  15. Augmented Adaptive Control of a Wind Turbine in the Presence of Structural Modes

    NASA Technical Reports Server (NTRS)

    Frost, Susan A.; Balas, Mark J.; Wright, Alan D.

    2010-01-01

    Wind turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, potentially causing component fatigue and failure. Two key technology drivers for turbine manufacturers are increasing turbine up time and reducing maintenance costs. Since the trend in wind turbine design is towards larger, more flexible turbines with lower frequency structural modes, manufacturers will want to develop methods to operate in the presence of these modes. Accurate models of the dynamic characteristics of new wind turbines are often not available due to the complexity and expense of the modeling task, making wind turbines ideally suited to adaptive control. In this paper, we develop theory for adaptive control with rejection of disturbances in the presence of modes that inhibit the controller. We use this method to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the interference of certain structural modes in feedback. The control objective is accomplished by collectively pitching the turbine blades. The adaptive pitch controller for Region 3 is compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller.

  16. Parallel Control of Velocity Control and Energy-Saving Control for a Hydraulic Valve-Controlled Cylinder System Using Self-Organizing Fuzzy Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Chiang, Mao-Hsiung; Chien, Yu-Wei

    Conventional hydraulic valve-controlled systems that incorporate positive displacement pumps and relief valves have a problem of low energy efficiency. The objective of the research is to implement parallel control of energy-saving control in an electro-hydraulic load-sensing system and velocity control in a hydraulic valve-controlled cylinder system to achieve both high velocity control accuracy and low input power simultaneously. The overall control system is a two-input two-output system. For that, the control strategy of self-organizing fuzzy sliding mode control (SOFSMC) is developed in this study to reduce the fuzzy rule number and to self-organize on-line the fuzzy rules. To compare the energy-saving performance, the velocity control is implemented under three different energy-saving control systems, such as load-sensing control system, constant supply pressure control system and conventional hydraulic system. The parallel control of the velocity control and energy-saving control by the SOFSMC is implemented experimentally.

  17. Photonic Lantern Adaptive Spatial Mode Control in LMA Fiber Amplifiers using SPGD

    DTIC Science & Technology

    2015-12-15

    fiber amplifiers using SPGD ** Juan Montoya 1,* , Chris Aleshire 1 , Christopher Hwang 1 , Nicolas K. Fontaine 2 , Amado Velazquez 3 , Dale H. Martz...ll.mit.edu Abstract: We demonstrate adaptive-spatial mode control (ASMC) in few- moded double-clad large mode area (LMA) fiber amplifiers by using an...D. V. Murphy, A. Sanchez, and T. Y. Fan, "Coherent combining of a 4 kW, eight-element fiber amplifier array," Opt. Lett. 36, 2686-2688 (2011). 3. F

  18. Efficient coupling of starlight into single mode photonics using Adaptive Injection (AI)

    NASA Astrophysics Data System (ADS)

    Norris, Barnaby; Cvetojevic, Nick; Gross, Simon; Arriola, Alexander; Tuthill, Peter; Lawrence, Jon; Richards, Samuel; Goodwin, Michael; Zheng, Jessica

    2016-08-01

    Using single-mode fibres in astronomy enables revolutionary techniques including single-mode interferometry and spectroscopy. However, injection of seeing-limited starlight into single mode photonics is extremely difficult. One solution is Adaptive Injection (AI). The telescope pupil is segmented into a number of smaller subapertures each with size r0, such that seeing can be approximated as a single tip / tilt / piston term for each subaperture, and then injected into a separate fibre via a facet of a segmented MEMS deformable mirror. The injection problem is then reduced to a set of individual tip tilt loops, resulting in high overall coupling efficiency.

  19. How to adapt broad-band gravitational-wave searches for r-modes

    SciTech Connect

    Owen, Benjamin J.

    2010-11-15

    Up to now there has been no search for gravitational waves from the r-modes of neutron stars in spite of the theoretical interest in the subject. Several oddities of r-modes must be addressed to obtain an observational result: The gravitational radiation field is dominated by the mass current (gravitomagnetic) quadrupole rather than the usual mass quadrupole, and the consequent difference in polarization affects detection statistics and parameter estimation. To astrophysically interpret a detection or upper limit it is necessary to convert the gravitational-wave amplitude to an r-mode amplitude. Also, it is helpful to know indirect limits on gravitational-wave emission to gauge the interest of various searches. Here I address these issues, thereby providing the ingredients to adapt broad-band searches for continuous gravitational waves to obtain r-mode results. I also show that searches of existing data can already have interesting sensitivities to r-modes.

  20. Passive position-adaptive radar modes for non-LOS interrogation of embedded targets

    NASA Astrophysics Data System (ADS)

    Mitra, Atindra K.

    2004-08-01

    A position-adaptive radar system concept is presented for purposes of interrogating difficult and obscured targets via the application of low-altitude smart or robotic-type UAV platforms. Under this concept, a high-altitude radiating platform is denoted as a HUAV and a low-altitude "position-adaptive" platform is denoted as a LUAV. The system concept is described by two modes. In Mode-1, real-time onboard LUAV computation of a phase parameter denoted as "signal differential path length" allows the LUAV to position-adaptively isolate a "signal leakage point", for example, between two buildings. After the LUAV position-adaptively converges to an optimum location, the system enters Mode-2. Under this Mode-2 concept, a technique denoted as "exploitation of leakage signals via path trajectory diversity" (E-LS-PTD) is developed. This technique is based on modulating scattering centers on embedded objects by implementing a fast trajectory on the HUAV while the LUAV is hovering in front of an "obscuration channel." Analytical results include sample outputs from an initial set numerical electromagnetic simulations.

  1. Fault Diagnosis of Rotating Machinery Based on an Adaptive Ensemble Empirical Mode Decomposition

    PubMed Central

    Lei, Yaguo; Li, Naipeng; Lin, Jing; Wang, Sizhe

    2013-01-01

    The vibration based signal processing technique is one of the principal tools for diagnosing faults of rotating machinery. Empirical mode decomposition (EMD), as a time-frequency analysis technique, has been widely used to process vibration signals of rotating machinery. But it has the shortcoming of mode mixing in decomposing signals. To overcome this shortcoming, ensemble empirical mode decomposition (EEMD) was proposed accordingly. EEMD is able to reduce the mode mixing to some extent. The performance of EEMD, however, depends on the parameters adopted in the EEMD algorithms. In most of the studies on EEMD, the parameters were selected artificially and subjectively. To solve the problem, a new adaptive ensemble empirical mode decomposition method is proposed in this paper. In the method, the sifting number is adaptively selected, and the amplitude of the added noise changes with the signal frequency components during the decomposition process. The simulation, the experimental and the application results demonstrate that the adaptive EEMD provides the improved results compared with the original EEMD in diagnosing rotating machinery. PMID:24351666

  2. Fault diagnosis of rotating machinery based on an adaptive ensemble empirical mode decomposition.

    PubMed

    Lei, Yaguo; Li, Naipeng; Lin, Jing; Wang, Sizhe

    2013-12-09

    The vibration based signal processing technique is one of the principal tools for diagnosing faults of rotating machinery. Empirical mode decomposition (EMD), as a time-frequency analysis technique, has been widely used to process vibration signals of rotating machinery. But it has the shortcoming of mode mixing in decomposing signals. To overcome this shortcoming, ensemble empirical mode decomposition (EEMD) was proposed accordingly. EEMD is able to reduce the mode mixing to some extent. The performance of EEMD, however, depends on the parameters adopted in the EEMD algorithms. In most of the studies on EEMD, the parameters were selected artificially and subjectively. To solve the problem, a new adaptive ensemble empirical mode decomposition method is proposed in this paper. In the method, the sifting number is adaptively selected, and the amplitude of the added noise changes with the signal frequency components during the decomposition process. The simulation, the experimental and the application results demonstrate that the adaptive EEMD provides the improved results compared with the original EEMD in diagnosing rotating machinery.

  3. Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes

    NASA Technical Reports Server (NTRS)

    Frost, Susan Alane; Balas, Mark J.; Wright, Alan D.

    2010-01-01

    Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine.

