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Sample records for biped locomotion controller

  1. Modeling, Control and Simulation of Three-Dimensional Robotic Systems with Applications to Biped Locomotion.

    NASA Astrophysics Data System (ADS)

    Zheng, Yuan-Fang

    A three-dimensional, five link biped system is established. Newton-Euler state space formulation is employed to derive the equations of the system. The constraint forces involved in the equations can be eliminated by projection onto a smaller state space system for deriving advanced control laws. A model-referenced adaptive control scheme is developed to control the system. Digital computer simulations of point to point movement are carried out to show that the model-referenced adaptive control increases the dynamic range and speeds up the response of the system in comparison with linear and nonlinear feedback control. Further, the implementation of the controller is simpler. Impact effects of biped contact with the environment are modeled and studied. The instant velocity change at the moment of impact is derived as a function of the biped state and contact speed. The effects of impact on the state, as well as constraints are studied in biped landing on heels and toes simultaneously or on toes first. Rate and nonlinear position feedback are employed for stability of the biped after the impact. The complex structure of the foot is properly modeled. A spring and dashpot pair is suggested to represent the action of plantar fascia during the impact. This action prevents the arch of the foot from collapsing. A mathematical model of the skeletal muscle is discussed. A direct relationship between the stimulus rate and the active state is established. A piecewise linear relation between the length of the contractile element and the isometric force is considered. Hill's characteristic equation is maintained for determining the actual output force during different shortening velocities. A physical threshold model is proposed for recruitment which encompasses the size principle, its manifestations and exceptions to the size principle. Finally the role of spindle feedback in stability of the model is demonstrated by study of a pair of muscles.

  2. Innovization procedure applied to a multi-objective optimization of a biped robot locomotion

    NASA Astrophysics Data System (ADS)

    Oliveira, Miguel; Santos, Cristina P.; Costa, Lino

    2013-10-01

    This paper proposes an Innovization procedure approach for a bio-inspired biped gait locomotion controller. We combine a multi-objective evolutionary algorithm and a bio-inspired Central Patterns Generator locomotion controller to generates the necessary limb movements to perform the walking gait of a biped robot. The search for the best set of CPG parameters is optimized by considering multiple objectives along a staged evolution. An innovation analysis is issued to verify relationships between the parameters and the objectives and between objectives themselves in order to find relevant motor behaviors characteristics. The simulation results show the effectiveness of the proposed approach.

  3. A new biarticular actuator design facilitates control of leg function in BioBiped3.

    PubMed

    Sharbafi, Maziar Ahmad; Rode, Christian; Kurowski, Stefan; Scholz, Dorian; Möckel, Rico; Radkhah, Katayon; Zhao, Guoping; Rashty, Aida Mohammadinejad; Stryk, Oskar von; Seyfarth, Andre

    2016-01-01

    Bioinspired legged locomotion comprises different aspects, such as (i) benefiting from reduced complexity control approaches as observed in humans/animals, (ii) combining embodiment with the controllers and (iii) reflecting neural control mechanisms. One of the most important lessons learned from nature is the significant role of compliance in simplifying control, enhancing energy efficiency and robustness against perturbations for legged locomotion. In this research, we investigate how body morphology in combination with actuator design may facilitate motor control of leg function. Inspired by the human leg muscular system, we show that biarticular muscles have a key role in balancing the upper body, joint coordination and swing leg control. Appropriate adjustment of biarticular spring rest length and stiffness can simplify the control and also reduce energy consumption. In order to test these findings, the BioBiped3 robot was developed as a new version of BioBiped series of biologically inspired, compliant musculoskeletal robots. In this robot, three-segmented legs actuated by mono- and biarticular series elastic actuators mimic the nine major human leg muscle groups. With the new biarticular actuators in BioBiped3, novel simplified control concepts for postural balance and for joint coordination in rebounding movements (drop jumps) were demonstrated and approved. PMID:27367459

  4. A reflexive neural network for dynamic biped walking control.

    PubMed

    Geng, Tao; Porr, Bernd; Wörgötter, Florentin

    2006-05-01

    Biped walking remains a difficult problem, and robot models can greatly facilitate our understanding of the underlying biomechanical principles as well as their neuronal control. The goal of this study is to specifically demonstrate that stable biped walking can be achieved by combining the physical properties of the walking robot with a small, reflex-based neuronal network governed mainly by local sensor signals. Building on earlier work (Taga, 1995; Cruse, Kindermann, Schumm, Dean, & Schmitz, 1998), this study shows that human-like gaits emerge without specific position or trajectory control and that the walker is able to compensate small disturbances through its own dynamical properties. The reflexive controller used here has the following characteristics, which are different from earlier approaches: (1) Control is mainly local. Hence, it uses only two signals (anterior extreme angle and ground contact), which operate at the interjoint level. All other signals operate only at single joints. (2) Neither position control nor trajectory tracking control is used. Instead, the approximate nature of the local reflexes on each joint allows the robot mechanics itself (e.g., its passive dynamics) to contribute substantially to the overall gait trajectory computation. (3) The motor control scheme used in the local reflexes of our robot is more straightforward and has more biological plausibility than that of other robots, because the outputs of the motor neurons in our reflexive controller are directly driving the motors of the joints rather than working as references for position or velocity control. As a consequence, the neural controller and the robot mechanics are closely coupled as a neuromechanical system, and this study emphasizes that dynamically stable biped walking gaits emerge from the coupling between neural computation and physical computation. This is demonstrated by different walking experiments using a real robot as well as by a Poincaré map analysis

  5. Foot and body control of biped robots to walk on irregularly protruded uneven surfaces.

    PubMed

    Park, Jong Hyeon; Kim, Eung Seo

    2009-02-01

    This correspondence proposes a control method for biped robots walking on a geometrically uneven surface with irregular protrusions. The focus is to maintain robot stability in leg and foot motions in order to adapt the foot to uneven terrains. Under the assumption that contact sensors are evenly installed at the foot soles, the geometric information under the landing foot is represented by a terrain matrix, whose elements represent the height of protruded cones. The control strategy of a landing phase (LP) is to form a large polygon with the contact points between the foot and the ground, based on the current zero-moment point (ZMP) and the locations of contact points during the transition from the LP to the stable double-support phase. The center of the polygon formed by the contact points at the end of the LP is to be used as the ZMP when the trajectory for the next step is generated. The gravity-compensated inverted-pendulum-mode-based trajectory is modified based on the newly located ZMP position and is interpolated to remove any trajectory discontinuity and to ensure a smooth transition. A series of computer simulations of a 28-degree-of-freedom (DOF) biped robot with a six-DOF environment model using SimMechanics shows that a stable compliant locomotion on uneven surfaces is successfully achieved with the proposed method. PMID:19068443

  6. Stability analysis via the concept of Lyapunov exponents: a case study in optimal controlled biped standing

    NASA Astrophysics Data System (ADS)

    Sun, Yuming; Wu, Christine Qiong

    2012-12-01

    Balancing control is important for biped standing. In spite of large efforts, it is very difficult to design balancing control strategies satisfying three requirements simultaneously: maintaining postural stability, improving energy efficiency and satisfying the constraints between the biped feet and the ground. In this article, a proportional-derivative (PD) controller is proposed for a standing biped, which is simplified as a two-link inverted pendulum with one additional rigid foot-link. The genetic algorithm (GA) is used to search for the control gain meeting all three requirements. The stability analysis of such a deterministic biped control system is carried out using the concept of Lyapunov exponents (LEs), based on which, the system stability, where the disturbance comes from the initial states, and the structural stability, where the disturbance comes from the PD gains, are examined quantitively in terms of stability region. This article contributes to the biped balancing control, more significantly, the method shown in the studied case of biped provides a general framework of systematic stability analysis for certain deterministic nonlinear dynamical systems.

  7. Robust disturbance rejection control of a biped robotic system using high-order extended state observer.

    PubMed

    Martínez-Fonseca, Nadhynee; Castañeda, Luis Ángel; Uranga, Agustín; Luviano-Juárez, Alberto; Chairez, Isaac

    2016-05-01

    This study addressed the problem of robust control of a biped robot based on disturbance estimation. Active disturbance rejection control was the paradigm used for controlling the biped robot by direct active estimation. A robust controller was developed to implement disturbance cancelation based on a linear extended state observer of high gain class. A robust high-gain scheme was proposed for developing a state estimator of the biped robot despite poor knowledge of the plant and the presence of uncertainties. The estimated states provided by the state estimator were used to implement a feedback controller that was effective in actively rejecting the perturbations as well as forcing the trajectory tracking error to within a small vicinity of the origin. The theoretical convergence of the tracking error was proven using the Lyapunov theory. The controller was implemented by numerical simulations that showed the convergence of the tracking error. A comparison with a high-order sliding-mode-observer-based controller confirmed the superior performance of the controller using the robust observer introduced in this study. Finally, the proposed controller was implemented on an actual biped robot using an embedded hardware-in-the-loop strategy.

  8. Robust disturbance rejection control of a biped robotic system using high-order extended state observer.

    PubMed

    Martínez-Fonseca, Nadhynee; Castañeda, Luis Ángel; Uranga, Agustín; Luviano-Juárez, Alberto; Chairez, Isaac

    2016-05-01

    This study addressed the problem of robust control of a biped robot based on disturbance estimation. Active disturbance rejection control was the paradigm used for controlling the biped robot by direct active estimation. A robust controller was developed to implement disturbance cancelation based on a linear extended state observer of high gain class. A robust high-gain scheme was proposed for developing a state estimator of the biped robot despite poor knowledge of the plant and the presence of uncertainties. The estimated states provided by the state estimator were used to implement a feedback controller that was effective in actively rejecting the perturbations as well as forcing the trajectory tracking error to within a small vicinity of the origin. The theoretical convergence of the tracking error was proven using the Lyapunov theory. The controller was implemented by numerical simulations that showed the convergence of the tracking error. A comparison with a high-order sliding-mode-observer-based controller confirmed the superior performance of the controller using the robust observer introduced in this study. Finally, the proposed controller was implemented on an actual biped robot using an embedded hardware-in-the-loop strategy. PMID:26928517

  9. Controlling legs for locomotion-insights from robotics and neurobiology.

    PubMed

    Buschmann, Thomas; Ewald, Alexander; von Twickel, Arndt; Büschges, Ansgar

    2015-08-01

    Walking is the most common terrestrial form of locomotion in animals. Its great versatility and flexibility has led to many attempts at building walking machines with similar capabilities. The control of walking is an active research area both in neurobiology and robotics, with a large and growing body of work. This paper gives an overview of the current knowledge on the control of legged locomotion in animals and machines and attempts to give walking control researchers from biology and robotics an overview of the current knowledge in both fields. We try to summarize the knowledge on the neurobiological basis of walking control in animals, emphasizing common principles seen in different species. In a section on walking robots, we review common approaches to walking controller design with a slight emphasis on biped walking control. We show where parallels between robotic and neurobiological walking controllers exist and how robotics and biology may benefit from each other. Finally, we discuss where research in the two fields diverges and suggest ways to bridge these gaps. PMID:26119450

  10. Controlling legs for locomotion-insights from robotics and neurobiology.

    PubMed

    Buschmann, Thomas; Ewald, Alexander; von Twickel, Arndt; Büschges, Ansgar

    2015-06-29

    Walking is the most common terrestrial form of locomotion in animals. Its great versatility and flexibility has led to many attempts at building walking machines with similar capabilities. The control of walking is an active research area both in neurobiology and robotics, with a large and growing body of work. This paper gives an overview of the current knowledge on the control of legged locomotion in animals and machines and attempts to give walking control researchers from biology and robotics an overview of the current knowledge in both fields. We try to summarize the knowledge on the neurobiological basis of walking control in animals, emphasizing common principles seen in different species. In a section on walking robots, we review common approaches to walking controller design with a slight emphasis on biped walking control. We show where parallels between robotic and neurobiological walking controllers exist and how robotics and biology may benefit from each other. Finally, we discuss where research in the two fields diverges and suggest ways to bridge these gaps.

  11. Controlled Reduction of a Five-Link 3D Biped with Unactuated Yaw

    PubMed Central

    Gregg, Robert D.

    2014-01-01

    This paper presents a formulation of controlled geometric reduction with one degree of underactuation for mechanical systems with an unactuated cyclic variable subject to passive damping. We show that the first control term in the fully actuated case reduces to passive joint-velocity feedback, which can be equivalently provided by viscous friction. The underactuated control strategy is applied to a five-link 3D biped with a hip, torso, knees, and unactuated yaw at the foot contact point. We show asymptotically stable walking in the presence of passive yawing for realistic friction coefficients. PMID:25663742

  12. Walking motion generation, synthesis, and control for biped robot by using PGRL, LPI, and fuzzy logic.

    PubMed

    Li, Tzuu-Hseng S; Su, Yu-Te; Lai, Shao-Wei; Hu, Jhen-Jia

    2011-06-01

    This paper proposes the implementation of fuzzy motion control based on reinforcement learning (RL) and Lagrange polynomial interpolation (LPI) for gait synthesis of biped robots. First, the procedure of a walking gait is redefined into three states, and the parameters of this designed walking gait are determined. Then, the machine learning approach applied to adjusting the walking parameters is policy gradient RL (PGRL), which can execute real-time performance and directly modify the policy without calculating the dynamic function. Given a parameterized walking motion designed for biped robots, the PGRL algorithm automatically searches the set of possible parameters and finds the fastest possible walking motion. The reward function mainly considered is first the walking speed, which can be estimated from the vision system. However, the experiment illustrates that there are some stability problems in this kind of learning process. To solve these problems, the desired zero moment point trajectory is added to the reward function. The results show that the robot not only has more stable walking but also increases its walking speed after learning. This is more effective and attractive than manual trial-and-error tuning. LPI, moreover, is employed to transform the existing motions to the motion which has a revised angle determined by the fuzzy motion controller. Then, the biped robot can continuously walk in any desired direction through this fuzzy motion control. Finally, the fuzzy-based gait synthesis control is demonstrated by tasks and point- and line-target tracking. The experiments show the feasibility and effectiveness of gait learning with PGRL and the practicability of the proposed fuzzy motion control scheme.

  13. Generation of the Human Biped Stance by a Neural Controller Able to Compensate Neurological Time Delay

    PubMed Central

    Jiang, Ping; Chiba, Ryosuke; Takakusaki, Kaoru; Ota, Jun

    2016-01-01

    The development of a physiologically plausible computational model of a neural controller that can realize a human-like biped stance is important for a large number of potential applications, such as assisting device development and designing robotic control systems. In this paper, we develop a computational model of a neural controller that can maintain a musculoskeletal model in a standing position, while incorporating a 120-ms neurological time delay. Unlike previous studies that have used an inverted pendulum model, a musculoskeletal model with seven joints and 70 muscular-tendon actuators is adopted to represent the human anatomy. Our proposed neural controller is composed of both feed-forward and feedback controls. The feed-forward control corresponds to the constant activation input necessary for the musculoskeletal model to maintain a standing posture. This compensates for gravity and regulates stiffness. The developed neural controller model can replicate two salient features of the human biped stance: (1) physiologically plausible muscle activations for quiet standing; and (2) selection of a low active stiffness for low energy consumption. PMID:27655271

  14. Disturbance Compensating Control of a Biped Walking Machine Based on Reflex Motions

    NASA Astrophysics Data System (ADS)

    Funabashi, Hiroaki; Takeda, Yukio; Itoh, Shigenari; Higuchi, Masaru

    A control system that utilizes the concept of reflex control in animals is proposed for a biped walking machine with consideration of compensation of external disturbances. A walking machine was modeled as a sequential machine, and a series of single-reflex motions was synthesized for it. A hierarchical three-level control system was constructed. As disturbances, two types of external forces were considered: “impulsive” force with a large magnitude and short action-time and “continuous” force with a small magnitude and long action time. Appropriate state variables for rapid and reliable sensing of each disturbance were investigated and the thresholds of their values used as the triggers for changing the gait from a periodic gait to a disturbance compensation one were determined. Motions of disturbance compensation gaits were determined by combining some single-reflex motions. A control system for an experimental biped walking machine whose mass is 18kg, total height is 0.66m, step length is 0.25m and walking cycle is 133 steps/min was constructed and tested. The proposed control system enabled the walking machine to successfully avoid tumbling when it was subjected to the two external forces and return to a periodic gait.

  15. Pareto design of state feedback tracking control of a biped robot via multiobjective PSO in comparison with sigma method and genetic algorithms: modified NSGAII and MATLAB's toolbox.