  4. Self-adaptive image denoising based on bidimensional empirical mode decomposition (BEMD).

    PubMed

    Guo, Song; Luan, Fangjun; Song, Xiaoyu; Li, Changyou

    2014-01-01

    To better analyze images with the Gaussian white noise, it is necessary to remove the noise before image processing. In this paper, we propose a self-adaptive image denoising method based on bidimensional empirical mode decomposition (BEMD). Firstly, normal probability plot confirms that 2D-IMF of Gaussian white noise images decomposed by BEMD follow the normal distribution. Secondly, energy estimation equation of the ith 2D-IMF (i=2,3,4,......) is proposed referencing that of ith IMF (i=2,3,4,......) obtained by empirical mode decomposition (EMD). Thirdly, the self-adaptive threshold of each 2D-IMF is calculated. Eventually, the algorithm of the self-adaptive image denoising method based on BEMD is described. From the practical perspective, this is applied for denoising of the magnetic resonance images (MRI) of the brain. And the results show it has a better denoising performance compared with other methods.

  5. A magnetorheological damper-based prosthetic knee (MRPK) and sliding mode tracking control method for an MRPK-based lower limb prosthesis

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Wang, Dai-Hua; Xu, Lei; Yuan, Gang

    2017-04-01

    Based on a two-bar linkage and a magnetorheological damper (MRD) with a double-ended structure and shearing operation mode of the magnetorheological fluid, an MRD-based prosthetic knee (MRPK) is realized. Utilizing the developed MRPK, an MRD-based lower limb prosthesis (MRLLP) is developed, modeled, and simulated in this paper, to analyse the effects of hysteresis of the integrated MRD on the swing angle of the shank of the MRLLP. Based on this, a sliding mode tracking control (SMTC) method for controlling the swing angle of the shank of the MRLLP is proposed to suppress hysteresis, along with a robustness analysis. Utilizing the SMTC method, co-simulations on controlling the swing angle of the shank of the MRLLP are carried out in ADAMS and Simulink. The simulation results show that the root mean square error (RMSE) of the swing angle of the shank of the MRLLP produced by the SMTC method is 80% less than that from the computed torque plus PD (CT+PD) control method. Therefore, the SMTC method is effective in suppressing hysteresis of the MRD. Furthermore, when the MRLLP is disturbed, the RMSE of the swing angle of the shank of the MRLLP produced by the SMTC method is 67% less than that from the CT+PD control method. Therefore, the SMTC method has strong robustness to random disturbance. A rapid control prototype of the MRLLP system and a corresponding experimental test system are established. On the established experimental test system, experiments are carried out on control of the swing angle of the shank of the MRLLP via the SMTC method. The results are compared with those from the ON/OFF and the CT+PD control methods. The experimental results show that the MRPK has controllable joint torque, and can be used to imitate the natural swing of a human knee joint. Additionally, the RMSE of the controlled swing angle of the shank of the MRLLP produced by the SMTC method is 34% less than that produced by the CT+PD control method and is 37% less than that from the ON

  6. Dynamic analysis and fractional-order adaptive sliding mode control for a novel fractional-order ferroresonance system

    NASA Astrophysics Data System (ADS)

    Yang, Ningning; Han, Yuchao; Wu, Chaojun; Jia, Rong; Liu, Chongxin

    2017-08-01

    Not Available Project supported by the National Natural Science Foundation of China (Grant No. 51507134) and the Science Fund from the Education Department of Shaanxi Province, China (Grant No. 15JK1537).

  7. Adaptive mechanical backup ventilation for preterm infants on respiratory assist modes - a pilot study.

    PubMed

    Herber-Jonat, Susanne; Rieger-Fackeldey, Esther; Hummler, Helmut; Schulze, Andreas

    2006-02-01

    Mechanical respiratory-assist modes, such as assist/control, low-rate intermittent mandatory ventilation, continuous positive airway pressure, or proportional assist ventilation (PAV), require a continuous respiratory effort. Because of the frequent occurrence of periodic breathing and/or apnea, mechanical backup ventilation must be initiated during episodes of reduced or absent respiratory drive to maintain gas exchange. The common approach to this problem is a regular conventional mechanical ventilation, which is initiated and withdrawn in an "on/off" function. To develop and evaluate a mechanical backup ventilation mode that is adaptive to the rapidly changing breathing pattern of preterm infants. Prospective randomized clinical crossover trial. Neonatal intensive care unit at the University of Munich, Germany. Preterm infants undergoing PAV. The infants were ventilated with PAV using a newly developed adaptive backup support, with and without pulse-oximetry-guided operation (SpO(2)-sensitive backup). Each infant was ventilated with both modes of backup support on 2 consecutive days, with the sequence randomized. The analysis on 11 preterm infants showed a statistically significant and clinically relevant reduction of the incidence (33%) and duration of oxygen desaturations (52%) when SpO(2)-sensitive adaptive backup support was used. SpO(2)-sensitive adaptive backup proved safe and effective in reducing the incidence and duration of oxygen desaturation in this short-term trial. This technology is potentially applicable to other assisted modalities of ventilation, such as noninvasive nasal ventilation.

  8. Fast image-formation algorithm for ultrahigh-resolution airborne squint spotlight synthetic aperture radar based on adaptive sliding receive-window technique

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Zeng, Hong-cheng; Chen, Jie; Wang, Peng-bo

    2014-01-01

    Adaptive sliding receive-window (ASRW) technique was usually introduced in airborne squint synthetic aperture radar (SAR) systems. Airborne squint spotlight SAR varies its receive-window starting time pulse-by-pulse as a function of range-walk, namely, the linear term of range cell migration (RCM). As a result, a huge data volume of the highly squint spotlight SAR echo signal can be significantly reduced. Because the ASRW technique changes the echo-receive starting time and Doppler history, the conventional image algorithm cannot be employed to directly focus airborne squint spotlight ASRW-SAR data. Therefore, a fast image-formation algorithm, based on the principle of the wave number domain algorithm (WDA) and azimuth deramping processing, was proposed for accurately and efficiently focusing the squint spotlight ASRW-SAR data. Azimuth deramping preprocessing was implemented for eliminating azimuth spectrum aliasing. Moreover, bulk compression and modified Stolt mapping were utilized for high-precision focusing. Additionally, geometric correction was employed for compensating the image distortion resulting from the ASRW technique. The proposed algorithm was verified by evaluating the image performance of point targets in different squint angles. In addition, a detailed analysis of computation loads in the appendix indicates that the processing efficiency can be greatly improved, e.g., the processing efficiency could be improved by 17 times in the 70-deg squint angle by applying the proposed image algorithm to the squint spotlight ASRW-SAR data.

  9. An analysis toolbox to explore mesenchymal migration heterogeneity reveals adaptive switching between distinct modes

    PubMed Central

    Shafqat-Abbasi, Hamdah; Kowalewski, Jacob M; Kiss, Alexa; Gong, Xiaowei; Hernandez-Varas, Pablo; Berge, Ulrich; Jafari-Mamaghani, Mehrdad; Lock, John G; Strömblad, Staffan

    2016-01-01

    Mesenchymal (lamellipodial) migration is heterogeneous, although whether this reflects progressive variability or discrete, 'switchable' migration modalities, remains unclear. We present an analytical toolbox, based on quantitative single-cell imaging data, to interrogate this heterogeneity. Integrating supervised behavioral classification with multivariate analyses of cell motion, membrane dynamics, cell-matrix adhesion status and F-actin organization, this toolbox here enables the detection and characterization of two quantitatively distinct mesenchymal migration modes, termed 'Continuous' and 'Discontinuous'. Quantitative mode comparisons reveal differences in cell motion, spatiotemporal coordination of membrane protrusion/retraction, and how cells within each mode reorganize with changed cell speed. These modes thus represent distinctive migratory strategies. Additional analyses illuminate the macromolecular- and cellular-scale effects of molecular targeting (fibronectin, talin, ROCK), including 'adaptive switching' between Continuous (favored at high adhesion/full contraction) and Discontinuous (low adhesion/inhibited contraction) modes. Overall, this analytical toolbox now facilitates the exploration of both spontaneous and adaptive heterogeneity in mesenchymal migration. DOI: http://dx.doi.org/10.7554/eLife.11384.001 PMID:26821527

  10. JCMmode: an adaptive finite element solver for the computation of leaky modes

    NASA Astrophysics Data System (ADS)

    Zschiedrich, Lin W.; Burger, Sven; Klose, Roland; Schaedle, Achim; Schmidt, Frank

    2005-03-01

    We present our simulation tool JCMmode for calculating propagating modes of an optical waveguide. As ansatz functions we use higher order, vectorial elements (Nedelec elements, edge elements). Further we construct transparent boundary conditions to deal with leaky modes even for problems with inhomogeneous exterior domains as for integrated hollow core Arrow waveguides. We have implemented an error estimator which steers the adaptive mesh refinement. This allows the precise computation of singularities near the metal's corner of a Plasmon-Polariton waveguide even for irregular shaped metal films on a standard personal computer.

  11. Capacity of coherent-state adaptive decoders with interferometry and single-mode detectors

    NASA Astrophysics Data System (ADS)

    Rosati, Matteo; Mari, Andrea; Giovannetti, Vittorio

    2017-07-01

    A class of adaptive decoders (ADs) for coherent-state sequences is studied, including in particular the most common technology for optical-signal processing, e.g., interferometers, coherent displacements, and photon-counting detectors. More generally we consider ADs comprising adaptive procedures based on passive multimode Gaussian unitaries and arbitrary single-mode destructive measurements. For classical communication on quantum phase-insensitive Gaussian channels with a coherent-state encoding, we show that the AD's optimal information transmission rate is not greater than that of a single-mode decoder. Our result also implies that the ultimate classical capacity of quantum phase-insensitive Gaussian channels is unlikely to be achieved with the considered class of ADs.

  12. EMD self-adaptive selecting relevant modes algorithm for FBG spectrum signal

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Wu, Chun-ting; Liu, Huan-lin

    2017-07-01

    Noise may reduce the demodulation accuracy of fiber Bragg grating (FBG) sensing signal so as to affect the quality of sensing detection. Thus, the recovery of a signal from observed noisy data is necessary. In this paper, a precise self-adaptive algorithm of selecting relevant modes is proposed to remove the noise of signal. Empirical mode decomposition (EMD) is first used to decompose a signal into a set of modes. The pseudo modes cancellation is introduced to identify and eliminate false modes, and then the Mutual Information (MI) of partial modes is calculated. MI is used to estimate the critical point of high and low frequency components. Simulation results show that the proposed algorithm estimates the critical point more accurately than the traditional algorithms for FBG spectral signal. While, compared to the similar algorithms, the signal noise ratio of the signal can be improved more than 10 dB after processing by the proposed algorithm, and correlation coefficient can be increased by 0.5, so it demonstrates better de-noising effect.

  13. Dynamic formant extraction of wa language based on adaptive variational mode decomposition

    NASA Astrophysics Data System (ADS)

    Fu, Meijun; Dong, Huazhen; Pan, Wenlin

    2017-08-01

    Wa language is one of Chinese minority languages spoken by the Wa nationality who lives in Yunnan Province, China. Until now, it has not been studied from the perspective of Engineering Phonetics. In this paper, for the above reason, by the adaptive variational mode decomposition (AVMD) we have investigated the dynamic formant characteristics of Wa language. Firstly, more precisely, use the synthetic dimension to split Wa language isolated words into voiceless and voiced segment, initials and finals. Secondly, use Linear Prediction Coding to estimate the first three formant frequencies and their bandwidths roughly. Thirdly, select the appropriate equilibrium constraint parameter and the number of decomposed layers so that Adaptive Variational Mode Decomposition (AVMD) can decompose the signal into some intrinsic mode functions (IMFs) without pattern aliasing. Fourthly, use the estimated formant frequencies and bandwidths to determine precisely the required IMFs. Fifthly, use the Hilbert transform to calculate the instantaneous frequency of the above determinate IMFs. Further, we implement the weight average operation on instantaneous frequencies to obtain the first three formant frequencies for each frame. Finally, comparing the first three formant frequencies obtained by the adaptive variance modal decomposition and by Praat software respectively, so we have drawn the conclusion that the relative correct rate of the former to the latter can reach 86% averagely in terms of the selected isolated words, which has shown that our method is effective on Wa language.

  14. Multi-modal iterative adaptive processing (MIAP) performance in the discrimination mode for landmine detection

    NASA Astrophysics Data System (ADS)

    Yu, Yongli; Collins, Leslie M.

    2005-06-01

    Due to the nature of landmine detection, a high detection probability (Pd) is required to avoid casualties and injuries. However, high Pd is often obtained at the price of extremely high false alarm rates. It is widely accepted that no single sensor technology has the ability to achieve the required detection rate while keeping acceptably low false alarm rates for all types of mines in all types of soil and with all types of false targets. Remarkable advances in sensor technology for landmine detection have made multi-sensor fusion an attractive alternative to single sensor detection techniques. Hence, multi-sensor fusion mine detection systems, which use complementary sensor technologies, are proposed. Previously we proposed a new multi-sensor fusion algorithm called Multi-modal Iterative Adaptive Processing (MIAP), which incorporates information from multiple sensors in an adaptive Bayesian decision framework and the identification capabilities of multiple sensors are utilized to modify the statistical models utilized by the mine detector. Simulation results demonstrate the improvement in performance obtained using the MIAP algorithm. In this paper, we assume a hand-held mine detection system utilizing both an electromagnetic induction sensor (EMI) and a ground-penetrating radar (GPR). The hand-held mine detection sensors are designed to have two modes of operations: search mode and discrimination mode. Search mode generates an initial causal detection on the suspected location; and discrimination mode confirms whether there is a mine. The MIAP algorithm is applied in the discrimination mode for hand-held mine detection. The performance of the detector is evaluated on a data set collected by the government, and the performance is compared with the other traditional fusion results.

  15. Toward design of an environment-aware adaptive locomotion-mode-recognition system.

    PubMed

    Du, Lin; Zhang, Fan; Liu, Ming; Huang, He

    2012-10-01

    In this study, we aimed to improve the performance of a locomotion-mode-recognition system based on neuromuscular-mechanical fusion by introducing additional information about the walking environment. Linear-discriminant-analysis-based classifiers were first designed to identify a lower limb prosthesis user's locomotion mode based on electromyographic signals recorded from residual leg muscles and ground reaction forces measured from the prosthetic pylon. Nine transfemoral amputees who wore a passive hydraulic knee or powered prosthetic knee participated in this study. Information about the walking terrain was simulated and modeled as prior probability based on the principle of maximum entropy and integrated into the discriminant functions of the classifier. When the correct prior knowledge of walking terrain was simulated, the classification accuracy for each locomotion mode significantly increased and no task transitions were missed. In addition, simulated incorrect prior knowledge did not significantly reduce system performance, indicating that our design is robust against noisy and imperfect prior information. Furthermore, these observations were independent of the type of prosthesis applied. The promising results in this study may assist the further development of an environment-aware adaptive system for locomotion-mode recognition for powered lower limb prostheses or orthoses.

  16. Toward Design of an Environment-Aware Adaptive Locomotion-Mode-Recognition System

    PubMed Central

    Du, Lin; Zhang, Fan; Liu, Ming

    2013-01-01

    In this study, we aimed to improve the performance of a locomotion-mode-recognition system based on neuromuscular-mechanical fusion by introducing additional information about the walking environment. Linear-discriminant-analysis-based classifiers were first designed to identify a lower limb prosthesis user’s locomotion mode based on electromyographic signals recorded from residual leg muscles and ground reaction forces measured from the prosthetic pylon. Nine transfemoral amputees who wore a passive hydraulic knee or powered prosthetic knee participated in this study. Information about the walking terrain was simulated and modeled as prior probability based on the principle of maximum entropy and integrated into the discriminant functions of the classifier. When the correct prior knowledge of walking terrain was simulated, the classification accuracy for each locomotion mode significantly increased and no task transitions were missed. In addition, simulated incorrect prior knowledge did not significantly reduce system performance, indicating that our design is robust against noisy and imperfect prior information. Furthermore, these observations were independent of the type of prosthesis applied. The promising results in this study may assist the further development of an environment-aware adaptive system for locomotion-mode recognition for powered lower limb prostheses or orthoses. PMID:22996721

  17. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas.