    PubMed

    Mahmoodabadi, M J; Taherkhorsandi, M; Bagheri, A

    2014-01-01

    An optimal robust state feedback tracking controller is introduced to control a biped robot. In the literature, the parameters of the controller are usually determined by a tedious trial and error process. To eliminate this process and design the parameters of the proposed controller, the multiobjective evolutionary algorithms, that is, the proposed method, modified NSGAII, Sigma method, and MATLAB's Toolbox MOGA, are employed in this study. Among the used evolutionary optimization algorithms to design the controller for biped robots, the proposed method operates better in the aspect of designing the controller since it provides ample opportunities for designers to choose the most appropriate point based upon the design criteria. Three points are chosen from the nondominated solutions of the obtained Pareto front based on two conflicting objective functions, that is, the normalized summation of angle errors and normalized summation of control effort. Obtained results elucidate the efficiency of the proposed controller in order to control a biped robot.

  16. Evolution of neural controllers for salamanderlike locomotion

    NASA Astrophysics Data System (ADS)

    Ijspeert, Auke J.

    1999-08-01

    This paper presents an experiment in which evolutionary algorithms are used for the development of neural controllers for salamander locomotion. The aim of the experiment is to investigate which kind of neural circuitry can produce the typical swimming and trotting gaits of the salamander, and to develop a synthetic approach to neurobiology by using genetic algorithms as design tool. A 2D bio-mechanical simulation of the salamander's body is developed whose muscle contraction is determined by the locomotion controller simulated as continuous-time neural networks. While the connectivity of the neural circuitry underlying locomotion in the salamander has not been decoded for the moment, the general organization of the designed neural circuits corresponds to that hypothesized by neurobiologist for the real animal. In particular, the locomotion controllers are based on a body central pattern generator (CPG) corresponding to a lamprey-like swimming controller as developed by Ekeberg, and are extended with a limb CPG for controlling the salamander's body. A genetic algorithm is used to instantiate synaptic weights of the connections within the limb CPG and from the limb CPG to the body CPG given a high level description of the desired gaits. A set of biologically plausible controllers are thus developed which can produce a neural activity and locomotion gaits very similar to those observed in the real salamander. By simply varying the external excitation applied to the network, the speed, direction and type of gait can be varied.

  17. Adaptive, Fast Walking in a Biped Robot under Neuronal Control and Learning

    PubMed Central

    Kulvicius, Tomas; Porr, Bernd; Wörgötter, Florentin

    2007-01-01

    Human walking is a dynamic, partly self-stabilizing process relying on the interaction of the biomechanical design with its neuronal control. The coordination of this process is a very difficult problem, and it has been suggested that it involves a hierarchy of levels, where the lower ones, e.g., interactions between muscles and the spinal cord, are largely autonomous, and where higher level control (e.g., cortical) arises only pointwise, as needed. This requires an architecture of several nested, sensori–motor loops where the walking process provides feedback signals to the walker's sensory systems, which can be used to coordinate its movements. To complicate the situation, at a maximal walking speed of more than four leg-lengths per second, the cycle period available to coordinate all these loops is rather short. In this study we present a planar biped robot, which uses the design principle of nested loops to combine the self-stabilizing properties of its biomechanical design with several levels of neuronal control. Specifically, we show how to adapt control by including online learning mechanisms based on simulated synaptic plasticity. This robot can walk with a high speed (>3.0 leg length/s), self-adapting to minor disturbances, and reacting in a robust way to abruptly induced gait changes. At the same time, it can learn walking on different terrains, requiring only few learning experiences. This study shows that the tight coupling of physical with neuronal control, guided by sensory feedback from the walking pattern itself, combined with synaptic learning may be a way forward to better understand and solve coordination problems in other complex motor tasks. PMID:17630828

  18. Dynamics and control of motion on the ground and in the air with application to biped robots

    NASA Astrophysics Data System (ADS)

    Hemami, H.; Zheng, Y.-F.

    The dynamics of a multi-linkage model of natural or man-made systems with arbitrary holonomic and non-holonomic constraints at the joints are formulated. The formulation is equally applicable to movements on the ground or in the air. Nonlinear control strategies for postural balance and rhythmic motion are presented. A predictive algorithm to compensate for computation or transmission delay is proposed. Digital computer simulations are presented to demonstrate the effectiveness of the control strategy for a five-link three-dimensional biped.

  19. Locomotion control of hybrid cockroach robots

    PubMed Central

    Sanchez, Carlos J.; Chiu, Chen-Wei; Zhou, Yan; González, Jorge M.; Vinson, S. Bradleigh; Liang, Hong

    2015-01-01

    Natural systems retain significant advantages over engineered systems in many aspects, including size and versatility. In this research, we develop a hybrid robotic system using American (Periplaneta americana) and discoid (Blaberus discoidalis) cockroaches that uses the natural locomotion and robustness of the insect. A tethered control system was firstly characterized using American cockroaches, wherein implanted electrodes were used to apply an electrical stimulus to the prothoracic ganglia. Using this approach, larger discoid cockroaches were engineered into a remotely controlled hybrid robotic system. Locomotion control was achieved through electrical stimulation of the prothoracic ganglia, via a remotely operated backpack system and implanted electrodes. The backpack consisted of a microcontroller with integrated transceiver protocol, and a rechargeable battery. The hybrid discoid roach was able to walk, and turn in response to an electrical stimulus to its nervous system with high repeatability of 60%. PMID:25740855

  20. Locomotion control of hybrid cockroach robots.

    PubMed

    Sanchez, Carlos J; Chiu, Chen-Wei; Zhou, Yan; González, Jorge M; Vinson, S Bradleigh; Liang, Hong

    2015-04-01

    Natural systems retain significant advantages over engineered systems in many aspects, including size and versatility. In this research, we develop a hybrid robotic system using American (Periplaneta americana) and discoid (Blaberus discoidalis) cockroaches that uses the natural locomotion and robustness of the insect. A tethered control system was firstly characterized using American cockroaches, wherein implanted electrodes were used to apply an electrical stimulus to the prothoracic ganglia. Using this approach, larger discoid cockroaches were engineered into a remotely controlled hybrid robotic system. Locomotion control was achieved through electrical stimulation of the prothoracic ganglia, via a remotely operated backpack system and implanted electrodes. The backpack consisted of a microcontroller with integrated transceiver protocol, and a rechargeable battery. The hybrid discoid roach was able to walk, and turn in response to an electrical stimulus to its nervous system with high repeatability of 60%.

  1. Locomotion control of hybrid cockroach robots.

    PubMed

    Sanchez, Carlos J; Chiu, Chen-Wei; Zhou, Yan; González, Jorge M; Vinson, S Bradleigh; Liang, Hong

    2015-04-01

    Natural systems retain significant advantages over engineered systems in many aspects, including size and versatility. In this research, we develop a hybrid robotic system using American (Periplaneta americana) and discoid (Blaberus discoidalis) cockroaches that uses the natural locomotion and robustness of the insect. A tethered control system was firstly characterized using American cockroaches, wherein implanted electrodes were used to apply an electrical stimulus to the prothoracic ganglia. Using this approach, larger discoid cockroaches were engineered into a remotely controlled hybrid robotic system. Locomotion control was achieved through electrical stimulation of the prothoracic ganglia, via a remotely operated backpack system and implanted electrodes. The backpack consisted of a microcontroller with integrated transceiver protocol, and a rechargeable battery. The hybrid discoid roach was able to walk, and turn in response to an electrical stimulus to its nervous system with high repeatability of 60%. PMID:25740855

  2. Intermittent locomotion as an optimal control strategy

    PubMed Central

    Paoletti, P.; Mahadevan, L.

    2014-01-01

    Birds, fish and other animals routinely use unsteady effects to save energy by alternating between phases of active propulsion and passive coasting. Here, we construct a minimal model for such behaviour that can be couched as an optimal control problem via an analogy to travelling with a rechargeable battery. An analytical solution of the optimal control problem proves that intermittent locomotion has lower energy requirements relative to steady-state strategies. Additional realistic hypotheses, such as the assumption that metabolic cost at a given power should be minimal (the fixed gear hypothesis), a nonlinear dependence of the energy storage rate on propulsion and/or a preferred average speed, allow us to generalize the model and demonstrate the flexibility of intermittent locomotion with implications for biological and artificial systems. PMID:24711718

  3. Reinforcement learning for a biped robot based on a CPG-actor-critic method.

    PubMed

    Nakamura, Yutaka; Mori, Takeshi; Sato, Masa-aki; Ishii, Shin

    2007-08-01

    Animals' rhythmic movements, such as locomotion, are considered to be controlled by neural circuits called central pattern generators (CPGs), which generate oscillatory signals. Motivated by this biological mechanism, studies have been conducted on the rhythmic movements controlled by CPG. As an autonomous learning framework for a CPG controller, we propose in this article a reinforcement learning method we call the "CPG-actor-critic" method. This method introduces a new architecture to the actor, and its training is roughly based on a stochastic policy gradient algorithm presented recently. We apply this method to an automatic acquisition problem of control for a biped robot. Computer simulations show that training of the CPG can be successfully performed by our method, thus allowing the biped robot to not only walk stably but also adapt to environmental changes. PMID:17412559

  4. Active control of locomotion facilitates nonvisual navigation.

    PubMed

    Philbeck, J W; Klatzky, R L; Behrmann, M; Loomis, J M; Goodridge, J

    2001-02-01

    In some navigation tasks, participants are more accurate if they view the environment beforehand. To characterize the benefits associated with visual previews, 32 blindfolded participants were guided along simple paths and asked to walk unassisted to a specified destination (e.g., the origin). Paths were completed without vision, with or without a visual preview of the environment. Previews did not necessarily improve nonvisual navigation. When previewed landmarks stood near the origin or at off-path locations, they provided little benefit; by contrast, when they specified intermediate destinations (thereby increasing the degree of active control), performance was greatly enhanced. The results suggest that the benefit of a visual preview stems from the information it supplies for actively controlled locomotion. Accuracy in reaching the final destination, however, is strongly contingent upon the destination's location during the preview.

  5. Hydrodynamics and control of microbial locomotion

    NASA Astrophysics Data System (ADS)

    Dunkel, Jorn; Kantsler, Vasily; Polin, Marco; Wioland, Hugo; Goldstein, Raymond

    2014-03-01

    Interactions between swimming cells, surfaces and fluid flow are essential to many microbiological processes, from the formation of biofilms to the fertilization of human egg cells. Yet, relatively little remains known quantitatively about the physical mechanisms that govern the response of bacteria, algae and sperm cells to flow velocity gradients and solid surfaces. A better understanding of cell-surface and cell-flow interactions promises new biological insights and may advance microfluidic techniques for controlling microbial and sperm locomotion, with potential applications in diagnostics and therapeutic protein synthesis. Here, we report new experimental measurements that quantify surface interactions of bacteria, unicellular green algae and mammalian spermatozoa. These experiments show that the subtle interplay of hydrodynamics and surface interactions can stabilize collective bacterial motion, that direct ciliary contact interactions dominate surface scattering of eukaryotic biflagellate algae, and that rheotaxis combined with steric surface interactions provides a robust long-range navigation mechanism for sperm cells.

  6. Goal Directed Locomotion and Balance Control in Autistic Children

    ERIC Educational Resources Information Center

    Vernazza-Martin, S.; Martin, N.; Vernazza, A.; Lepellec-Muller, A.; Rufo, M.; Massion, J.; Assaiante, C.

    2005-01-01

    This article focuses on postural anticipation and multi-joint coordination during locomotion in healthy and autistic children. Three questions were addressed: (1) Are gait parameters modified in autistic children? (2) Is equilibrium control affected in autistic children? (3) Is locomotion adjusted to the experimenter-imposed goal? Six healthy…

  7. Dynamic legged locomotion in robots and animals

    NASA Astrophysics Data System (ADS)

    Raibert, Marc; Playter, Robert; Ringrose, Robert; Bailey, Dave; Leeser, Karl

    1995-01-01

    This report documents our study of active legged systems that balance actively and move dynamically. The purpose of this research is to build a foundation of knowledge that can lead both to the construction of useful legged vehicles and to a better understanding of how animal locomotion works. In this report we provide an update on progress during the past year. Here are the topics covered in this report: (1) Is cockroach locomotion dynamic? To address this question we created three models of cockroaches, each abstracted at a different level. We provided each model with a control system and computer simulation. One set of results suggests that 'Groucho Running,' a type of dynamic walking, seems feasible at cockroach scale. (2) How do bipeds shift weight between the legs? We built a simple planar biped robot specifically to explore this question. It shifts its weight from one curved foot to the other, using a toe-off and toe-on strategy, in conjunction with dynamic tipping. (3) 3D biped gymnastics: The 3D biped robot has done front somersaults in the laboratory. The robot changes its leg length in flight to control rotation rate. This in turn provides a mechanism for controlling the landing attitude of the robot once airborne. (4) Passively stabilized layout somersault: We have found that the passive structure of a gymnast, the configuration of masses and compliances, can stabilize inherently unstable maneuvers. This means that body biomechanics could play a larger role in controlling behavior than is generally thought. We used a physical 'doll' model and computer simulation to illustrate the point. (5) Twisting: Some gymnastic maneuvers require twisting. We are studying how to couple the biomechanics of the system to its control to produce efficient, stable twisting maneuvers.

  8. Simulation and robotics studies of salamander locomotion: applying neurobiological principles to the control of locomotion in robots.

    PubMed

    Ijspeert, Auke Jan; Crespi, Alessandro; Cabelguen, Jean-Marie

    2005-01-01

    This article presents a project that aims at understanding the neural circuitry controlling salamander locomotion, and developing an amphibious salamander-like robot capable of replicating its bimodal locomotion, namely swimming and terrestrial walking. The controllers of the robot are central pattern generator models inspired by the salamander's locomotion control network. The goal of the project is twofold: (1) to use robots as tools for gaining a better understanding of locomotion control in vertebrates and (2) to develop new robot and control technologies for developing agile and adaptive outdoor robots. The article has four parts. We first describe the motivations behind the project. We then present neuromechanical simulation studies of locomotion control in salamanders. This is followed by a description of the current stage of the robotic developments. We conclude the article with a discussion on the usefulness of robots in neuroscience research with a special focus on locomotion control.

  9. 49 CFR 229.15 - Remote control locomotives.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...'s having the capability to control more than one RCL shall have a means to lock in one RCL... eliminate tractive effort to the locomotive; (xi) Audio/visual indication of wheel slip, only if an...

  10. Visuomotor Control of Human Adaptive Locomotion: Understanding the Anticipatory Nature

    PubMed Central

    Higuchi, Takahiro

    2013-01-01

    To maintain balance during locomotion, the central nervous system (CNS) accommodates changes in the constraints of spatial environment (e.g., existence of an obstacle or changes in the surface properties). Locomotion while modifying the basic movement patterns in response to such constraints is referred to as adaptive locomotion. The most powerful means of ensuring balance during adaptive locomotion is to visually perceive the environmental properties at a distance and modify the movement patterns in an anticipatory manner to avoid perturbation altogether. For this reason, visuomotor control of adaptive locomotion is characterized, at least in part, by its anticipatory nature. The purpose of the present article is to review the relevant studies which revealed the anticipatory nature of the visuomotor control of adaptive locomotion. The anticipatory locomotor adjustments for stationary and changeable environment, as well as the spatio-temporal patterns of gaze behavior to support the anticipatory locomotor adjustments are described. Such description will clearly show that anticipatory locomotor adjustments are initiated when an object of interest (e.g., a goal or obstacle) still exists in far space. This review also show that, as a prerequisite of anticipatory locomotor adjustments, environmental properties are accurately perceived from a distance in relation to individual’s action capabilities. PMID:23720647

  11. Advanced underground Vehicle Power and Control: The locomotive Research Platform

    SciTech Connect

    Vehicle Projects LLC

    2003-01-28

    Develop a fuelcell mine locomotive with metal-hydride hydrogen storage. Test the locomotive for fundamental limitations preventing successful commercialization of hydride fuelcells in underground mining. During Phase 1 of the DOE-EERE sponsored project, FPI and its partner SNL, completed work on the development of a 14.4 kW fuelcell power plant and metal-hydride energy storage. An existing battery-electric locomotive with similar power requirements, minus the battery module, was used as the base vehicle. In March 2001, Atlas Copco Wagner of Portland, OR, installed the fuelcell power plant into the base vehicle and initiated integration of the system into the vehicle. The entire vehicle returned to Sandia in May 2001 for further development and integration. Initial system power-up took place in December 2001. A revision to the original contract, Phase 2, at the request of DOE Golden Field Office, established Vehicle Projects LLC as the new prime contractor,. Phase 2 allowed industry partners to conduct surface tests, incorporate enhancements to the original design by SNL, perform an extensive risk and safety analysis, and test the fuelcell locomotive underground under representative production mine conditions. During the surface tests one of the fuelcell stacks exhibited reduced power output resulting in having to replace both fuelcell stacks. The new stacks were manufactured with new and improved technology resulting in an increase of the gross power output from 14.4 kW to 17 kW. Further work by CANMET and Hatch Associates, an engineering consulting firm specializing in safety analysis for the mining industry, both under subcontract to Vehicle Projects LLC, established minimum requirements for underground testing. CANMET upgraded the Programmable Logic Control (PLC) software used to monitor and control the fuelcell power plant, taking into account locomotive operator's needs. Battery Electric, a South Africa manufacturer, designed and manufactured (at no cost to

  12. Locomotion of the blind controlled by natural sound cues.

    PubMed

    Strelow, E R; Brabyn, J A

    1982-01-01

    Measures of the accuracy of locomotion control were taken with blind and blindfolded sighted subjects using the natural auditory obstacle sense to locate a travel path. These measures were compared with the accuracy of visual guidance. While the blind show a greater skill than blindfolded sighted subjects in using auditory cues for guidance, auditory guidance is notably inferior to visual guidance and deteriorates markedly when smaller targets are used to define the travel path. The natural obstacle sense thus appears to give only a rudimentary perception of the presence of objects and does not provide sufficient spatial information to allow accurate locomotion control.

  13. Design of a biped robot actuated by pneumatic artificial muscles.

    PubMed

    Liu, Yixiang; Zang, Xizhe; Liu, Xinyu; Wang, Lin

    2015-01-01

    High compliant legs are essential for the efficient versatile locomotion and shock absorbency of humans. This study proposes a biped robot actuated by pneumatic artificial muscles to mimic human locomotion. On the basis of the musculoskeletal architecture of human lower limbs, each leg of the biped robot is modeled as a system of three segments, namely, hip joint, knee joint, and ankle joint, and eleven muscles, including both monoarticular and biarticular muscles. Each rotational joint is driven by a pair of antagonistic muscles, enabling joint compliance to be tuned by operating the pressure inside the muscles. Biarticular muscles play an important role in transferring power between joints. Walking simulations verify that biarticular muscles contribute to joint compliance and can absorb impact energy when the robot makes an impact upon ground contact. PMID:26406072

  14. Design of a biped robot actuated by pneumatic artificial muscles.

    PubMed

    Liu, Yixiang; Zang, Xizhe; Liu, Xinyu; Wang, Lin

    2015-01-01

    High compliant legs are essential for the efficient versatile locomotion and shock absorbency of humans. This study proposes a biped robot actuated by pneumatic artificial muscles to mimic human locomotion. On the basis of the musculoskeletal architecture of human lower limbs, each leg of the biped robot is modeled as a system of three segments, namely, hip joint, knee joint, and ankle joint, and eleven muscles, including both monoarticular and biarticular muscles. Each rotational joint is driven by a pair of antagonistic muscles, enabling joint compliance to be tuned by operating the pressure inside the muscles. Biarticular muscles play an important role in transferring power between joints. Walking simulations verify that biarticular muscles contribute to joint compliance and can absorb impact energy when the robot makes an impact upon ground contact.

  15. Decoding the organization of spinal circuits that control locomotion

    PubMed Central

    Kiehn, Ole

    2016-01-01

    Unravelling the functional operation of neuronal networks and linking cellular activity to specific behavioural outcomes are among the biggest challenges in neuroscience. In this broad field of research, substantial progress has been made in studies of the spinal networks that control locomotion. Through united efforts using electrophysiological and molecular genetic network approaches and behavioural studies in phylogenetically diverse experimental models, the organization of locomotor networks has begun to be decoded. The emergent themes from this research are that the locomotor networks have a modular organization with distinct transmitter and molecular codes and that their organization is reconfigured with changes to the speed of locomotion or changes in gait. PMID:26935168

  16. Optimizing Locomotion Controllers Using Biologically-Based Actuators and Objectives

    PubMed Central

    Wang, Jack M.; Hamner, Samuel R.; Delp, Scott L.; Koltun, Vladlen

    2015-01-01

    We present a technique for automatically synthesizing walking and running controllers for physically-simulated 3D humanoid characters. The sagittal hip, knee, and ankle degrees-of-freedom are actuated using a set of eight Hill-type musculotendon models in each leg, with biologically-motivated control laws. The parameters of these control laws are set by an optimization procedure that satisfies a number of locomotion task terms while minimizing a biological model of metabolic energy expenditure. We show that the use of biologically-based actuators and objectives measurably increases the realism of gaits generated by locomotion controllers that operate without the use of motion capture data, and that metabolic energy expenditure provides a simple and unifying measurement of effort that can be used for both walking and running control optimization. PMID:26251560

  17. Some historical reflections on the neural control of locomotion.

    PubMed

    Clarac, François

    2008-01-01

    Thought on the neural control of locomotion dates back to antiquity. In this article, however, the focus is more recent by starting with some major 17th century concepts, which were developed by René Descartes, a French philosopher; Thomas Willis, an English anatomist; and Giovanni Borelli, an Italian physiologist and physicist. Each relied on his personal expertise to theorize on the organization and control of movements. The 18th and early 19th centuries saw work on both the central and peripheral control of movement: the former most notably by Johann Unzer, Marie Jean-Pierre Flourens and Julien-Jean-César Legallois, and the latter by Unzer, Jirí Procháska and many others. Next in the 19th century, neurologists used human locomotion as a precise tool for characterizing motor pathologies: e.g., Guillaume Duchenne de Boulogne's description of locomotor ataxia. Jean-Martin Charcot considered motor control to be organized at two levels of the central nervous system: the cerebral cortex and the spinal cord. Maurice Philippson's defined the dog's step cycle and considered that locomotion used both central and reflex mechanisms. Charles Sherrington explained that locomotor control was usually thought to consist of a succession of peripheral reflexes (e.g., the stepping reflexes). Thomas Graham Brown's then contemporary evidence for the spinal origin of locomotor rhythmicity languished in obscurity until the early 1960s. By then the stage was set for an international assault on the neural control of locomotion, which featured research conducted on both invertebrate and vertebrate animal models. These contributions have progressively became more integrated and interactive, with current work emphasizing that locomotor control involves a seamless integration between central locomotor networks and peripheral feedback.

  18. Controlled regular locomotion of algae cell microrobots.

    PubMed

    Xie, Shuangxi; Jiao, Niandong; Tung, Steve; Liu, Lianqing

    2016-06-01

    Algae cells can be considered as microrobots from the perspective of engineering. These organisms not only have a strong reproductive ability but can also sense the environment, harvest energy from the surroundings, and swim very efficiently, accommodating all these functions in a body of size on the order of dozens of micrometers. An interesting topic with respect to random swimming motions of algae cells in a liquid is how to precisely control them as microrobots such that they swim according to manually set routes. This study developed an ingenious method to steer swimming cells based on the phototaxis. The method used a varying light signal to direct the motion of the cells. The swimming trajectory, speed, and force of algae cells were analyzed in detail. Then the algae cell could be controlled to swim back and forth, and traverse a crossroad as a microrobot obeying specific traffic rules. Furthermore, their motions along arbitrarily set trajectories such as zigzag, and triangle were realized successfully under optical control. Robotize algae cells can be used to precisely transport and deliver cargo such as drug particles in microfluidic chip for biomedical treatment and pharmacodynamic analysis. The study findings are expected to bring significant breakthrough in biological drives and new biomedical applications.

  19. Support afferentation in the posture and locomotion control system

    NASA Astrophysics Data System (ADS)

    Grigoriev, Anatoly; Tomilovskaya, Elena; Kozlovskaya, Inesa

    Mechanisms of support afferentation contribution in posture and locomotion control, which were uncertain up to now, became the point of intensive studies recently. This became possible since the space flights era started which created the conditions for simulated microgravity experiments under conditions of dry immersion and bedrest. The results of neurophysiological studies performed under the conditions of supportlessness have shown that decline or elimination of support loads is followed by deep and fast developing alterations in postural tonic system, including development of postural muscle atonia, changes of recruitment order of motoneurons innervating the shin muscles, spinal hyperreflexia development etc. (Kozlovskaya I.B. et al., 1987). It has been also shown that application of artificial support stimulation in the regimen of natural locomotion under these conditions decreases significantly or even eliminates the development of mentioned changes. The results of these studies laid down the basis for a new hypothesis on the trigger role of support afferentation in postural tonic system and its role in organization and control of postural synergies (Grigoriev A.I. et al., 2004). According to this hypothesis the muscle reception is considered to be the leading afferent input in the control of locomotion. However the data of recent studies pointed out strongly to the participation of support afferentation in definition of cognitive strategies and motor programs of locomotor movements (Chernikova L.A. et al., 2013) and, consequently, in the processes of their initiation (Gerasimenko Yu.P. et al., 2012). The cortical locomotor reflex composes apparently the basis of these processes. The receptive field of this reflex is located in the support zones of the soles and the central part is located in the posterior parietal areas (IPL) of brain cortex. The study is supported by RFBR grant N 13-04-12091 OFI-m.

  20. Circuits controlling vertebrate locomotion: moving in a new direction

    PubMed Central

    Goulding, Martyn

    2010-01-01

    Neurobiologists have long sought to understand how circuits in the nervous system are organized and generate the precise neural outputs that underlie particular behaviors. The motor circuits in the spinal cord that control locomotion and are commonly referred to as central pattern generator (CPG) networks, provide an experimentally tractable model system for investigating how moderately complex ensembles of neurons generate select motor behaviors. The advent of novel molecular genetic techniques coupled with recent advances in our knowledge of spinal cord development means that a comprehensive understanding of how the motor circuitry is organized and operates may now be within our grasp. PMID:19543221

  1. 49 CFR 236.566 - Locomotive of each train operating in train stop, train control or cab signal territory; equipped.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locomotive of each train operating in train stop... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Locomotives § 236.566 Locomotive of each train operating...

  2. Investigation of the impact of locomotive creep control on wear under changing contact conditions

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Liu, Sheng; Daniel, William(Bill) J. T.; Meehan, Paul A.

    2015-05-01

    This paper presents the locomotive traction controller performance with respect to the track wear under different operation conditions. In particular, an investigation into the dynamic response of a locomotive under changing wheel-rail friction conditions is performed with an aim to determine the effect of controller setting on track wear. Simulation using a full-scale longitudinal-vertical locomotive dynamic model shows that the appropriately designed creep threshold, controller, settings can effectively maintain a high tractive effort while avoiding excessive rail damage due to wear, especially during acceleration under low speed.

  3. Locomotion training of legged robots using hybrid machine learning techniques

    NASA Technical Reports Server (NTRS)

    Simon, William E.; Doerschuk, Peggy I.; Zhang, Wen-Ran; Li, Andrew L.

    1995-01-01

    In this study artificial neural networks and fuzzy logic are used to control the jumping behavior of a three-link uniped robot. The biped locomotion control problem is an increment of the uniped locomotion control. Study of legged locomotion dynamics indicates that a hierarchical controller is required to control the behavior of a legged robot. A structured control strategy is suggested which includes navigator, motion planner, biped coordinator and uniped controllers. A three-link uniped robot simulation is developed to be used as the plant. Neurocontrollers were trained both online and offline. In the case of on-line training, a reinforcement learning technique was used to train the neurocontroller to make the robot jump to a specified height. After several hundred iterations of training, the plant output achieved an accuracy of 7.4%. However, when jump distance and body angular momentum were also included in the control objectives, training time became impractically long. In the case of off-line training, a three-layered backpropagation (BP) network was first used with three inputs, three outputs and 15 to 40 hidden nodes. Pre-generated data were presented to the network with a learning rate as low as 0.003 in order to reach convergence. The low learning rate required for convergence resulted in a very slow training process which took weeks to learn 460 examples. After training, performance of the neurocontroller was rather poor. Consequently, the BP network was replaced by a Cerebeller Model Articulation Controller (CMAC) network. Subsequent experiments described in this document show that the CMAC network is more suitable to the solution of uniped locomotion control problems in terms of both learning efficiency and performance. A new approach is introduced in this report, viz., a self-organizing multiagent cerebeller model for fuzzy-neural control of uniped locomotion is suggested to improve training efficiency. This is currently being evaluated for a possible

  4. The hippocampus participates in the control of locomotion speed.

    PubMed

    López Ruiz, J R; Osuna Carrasco, L P; López Valenzuela, C L; Franco Rodríguez, N E; de la Torre Valdovinos, B; Jiménez Estrada, I; Dueñas Jiménez, J M; Dueñas Jiménez, S H

    2015-12-17

    The hippocampus role in sensory-motor integration remains unclear. In these experiments we study its function in the locomotor control. To establish the connection between the hippocampus and the locomotor system, electrical stimulation in the CA1 region was applied and EMG recordings were obtained. We also evaluated the hindlimbs and forelimbs kinematic patterns in rats with a penetrating injury (PI) in the hippocampus as well as in a cortex-injured group (CI), which served as control. After the PI, tamoxifen a selective estrogen receptor modulator (SERM) that has been described as a neuroprotector and antiinflammatory drug, or vehicle was administered. Electrical stimulation in the hippocampus produces muscle contractions in the contralateral triceps, when 6 Hz or 8 Hz pulse trains were applied. The penetrating injury in the hippocampus reduced the EMG amplitude after the electrical stimulation. At 7 DPI (days post-injury) we observed an increase in the strides speed in all four limbs of the non-treated group, decreasing the correlation percentage of the studied joints. After 15 DPI the strides speed in the non-treated returned to normal. These changes did not occur in the tamoxifen group nor in cortex-injured group. After 30 days, the nontreated group presented a reduction in the number of pyramidal cell layer neurons at the injury site, in comparison to the tam-treated group. The loss of neurons, may cause the interruption of the trisynaptic circuit and changes in the locomotion speed. Tamoxifen preserves the pyramidal neurons after the injury, probably resulting in the strides speed recovery.

  5. The hippocampus participates in the control of locomotion speed.

    PubMed

    López Ruiz, J R; Osuna Carrasco, L P; López Valenzuela, C L; Franco Rodríguez, N E; de la Torre Valdovinos, B; Jiménez Estrada, I; Dueñas Jiménez, J M; Dueñas Jiménez, S H

    2015-12-17

    The hippocampus role in sensory-motor integration remains unclear. In these experiments we study its function in the locomotor control. To establish the connection between the hippocampus and the locomotor system, electrical stimulation in the CA1 region was applied and EMG recordings were obtained. We also evaluated the hindlimbs and forelimbs kinematic patterns in rats with a penetrating injury (PI) in the hippocampus as well as in a cortex-injured group (CI), which served as control. After the PI, tamoxifen a selective estrogen receptor modulator (SERM) that has been described as a neuroprotector and antiinflammatory drug, or vehicle was administered. Electrical stimulation in the hippocampus produces muscle contractions in the contralateral triceps, when 6 Hz or 8 Hz pulse trains were applied. The penetrating injury in the hippocampus reduced the EMG amplitude after the electrical stimulation. At 7 DPI (days post-injury) we observed an increase in the strides speed in all four limbs of the non-treated group, decreasing the correlation percentage of the studied joints. After 15 DPI the strides speed in the non-treated returned to normal. These changes did not occur in the tamoxifen group nor in cortex-injured group. After 30 days, the nontreated group presented a reduction in the number of pyramidal cell layer neurons at the injury site, in comparison to the tam-treated group. The loss of neurons, may cause the interruption of the trisynaptic circuit and changes in the locomotion speed. Tamoxifen preserves the pyramidal neurons after the injury, probably resulting in the strides speed recovery. PMID:26597762

  6. A hybrid active/passive exhaust noise control system for locomotives

    NASA Astrophysics Data System (ADS)

    Remington, Paul J.; Knight, J. Scott; Hanna, Doug; Rowley, Craig

    2005-01-01

    A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal. .

  7. A hybrid active/passive exhaust noise control system for locomotives.

    PubMed

    Remington, Paul J; Knight, J Scott; Hanna, Doug; Rowley, Craig

    2005-01-01

    A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal.

  8. A hybrid active/passive exhaust noise control system for locomotives.

    PubMed

    Remington, Paul J; Knight, J Scott; Hanna, Doug; Rowley, Craig

    2005-01-01

    A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal. PMID:15704399

  9. Taking the next step: cortical contributions to the control of locomotion.

    PubMed

    Drew, Trevor; Marigold, Daniel S

    2015-08-01

    The planning and execution of both discrete voluntary movements and visually guided locomotion depends on the contribution of multiple cortical areas. In this review, we discuss recent experiments that address the contribution of the posterior parietal cortex (PPC) and the motor cortex to the control of locomotion. The results from these experiments show that the PPC contributes to the planning of locomotion by providing an estimate of the position of an animal with respect to objects in its path. In contrast, the motor cortex contributes primarily to the execution of gait modifications by modulating the activity of groups of synergistic muscles active at different times during the gait cycle. PMID:25643847

  10. Anticipatory control using substrate manipulation enables trajectory control of legged locomotion on heterogeneous granular media

    NASA Astrophysics Data System (ADS)

    Qian, Feifei; Goldman, Daniel

    2015-05-01

    Legged robots must traverse complex terrain consisting of particles of varying size, shape and texture. While much is known about how robots can effectively locomote on hard ground and increasingly on homogeneous granular media, principles of locomotion over heterogeneous granular substrates are relatively unexplored. To systematically discover how substrate heterogeneity affects ambulatory locomotion, we investigate how the presence of a single boulder (3D printed convex objects of different geometries) embedded in fine granular media affects the trajectory of a small (150 g) six legged robot. Using an automated system to collect thousands of locomotion trials, we observed that trajectories were straight before the interaction with the boulder, and scattered to different angles after the interaction depending on the leg-boulder contact positions. However, this dependence of scattering angle upon contact zone was relatively insensitive to boulder shape, orientation and roughness.1 Inspired by this insensitivity, here we develop an anticipatory control scheme which uses the scattering information in coordination with a tail induced substrate jamming. Our scheme allows the robot to "envision" outcomes of the interaction such that the robot can prevent trajectory deviation before the scattering occurs. We hypothesize that (particularly during rapid running or in the presence of noisy sensors) appropriate substrate manipulation can allow a robot to remain in a favorable locomotor configuration and avoid catastrophic interactions.