    PubMed

    Gualda, Emilio J; Vázquez de Aldana, Javier R; Martínez-García, M Carmen; Moreno, Pablo; Hernández-Toro, Juan; Roso, Luis; Artal, Pablo; Bueno, Juan M

    2011-11-01

    The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures.

  18. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas

    PubMed Central

    Gualda, Emilio J.; Vázquez de Aldana, Javier R.; Martínez-García, M. Carmen; Moreno, Pablo; Hernández-Toro, Juan; Roso, Luis; Artal, Pablo; Bueno, Juan M.

    2011-01-01

    The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures. PMID:22076258

  19. Mode-dependent control of human walking and running as revealed by split-belt locomotor adaptation.

    PubMed

    Ogawa, Tetsuya; Kawashima, Noritaka; Obata, Hiroki; Kanosue, Kazuyuki; Nakazawa, Kimitaka

    2015-10-01

    Here, we investigate the association of neural control between walking and running, and in particular, how these two gait modes at different velocities are controlled by the central nervous system. The subjects were fully adapted by acquiring modified motor patterns to either walk or run on a split-belt treadmill driven in split mode (asymmetry in the velocities of two belts at 1.0 and 2.0 m s(-1)). Subsequently, we tested how the adaptation affected walking and running at three different velocities in the tied mode (equal belt velocities). At 0.75 m s(-1), we found a preference to walk, at 1.50 m s(-1), there was a preference to both walk and run, and at a velocity of 2.25 m s(-1) there was a preference to run. Both walking and running on the split belt resulted in the emergence of a significant aftereffect (asymmetrical movement) at all of the velocities tested when walking after adapting to walk and running after adapting to run. However, for contrasting modes (i.e. running after adapting to walk and walking after adapting to run), such aftereffects were far less evident at all velocities; thus showing only limited transfer across gait modes. The results demonstrate a clear mode dependency in the neural control of human walking and running. In addition, only for walking, was there a degree of velocity dependency.

  20. Dip-separated structural filtering using seislet transform and adaptive empirical mode decomposition based dip filter

    NASA Astrophysics Data System (ADS)

    Chen, Yangkang

    2016-07-01

    The seislet transform has been demonstrated to have a better compression performance for seismic data compared with other well-known sparsity promoting transforms, thus it can be used to remove random noise by simply applying a thresholding operator in the seislet domain. Since the seislet transform compresses the seismic data along the local structures, the seislet thresholding can be viewed as a simple structural filtering approach. Because of the dependence on a precise local slope estimation, the seislet transform usually suffers from low compression ratio and high reconstruction error for seismic profiles that have dip conflicts. In order to remove the limitation of seislet thresholding in dealing with conflicting-dip data, I propose a dip-separated filtering strategy. In this method, I first use an adaptive empirical mode decomposition based dip filter to separate the seismic data into several dip bands (5 or 6). Next, I apply seislet thresholding to each separated dip component to remove random noise. Then I combine all the denoised components to form the final denoised data. Compared with other dip filters, the empirical mode decomposition based dip filter is data-adaptive. One only needs to specify the number of dip components to be separated. Both complicated synthetic and field data examples show superior performance of my proposed approach than the traditional alternatives. The dip-separated structural filtering is not limited to seislet thresholding, and can also be extended to all those methods that require slope information.

  1. Adaptive multi-step Full Waveform Inversion based on Waveform Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Hu, Yong; Han, Liguo; Xu, Zhuo; Zhang, Fengjiao; Zeng, Jingwen

    2017-04-01

    Full Waveform Inversion (FWI) can be used to build high resolution velocity models, but there are still many challenges in seismic field data processing. The most difficult problem is about how to recover long-wavelength components of subsurface velocity models when seismic data is lacking of low frequency information and without long-offsets. To solve this problem, we propose to use Waveform Mode Decomposition (WMD) method to reconstruct low frequency information for FWI to obtain a smooth model, so that the initial model dependence of FWI can be reduced. In this paper, we use adjoint-state method to calculate the gradient for Waveform Mode Decomposition Full Waveform Inversion (WMDFWI). Through the illustrative numerical examples, we proved that the low frequency which is reconstructed by WMD method is very reliable. WMDFWI in combination with the adaptive multi-step inversion strategy can obtain more faithful and accurate final inversion results. Numerical examples show that even if the initial velocity model is far from the true model and lacking of low frequency information, we still can obtain good inversion results with WMD method. From numerical examples of anti-noise test, we see that the adaptive multi-step inversion strategy for WMDFWI has strong ability to resist Gaussian noise. WMD method is promising to be able to implement for the land seismic FWI, because it can reconstruct the low frequency information, lower the dominant frequency in the adjoint source, and has a strong ability to resist noise.

  2. An Automated Slide Classification System at Georgia Tech

    ERIC Educational Resources Information Center

    LoPresti, Maryellen

    1973-01-01

    The Georgia Tech Architecture Library slide collection is being revolutionized by adapting the Santa Cruz Slide Classification System. The slide catalog record is being transferred inexpensively to tapes and updated by the computer. Computer programs print out indexes in any of fifteen different sort fields. (Author)

  3. Adaptive Control of Non-Minimum Phase Modal Systems Using Residual Mode Filters2. Parts 1 and 2

    NASA Technical Reports Server (NTRS)

    Balas, Mark J.; Frost, Susan

    2011-01-01

    Many dynamic systems containing a large number of modes can benefit from adaptive control techniques, which are well suited to applications that have unknown parameters and poorly known operating conditions. In this paper, we focus on a direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend this adaptive control theory to accommodate problematic modal subsystems of a plant that inhibit the adaptive controller by causing the open-loop plant to be non-minimum phase. We will modify the adaptive controller with a Residual Mode Filter (RMF) to compensate for problematic modal subsystems, thereby allowing the system to satisfy the requirements for the adaptive controller to have guaranteed convergence and bounded gains. This paper will be divided into two parts. Here in Part I we will review the basic adaptive control approach and introduce the primary ideas. In Part II, we will present the RMF methodology and complete the proofs of all our results. Also, we will apply the above theoretical results to a simple flexible structure example to illustrate the behavior with and without the residual mode filter.

  4. High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force.

    PubMed

    Ren, Juan; Zou, Qingze

    2014-07-01

    In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.

  5. High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force

    SciTech Connect

    Ren, Juan; Zou, Qingze

    2014-07-15

    In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.

  6. Holographic sliding stripes

    NASA Astrophysics Data System (ADS)

    Jokela, Niko; Järvinen, Matti; Lippert, Matthew

    2017-04-01

    Holographic models provide unique laboratories to investigate nonlinear physics of transport in inhomogeneous systems. We provide a detailed account of both dc and ac conductivities in a defect conformal field theory with spontaneous stripe order. The spatial symmetry is broken at large chemical potential, and the resulting ground state is a combination of a spin and charge density wave. An infinitesimal applied electric field across the stripes will cause the stripes to slide over the underlying density of smeared impurities, a phenomenon which can be associated with the Goldstone mode for the spontaneously broken translation symmetry. We show that the presence of a spatially modulated background magnetization current thwarts the expression of some dc conductivities in terms of horizon data.

  7. MIMO equalization with adaptive step size for few-mode fiber transmission systems.

    PubMed

    van Uden, Roy G H; Okonkwo, Chigo M; Sleiffer, Vincent A J M; de Waardt, Hugo; Koonen, Antonius M J

    2014-01-13

    Optical multiple-input multiple-output (MIMO) transmission systems generally employ minimum mean squared error time or frequency domain equalizers. Using an experimental 3-mode dual polarization coherent transmission setup, we show that the convergence time of the MMSE time domain equalizer (TDE) and frequency domain equalizer (FDE) can be reduced by approximately 50% and 30%, respectively. The criterion used to estimate the system convergence time is the time it takes for the MIMO equalizer to reach an average output error which is within a margin of 5% of the average output error after 50,000 symbols. The convergence reduction difference between the TDE and FDE is attributed to the limited maximum step size for stable convergence of the frequency domain equalizer. The adaptive step size requires a small overhead in the form of a lookup table. It is highlighted that the convergence time reduction is achieved without sacrificing optical signal-to-noise ratio performance.