  11. A biologically inspired modular structure to control the sit-to-stand transfer of a biped robot.

    PubMed

    Andani, M Emadi; Bahrami, F; Maralani, P Jabedar

    2007-01-01

    In this study, a biologically inspired control structure to control the sit-to-stand (STS) transfer from a chair is developed and simulated. STS movement is consisted of two main phases. First phase of the movement is before leaving the seat (seat-off moment). In this phase seat reactions forces act on the body parts which are in contact with the seat. The second phase is after seat-off, where the only external forces acting on the body are ground reaction forces. A proper control algorithm of the STS transfer needs to consider switching between these two phases, which correspond to two different dynamical structures. The control structure developed and discussed in this work is based on the MOSAIC structure, proposed first by Wolpert and Kawato [1]. Original MOSAIC structure has a modular architecture which is based on multiple pairs of forward and inverse models of the dynamical system to be controlled, and each module is trained separately to learn one part of a given task. The number of effective modules is predetermined. We have developed a new method to train all modules simultaneously. This method is based on reinforcement and cooperative competitive learning, and the number of effective modules is determined automatically. In this study, the simulation was begun with four modules. Our results showed that only two modules out of four were selected to control the STS task. Responsibility of controlling the task was switched between the two modules around the seat-off moment.

  12. Robotic and mathematical modeling reveal general principles of appendage control and coordination in terrestrial locomotion

    NASA Astrophysics Data System (ADS)

    McInroe, Benjamin; Astley, Henry; Gong, Chaohui; Kawano, Sandy; Schiebel, Perrin; Choset, Howie; Goldman, Daniel I.

    The transition from aquatic to terrestrial life presented new challenges to early walkers, necessitating robust locomotion on complex, flowable substrates (e.g. sand, mud). Locomotion on such substrates is sensitive to limb morphology and kinematics. Although early walker morphologies are known, principles of appendage control remain elusive. To reveal limb control strategies that facilitated the invasion of land, we study both robotic and mathematical models. Robot experiments show that an active tail is critical for robust locomotion on granular media, enabling locomotion even with poor foot placement and limited ability to lift the body. Using a granular resistive force theory model, we construct connection vector fields that reveal how appendage coordination and terrain inclination impact locomotor performance. This model replicates experimental results, showing that moving limbs/tail in phase is most effective (suggesting a locomotor template). Varying limb trajectories and contacts, we find gaits for which tail use can be neutral or harmful, suggesting limb-tail coordination to be a nontrivial aspect of locomotion. Our findings show that robot experiments coupled with geometric mechanics provide a general framework to reveal principles of robust terrestrial locomotion. This work was supported by NSF PoLS.

  13. The role of vision in Parkinson's disease locomotion control: free walking task.

    PubMed

    Vitório, Rodrigo; Lirani-Silva, Ellen; Barbieri, Fabio Augusto; Raile, Vivian; Batistela, Rosangela Alice; Stella, Florindo; Gobbi, Lilian Teresa Bucken

    2012-02-01

    The current study addressed the role of visual information in the control of locomotion in people with Parkinson's disease. Twelve healthy individuals and 12 mild to moderate Parkinson's disease patients were examined while walking at self-selected velocities, under three visual sampling conditions: dynamic (normal lighting), static (static visual samples) and voluntary visual sampling. Subjects wore liquid crystal glasses for visual manipulation. Outcome measures included spatial-temporal parameters, braking and propulsive impulses, number of samples and total duration of voluntary visual samples. Interaction between groups and visual conditions was not observed for kinematic parameters or braking and propulsive impulses. There were no significant differences between groups for voluntary visual sampling variables. These findings suggest that the visual control of locomotion in Parkinson's disease patients was similar to that observed in controls. Furthermore, Parkinson's disease patients were not more dependent on visual information than healthy individuals for the locomotion control.

  14. Limb and Trunk Mechanisms for Balance Control during Locomotion in Quadrupeds

    PubMed Central

    Musienko, Pavel E.; Deliagina, Tatiana G.; Gerasimenko, Yury P.; Orlovsky, Grigori N.

    2014-01-01

    In quadrupeds, the most critical aspect of postural control during locomotion is lateral stability. However, neural mechanisms underlying lateral stability are poorly understood. Here, we studied lateral stability in decerebrate cats walking on a treadmill with their hindlimbs. Two destabilizing factors were used: a brief lateral push of the cat and a sustained lateral tilt of the treadmill. It was found that the push caused considerable trunk bending and twisting, as well as changes in the stepping pattern, but did not lead to falling. Due to postural reactions, locomotion with normal body configuration was restored in a few steps. It was also found that the decerebrate cat could keep balance during locomotion on the laterally tilted treadmill. This postural adaptation was based on the transformation of the symmetrical locomotor pattern into an asymmetrical one, with different functional lengths of the right and left limbs. Then, we analyzed limb and trunk neural mechanisms contributing to postural control during locomotion. It was found that one of the limb mechanisms operates in the transfer phase and secures a standard (relative to the trunk) position for limb landing. Two other limb mechanisms operate in the stance phase; they counteract distortions of the locomotor pattern by regulating the limb stiffness. The trunk configuration mechanism controls the body shape on the basis of sensory information coming from trunk afferents. We suggest that postural reactions generated by these four mechanisms are integrated, thus forming a response of the whole system to perturbation of balance during locomotion. PMID:24741060

  15. 49 CFR 236.566 - Locomotive of each train operating in train stop, train control or cab signal territory; equipped.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Locomotive of each train operating in train stop... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and... train stop, train control or cab signal territory; equipped. The locomotive from which brakes...

  16. 49 CFR 236.566 - Locomotive of each train operating in train stop, train control or cab signal territory; equipped.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Locomotive of each train operating in train stop... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and... train stop, train control or cab signal territory; equipped. The locomotive from which brakes...

  17. 49 CFR 236.566 - Locomotive of each train operating in train stop, train control or cab signal territory; equipped.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Locomotive of each train operating in train stop... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and... train stop, train control or cab signal territory; equipped. The locomotive from which brakes...

  18. 49 CFR 236.566 - Locomotive of each train operating in train stop, train control or cab signal territory; equipped.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Locomotive of each train operating in train stop... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and... train stop, train control or cab signal territory; equipped. The locomotive from which brakes...

  19. Contribution of different limb controllers to modulation of motor cortex neurons during locomotion.

    PubMed

    Zelenin, Pavel V; Deliagina, Tatiana G; Orlovsky, Grigori N; Karayannidou, Anastasia; Dasgupta, Namrata M; Sirota, Mikhail G; Beloozerova, Irina N

    2011-03-23

    During locomotion, neurons in motor cortex exhibit profound step-related frequency modulation. The source of this modulation is unclear. The aim of this study was to reveal the contribution of different limb controllers (locomotor mechanisms of individual limbs) to the periodic modulation of motor cortex neurons during locomotion. Experiments were conducted in chronically instrumented cats. The activity of single neurons was recorded during regular quadrupedal locomotion (control), as well as when only one pair of limbs (fore, hind, right, or left) was walking while another pair was standing. Comparison of the modulation patterns in these neurons (their discharge profile with respect to the step cycle) during control and different bipedal locomotor tasks revealed several groups of neurons that receive distinct combinations of inputs from different limb controllers. In the majority (73%) of neurons from the forelimb area of motor cortex, modulation during control was determined exclusively by forelimb controllers (right, left, or both), while in the minority (27%), hindlimb controllers also contributed. By contrast, only in 30% of neurons from the hindlimb area was modulation determined exclusively by hindlimb controllers (right or both), while in 70% of them, the controllers of forelimbs also contributed. We suggest that such organization of inputs allows the motor cortex to contribute to the right-left limbs' coordination within each of the girdles during locomotion, and that it also allows hindlimb neurons to participate in coordination of the movements of the hindlimbs with those of the forelimbs.

  20. Simplified and advanced modelling of traction control systems of heavy-haul locomotives

    NASA Astrophysics Data System (ADS)

    Spiryagin, Maksym; Wolfs, Peter; Szanto, Frank; Cole, Colin

    2015-05-01

    Improving tractive effort is a very complex task in locomotive design. It requires the development of not only mechanical systems but also power systems, traction machines and traction algorithms. At the initial design stage, traction algorithms can be verified by means of a simulation approach. A simple single wheelset simulation approach is not sufficient because all locomotive dynamics are not fully taken into consideration. Given that many traction control strategies exist, the best solution is to use more advanced approaches for such studies. This paper describes the modelling of a locomotive with a bogie traction control strategy based on a co-simulation approach in order to deliver more accurate results. The simplified and advanced modelling approaches of a locomotive electric power system are compared in this paper in order to answer a fundamental question. What level of modelling complexity is necessary for the investigation of the dynamic behaviours of a heavy-haul locomotive running under traction? The simulation results obtained provide some recommendations on simulation processes and the further implementation of advanced and simplified modelling approaches.

  1. Adaptation to a cortex controlled robot attached at the pelvis and engaged during locomotion in rats

    PubMed Central

    Song, Weiguo; Giszter, Simon F.

    2011-01-01

    Brain Machine Interfaces (BMIs) should ideally show robust adaptation of the BMI across different tasks and daily activities. Most BMIs have used over-practiced tasks. Little is known about BMIs in dynamic environments. How are mechanically body-coupled BMIs integrated into ongoing rhythmic dynamics, e.g., in locomotion? To examine this we designed a novel BMI using neural discharge in the hindlimb/trunk motor cortex in rats during locomotion to control a robot attached at the pelvis. We tested neural adaptation when rats experienced (a) control locomotion, (b) ‘simple elastic load’ (a robot load on locomotion without any BMI neural control) and (c) ‘BMI with elastic load’ (in which the robot loaded locomotion and a BMI neural control could counter this load). Rats significantly offset applied loads with the BMI while preserving more normal pelvic height compared to load alone. Adaptation occurred over about 100–200 step cycles in a trial. Firing rates increased in both the loaded conditions compared to baseline. Mean phases of cells’ discharge in the step cycle shifted significantly between BMI and the simple load condition. Over time more BMI cells became positively correlated with the external force and modulated more deeply, and neurons’ network correlations on a 100ms timescale increased. Loading alone showed none of these effects. The BMI neural changes of rate and force correlations persisted or increased over repeated trials. Our results show that rats have the capacity to use motor adaptation and motor learning to fairly rapidly engage hindlimb/trunk coupled BMIs in their locomotion. PMID:21414932

  2. Locomotion and eye behaviour under controlled environment in individuals with Alzheimer's disease.

    PubMed

    Suzuki, Tatsuto; Yong, Keir; Yang, Biao; Carton, Amelia; McCarthy, Ian; Papadosifos, Nikolaos; Boampong, Derrick; Holloway, Catherine; Tyler, Nick; Crutch, Sebastian

    2015-01-01

    This study aimed to examine simple locomotion and eye behaviour of individuals with Posterior Cortical Atrophy (PCA) and typical Alzheimer's disease (tAD) within a simulated real-world environment. Posterior cortical atrophy (PCA) is a neurodegenerative condition characterised by parietal, occipital and occipito-temporal tissue loss and progressive impairment of higher-order visual function in contrast to relatively spared memory and language. Targeted types of locomotion were walking in a series of corridors, up or down stairs, and across an open room with or without the presence of an obstacle. Eye tracking measures and inertial moment units (IMU) were used in this experiment, and resultant acceleration of left foot and fixation duration were extracted. Findings from three participants are presented as a case series: one control, one PCA and one tAD patient. The averaged resultant acceleration of PCA patient was the slowest in all types of locomotion, especially in stairs. The averaged resultant accelerations of PCA and tAD participants were slower than the control participant. The PCA participant had longer mean fixation durations than the tAD and control participants, however, mean fixation duration was similar between tAD and control participants. Results may help characterise locomotion and eye behaviour in PCA and tAD and may suggest ways to support effective diagnosis and assessment of disease progression. PMID:26737804

  3. The perceptual control of goal-directed locomotion: a common control architecture for interception and navigation?

    PubMed

    Chardenon, A; Montagne, G; Laurent, M; Bootsma, R J

    2004-09-01

    Intercepting a moving object while locomoting is a highly complex and demanding ability. Notwithstanding the identification of several informational candidates, the role of perceptual variables in the control process underlying such skills remains an open question. In this study we used a virtual reality set-up for studying locomotor interception of a moving ball. The subject had to walk along a straight path and could freely modify forward velocity, if necessary, in order to intercept-with the head-a ball moving along a straight path that led it to cross the agent's displacement axis. In a series of experiments we manipulated a local (ball size) and a global (focus of expansion) component of the visual flow but also the egocentric orientation of the ball. The experimental observations are well captured by a dynamic model linking the locomotor acceleration to properties of both global flow and egocentric direction. More precisely the changes in locomotor velocity depend on a linear combination of the change in bearing angle and the change in egocentric orientation, allowing the emergence of adaptive behavior under a variety of circumstances. We conclude that the mechanisms underlying the control of different goal-directed locomotion tasks (i.e. steering and interceptive tasks) could share a common architecture. PMID:15042262

  4. 49 CFR 1242.67 - Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 9 2014-10-01 2014-10-01 false Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive power; operating switches...; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive...

  5. 49 CFR 1242.67 - Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 9 2012-10-01 2012-10-01 false Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive power; operating switches...; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive...

  6. 49 CFR 1242.67 - Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 9 2011-10-01 2011-10-01 false Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive power; operating switches...; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive...

  7. 49 CFR 1242.67 - Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 9 2013-10-01 2013-10-01 false Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive power; operating switches...; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive...

  8. Similar Motor Cortical Control Mechanisms for Precise Limb Control during Reaching and Locomotion

    PubMed Central

    Yakovenko, Sergiy

    2015-01-01

    Throughout the course of evolution there has been a parallel development of the complexity and flexibility of the nervous system and the skeletomuscular system that it controls. This development is particularly evident for the cerebral cortical areas and the transformation of the use of the upper limbs from a purely locomotor function to one including, or restricted to, reaching and grasping. This study addresses the issue of whether the control of reaching has involved the development of new cortical circuits or whether the same neurons are used to control both locomotion and reaching. We recorded the activity of pyramidal tract neurons in the motor cortex of the cat both during voluntary gait modifications and during reaching. All cells showed generally similar patterns of activity in both tasks. More specifically, we showed that, in many cases, cells maintained a constant temporal relationship to the activity of synergistic muscle groups in each task. In addition, in some cells the relationship between the intensity of the cell discharge activity and the magnitude of the EMG activity was equally constant during gait modifications and reaching. As such, the results are compatible with the hypothesis that the corticospinal circuits used to control reaching evolved from those used to precisely modify gait. SIGNIFICANCE STATEMENT In an article in 1989, Georgopoulos and Grillner (1989) proposed that the corticospinal control mechanisms used for reaching movements in primates may have evolved from those used to control precise modifications of gait during quadrupedal locomotion. In this article, we provide a test of this hypothesis by recording the activity of individual motor cortical cells during both behaviors. Our results are compatible with the hypothesis in that they demonstrate that individual cortical neurons exhibit similar qualitative and quantitative patterns during each behavior. Beyond a general similarity of activity patterns, we show that some cortical

  9. FPGA implementation of a configurable neuromorphic CPG-based locomotion controller.

    PubMed

    Barron-Zambrano, Jose Hugo; Torres-Huitzil, Cesar

    2013-09-01

    Neuromorphic engineering is a discipline devoted to the design and development of computational hardware that mimics the characteristics and capabilities of neuro-biological systems. In recent years, neuromorphic hardware systems have been implemented using a hybrid approach incorporating digital hardware so as to provide flexibility and scalability at the cost of power efficiency and some biological realism. This paper proposes an FPGA-based neuromorphic-like embedded system on a chip to generate locomotion patterns of periodic rhythmic movements inspired by Central Pattern Generators (CPGs). The proposed implementation follows a top-down approach where modularity and hierarchy are two desirable features. The locomotion controller is based on CPG models to produce rhythmic locomotion patterns or gaits for legged robots such as quadrupeds and hexapods. The architecture is configurable and scalable for robots with either different morphologies or different degrees of freedom (DOFs). Experiments performed on a real robot are presented and discussed. The obtained results demonstrate that the CPG-based controller provides the necessary flexibility to generate different rhythmic patterns at run-time suitable for adaptable locomotion.

  10. Motoneuronal and muscle synergies involved in cat hindlimb control during fictive and real locomotion: a comparison study.

    PubMed

    Markin, Sergey N; Lemay, Michel A; Prilutsky, Boris I; Rybak, Ilya A

    2012-04-01

    We compared the activity profiles and synergies of spinal motoneurons recorded during fictive locomotion evoked in immobilized decerebrate cat preparations by midbrain stimulation to the activity profiles and synergies of the corresponding hindlimb muscles obtained during forward level walking in cats. The fictive locomotion data were collected in the Spinal Cord Research Centre, University of Manitoba, and provided by Dr. David McCrea; the real locomotion data were obtained in the laboratories of M. A. Lemay and B. I. Prilutsky. Scatterplot representation and minimum spanning tree clustering algorithm were used to identify the possible motoneuronal and muscle synergies operating during both fictive and real locomotion. We found a close similarity between the activity profiles and synergies of motoneurons innervating one-joint muscles during fictive locomotion and the profiles and synergies of the corresponding muscles during real locomotion. However, the activity patterns of proximal nerves controlling two-joint muscles, such as posterior biceps and semitendinosus (PBSt) and rectus femoris (RF), were not uniform in fictive locomotion preparations and differed from the activity profiles of the corresponding two-joint muscles recorded during forward level walking. Moreover, the activity profiles of these nerves and the corresponding muscles were unique and could not be included in the synergies identified in fictive and real locomotion. We suggest that afferent feedback is involved in the regulation of locomotion via motoneuronal synergies controlled by the spinal central pattern generator (CPG) but may also directly affect the activity of motoneuronal pools serving two-joint muscles (e.g., PBSt and RF). These findings provide important insights into the organization of the spinal CPG in mammals, the motoneuronal and muscle synergies engaged during locomotion, and their afferent control.

  11. Robustness of a distributed neural network controller for locomotion in a hexapod robot

    NASA Technical Reports Server (NTRS)

    Chiel, Hillel J.; Beer, Randall D.; Quinn, Roger D.; Espenschied, Kenneth S.

    1992-01-01

    A distributed neural-network controller for locomotion, based on insect neurobiology, has been used to control a hexapod robot. How robust is this controller? Disabling any single sensor, effector, or central component did not prevent the robot from walking. Furthermore, statically stable gaits could be established using either sensor input or central connections. Thus, a complex interplay between central neural elements and sensor inputs is responsible for the robustness of the controller and its ability to generate a continuous range of gaits. These results suggest that biologically inspired neural-network controllers may be a robust method for robotic control.

  12. Aerial and terrestrial locomotion control of lift assisted insect biobots.

    PubMed

    Bozkurt, Alper; Lal, Amit; Gilmour, Robert

    2009-01-01

    This paper presents results on remote control navigation of moths implanted with neuromuscular probes. We have previously demonstrated that the technique of metamorphosis based surgical insertions enables the concept of "insect-based" centimeter scale biobots. Here, we demonstrate for the first time, the control of gait with a radio controlled, balloon-suspended, electrode-instrumented Manduca sexta by altering the direction of turn through applied neuromuscular pulses. We also present sustained flight control in Manduca sexta with demonstration of take-off, controlled yaw, and controlled landing. The assist of the helium balloon for lifting payloads allows for a wide-range of application space where insect biobots can be deployed.

  13. 49 CFR 229.15 - Remote control locomotives.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... respond only to the operator control units (OCUs) assigned to that receiver. (2) If one or more OCUs are... functions shall remain active. The remote control system shall be designed so that if the signal from the OCU to the RCL is interrupted for a set period not to exceed five seconds, the remote control...

  14. 49 CFR 229.15 - Remote control locomotives.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... respond only to the operator control units (OCUs) assigned to that receiver. (2) If one or more OCUs are... functions shall remain active. The remote control system shall be designed so that if the signal from the OCU to the RCL is interrupted for a set period not to exceed five seconds, the remote control...

  15. Aerial and terrestrial locomotion control of lift assisted insect biobots.

    PubMed

    Bozkurt, Alper; Lal, Amit; Gilmour, Robert

    2009-01-01

    This paper presents results on remote control navigation of moths implanted with neuromuscular probes. We have previously demonstrated that the technique of metamorphosis based surgical insertions enables the concept of "insect-based" centimeter scale biobots. Here, we demonstrate for the first time, the control of gait with a radio controlled, balloon-suspended, electrode-instrumented Manduca sexta by altering the direction of turn through applied neuromuscular pulses. We also present sustained flight control in Manduca sexta with demonstration of take-off, controlled yaw, and controlled landing. The assist of the helium balloon for lifting payloads allows for a wide-range of application space where insect biobots can be deployed. PMID:19964777

  16. Full-Body Gaze Control Mechanisms Elicited During Locomotion: Effects Of VOR Adaptation

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Houser, J.; Peters, B.; Miller, C.; Richards, J.; Marshburn, A.; Brady, R.; Cohen, H.; Bloomberg, J. J.

    2004-01-01

    Control of locomotion requires precise interaction between several sensorimotor subsystems. During locomotion the performer must satisfy two performance criteria: maintain stable forward translation and to stabilize gaze (McDonald, et al., 1997). Precise coordination demands integration of multiple sensorimotor subsystems for fulfilling both criteria. In order to test the general hypothesis that the whole body can serve as an integrated gaze stabilization system, we have previously investigated how the multiple, interdependent full-body sensorimotor subsystems respond to changes in gaze stabilization task constraints during locomotion (Mulavara and Bloomberg, 2003). The results suggest that the full body contributes to gaze stabilization during locomotion, and that its different functional elements respond to changes in visual task constraints. The goal of this study was to determine how the multiple, interdependent, full-body sensorimotor subsystems aiding gaze stabilization during locomotion are functionally coordinated after the vestibulo-ocular reflex (VOR) gain has been altered. We investigated the potential of adaptive remodeling of the full-body gaze control system following exposure to visual-vestibular conflict known to adaptively reduce the VOR. Subjects (n=14) walked (6.4 km/h) on the treadmill before and after they were exposed to 0.5X manifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. In this study we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. Results indicate that, following exposure to the 0.5X minifying lenses, there was a significant increase in the duration of stance and stride times, alteration in the amplitude of head movement with respect to space and a significant increase in

  17. Differential thermosensor control of thermoregulatory grooming, locomotion, and relaxed postural extension.

    PubMed

    Roberts, W W

    1988-01-01

    The rat displays three behaviors when surface and/or deep body temperatures rise above their normal levels: grooming, which spreads saliva over the fur to cool by evaporation; locomotion, which results in escape to a cooler environment; and relaxed postural extension, which reduces heat production by muscle activity and increases heat dissipation by increasing body surface area. Each of these behaviors can be elicited in pure or nearly pure form by localized warming of thermosensors in different brain areas. In addition, localized warming of superficial and deep peripheral thermosensors elicits grooming and locomotion, but little or no postural extension. Because of the marked differences in the behaviors induced by localized warming of different sets of thermosensors, it is concluded that sensors are linked to the effector mechanisms for these behaviors by relatively separate and independent pathways rather than a master controller through which sensory signals are integrated to produce a unitary error signal that drives all responses. When more generalized hyperthermia in natural heat stress situations affects mainly superficial thermosensors, as during the initial phase of exposure to ambient heat, grooming and locomotion are predominant and extension is absent or weak. When deep hyperthermia is predominant and superficial hyperthermia is relatively weak, as occurs after escape from ambient heat to thermoneutrality or during and following exercise in a thermally neutral environment, the resulting predominant activation of deep sensors elicits marked postural extension, but little or no grooming or locomotion. When both superficial and deep sensors are hyperthermic, as in the later stages of exposure to ambient heat, all three behaviors are present, although locomotion is somewhat greater and grooming is somewhat less than during predominantly superficial hyperthermia, and extension is somewhat less than during predominantly deep hyperthermia. As a consequence

  18. Similar Motor Cortical Control Mechanisms for Precise Limb Control during Reaching and Locomotion.

    PubMed

    Yakovenko, Sergiy; Drew, Trevor

    2015-10-28

    Throughout the course of evolution there has been a parallel development of the complexity and flexibility of the nervous system and the skeletomuscular system that it controls. This development is particularly evident for the cerebral cortical areas and the transformation of the use of the upper limbs from a purely locomotor function to one including, or restricted to, reaching and grasping. This study addresses the issue of whether the control of reaching has involved the development of new cortical circuits or whether the same neurons are used to control both locomotion and reaching. We recorded the activity of pyramidal tract neurons in the motor cortex of the cat both during voluntary gait modifications and during reaching. All cells showed generally similar patterns of activity in both tasks. More specifically, we showed that, in many cases, cells maintained a constant temporal relationship to the activity of synergistic muscle groups in each task. In addition, in some cells the relationship between the intensity of the cell discharge activity and the magnitude of the EMG activity was equally constant during gait modifications and reaching. As such, the results are compatible with the hypothesis that the corticospinal circuits used to control reaching evolved from those used to precisely modify gait.

  19. Control of Vertebrate Respiration and Locomotion: A Brief Account.

    ERIC Educational Resources Information Center

    Feldman, Jack L.; Grillner, Sten

    1983-01-01

    Areas considered in this discussion include: activation/modulation of movement; control of motoneuronal discharge by excitation/inhibition; neural generation of movement synergies (considering interaction of central/peripheral elements, phasic gating of reflex effects, and neuronal organization of central pattern generators); protean nature of…

  20. Initial experiments in thrusterless locomotion control of a free-flying robot

    NASA Technical Reports Server (NTRS)

    Jasper, W. J.; Cannon, R. H., Jr.

    1990-01-01

    A two-arm free-flying robot has been constructed to study thrusterless locomotion in space. This is accomplished by pushing off or landing on a large structure in a coordinated two-arm maneuver. A new control method, called system momentum control, allows the robot to follow desired momentum trajectories and thus leap or crawl from one structure to another. The robot floats on an air-cushion, simulating in two dimensions the drag-free zero-g environment of space. The control paradigm has been verified experimentally by commanding the robot to push off a bar with both arms, rotate 180 degrees, and catch itself on another bar.

  1. Numerical Analysis of Energy-Efficient Walking Gait with Flexed Knee for a Four-DOF Planar Biped Model

    NASA Astrophysics Data System (ADS)

    Peng, Chunye; Ono, Kyosuke

    In this paper we solve the energy-efficient periodic gaits for a biped mechanism walking in the sagittal plane. The biped locomotion mechanism that has thighs, shanks and small feet is modeled as a four-degree-of-freedom (DOF) link system composed of a two-DOF stance leg and a two-DOF swing leg that are connected directly at the hip joint. Using the optimal trajectory planning method based on function approximation, we obtained minimum square input torque trajectories of cyclic walking gaits with flexed knee stance leg for both full-actuated and under-actuated models that are similar to those of the human walking. Also, the validity of this gait generating method is confirmed by forward dynamic simulation.

  2. Controlled locomotion of robots driven by a vibrating surface

    NASA Astrophysics Data System (ADS)

    Umbanhowar, Paul; Lynch, Kevin M.

    Robots typically derive their powers of movement from onboard actuators and power sources, but other scenarios are possible where the external environment provides part or all of the necessary forcing and control. I will discuss details of a system where the ``robots'' are just planar solid objects and the requisite driving forces originate from frictional sliding-interactions with a periodically oscillated and nominally horizontal surface. For the robots to move, the temporal symmetry of the frictional forces must be broken, which is achieved here by modulating the normal force using vertical acceleration of the surface. Independent of the initial conditions and vibration waveform, a sliding locomotor reaches a unique velocity limit cycle at a given position. Its resulting motion can be described in terms of velocity fields which specify the robot's cycle-averaged velocity as a function of position. Velocity fields with non-zero spatial divergence can be generated by combining translational and rotational surface motions; this allows the simultaneous and open-loop collection, dispersal, and transport of multiple robots. Fields and field sequences can simultaneously move multiple robots between arbitrary positions and, potentially, along arbitrary trajectories. Supported by NSF CMMI #0700537.

  3. 49 CFR 1242.67 - Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive power; operating switches signals, retarders, and humps; and servicing locomotives (accounts XX-52-64, XX-52-65, XX-52-66, XX-52-59, XX-52-67, XX-52-68 and...

  4. Electroencephalography(EEG)-based instinctive brain-control of a quadruped locomotion robot.

    PubMed

    Jia, Wenchuan; Huang, Dandan; Luo, Xin; Pu, Huayan; Chen, Xuedong; Bai, Ou

    2012-01-01

    Artificial intelligence and bionic control have been applied in electroencephalography (EEG)-based robot system, to execute complex brain-control task. Nevertheless, due to technical limitations of the EEG decoding, the brain-computer interface (BCI) protocol is often complex, and the mapping between the EEG signal and the practical instructions lack of logic associated, which restrict the user's actual use. This paper presents a strategy that can be used to control a quadruped locomotion robot by user's instinctive action, based on five kinds of movement related neurophysiological signal. In actual use, the user drives or imagines the limbs/wrists action to generate EEG signal to adjust the real movement of the robot according to his/her own motor reflex of the robot locomotion. This method is easy for real use, as the user generates the brain-control signal through the instinctive reaction. By adopting the behavioral control of learning and evolution based on the proposed strategy, complex movement task may be realized by instinctive brain-control.

  5. Walking biped humanoids that perform manual labour.

    PubMed

    Hirukawa, Hirohisa

    2007-01-15

    The Humanoid Robotics Project of the Ministry of Economy, Trade and Industry of Japan realized that biped humanoid robots can perform manual labour. The project developed humanoid robot platforms, consisting of humanoid robot hardware and a package of fundamental software, and explored applications of humanoid robots on them. The applications include maintenance tasks of industrial plants, teleoperation of industrial vehicles, cooperative tasks with a human, guarding the home and office and the care of patients in beds.

  6. Neural control and adaptive neural forward models for insect-like, energy-efficient, and adaptable locomotion of walking machines

    PubMed Central

    Manoonpong, Poramate; Parlitz, Ulrich; Wörgötter, Florentin

    2013-01-01

    Living creatures, like walking animals, have found fascinating solutions for the problem of locomotion control. Their movements show the impression of elegance including versatile, energy-efficient, and adaptable locomotion. During the last few decades, roboticists have tried to imitate such natural properties with artificial legged locomotion systems by using different approaches including machine learning algorithms, classical engineering control techniques, and biologically-inspired control mechanisms. However, their levels of performance are still far from the natural ones. By contrast, animal locomotion mechanisms seem to largely depend not only on central mechanisms (central pattern generators, CPGs) and sensory feedback (afferent-based control) but also on internal forward models (efference copies). They are used to a different degree in different animals. Generally, CPGs organize basic rhythmic motions which are shaped by sensory feedback while internal models are used for sensory prediction and state estimations. According to this concept, we present here adaptive neural locomotion control consisting of a CPG mechanism with neuromodulation and local leg control mechanisms based on sensory feedback and adaptive neural forward models with efference copies. This neural closed-loop controller enables a walking machine to perform a multitude of different walking patterns including insect-like leg movements and gaits as well as energy-efficient locomotion. In addition, the forward models allow the machine to autonomously adapt its locomotion to deal with a change of terrain, losing of ground contact during stance phase, stepping on or hitting an obstacle during swing phase, leg damage, and even to promote cockroach-like climbing behavior. Thus, the results presented here show that the employed embodied neural closed-loop system can be a powerful way for developing robust and adaptable machines. PMID:23408775

  7. Neural control and adaptive neural forward models for insect-like, energy-efficient, and adaptable locomotion of walking machines.