  8. Study of fuzzy adaptive PID controller on thermal frequency stabilizing laser with double longitudinal modes

    NASA Astrophysics Data System (ADS)

    Mo, Qingkai; Zhang, Tao; Yan, Yining

    2016-10-01

    There are contradictions among speediness, anti-disturbance performance, and steady-state accuracy caused by traditional PID controller in the existing light source systems of thermal frequency stabilizing laser with double longitudinal modes. In this paper, a new kind of fuzzy adaptive PID controller was designed by combining fuzzy PID control technology and expert system to make frequency stabilizing system obtain the optimal performance. The experiments show that the frequency stability of the designed PID controller is similar to the existing PID controller (the magnitude of frequency stability is less than 10-9 in constant temperature and 10-7 in open air). But the preheating time is shortened obviously (from 10 minutes to 5 minutes) and the anti-disturbance capability is improved significantly (the recovery time needed after strong interference is reduced from 1 minute to 10 seconds).

  9. Empirical mode decomposition-adaptive least squares method for dynamic calibration of pressure sensors

    NASA Astrophysics Data System (ADS)

    Yao, Zhenjian; Wang, Zhongyu; Yi-Lin Forrest, Jeffrey; Wang, Qiyue; Lv, Jing

    2017-04-01

    In this paper, an approach combining empirical mode decomposition (EMD) with adaptive least squares (ALS) is proposed to improve the dynamic calibration accuracy of pressure sensors. With EMD, the original output of the sensor can be represented as sums of zero-mean amplitude modulation frequency modulation components. By identifying and excluding those components involved in noises, the noise-free output could be reconstructed with the useful frequency modulation ones. Then the least squares method is iteratively performed to estimate the optimal order and parameters of the mathematical model. The dynamic characteristic parameters of the sensor can be derived from the model in both time and frequency domains. A series of shock tube calibration tests are carried out to validate the performance of this method. Experimental results show that the proposed method works well in reducing the influence of noise and yields an appropriate mathematical model. Furthermore, comparative experiments also demonstrate the superiority of the proposed method over the existing ones.

  10. Adaptive-projection intrinsically transformed multivariate empirical mode decomposition in cooperative brain–computer interface applications

    PubMed Central

    Hemakom, Apit; Goverdovsky, Valentin; Looney, David; Mandic, Danilo P.

    2016-01-01

    An extension to multivariate empirical mode decomposition (MEMD), termed adaptive-projection intrinsically transformed MEMD (APIT-MEMD), is proposed to cater for power imbalances and inter-channel correlations in real-world multichannel data. It is shown that the APIT-MEMD exhibits similar or better performance than MEMD for a large number of projection vectors, whereas it outperforms MEMD for the critical case of a small number of projection vectors within the sifting algorithm. We also employ the noise-assisted APIT-MEMD within our proposed intrinsic multiscale analysis framework and illustrate the advantages of such an approach in notoriously noise-dominated cooperative brain–computer interface (BCI) based on the steady-state visual evoked potentials and the P300 responses. Finally, we show that for a joint cognitive BCI task, the proposed intrinsic multiscale analysis framework improves system performance in terms of the information transfer rate. PMID:26953174

  11. Standard Deviation and Intra Prediction Mode Based Adaptive Spatial Error Concealment (SEC) in H.264/AVC

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Wang, Lei; Ikenaga, Takeshi; Goto, Satoshi

    Transmission of compressed video over error prone channels may result in packet losses or errors, which can significantly degrade the image quality. Therefore an error concealment scheme is applied at the video receiver side to mask the damaged video. Considering there are 3 types of MBs (Macro Blocks) in natural video frame, i. e., Textural MB, Edged MB, and Smooth MB, this paper proposes an adaptive spatial error concealment which can choose 3 different methods for these 3 different MBs. For criteria of choosing appropriate method, 2 factors are taken into consideration. Firstly, standard deviation of our proposed edge statistical model is exploited. Secondly, some new features of latest video compression standard H.264/AVC, i. e., intra prediction mode is also considered for criterion formulation. Compared with previous works, which are only based on deterministic measurement, proposed method achieves the best image recovery. Subjective and objective image quality evaluations in experiments confirmed this.

  12. Adaptive-projection intrinsically transformed multivariate empirical mode decomposition in cooperative brain-computer interface applications.

    PubMed

    Hemakom, Apit; Goverdovsky, Valentin; Looney, David; Mandic, Danilo P

    2016-04-13

    An extension to multivariate empirical mode decomposition (MEMD), termed adaptive-projection intrinsically transformed MEMD (APIT-MEMD), is proposed to cater for power imbalances and inter-channel correlations in real-world multichannel data. It is shown that the APIT-MEMD exhibits similar or better performance than MEMD for a large number of projection vectors, whereas it outperforms MEMD for the critical case of a small number of projection vectors within the sifting algorithm. We also employ the noise-assisted APIT-MEMD within our proposed intrinsic multiscale analysis framework and illustrate the advantages of such an approach in notoriously noise-dominated cooperative brain-computer interface (BCI) based on the steady-state visual evoked potentials and the P300 responses. Finally, we show that for a joint cognitive BCI task, the proposed intrinsic multiscale analysis framework improves system performance in terms of the information transfer rate. © 2016 The Author(s).

  13. Adapting 3D Equilibrium Reconstruction to Reconstruct Weakly 3D H-mode Tokamaks

    NASA Astrophysics Data System (ADS)

    Cianciosa, M. R.; Hirshman, S. P.; Seal, S. K.; Unterberg, E. A.; Wilcox, R. S.; Wingen, A.; Hanson, J. D.

    2015-11-01

    The application of resonant magnetic perturbations for edge localized mode (ELM) mitigation breaks the toroidal symmetry of tokamaks. In these scenarios, the axisymmetric assumptions of the Grad-Shafranov equation no longer apply. By extension, equilibrium reconstruction tools, built around these axisymmetric assumptions, are insufficient to fully reconstruct a 3D perturbed equilibrium. 3D reconstruction tools typically work on systems where the 3D components of signals are a significant component of the input signals. In nominally axisymmetric systems, applied field perturbations can be on the order of 1% of the main field or less. To reconstruct these equilibria, the 3D component of signals must be isolated from the axisymmetric portions to provide the necessary information for reconstruction. This presentation will report on the adaptation to V3FIT for application on DIII-D H-mode discharges with applied resonant magnetic perturbations (RMPs). Newly implemented motional stark effect signals and modeling of electric field effects will also be discussed. Work supported under U.S. DOE Cooperative Agreement DE-AC05-00OR22725.

  14. Method for reconstructing nonlinear modes with adaptive structure from multidimensional data

    NASA Astrophysics Data System (ADS)

    Gavrilov, Andrey; Mukhin, Dmitry; Loskutov, Evgeny; Volodin, Evgeny; Feigin, Alexander; Kurths, Juergen

    2016-12-01

    We present a detailed description of a new approach for the extraction of principal nonlinear dynamical modes (NDMs) from high-dimensional data. The method of NDMs allows the joint reconstruction of hidden scalar time series underlying the observational variability together with a transformation mapping these time series to the physical space. Special Bayesian prior restrictions on the solution properties provide an efficient recognition of spatial patterns evolving in time and characterized by clearly separated time scales. In particular, we focus on adaptive properties of the NDMs and demonstrate for model examples of different complexities that, depending on the data properties, the obtained NDMs may have either substantially nonlinear or linear structures. It is shown that even linear NDMs give us more information about the internal system dynamics than the traditional empirical orthogonal function decomposition. The performance of the method is demonstrated on two examples. First, this approach is successfully tested on a low-dimensional problem to decode a chaotic signal from nonlinearly entangled time series with noise. Then, it is applied to the analysis of 250-year preindustrial control run of the INMCM4.0 global climate model. There, a set of principal modes of different nonlinearities is found capturing the internal model variability on the time scales from annual to multidecadal.