    PubMed

    Manoonpong, Poramate; Parlitz, Ulrich; Wörgötter, Florentin

    2013-01-01

    Living creatures, like walking animals, have found fascinating solutions for the problem of locomotion control. Their movements show the impression of elegance including versatile, energy-efficient, and adaptable locomotion. During the last few decades, roboticists have tried to imitate such natural properties with artificial legged locomotion systems by using different approaches including machine learning algorithms, classical engineering control techniques, and biologically-inspired control mechanisms. However, their levels of performance are still far from the natural ones. By contrast, animal locomotion mechanisms seem to largely depend not only on central mechanisms (central pattern generators, CPGs) and sensory feedback (afferent-based control) but also on internal forward models (efference copies). They are used to a different degree in different animals. Generally, CPGs organize basic rhythmic motions which are shaped by sensory feedback while internal models are used for sensory prediction and state estimations. According to this concept, we present here adaptive neural locomotion control consisting of a CPG mechanism with neuromodulation and local leg control mechanisms based on sensory feedback and adaptive neural forward models with efference copies. This neural closed-loop controller enables a walking machine to perform a multitude of different walking patterns including insect-like leg movements and gaits as well as energy-efficient locomotion. In addition, the forward models allow the machine to autonomously adapt its locomotion to deal with a change of terrain, losing of ground contact during stance phase, stepping on or hitting an obstacle during swing phase, leg damage, and even to promote cockroach-like climbing behavior. Thus, the results presented here show that the employed embodied neural closed-loop system can be a powerful way for developing robust and adaptable machines. PMID:23408775

  8. Experiments in thrusterless robot locomotion control for space applications. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Jasper, Warren Joseph

    1990-01-01

    While performing complex assembly tasks or moving about in space, a space robot should minimize the amount of propellant consumed. A study is presented of space robot locomotion and orientation without the use of thrusters. The goal was to design a robot control paradigm that will perform thrusterless locomotion between two points on a structure, and to implement this paradigm on an experimental robot. A two arm free flying robot was constructed which floats on a cushion of air to simulate in 2-D the drag free, zero-g environment of space. The robot can impart momentum to itself by pushing off from an external structure in a coordinated two arm maneuver, and can then reorient itself by activating a momentum wheel. The controller design consists of two parts: a high level strategic controller and a low level dynamic controller. The control paradigm was verified experimentally by commanding the robot to push off from a structure with both arms, rotate 180 degs while translating freely, and then to catch itself on another structure. This method, based on the computed torque, provides a linear feedback law in momentum and its derivatives for a system of rigid bodies.

  9. Vestibular-somatosensory convergence in head movement control during locomotion after long-duration space flight.

    PubMed

    Mulavara, A P; Ruttley, T; Cohen, H S; Peters, B T; Miller, C; Brady, R; Merkle, L; Bloomberg, J J

    2012-01-01

    Space flight causes astronauts to be exposed to adaptation in both the vestibular and body load-sensing somatosensory systems. The goal of these studies was to examine the contributions of vestibular and body load-sensing somatosensory influences on vestibular mediated head movement control during locomotion after long-duration space flight. Subjects walked on a motor driven treadmill while performing a gaze stabilization task. Data were collected from three independent subject groups that included bilateral labyrinthine deficient (LD) patients, normal subjects before and after 30 minutes of 40% bodyweight unloaded treadmill walking, and astronauts before and after long-duration space flight. Motion data from the head and trunk segments were used to calculate the amplitude of angular head pitch and trunk vertical translation movement while subjects performed a gaze stabilization task, to estimate the contributions of vestibular reflexive mechanisms in head pitch movements. Exposure to unloaded locomotion caused a significant increase in head pitch movements in normal subjects, whereas the head pitch movements of LD patients were significantly decreased. This is the first evidence of adaptation of vestibular mediated head movement responses to unloaded treadmill walking. Astronaut subjects showed a heterogeneous response of both increases and decreases in the amplitude of head pitch movement. We infer that body load-sensing somatosensory input centrally modulates vestibular input and can adaptively modify vestibularly mediated head-movement control during locomotion. Thus, space flight may cause central adaptation of the converging vestibular and body load-sensing somatosensory systems leading to alterations in head movement control.

  10. The role of reafference in recalibration of limb movement control and locomotion.

    PubMed

    Lackner, J R; DiZio, P

    1997-01-01

    The reafference model has frequently been used to explain spatial constancy during eye and head movements. We have found that its basic concepts also form part of the information processing necessary for the control and recalibration of reaching movements. Reaching was studied in a novel force environment--a rotating room that creates centripetal forces of the type that could someday substitute for gravity in space flight, and Coriolis forces which are side effects of rotation. We found that inertial, noncontacting Coriolis forces deviate the path and endpoint of reaching movements, a finding that shows the inadequacy of equilibrium position models of movement control. Repeated movements in the rotating room quickly lead to normal movement patterns and to a failure to perceive the perturbing forces. The first movements made after rotation stops, without Coriolis forces present, show mirror-image deviations and evoke perception of a perturbing force even though none is present. These patterns of sensorimotor control and adaptation can largely be explained on the basis of comparisons of efference copy, reafferent muscle spindle, and cutaneous mechanoreceptor signals. We also describe experiments on human locomotion using an apparatus similar to that which Mittelstaedt used to study the optomotor response of the Eristalis fly. These results show that the reafference principle relates as well to the perception of the forces acting on and exerted by the body during voluntary locomotion. PMID:9218244

  11. Self-Organizing Map With Time-Varying Structure to Plan and Control Artificial Locomotion.

    PubMed

    Araujo, Aluizio F R; Santana, Orivaldo V

    2015-08-01

    This paper presents an algorithm, self-organizing map-state trajectory generator (SOM-STG), to plan and control legged robot locomotion. The SOM-STG is based on an SOM with a time-varying structure characterized by constructing autonomously close-state trajectories from an arbitrary number of robot postures. Each trajectory represents a cyclical movement of the limbs of an animal. The SOM-STG was designed to possess important features of a central pattern generator, such as rhythmic pattern generation, synchronization between limbs, and swapping between gaits following a single command. The acquisition of data for SOM-STG is based on learning by demonstration in which the data are obtained from different demonstrator agents. The SOM-STG can construct one or more gaits for a simulated robot with six legs, can control the robot with any of the gaits learned, and can smoothly swap gaits. In addition, SOM-STG can learn to construct a state trajectory form observing an animal in locomotion. In this paper, a dog is the demonstrator agent.

  12. A dynamical systems analysis of afferent control in a neuromechanical model of locomotion: I. Rhythm generation

    NASA Astrophysics Data System (ADS)

    Spardy, Lucy E.; Markin, Sergey N.; Shevtsova, Natalia A.; Prilutsky, Boris I.; Rybak, Ilya A.; Rubin, Jonathan E.

    2011-10-01

    Locomotion in mammals is controlled by a spinal central pattern generator (CPG) coupled to a biomechanical limb system, with afferent feedback to the spinal circuits and CPG closing the control loop. We have considered a simplified model of this system, in which the CPG establishes a rhythm when a supra-spinal activating drive is present and afferent signals from a single-joint limb feed back to affect CPG operation. Using dynamical system methods, in a series of two papers we analyze the mechanisms by which this model produces oscillations, and the characteristics of these oscillations, in the closed- and open-loop regimes. In this first paper, we analyze the phase transition mechanisms operating within the CPG and use the results to explain how afferent feedback allows oscillations to occur at a wider range of drive values to the CPG than the range over which oscillations occur in the CPG without feedback, and then to comment on why stronger feedback leads to faster oscillations. Linking these transitions to structures in the phase plane associated with the limb segment clarifies how increased weights of afferent feedback to the CPG can restore locomotion after removal of supra-spinal drive to simulate spinal cord injury.

  13. Rate-dependent control strategies stabilize limb forces during human locomotion

    PubMed Central

    Yen, Jasper T.; Chang, Young-Hui

    2010-01-01

    A spring-mass model accurately predicts centre of mass dynamics for hopping and running animals and is pervasive throughout experimental and theoretical studies of legged locomotion. Given the neuromechanical complexity of the leg, it remains unclear how joint dynamics are selected to achieve such simple centre of mass movements consistently from step to step and across changing conditions. Human hopping is a tractable experimental model to study how net muscle moments, or joint torques, are coordinated for spring-mass dynamics, which include stable, or invariant, vertical ground forces. Subjects were equally able to stabilize vertical forces at all hopping frequencies (2.2, 2.8, 3.2 Hz) by selecting force-equivalent joint torque combinations. Using a hybrid-uncontrolled manifold permutation analysis, however, we discovered that force stabilization relies less on interjoint coordination at greater hopping frequencies and more on selection of appropriate ankle joint torques. We conclude that control strategies for selecting the joint torques that stabilize forces generated on the ground are adjusted to the rate of movement. Moreover, this indicates that legged locomotion may involve the differential regulation of several redundant motor control strategies that are accessed as needed to match changing environmental conditions. PMID:19828502

  14. Unsteady locomotion: integrating muscle function with whole body dynamics and neuromuscular control.

    PubMed

    Biewener, Andrew A; Daley, Monica A

    2007-09-01

    By integrating studies of muscle function with analysis of whole body and limb dynamics, broader appreciation of neuromuscular function can be achieved. Ultimately, such studies need to address non-steady locomotor behaviors relevant to animals in their natural environments. When animals move slowly they likely rely on voluntary coordination of movement involving higher brain centers. However, when moving fast, their movements depend more strongly on responses controlled at more local levels. Our focus here is on control of fast-running locomotion. A key observation emerging from studies of steady level locomotion is that simple spring-mass dynamics, which help to economize energy expenditure, also apply to stabilization of unsteady running. Spring-mass dynamics apply to conditions that involve lateral impulsive perturbations, sudden changes in terrain height, and sudden changes in substrate stiffness or damping. Experimental investigation of unsteady locomotion is challenging, however, due to the variability inherent in such behaviors. Another emerging principle is that initial conditions associated with postural changes following a perturbation define different context-dependent stabilization responses. Distinct stabilization modes following a perturbation likely result from proximo-distal differences in limb muscle architecture, function and control strategy. Proximal muscles may be less sensitive to sudden perturbations and appear to operate, in such circumstances, under feed-forward control. In contrast, multiarticular distal muscles operate, via their tendons, to distribute energy among limb joints in a manner that also depends on the initial conditions of limb contact with the ground. Intrinsic properties of these distal muscle-tendon elements, in combination with limb and body dynamics, appear to provide rapid initial stabilizing mechanisms that are often consistent with spring-mass dynamics. These intrinsic mechanisms likely help to simplify the neural

  15. Unsteady locomotion: integrating muscle function with whole body dynamics and neuromuscular control

    PubMed Central

    Biewener, Andrew A.; Daley, Monica A.

    2009-01-01

    Summary By integrating studies of muscle function with analysis of whole body and limb dynamics, broader appreciation of neuromuscular function can be achieved. Ultimately, such studies need to address non-steady locomotor behaviors relevant to animals in their natural environments. When animals move slowly they likely rely on voluntary coordination of movement involving higher brain centers. However, when moving fast, their movements depend more strongly on responses controlled at more local levels. Our focus here is on control of fast-running locomotion. A key observation emerging from studies of steady level locomotion is that simple spring-mass dynamics, which help to economize energy expenditure, also apply to stabilization of unsteady running. Spring-mass dynamics apply to conditions that involve lateral impulsive perturbations, sudden changes in terrain height, and sudden changes in substrate stiffness or damping. Experimental investigation of unsteady locomotion is challenging, however, due to the variability inherent in such behaviors. Another emerging principle is that initial conditions associated with postural changes following a perturbation define different context-dependent stabilization responses. Distinct stabilization modes following a perturbation likely result from proximo-distal differences in limb muscle architecture, function and control strategy. Proximal muscles may be less sensitive to sudden perturbations and appear to operate, in such circumstances, under feed-forward control. In contrast, multiarticular distal muscles operate, via their tendons, to distribute energy among limb joints in a manner that also depends on the initial conditions of limb contact with the ground. Intrinsic properties of these distal muscle–tendon elements, in combination with limb and body dynamics, appear to provide rapid initial stabilizing mechanisms that are often consistent with spring-mass dynamics. These intrinsic mechanisms likely help to simplify the

  16. Fifteen observations on the structure of energy-minimizing gaits in many simple biped models.

    PubMed

    Srinivasan, Manoj

    2011-01-01

    A popular hypothesis regarding legged locomotion is that humans and other large animals walk and run in a manner that minimizes the metabolic energy expenditure for locomotion. Here, using numerical optimization and supporting analytical arguments, I obtain the energy-minimizing gaits of many different simple biped models. I consider bipeds with point-mass bodies and massless legs, with or without a knee, with or without a springy tendon in series with the leg muscle and minimizing one of many different 'metabolic cost' models-correlated with muscle work, muscle force raised to some power, the Minetti-Alexander quasi-steady approximation to empirical muscle metabolic rate (from heat and ATPase activity), a new cost function called the 'generalized work cost' C(g) having some positivity and convexity properties (and includes the Minetti-Alexander cost and the work cost as special cases), and generalizations thereof. For many of these models, walking-like gaits are optimal at low speeds and running-like gaits at higher speeds, so a gait transition is optimal. Minimizing the generalized work cost C(g) appears mostly indistinguishable from minimizing muscle work for all the models. Inverted pendulum walking and impulsive running gaits minimize the work cost, generalized work costs C(g) and a few other costs for the springless bipeds; in particular, a knee-torque-squared cost, appropriate as a simplified model for electric motor power for a kneed robot biped. Many optimal gaits had symmetry properties; for instance, the left stance phase was identical to the right stance phases. Muscle force-velocity relations and legs with masses have predictable qualitative effects, if any, on the optima. For bipeds with compliant tendons, the muscle work-minimizing strategies have close to zero muscle work (isometric muscles), with the springs performing all the leg work. These zero work gaits also minimize the generalized work costs C(g) with substantial additive force or force rate

  17. Fifteen observations on the structure of energy-minimizing gaits in many simple biped models

    PubMed Central

    Srinivasan, Manoj

    2011-01-01

    A popular hypothesis regarding legged locomotion is that humans and other large animals walk and run in a manner that minimizes the metabolic energy expenditure for locomotion. Here, using numerical optimization and supporting analytical arguments, I obtain the energy-minimizing gaits of many different simple biped models. I consider bipeds with point-mass bodies and massless legs, with or without a knee, with or without a springy tendon in series with the leg muscle and minimizing one of many different ‘metabolic cost’ models—correlated with muscle work, muscle force raised to some power, the Minetti–Alexander quasi-steady approximation to empirical muscle metabolic rate (from heat and ATPase activity), a new cost function called the ‘generalized work cost’ Cg having some positivity and convexity properties (and includes the Minetti–Alexander cost and the work cost as special cases), and generalizations thereof. For many of these models, walking-like gaits are optimal at low speeds and running-like gaits at higher speeds, so a gait transition is optimal. Minimizing the generalized work cost Cg appears mostly indistinguishable from minimizing muscle work for all the models. Inverted pendulum walking and impulsive running gaits minimize the work cost, generalized work costs Cg and a few other costs for the springless bipeds; in particular, a knee-torque-squared cost, appropriate as a simplified model for electric motor power for a kneed robot biped. Many optimal gaits had symmetry properties; for instance, the left stance phase was identical to the right stance phases. Muscle force–velocity relations and legs with masses have predictable qualitative effects, if any, on the optima. For bipeds with compliant tendons, the muscle work-minimizing strategies have close to zero muscle work (isometric muscles), with the springs performing all the leg work. These zero work gaits also minimize the generalized work costs Cg with substantial additive force or

  18. Functional Coordination of a Full-Body Gaze Control Mechanisms Elicited During Locomotion

    NASA Technical Reports Server (NTRS)

    Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Cohen, Helen S.

    2003-01-01

    Control of locomotion requires precise interaction between several sensorimotor subsystems. Exposure to the microgravity environment of spaceflight leads to postflight adaptive alterations in these multiple subsystems leading to postural and gait disturbances. Countermeasures designed to mitigate these postflight gait alterations will need to be assessed with a new generation of functional tests that evaluate the interaction of various elements central to locomotor control. The goal of this study is to determine how the multiple, interdependent, full- body sensorimotor subsystems aiding gaze stabilization during locomotion are functionally coordinated. To explore this question two experiments were performed. In the first study (Study 1) we investigated how alteration in gaze tasking changes full-body locomotor control strategies. Subjects (n=9) performed two discreet gaze stabilization tasks while walking at 6.4 km/hr on a motorized treadmill: 1) focusing on a central point target; 2) reading numeral characters; both presented at 2m in front at eye level. The second study (Study 2) investigated the potential of adaptive remodeling of the full-body gaze control systems following exposure to visual-vestibular conflict. Subjects (n=14) walked (6.4 km/h) on the treadmill before and after they were exposed to 0.5X minifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. In both studies we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. Results from Study 1 showed that while reading numeral characters as compared to the central point target: 1) compensatory head pitch movements were on average 22% greater 2) the peak acceleration measured at the head was significantly reduced by an average of 13% in four of the six

  19. Learning tensegrity locomotion using open-loop control signals and coevolutionary algorithms.

    PubMed

    Iscen, Atil; Caluwaerts, Ken; Bruce, Jonathan; Agogino, Adrian; SunSpiral, Vytas; Tumer, Kagan

    2015-01-01

    Soft robots offer many advantages over traditional rigid robots. However, soft robots can be difficult to control with standard control methods. Fortunately, evolutionary algorithms can offer an elegant solution to this problem. Instead of creating controls to handle the intricate dynamics of these robots, we can simply evolve the controls using a simulation to provide an evaluation function. In this article, we show how such a control paradigm can be applied to an emerging field within soft robotics: robots based on tensegrity structures. We take the model of the Spherical Underactuated Planetary Exploration Robot ball (SUPERball), an icosahedron tensegrity robot under production at NASA Ames Research Center, develop a rolling locomotion algorithm, and study the learned behavior using an accurate model of the SUPERball simulated in the NASA Tensegrity Robotics Toolkit. We first present the historical-average fitness-shaping algorithm for coevolutionary algorithms to speed up learning while favoring robustness over optimality. Second, we use a distributed control approach by coevolving open-loop control signals for each controller. Being simple and distributed, open-loop controllers can be readily implemented on SUPERball hardware without the need for sensor information or precise coordination. We analyze signals of different complexities and frequencies. Among the learned policies, we take one of the best and use it to analyze different aspects of the rolling gait, such as lengths, tensions, and energy consumption. We also discuss the correlation between the signals controlling different parts of the tensegrity robot. PMID:25951199

  20. Distinct Thalamo-Cortical Controls for Shoulder, Elbow, and Wrist during Locomotion

    PubMed Central

    Beloozerova, Irina N.; Stout, Erik E.; Sirota, Mikhail G.

    2013-01-01

    Recent data from this laboratory on differential controls for the shoulder, elbow, and wrist exerted by the thalamo-cortical network during locomotion is presented, based on experiments involving chronically instrumented cats walking on a flat surface and along a horizontal ladder. The activity of the following three groups of neurons is characterized: (1) neurons of the motor cortex that project to the pyramidal tract (PTNs), (2) neurons of the ventrolateral thalamus (VL), many identified as projecting to the motor cortex (thalamo-cortical neurons, TCs), and (3) neurons of the reticular nucleus of thalamus (RE), which inhibit TCs. Neurons were grouped according to their receptive field into shoulder-, elbow-, and wrist/paw-related categories. During simple locomotion, shoulder-related PTNs were most active in the late stance and early swing, and on the ladder, often increased activity and stride-related modulation while reducing discharge duration. Elbow-related PTNs were most active during late swing/early stance and typically remained similar on the ladder. Wrist-related PTNs were most active during swing, and on the ladder often decreased activity and increased modulation while reducing discharge duration. In the VL, shoulder-related neurons were more active during the transition from swing-to-stance. Elbow-related cells tended to be more active during the transition from stance-to-swing and on the ladder often decreased their activity and increased modulation. Wrist-related neurons were more active throughout the stance phase. In the RE, shoulder-related cells had low discharge rates and depths of modulation and long periods of activity distributed evenly across the cycle. In sharp contrast, wrist/paw-related cells discharged synchronously during the end of stance and swing with short periods of high activity, high modulation, and frequent sleep-type bursting. We conclude that thalamo-cortical network processes information related to different segments of the

  1. Neural network and fuzzy control in FES-assisted locomotion for the hemiplegic.

    PubMed

    Chen, Yu-Luen; Chen, Shih-Ching; Chen, Weoi-Luen; Hsiao, Chin-Chih; Kuo, Te-Son; Lai, Jin-Shin

    2004-01-01

    This study is aimed at establishing a neural network and fuzzy feedback control FES system used for adjusting the optimum electrical stimulating current to control the motion of an ankle joint. The proposed method further improves the drop-foot problem existing in hemiplegia patients. The proposed system includes both hardware and software. The hardware system determines the patient's ankle joint angle using a position sensor located in the patient's affected side. This sensor stimulates the tibialis anterior with an electrical stimulator that induces the dorsiflexion action and achieves the ideal ankle joint trace motion. The software system estimates the stimulating current using a neural network. The fuzzy controller solves the nonlinear problem by compensating the motion trace errors between the neural network control and actual system. The control qualities of various controllers for four subjects were compared in the clinical test. It was found that both the root mean square error and the mean error were minimal when using the neural network and fuzzy controller. The drop-foot problem in hemiplegic's locomotion was effectively improved by incorporating the neural network and fuzzy controller with the functional electrical simulator.

  2. The Role of Visual and Nonvisual Information in the Control of Locomotion

    ERIC Educational Resources Information Center

    Wilkie, Richard M.; Wann, John P.

    2005-01-01

    During locomotion, retinal flow, gaze angle, and vestibular information can contribute to one's perception of self-motion. Their respective roles were investigated during active steering: Retinal flow and gaze angle were biased by altering the visual information during computer-simulated locomotion, and vestibular information was controlled…

  3. The control of ventilation is dissociated from locomotion during walking in sheep

    PubMed Central

    Haouzi, Philippe; Chenuel, Bruno; Chalon, Bernard

    2004-01-01

    This study was designed to test the hypothesis that the frequency response of the systems controlling the motor activity of breathing and walking in quadrupeds is compatible with the idea that supra-spinal locomotor centres could proportionally drive locomotion and ventilation. The locomotor and the breath-by-breath ventilatory and gas exchange (CO2 output (V̇CO2) and O2 uptake (V̇CO2)) responses were studied in five sheep spontaneously walking on a treadmill. The speed of the treadmill was changed in a sinusoidal pattern of various periods (from 10 to 1 minute) and in a step-like manner. The frequency and amplitude of the limb movements, oscillating at the same period as the treadmill speed changes, had a constant gain with no phase lag (determined by Fourier analysis) regardless the periods of oscillations. In marked contrast, when the periods of speed oscillations decreased, the amplitude (peak-to-mean) of minute ventilation (V̇E) oscillations decreased sharply and significantly (from 6.1 ± 0.4 l min−1 to 1.9 ± 0.2 l min−1) and the phase lag between ventilation and treadmill speed oscillations increased (to 105 ± 25 ° during the 1 min oscillation periods). V̇E response followed V̇CO2 very closely. The drop in V̇E amplitude ratio was proportional to that in V̇CO2 (from 149 ± 48 ml min−1 to 38 ± 5 ml min−1) with a slightly longer phase lag for ventilation than for V̇CO2. These results show that beyond the onset period of a locomotor activity, the amplitude and phase lag of the V̇E response depends on the period of the walking speed oscillations, tracking the gas exchange rate, regardless of the amplitude of the motor act of walking. Locomotion thus appears unlikely to cause a simple parallel and proportional increase in ventilation in walking sheep. PMID:15235099

  4. Dynamical analysis and performance evaluation of a biped robot under multi-source random disturbances

    NASA Astrophysics Data System (ADS)

    Gan, Chun-Biao; Ding, Chang-Tao; Yang, Shi-Xi

    2014-12-01

    During bipedal walking, it is critical to detect and adjust the robot postures by feedback control to maintain its normal state amidst multi-source random disturbances arising from some unavoidable uncertain factors. The radical basis function (RBF) neural network model of a five-link biped robot is established, and two certain disturbances and a randomly uncertain disturbance are then mixed with the optimal torques in the network model to study the performance of the biped robot by several evaluation indices and a specific Poincaré map. In contrast with the simulations, the response varies as desired under optimal inputting while the output is fluctuating in the situation of disturbance driving. Simulation results from noise inputting also show that the dynamics of the robot is less sensitive to the disturbance of knee joint input of the swing leg than those of the other three joints, the response errors of the biped will be increasing with higher disturbance levels, and especially there are larger output fluctuations in the knee and hip joints of the swing leg.

  5. Feed forward and feedback control for over-ground locomotion in anaesthetized cats

    NASA Astrophysics Data System (ADS)

    Mazurek, K. A.; Holinski, B. J.; Everaert, D. G.; Stein, R. B.; Etienne-Cummings, R.; Mushahwar, V. K.

    2012-04-01

    The biological central pattern generator (CPG) integrates open and closed loop control to produce over-ground walking. The goal of this study was to develop a physiologically based algorithm capable of mimicking the biological system to control multiple joints in the lower extremities for producing over-ground walking. The algorithm used state-based models of the step cycle each of which produced different stimulation patterns. Two configurations were implemented to restore over-ground walking in five adult anaesthetized cats using intramuscular stimulation (IMS) of the main hip, knee and ankle flexor and extensor muscles in the hind limbs. An open loop controller relied only on intrinsic timing while a hybrid-CPG controller added sensory feedback from force plates (representing limb loading), and accelerometers and gyroscopes (representing limb position). Stimulation applied to hind limb muscles caused extension or flexion in the hips, knees and ankles. A total of 113 walking trials were obtained across all experiments. Of these, 74 were successful in which the cats traversed 75% of the 3.5 m over-ground walkway. In these trials, the average peak step length decreased from 24.9 ± 8.4 to 21.8 ± 7.5 (normalized units) and the median number of steps per trial increased from 7 (Q1 = 6, Q3 = 9) to 9 (8, 11) with the hybrid-CPG controller. Moreover, within these trials, the hybrid-CPG controller produced more successful steps (step length ≤ 20 cm ground reaction force ≥ 12.5% body weight) than the open loop controller: 372 of 544 steps (68%) versus 65 of 134 steps (49%), respectively. This supports our previous preliminary findings, and affirms that physiologically based hybrid-CPG approaches produce more successful stepping than open loop controllers. The algorithm provides the foundation for a neural prosthetic controller and a framework to implement more detailed control of locomotion in the future.

  6. Feed forward and feedback control for over-ground locomotion in anaesthetized cats

    PubMed Central

    Mazurek, K A; Holinski, B J; Everaert, D G; Stein, R B; Etienne-Cummings, R; Mushahwar, V K

    2012-01-01

    The biological central pattern generator (CPG) integrates open and closed loop control to produce over-ground walking. The goal of this study was to develop a physiologically based algorithm capable of mimicking the biological system to control multiple joints in the lower extremities for producing over-ground walking. The algorithm used state-based models of the step cycle each of which produced different stimulation patterns. Two configurations were implemented to restore over-ground walking in five adult anaesthetized cats using intramuscular stimulation (IMS) of the main hip, knee and ankle flexor and extensor muscles in the hind limbs. An open loop controller relied only on intrinsic timing while a hybrid-CPG controller added sensory feedback from force plates (representing limb loading), and accelerometers and gyroscopes (representing limb position). Stimulation applied to hind limb muscles caused extension or flexion in the hips, knees and ankles. A total of 113 walking trials were obtained across all experiments. Of these, 74 were successful in which the cats traversed 75% of the 3.5 m over-ground walkway. In these trials, the average peak step length decreased from 24.9 ± 8.4 to 21.8 ± 7.5 (normalized units) and the median number of steps per trial increased from 7 (Q1=6, Q3 = 9) to 9 (8, 11) with the hybrid-CPG controller. Moreover, these trials, the hybrid-CPG controller produced more successful steps (step length ≤ 20 cm; ground reaction force ≥ 12.5% body weight) than the open loop controller: 372 of 544 steps (68%) versus 65 of 134 steps (49%), respectively. This supports our previous preliminary findings, and affirms that physiologically based hybrid-CPG approaches produce more successful stepping than open loop controllers. The algorithm provides the foundation for a neural prosthetic controller and a framework to implement more detailed control of locomotion in the future. PMID:22328615

  7. Mechatronic design and locomotion control of a robotic thunniform swimmer for fast cruising.

    PubMed

    Hu, Yonghui; Liang, Jianhong; Wang, Tianmiao

    2015-03-30

    This paper presents mechatronic design and locomotion control of a biomimetic robotic fish that swims using thunniform kinematics for fast cruising. Propulsion of the robotic fish is realized with a parallel four-bar propulsive mechanism that delivers combined translational and rotational motion to a lunate caudal fin. A central pattern generator controller, composed of two unidirectionally coupled Hopf oscillators, is employed to generate robust, smooth and coordinated oscillatory control signals for the tail joints. In order to maintain correct phase relation between joints during fast tail beating, a novel phase adjusting mechanism is proposed and incorporated into the controller. The attitude of the robotic fish in fast swimming is stabilized using an attitude and heading reference system unit and a pair of pitching pectoral fins. The maximum speed of the robotic fish can reach 2.0 m s(-1), which is the fastest speed that robotic fishes have achieved. Its outstanding swimming performance presents possibilities for deployment to real-world exploration, probe and survey missions.

  8. 40 CFR 92.214 - Production locomotives and engines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... locomotives or locomotive engines shall be representative of the engines, emission control systems, and fuel... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Production locomotives and engines. 92... (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Certification Provisions §...

  9. Control of locomotion in expert gymnasts in the absence of vision.

    PubMed

    Danion, F; Boyadjian, A; Marin, L

    2000-10-01

    The main aim of this study was to determine how gymnasts are affected by the removal of vision when executing simple moves. A secondary aim was to establish whether crucial sensory cues exist for blindfolded gymnasts. Eight expert gymnasts were asked to maintain a straight displacement during three types of blindfolded locomotion: walking, steering a wheelchair and verbally ordering a second person pushing their wheelchair. In the first two conditions, active displacement made proprioceptive cues available to update the body trajectory. In the last condition, however, proprioceptive cues were greatly reduced, since the gymnasts displaced passively. The performance of the gymnasts was compared to that of eight experts in other non-gymnastic sports (control group). The results showed that the participants veered in all conditions. However, except in the verbal condition, the gymnasts departed less from linearity than the controls. We conclude that: (1) even for a simple motor task, gymnasts' performance is altered by eliminating vision; (2) compared with other sportsmen and women, gymnasts are better able to deal with the absence of vision when proprioceptive cues are available. These findings suggest two possible explanations: (1) gymnasts are more able to 'pick up' crucial information and (2) a gymnast's proprioceptive system is more sensitive.

  10. Contact inhibition of locomotion in vivo controls neural crest directional migration.

    PubMed

    Carmona-Fontaine, Carlos; Matthews, Helen K; Kuriyama, Sei; Moreno, Mauricio; Dunn, Graham A; Parsons, Maddy; Stern, Claudio D; Mayor, Roberto

    2008-12-18

    Contact inhibition of locomotion was discovered by Abercrombie more than 50 years ago and describes the behaviour of fibroblast cells confronting each other in vitro, where they retract their protrusions and change direction on contact. Its failure was suggested to contribute to malignant invasion. However, the molecular basis of contact inhibition of locomotion and whether it also occurs in vivo are still unknown. Here we show that neural crest cells, a highly migratory and multipotent embryonic cell population, whose behaviour has been likened to malignant invasion, demonstrate contact inhibition of locomotion both in vivo and in vitro, and that this accounts for their directional migration. When two migrating neural crest cells meet, they stop, collapse their protrusions and change direction. In contrast, when a neural crest cell meets another cell type, it fails to display contact inhibition of locomotion; instead, it invades the other tissue, in the same manner as metastatic cancer cells. We show that inhibition of non-canonical Wnt signalling abolishes both contact inhibition of locomotion and the directionality of neural crest migration. Wnt-signalling members localize at the site of cell contact, leading to activation of RhoA in this region. These results provide the first example of contact inhibition of locomotion in vivo, provide an explanation for coherent directional migration of groups of cells and establish a previously unknown role for non-canonical Wnt signalling.

  11. How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?

    PubMed Central

    Gordon, Joanne C.; Rankin, Jeffery W.; Daley, Monica A.

    2015-01-01

    ABSTRACT Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s−1) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (<10% contrast, black/black), and (iii) repeated 5 cm high-contrast obstacles (>90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies. PMID:26254324

  12. How do treadmill speed and terrain visibility influence neuromuscular control of guinea fowl locomotion?

    PubMed

    Gordon, Joanne C; Rankin, Jeffery W; Daley, Monica A

    2015-10-01

    Locomotor control mechanisms must flexibly adapt to both anticipated and unexpected terrain changes to maintain movement and avoid a fall. Recent studies revealed that ground birds alter movement in advance of overground obstacles, but not treadmill obstacles, suggesting context-dependent shifts in the use of anticipatory control. We hypothesized that differences between overground and treadmill obstacle negotiation relate to differences in visual sensory information, which influence the ability to execute anticipatory manoeuvres. We explored two possible explanations: (1) previous treadmill obstacles may have been visually imperceptible, as they were low contrast to the tread, and (2) treadmill obstacles are visible for a shorter time compared with runway obstacles, limiting time available for visuomotor adjustments. To investigate these factors, we measured electromyographic activity in eight hindlimb muscles of the guinea fowl (Numida meleagris, N=6) during treadmill locomotion at two speeds (0.7 and 1.3 m s(-1)) and three terrain conditions at each speed: (i) level, (ii) repeated 5 cm low-contrast obstacles (<10% contrast, black/black), and (iii) repeated 5 cm high-contrast obstacles (>90% contrast, black/white). We hypothesized that anticipatory changes in muscle activity would be higher for (1) high-contrast obstacles and (2) the slower treadmill speed, when obstacle viewing time is longer. We found that treadmill speed significantly influenced obstacle negotiation strategy, but obstacle contrast did not. At the slower speed, we observed earlier and larger anticipatory increases in muscle activity and shifts in kinematic timing. We discuss possible visuomotor explanations for the observed context-dependent use of anticipatory strategies.