  15. Leg and calf press training modes and their impact on jump performance adaptations.

    PubMed

    Caruso, John F; Coday, Michael A; Ramsey, Charles A; Griswold, Shawn H; Polanski, David W; Drummond, Jan L; Walker, Ron H

    2008-05-01

    To examine the effects of resistance exercise (REX) mode on jump performance, subjects were assigned to one of three groups over a 6-week period with no cross-over. Subjects were assigned to leg and calf press REX on either a standard (n = 10) or ergometer (n = 9) device while a third group (n = 9) served as controls (CTRL). REX subjects worked out twice per week, which consisted of a three-set, 10-repetition paradigm for leg and calf press exercises. Immediately before and after the 6-week period, subjects performed tests that assessed jump (standing vertical jump, four-jump test protocol, depth jump) ability, while a fourth estimated knee extensor fast-twitch percentage (FT%) from fatigue incurred through a 50-repetition isokinetic protocol. Data analyses utilized 3 x 2 (group x time) repeated-measures ANCOVAs. Several dependent variables showed effects by group (standard REX, ergometer REX > CTRL) and time (post > pre). An interaction occurred for explosive leg power factor, a four-jump test variable, with standard REX post-test values as the interaction source. A trend for an interaction occurred for depth jump hang time, as ergometer REX values improved over time. Results suggest that mode-specific adaptations occur with REX training. Thus, athletes are best served with the selection of a REX device that is most specific to the demands of their jump performance task.

  16. Apparatus Would Stain Microscope Slides

    NASA Technical Reports Server (NTRS)

    Breeding, James D.

    1993-01-01

    Proposed apparatus meters specific amounts of fluid out of containers at specific times to stain microscope slides. Intended specifically for semiautomated staining of microbiological and hematological samples in microgravity, leakproof apparatus used in other environments in which technicians have little time to allocate to staining procedures and/or exposure to toxic staining agents or to micro-organisms to be stained hazardous. Apparatus adapted to perform almost any staining procedure and accommodates multiple staining reagents, useful for small or remote clinical laboratories.

  17. Apparatus Would Stain Microscope Slides

    NASA Technical Reports Server (NTRS)

    Breeding, James D.

    1993-01-01

    Proposed apparatus meters specific amounts of fluid out of containers at specific times to stain microscope slides. Intended specifically for semiautomated staining of microbiological and hematological samples in microgravity, leakproof apparatus used in other environments in which technicians have little time to allocate to staining procedures and/or exposure to toxic staining agents or to micro-organisms to be stained hazardous. Apparatus adapted to perform almost any staining procedure and accommodates multiple staining reagents, useful for small or remote clinical laboratories.

  18. Sliding vane geometry turbines

    DOEpatents

    Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R

    2014-12-30

    Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.

  19. Evidence of strain-mode-related cortical adaptation in the diaphysis of the horse radius.

    PubMed

    Mason, M W; Skedros, J G; Bloebaum, R D

    1995-09-01

    The relative importance that certain strain features, including mode (e.g., tension vs. compression) and magnitude, have in affecting adaptive bone remodeling seen in normal skeletally mature bones remains controversial. The equine radius is used as a model because in vivo strain data show that the mid-to-proximal diaphysis receives a consistent history of predominantly cranial-caudal bending loads, in contrast to the distal diaphysis which receives relatively more torsional loading superimposed on cranial-caudal bending. Medial and lateral cortices serve as control regions because they correspond to a neutral axis of bending. Equine radii were sectioned transversely at 65% (proximal), 50%, and 35% (distal) of length and cortical bone from the cranial ("tension"), caudal ("compression"), medial, and lateral regions was examined to determine if one, of many, structural and material features could be distinguished as being consistently related to the distribution of the prevailing strain modes. Mineral content (percent ash) differences, though statistically significant (p < 0.01), vary less than 1% between regions of the cortex at all sections. Porosity is not significantly different between any of the regions (p = 0.13). In the 65% and 50% sections, secondary osteon population density (OPD, osteons per square millimeter) and fractional area of secondary bone (FASB) are each nearly two times as great in the caudal regions than in the other three regions (p < 0.01). The 35% section shows a pattern opposite of that in the other sections--there are more than two times as many osteons in the cranial cortex than in the caudal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Analysis of modes and behavior of a multiconjugate adaptive optics system.

    PubMed

    Le Louarn, Miska; Tallon, Michel

    2002-05-01

    We study the so-called three-dimensional mapping of turbulence, a method solving the cone effect (or focus anisoplanatism) by using multiple laser guide stars (LGSs). This method also permits a widening of the corrected field of view much beyond the isoplanatic field. Multiple deformable mirrors, conjugated to planes at chosen altitudes among the turbulent layers, are used to correct in real time the wave fronts measured from the LGSs. We construct an interaction matrix describing the multiconjugate adaptive optics system and analyze the eigenmodes of the system. We show that the global tilt mode is singular because it cannot be localized in altitude, so that it must be corrected only once at any altitude. Furthermore, when the tilt from the LGS cannot be measured, the singularity of the global tilt yields the delocalization of particular forms of defocus and astigmatism. This imposes the use of a single natural guide star located anywhere in the corrected field to measure these modes. We show as an example that the cone effect can be corrected with a Strehl of 0.8 with four LGSs (tilt ignored) on an 8-m telescope in the visible when a single laser star provides a Strehl of 0.1. The maximum field of view of 100 arc sec in diameter can be reconstructed with an on-axis Strehl ratio of 30%. We also show that the measurement of the height of the layers can be done with current techniques and that additional layers, not accounted for, do not significantly degrade the performance in the configuration that we model.

  1. Neuromuscular adaptations to different modes of combined strength and endurance training.

    PubMed

    Eklund, D; Pulverenti, T; Bankers, S; Avela, J; Newton, R; Schumann, M; Häkkinen, K

    2015-02-01

    The present study investigated neuromuscular adaptations between same-session combined strength and endurance training with 2 loading orders and different day combined training over 24 weeks. 56 subjects were divided into different day (DD) combined strength and endurance training (4-6 d·wk(-1)) and same-session combined training: endurance preceding strength (E+S) or vice versa (S+E) (2-3 d·wk(-1)). Dynamic and isometric strength, EMG, voluntary activation, muscle cross-sectional area and endurance performance were measured. All groups increased dynamic one-repetition maximum (p<0.001; DD 13±7%, E+S 12±9% and S+E 17±12%) and isometric force (p<0.05-0.01), muscle cross-sectional area (p<0.001) and maximal power output during cycling (p<0.001). DD and S+E increased voluntary activation during training (p<0.05-0.01). In E+S no increase in voluntary activation was detected after 12 or 24 weeks. E+S also showed unchanged and S+E increased maximum EMG after 24 weeks during maximal isometric muscle actions. A high correlation (p<0.001, r=0.83) between the individual changes in voluntary activation and maximal knee extension force was found for E+S during weeks 13-24. Neural adaptations showed indications of being compromised and highly individual relating to changes in isometric strength when E+S-training was performed, while gains in one-repetition maximum, endurance performance and hypertrophy did not differ between the training modes.

  2. An Analysis of Fundamental Waffle Mode in Early AEOS Adaptive Optics Images

    NASA Astrophysics Data System (ADS)

    Makidon, Russell B.; Sivaramakrishnan, Anand; Perrin, Marshall D.; Roberts, Lewis C., Jr.; Oppenheimer, Ben R.; Soummer, Rémi; Graham, James R.

    2005-08-01

    Adaptive optics (AO) systems have significantly improved astronomical imaging capabilities over the last decade and are revolutionizing the kinds of science possible with 4-5 m class ground-based telescopes. A thorough understanding of AO system performance at the telescope can enable new frontiers of science as observations push AO systems to their performance limits. We look at recent advances with wave-front reconstruction (WFR) on the Advanced Electro-Optical System (AEOS) 3.6 m telescope to show how progress made in improving WFR can be measured directly in improved science images. We describe how a ``waffle mode'' wave-front error (which is not sensed by a Fried geometry Shack-Hartmann wave-front sensor) affects the AO point-spread function. We model details of AEOS AO to simulate a PSF that matches the actual AO PSF in the I band and show that while the older observed AEOS PSF contained several times more waffle error than expected, improved WFR techniques noticeably improve AEOS AO performance. We estimate the impact of these improved WFRs on H-band imaging at AEOS, chosen based on the optimization of the Lyot Project near-infrared coronagraph at this bandpass. Based on observations made at the Maui Space Surveillance System, operated by Detachment 15 of the US Air Force Research Laboratory's Directed Energy Directorate.

  3. Experimental demonstration of single-mode fiber coupling over relatively strong turbulence with adaptive optics.

    PubMed

    Chen, Mo; Liu, Chao; Xian, Hao

    2015-10-10

    High-speed free-space optical communication systems using fiber-optic components can greatly improve the stability of the system and simplify the structure. However, propagation through atmospheric turbulence degrades the spatial coherence of the signal beam and limits the single-mode fiber (SMF) coupling efficiency. In this paper, we analyze the influence of the atmospheric turbulence on the SMF coupling efficiency over various turbulences. The results show that the SMF coupling efficiency drops from 81% without phase distortion to 10% when phase root mean square value equals 0.3λ. The simulations of SMF coupling with adaptive optics (AO) indicate that it is inevitable to compensate the high-order aberrations for SMF coupling over relatively strong turbulence. The SMF coupling efficiency experiments, using an AO system with a 137-element deformable mirror and a Hartmann-Shack wavefront sensor, obtain average coupling efficiency increasing from 1.3% in open loop to 46.1% in closed loop under a relatively strong turbulence, D/r0=15.1.

  4. Designing Good Slides. Revised.

    ERIC Educational Resources Information Center

    Center for Disease Control (DHEW/PHS), Atlanta, GA.

    This guide is designed to help those who want to illustrate material in a formal presentation using 35mm double-frame slides, and it is also useful as a guide for teaching students how to work with slides. The guide provides a step-by-step procedure for each format. For instance, those who want to design a slide with copy only would go through a…

  5. Performance analysis of low-complexity adaptive frequency-domain equalization and MIMO signal processing for compensation of differential mode group delay in mode-division multiplexing communication systems using few-mode fibers

    NASA Astrophysics Data System (ADS)

    Weng, Yi; He, Xuan; Pan, Zhongqi

    2016-02-01

    Mode-division multiplexing (MDM) transmission systems utilizing few-mode fibers (FMF) have been intensively explored to sustain continuous traffic growth. The key challenges of MDM systems are inter-modal crosstalk due to random mode coupling (RMC), and largely-accumulated differential mode group delay (DMGD), whilst hinders mode-demultiplexer implementation. The adaptive multi-input multi-output (MIMO) frequency-domain equalization (FDE) can dynamically compensate DMGD using digital signal processing (DSP) algorithms. The frequency-domain least-mean squares (FD-LMS) algorithm has been universally adopted for high-speed MDM communications, mainly for its relatively low computational complexity. However, longer training sequence is appended for FD-LMS to achieve faster convergence, which incurs prohibitively higher system overhead and reduces overall throughput. In this paper, we propose a fast-convergent single-stage adaptive frequency-domain recursive least-squares (FD-RLS) algorithm with reduced complexity for DMGD compensation at MDM coherent receivers. The performance and complexity comparison of FD-RLS, with signal-PSD-dependent FD-LMS method and conventional FD-LMS approach, are performed in a 3000 km six-mode transmission system with 65 ps/km DMGD. We explore the convergence speed of three adaptive algorithms, including the normalized mean-square-error (NMSE) per fast Fourier transform (FFT) block at 14-30 dB OSNR. The fast convergence of FD-RLS is exploited at the expense of slightly-increased necessary tap numbers for MIMO equalizers, and it can partially save the overhead of training sequence. Furthermore, we demonstrate adaptive FD-RLS can also be used for chromatic dispersion (CD) compensation without increasing the filter tap length, thus prominently reducing the DSP implementation complexity for MDM systems.

  6. Fast adaptive early termination for mode selection in H.264/AVC standard based on ×264 implementation

    NASA Astrophysics Data System (ADS)

    Ren, Jianfeng; Kehtarnavaz, Nasser; Budagavi, Madhukar

    2008-02-01

    In the H.264/AVC video coding standard, the mode decision component involves a large amount of computation. This paper presents a fast or computationally efficient mode prediction and selection approach which has the following attributes: (a) both the spatial and temporal information are used to achieve early termination using adaptive thresholds, (b) inclusion of a modulator capable of trading off computational efficiency and accuracy, (c) a homogenous region detection procedure for 8×8 blocks based on adaptive thresholds. The developed approach consists of three main steps: (1) mode prediction, (2) early termination based on adaptive thresholds, and (3) refinement by checking all the modes. In addition, in order to avoid sub-partitions into smaller block sizes for 8x8 blocks, texture information is utilized. It is shown that the developed approach leads to a computationally efficient video coding implementation as compared to the previous fast approaches. The results obtained on QCIF, CIF, and HD format video sequences based on x264 are presented to demonstrate the computational efficiency of the developed approach at the expense of acceptably low losses in video quality.

  7. A unique mode of tissue oxygenation and the adaptive radiation of teleost fishes.

    PubMed

    Randall, D J; Rummer, J L; Wilson, J M; Wang, S; Brauner, C J

    2014-04-15

    for CO2 hydration/dehydration. Finally, RBC organophosphates (e.g. NTP) could be reduced during hypoxia to further increase Hb-O2 affinity without compromising tissue O2 delivery because high-affinity Hbs could still adequately deliver O2 to the tissues via Bohr/Root shifts. We suggest that the evolution of this unique mode of tissue O2 transfer evolved in the Triassic/Jurassic Period, when O2 levels were low, ultimately giving rise to the most extensive adaptive radiation of extant vertebrates, the teleost fishes.

  8. Adaptive synchronization control of coupled chaotic neurons in an external electrical stimulation

    NASA Astrophysics Data System (ADS)

    Yu, Hai-Tao; Wang, Jiang; Deng, Bin; Wei, Xi-Le; Chen, Ying-Yuan

    2013-05-01

    In this paper we present a combined algorithm for the synchronization control of two gap junction coupled chaotic FitzHugh—Nagumo (FHN) neurons in an external electrical stimulation. The controller consists of a combination of dynamical sliding mode control and adaptive backstepping control. The combined algorithm yields an adaptive dynamical sliding mode control law which has the advantage over static sliding mode-based controllers of being chattering-free, i.e., a sufficiently smooth control input signal is generated. It is shown that the proposed control scheme can not only compensate for the system uncertainty, but also guarantee the stability of the synchronized error system. In addition, numerical simulations are also performed to demonstrate the effectiveness of the proposed adaptive controller.

  9. Adaptive filtering of electroencephalogram signals using the empirical-modes method

    NASA Astrophysics Data System (ADS)

    Grubov, V. V.; Runnova, A. E.; Koronovskii, A. A.; Hramov, A. E.

    2017-07-01

    A new method for the removal of physiological artifacts in the experimental signals of human electroencephalograms (EEGs) has been developed. The method is based on decomposition of the signal in terms of empirical modes. The algorithm involves EEG signal decomposition in terms of empirical modes, searching for modes with artifacts, removing these modes, and restoration of the EEG signal. The method was tested on experimental data and showed high efficiency in the removal of various physiological artifacts in EEGs.

  10. Optical spectroscopy with a near-single-mode fiber-feed and adaptive optics

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Angel, J. Roger P.; Shelton, J. Christopher

    1998-07-01

    We report on first astronomical results with a cross-dispersed optical echelle spectrograph fed by a near single-mode fiber. We also present on a novel design of a new adaptive optics (AO) optimized fiber-fed cross-dispersed echelle spectrograph. The spectrograph is designed to match with AO corrected images in the optical bands provided by such as the Mt. Wilson 100 inch, Starfire Optical Range 3.5 m AO telescopes. Ultimately, it will be installed at the 6.5 m MMT, when this has high resolution AO correcting the optical spectrum. The spectrograph, fed by a 10 micron fused silica fiber, is unique in that the entire spectrum from 0.4 micron to 1.0 micron will be almost completely covered at resolution 200,000 in one exposure. The detector is a 2k X 4k AR coated back illuminated CCD with 15 micron pixel size. The close order spacing allowed by the sharp AO image makes the full cover possible. A 250 X 125 mm(superscript 2) Milton Roy R2 echelle grating with 23.2 grooves mm(superscript -1) and a blaze angle of 63.5 deg provides main dispersion. A double pass BK7 prism with 21 deg wedge angle provides cross dispersion, covering the spectrum from order 193 to 77. The spectrograph is used in the quasi- Littrow configuration with an off-axis Maksutov collimator/camera. The fiber feeds the AO corrected beams from the telescope Cassegrain focus to the spectrograph, which is set up on an optical bench. The spectrograph will be used mainly to study line profiles of solar type stars, to explore problems of indirect detection of planets and also study interstellar medium, circumstellar medium and metal abundance and isotopic ratios of extremely metal-poor stars.

  11. Herbaceous Ornamental Plants. Slide Script.

    ERIC Educational Resources Information Center

    Still, Steven

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with commercially important herbaceous ornamental plants. Included in the script are narrations for use with a total of 338 slides illustrating 150 different plants. Generally, two slides are used to illustrate each plant: one slide shows…

  12. Mailing microscope slides

    USDA-ARS?s Scientific Manuscript database

    Many insects feed agriculturally important crops, trees, and ornamental plants and cause millions of dollars of damage annually. Identification for some of these require the preparation of a microscope slide for examination. There are times when a microscope slide may need to be sent away to a speci...

  13. M4ARC: multi-model multi-mode adaptive resonant control for dynamically loaded flexible beam structures

    NASA Astrophysics Data System (ADS)

    Tjahyadi, H.; He, F.; Sammut, K.

    2008-08-01

    A hybrid multi-model-multi-mode adaptive resonant control (M4ARC) approach is proposed for dynamically loaded flexible beam structures to provide superior vibration damping performance as compared to its fixed-model and adaptive counterparts. The proposed approach uses a configurable controller, the parameters of which are updated using a fast and accurate on-line frequency identification method for N modes of interest. This method incorporates a simple supervision scheme that selects between the output of an N-mode filter bank (representing the multiple-fixed-model set) and the output of an estimator bank (representing the accurate model of the plant). The estimator bank comprises a multi-rate set of parallel N second-order recursive-least-squares estimators to achieve rapid parameter convergence. While the estimators are still in transition, the supervisor provides the configurable controller with an intermediate set of frequencies that correspond to the closest fixed model. Once the estimators converge, the supervisor selects the estimated frequency set to provide the configurable controller with an accurate representation of the current plant. This supervisor scheme significantly reduces the computational complexity as compared with existing counterparts. Experiments reveal that the proposed M4ARC approach offers the best compromise in terms of adapting to sudden and highly variable loading condition changes (within a bounded domain) while, at the same time, achieving fast transient performance.

  14. Phase correlation based adaptive mode decision for the H.264/AVC

    NASA Astrophysics Data System (ADS)

    Abdelazim, Abdelrahman; Mein, Stephen James; Varley, Martin Roy; Grecos, Christos; Ait-Boudaoud, Djamel

    2011-03-01

    The H.264 video coding standard achieves high performance compression and image quality at the expense of increased encoding complexity, due to the very refined Motion Estimation (ME) and mode decision processes. This paper focuses on decreasing the complexity of the mode selection process by effectively applying a novel fast mode decision algorithm. Firstly the phase correlation is analysed between a macroblock and its prediction obtained from the previously encoded adjacent block. Relationships are established between the correlation value and object size and also best fit motion vector. From this a novel fast mode decision and motion estimation technique has been developed utilising preprocessing frequency domain ME in order to accurately predict the best mode and the search range. We measure the correlation between a macroblock and the corresponding prediction. Based on the result we select the best mode, or limit the mode selection process to a subset of modes. Moreover the correlation result is also used to select an appropriate search range for the ME stage. Experimental results show that the proposed algorithm significantly reduces the motion estimation time whilst maintaining similar Rate Distortion performance, when compared to both the H.264/AVC Joint Model (JM) reference software and recently reported work.

  15. Design for slides.

    PubMed

    Johns, M

    1995-09-01

    The basic principles of design for projection slides are discussed, with particular reference to the impact of the personal computer and commercial presentation software on the material that is destined to end up on the screen at meetings and in seminar rooms. While modern software can be a boon to the presenter, allowing simple creation of slides, it can also encourage some of the worst excesses. The keynote of the design of slides for educational purposes should be simplicity, and ways of achieving simple but effective results are described.

  16. An adaptive two-stage energy-efficiency mechanism for the doze mode in EPON

    NASA Astrophysics Data System (ADS)

    Nikoukar, AliAkbar; Hwang, I.-Shyan; Su, Yu-Min; Liem, Andrew Tanny

    2016-07-01

    Sleep and doze power-saving modes are the common ways to reduce power consumption of optical network units (ONUs) in Ethernet passive optical network (EPON). The doze mode turns off the ONU transmitter when there is no traffic in the upstream direction while the sleep mode turns off the ONU transmitter and receiver. As the result, the sleep mode is more efficient compared to the doze mode, but it introduces additional complexity of scheduling and signaling, losses the clock synchronization and requires long clock recovery time; furthermore, it requires the cooperation of the optical line terminal (OLT) in the downstream direction to queue frames. To improve the energy-saving in the doze mode, a new two-stage mechanism is introduced that the doze sleep duration is extended for longer time with acceptable quality-of-services (QoS) metrics when ONU is idle in the current cycle. By this way the ONU enters the doze mode even in the high load traffic; moreover, the green dynamic bandwidth allocation (GBA) is proposed to calculate the doze sleep duration based on the ONU queue state and incoming traffic ratio. Simulation results show that the proposed mechanism significantly improves the energy-saving 74% and 54% when traffic load is from the light load to the high load in different traffic situations, and also promises the QoS performance.

  17. Slides, Swings and Science.

    ERIC Educational Resources Information Center

    Dreyer, Kay Jardon; Bryte, Janelle

    1990-01-01

    Described are eight science activities that may take place on a school playground using a parachute, balls, swings, slides, and a balance beam. Procedures and questions for each activity are included. (CW)

  18. Prototype Slide Stainer

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The prototype slide staining system capable of performing both one-component Wright's staining of blood smears and eight-step Gram staining of heat fixed slides of microorganisms is described. Attention was given to liquid containment, waste handling, absence of contamination from previous staining, and stability of the staining reagents. The unit is self-contained, capable of independent operation under one- or zero-g conditions, and compatible with Skylab A.

  19. Complexity reduction in the H.264/AVC using highly adaptive fast mode decision based on macroblock motion activity

    NASA Astrophysics Data System (ADS)

    Abdellah, Skoudarli; Mokhtar, Nibouche; Amina, Serir

    2015-11-01

    The H.264/AVC video coding standard is used in a wide range of applications from video conferencing to high-definition television according to its high compression efficiency. This efficiency is mainly acquired from the newly allowed prediction schemes including variable block modes. However, these schemes require a high complexity to select the optimal mode. Consequently, complexity reduction in the H.264/AVC encoder has recently become a very challenging task in the video compression domain, especially when implementing the encoder in real-time applications. Fast mode decision algorithms play an important role in reducing the overall complexity of the encoder. In this paper, we propose an adaptive fast intermode algorithm based on motion activity, temporal stationarity, and spatial homogeneity. This algorithm predicts the motion activity of the current macroblock from its neighboring blocks and identifies temporal stationary regions and spatially homogeneous regions using adaptive threshold values based on content video features. Extensive experimental work has been done in high profile, and results show that the proposed source-coding algorithm effectively reduces the computational complexity by 53.18% on average compared with the reference software encoder, while maintaining the high-coding efficiency of H.264/AVC by incurring only 0.097 dB in total peak signal-to-noise ratio and 0.228% increment on the total bit rate.

  20. Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator.

    PubMed

    Lin, Miao; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro

    2012-05-10

    Parallel phase-shifting digital holography using a phase-mode spatial light modulator (SLM) is proposed. The phase-mode SLM implements spatial distribution of phase retardation required in the parallel phase-shifting digital holography. This SLM can also compensate dynamically the phase distortion caused by optical elements such as beam splitters, lenses, and air fluctuation. Experimental demonstration using a static object is presented.