  13. Forebrain dopamine neurons project down to a brainstem region controlling locomotion.

    PubMed

    Ryczko, Dimitri; Grätsch, Swantje; Auclair, François; Dubé, Catherine; Bergeron, Saskia; Alpert, Michael H; Cone, Jackson J; Roitman, Mitchell F; Alford, Simon; Dubuc, Réjean

    2013-08-20

    The contribution of dopamine (DA) to locomotor control is traditionally attributed to ascending dopaminergic projections from the substantia nigra pars compacta and the ventral tegmental area to the basal ganglia, which in turn project down to the mesencephalic locomotor region (MLR), a brainstem region controlling locomotion in vertebrates. However, a dopaminergic innervation of the pedunculopontine nucleus, considered part of the MLR, was recently identified in the monkey. The origin and role of this dopaminergic input are unknown. We addressed these questions in a basal vertebrate, the lamprey. Here we report a functional descending dopaminergic pathway from the posterior tuberculum (PT; homologous to the substantia nigra pars compacta and/or ventral tegmental area of mammals) to the MLR. By using triple labeling, we found that dopaminergic cells from the PT not only project an ascending pathway to the striatum, but send a descending projection to the MLR. In an isolated brain preparation, PT stimulation elicited excitatory synaptic inputs into patch-clamped MLR cells, accompanied by activity in reticulospinal cells. By using voltammetry coupled with electrophysiological recordings, we demonstrate that PT stimulation evoked DA release in the MLR, together with the activation of reticulospinal cells. In a semi-intact preparation, stimulation of the PT elicited reticulospinal activity together with locomotor movements. Microinjections of a D1 antagonist in the MLR decreased the locomotor output elicited by PT stimulation, whereas injection of DA had an opposite effect. It appears that this descending dopaminergic pathway has a modulatory role on MLR cells that are known to receive glutamatergic projections and promotes locomotor output. PMID:23918379

  14. Numerical Simulations of Level-Ground Walking Based on Passive Walk for Planar Biped Robots with Torso by Hip Actuators

    NASA Astrophysics Data System (ADS)

    Narukawa, Terumasa; Takahashi, Masaki; Yoshida, Kazuo

    This study aims at a design technique of energy-efficient biped walking robots on level ground with simple mechanisms. To do this, we focus on the passive dynamic walkers which can walk stably down a shallow slope without actuators and controllers. On level ground, active walking should be studied because the mechanical energy is mainly lost through the swing-leg impacts with the ground. In this paper, numerical simulations show that planar biped robots with torso can walk efficiently on level ground over a wide range of speed by only using hip actuators. The hip actuators are used for a torso and swing-leg control based on passive-dynamic walking. The torso is used to generate active power replacing gravity used in the case of the passive walk. The swing-leg control is introduced to walk stably over a wide range of speed.

  15. Proprioceptive control of extensor activity during fictive scratching and weight support compared to fictive locomotion.

    PubMed

    Perreault, M C; Enriquez-Denton, M; Hultborn, H

    1999-12-15

    At rest, extensor group I afferents produce oligosynaptic inhibition of extensor motoneurons. During locomotor activity, however, such inhibition is replaced by oligosynaptic excitation. Oligosynaptic excitation from extensor group I afferents plays a crucial role in the regulation of extensor activity during walking. In this study we investigate the possibility that this mechanism also regulates extensor muscle activity during other motor tasks. We show that the reflex pathways responsible for extensor group I oligosynaptic excitation during fictive locomotion can be activated during both fictive scratching and fictive weight support (tonic motor activity induced by contralateral scratching). These observations suggest that the excitatory group I oligosynaptic reflex pathways are open for transmission during several forms of motor activities. We also show that extensor group I input during fictive scratching can affect the amplitude and the timing of extensor activity in a pattern similar to that observed during locomotion. Most likely these effects involve the activation of the excitatory group I oligosynaptic reflex pathways. Accordingly, it is suggested that extensor group I oligosynaptic excitation during motor activities other than locomotion is also used to regulate extensor muscle activity. Furthermore, the similarity of effects from extensor group I input on the rhythmicity during scratching and locomotion supports the hypothesis that both rhythms are generated by a common network.

  16. Online Fronto-cortical Control of Simple and Attention-Demanding Locomotion in Humans

    PubMed Central

    Holtzer, Roee; Mahoney, Jeannette R.; Izzetoglu, Meltem; Wang, Cuiling; England, Sarah; Verghese, Joe

    2015-01-01

    Knowledge of online functional brain mechanisms of locomotion is scarce due to technical limitations of traditional neuroimaging methods. Using functional Near Infrared Spectroscopy (fNIRS) we evaluated task-related changes in oxygenated hemoglobin levels (HbO2) in real-time over the pre-frontal-cortex (PFC) regions during simple (Normal Walk; NW) and attention-demanding (Walking While Talking; WWT) locomotion tasks in a large cohort of non-demented older adults. Results revealed that the assessment of task-related changes in HbO2 was internally consistent. Imposing greater demands on the attention system during locomotion resulted in robust bilateral PFC increases in HbO2 levels during WWT compared to NW and the cognitive interference tasks. Elevated PFC oxygenation levels were maintained throughout the course of WWT but not during the NW condition. Increased oxygenation levels in the PFC were related to greater stride length and better cognitive performance but not to faster gait velocity in WWT. These findings elucidate online brain mechanisms of locomotion, and confer significant implications for risk assessment and intervention for major mobility outcomes. PMID:25765257

  17. Foot Placement Modification for a Biped Humanoid Robot with Narrow Feet

    PubMed Central

    Hattori, Kentaro; Otani, Takuya; Lim, Hun-Ok; Takanishi, Atsuo

    2014-01-01

    This paper describes a walking stabilization control for a biped humanoid robot with narrow feet. Most humanoid robots have larger feet than human beings to maintain their stability during walking. If robot's feet are as narrow as humans, it is difficult to realize a stable walk by using conventional stabilization controls. The proposed control modifies a foot placement according to the robot's attitude angle. If a robot tends to fall down, a foot angle is modified about the roll axis so that a swing foot contacts the ground horizontally. And a foot-landing point is also changed laterally to inhibit the robot from falling to the outside. To reduce a foot-landing impact, a virtual compliance control is applied to the vertical axis and the roll and pitch axes of the foot. Verification of the proposed method is conducted through experiments with a biped humanoid robot WABIAN-2R. WABIAN-2R realized a knee-bended walking with 30 mm breadth feet. Moreover, WABIAN-2R mounted on a human-like foot mechanism mimicking a human's foot arch structure realized a stable walking with the knee-stretched, heel-contact, and toe-off motion. PMID:24592154

  18. Foot placement modification for a biped humanoid robot with narrow feet.

    PubMed

    Hashimoto, Kenji; Hattori, Kentaro; Otani, Takuya; Lim, Hun-Ok; Takanishi, Atsuo

    2014-01-01

    This paper describes a walking stabilization control for a biped humanoid robot with narrow feet. Most humanoid robots have larger feet than human beings to maintain their stability during walking. If robot's feet are as narrow as humans, it is difficult to realize a stable walk by using conventional stabilization controls. The proposed control modifies a foot placement according to the robot's attitude angle. If a robot tends to fall down, a foot angle is modified about the roll axis so that a swing foot contacts the ground horizontally. And a foot-landing point is also changed laterally to inhibit the robot from falling to the outside. To reduce a foot-landing impact, a virtual compliance control is applied to the vertical axis and the roll and pitch axes of the foot. Verification of the proposed method is conducted through experiments with a biped humanoid robot WABIAN-2R. WABIAN-2R realized a knee-bended walking with 30 mm breadth feet. Moreover, WABIAN-2R mounted on a human-like foot mechanism mimicking a human's foot arch structure realized a stable walking with the knee-stretched, heel-contact, and toe-off motion.

  19. Context-dependent changes in motor control and kinematics during locomotion: modulation and decoupling

    PubMed Central

    Foster, Kathleen L.; Higham, Timothy E.

    2014-01-01

    Successful locomotion through complex, heterogeneous environments requires the muscles that power locomotion to function effectively under a wide variety of conditions. Although considerable data exist on how animals modulate both kinematics and motor pattern when confronted with orientation (i.e. incline) demands, little is known about the modulation of muscle function in response to changes in structural demands like substrate diameter, compliance and texture. Here, we used high-speed videography and electromyography to examine how substrate incline and perch diameter affected the kinematics and muscle function of both the forelimb and hindlimb in the green anole (Anolis carolinensis). Surprisingly, we found a decoupling of the modulation of kinematics and motor activity, with kinematics being more affected by perch diameter than by incline, and muscle function being more affected by incline than by perch diameter. Also, muscle activity was most stereotyped on the broad, vertical condition, suggesting that, despite being classified as a trunk-crown ecomorph, this species may prefer trunks. These data emphasize the complex interactions between the processes that underlie animal movement and the importance of examining muscle function when considering both the evolution of locomotion and the impacts of ecology on function. PMID:24621949

  20. Optimal foot shape for a passive dynamic biped.

    PubMed

    Kwan, Maxine; Hubbard, Mont

    2007-09-21

    Passive walking dynamics describe the motion of a biped that is able to "walk" down a shallow slope without any actuation or control. Instead, the walker relies on gravitational and inertial effects to propel itself forward, exhibiting a gait quite similar to that of humans. These purely passive models depend on potential energy to overcome the energy lost when the foot impacts the ground. Previous research has demonstrated that energy loss at heel-strike can vary widely for a given speed, depending on the nature of the collision. The point of foot contact with the ground (relative to the hip) can have a significant effect: semi-circular (round) feet soften the impact, resulting in much smaller losses than point-foot walkers. Collisional losses are also lower if a single impulse is broken up into a series of smaller impulses that gradually redirect the velocity of the center of mass rather than a single abrupt impulse. Using this principle, a model was created where foot-strike occurs over two impulses, "heel-strike" and "toe-strike," representative of the initial impact of the heel and the following impact as the ball of the foot strikes the ground. Having two collisions with the flat-foot model did improve efficiency over the point-foot model. Representation of the flat-foot walker as a rimless wheel helped to explain the optimal flat-foot shape, driven by symmetry of the virtual spoke angles. The optimal long period foot shape of the simple passive walking model was not very representative of the human foot shape, although a reasonably anthropometric foot shape was predicted by the short period solution.

  1. 40 CFR 1033.652 - Special provisions for exported locomotives.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Special Compliance Provisions § 1033.652 Special provisions for exported locomotives. (a) Uncertified locomotives. Locomotives covered by an export exemption under 40 CFR 1068.230 may be introduced into U.S. commerce prior to being exported, but may not...

  2. 40 CFR 1033.652 - Special provisions for exported locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Special Compliance Provisions § 1033.652 Special provisions for exported locomotives. (a) Uncertified locomotives. Locomotives covered by an export exemption under 40 CFR 1068.230 may be introduced into U.S. commerce prior to being exported, but may not...

  3. Role of the cerebellum and motor cortex in the regulation of visually controlled locomotion.

    PubMed

    Armstrong, D M; Marple-Horvat, D E

    1996-04-01

    An account is given of the current state of knowledge of the contributions of the cerebellum and the forelimb motor cortex (MC) to the neural control of walking movements in the cat. The main emphasis is on information obtained by recording from single MC and cerebellar neurones in chronically instrumented cats engaged in walking on the rungs of a horizontal ladder, a form of locomotion that is heavily dependent on visual input and for which the integrity of MC is essential. Evidence from the authors' laboratory and from other studies is presented which establishes that MC neurones, including pyramidal tract neurones, show higher levels of activity during ladder walking than during overground walking (i.e., when less constraint exists over the locus of footfall) and that this increase is greatest in late swing-early stance in the contralateral forelimb, consistent with one role of MC being to help determine the locus of footfall. However, many MC neurones develop peak activity at other times in the step cycle, and a comparison with recordings during treadmill walking suggests MC may also help regulate stance duration when walking speed is an important performance variable. Recordings from Purkinje cells and cerebellar nuclear neurones show that during ladder walking step-related activity is widespread in the vermal, paravermal, and crural regions of cortex and in the interposed and dentate nuclei. Nuclear cell activity is so timed that it could be contributing to producing the locomotor rhythms evident in MC cells, although this is not yet proven. Results are also presented and discussed relating to MC and cerebellar neuronal responses that occur when a step onto an unstable rung results in an unexpected external perturbation of the forelimb step cycle. MC responses begin with onset latency as short as 20 ms so that MC may assist spinal reflex mechanisms to produce a post hoc compensatory change in motor output. However, work in progress suggests that corresponding

  4. Torsional locomotion

    PubMed Central

    Bigoni, D.; Dal Corso, F.; Misseroni, D.; Bosi, F.

    2014-01-01

    One edge of an elastic rod is inserted into a friction-less and fitting socket head, whereas the other edge is subjected to a torque, generating a uniform twisting moment. It is theoretically shown and experimentally proved that, although perfectly smooth, the constraint realizes an expulsive axial force on the elastic rod, which amount is independent of the shape of the socket head. The axial force explains why screwdrivers at high torque have the tendency to disengage from screw heads and demonstrates torsional locomotion along a perfectly smooth channel. This new type of locomotion finds direct evidence in the realization of a ‘torsional gun’, capable of transforming torque into propulsive force. PMID:25383038

  5. 40 CFR 92.214 - Production locomotives and engines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Production locomotives and engines. 92... (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Certification Provisions § 92.214 Production locomotives and engines. Any manufacturer or remanufacturer obtaining...

  6. Spine pruning drives antipsychotic-sensitive locomotion via circuit control of striatal dopamine.

    PubMed

    Kim, Il Hwan; Rossi, Mark A; Aryal, Dipendra K; Racz, Bence; Kim, Namsoo; Uezu, Akiyoshi; Wang, Fan; Wetsel, William C; Weinberg, Richard J; Yin, Henry; Soderling, Scott H

    2015-06-01

    Psychiatric and neurodevelopmental disorders may arise from anomalies in long-range neuronal connectivity downstream of pathologies in dendritic spines. However, the mechanisms that may link spine pathology to circuit abnormalities relevant to atypical behavior remain unknown. Using a mouse model to conditionally disrupt a critical regulator of the dendritic spine cytoskeleton, the actin-related protein 2/3 complex (Arp2/3), we report here a molecular mechanism that unexpectedly reveals the inter-relationship of progressive spine pruning, elevated frontal cortical excitation of pyramidal neurons and striatal hyperdopaminergia in a cortical-to-midbrain circuit abnormality. The main symptomatic manifestations of this circuit abnormality are psychomotor agitation and stereotypical behaviors, which are relieved by antipsychotics. Moreover, this antipsychotic-responsive locomotion can be mimicked in wild-type mice by optogenetic activation of this circuit. Collectively these results reveal molecular and neural-circuit mechanisms, illustrating how diverse pathologies may converge to drive behaviors relevant to psychiatric disorders.

  7. Locomotion- and mechanics-mediated tactile sensing: antenna reconfiguration simplifies control during high-speed navigation in cockroaches.

    PubMed

    Mongeau, Jean-Michel; Demir, Alican; Lee, Jusuk; Cowan, Noah J; Full, Robert J

    2013-12-15

    Animals can expend energy to acquire sensory information by emitting signals and/or moving sensory structures. We propose that the energy from locomotion itself could permit control of a sensor, whereby animals use the energy from movement to reconfigure a passive sensor. We investigated high-speed, antenna-mediated tactile navigation in the cockroach Periplaneta americana. We discovered that the passive antennal flagellum can assume two principal mechanical states, such that the tip is either projecting backward or forward. Using a combination of behavioral and robotic experiments, we demonstrate that a switch in the antenna's state is mediated via the passive interactions between the sensor and its environment, and this switch strongly influences wall-tracking control. When the tip of the antenna is projected backward, the animals maintain greater body-to-wall distance with fewer body collisions and less leg-wall contact than when the tip is projecting forward. We hypothesized that distally pointing mechanosensory hairs at the tip of the antenna mediate the switch in state by interlocking with asperities in the wall surface. To test this hypothesis, we performed laser ablation of chemo-mechanosensory hairs and added artificial hairs to a robotic antenna. In both the natural and artificial systems, the presence of hairs categorically increased an antenna's probability of switching state. Antennal hairs, once thought to only play a role in sensing, are sufficient for mechanically reconfiguring the state of the entire antenna when coupled with forward motion. We show that the synergy between antennal mechanics, locomotion and the environment simplifies tactile sensing.

  8. Locomotion- and mechanics-mediated tactile sensing: antenna reconfiguration simplifies control during high-speed navigation in cockroaches.

    PubMed

    Mongeau, Jean-Michel; Demir, Alican; Lee, Jusuk; Cowan, Noah J; Full, Robert J

    2013-12-15

    Animals can expend energy to acquire sensory information by emitting signals and/or moving sensory structures. We propose that the energy from locomotion itself could permit control of a sensor, whereby animals use the energy from movement to reconfigure a passive sensor. We investigated high-speed, antenna-mediated tactile navigation in the cockroach Periplaneta americana. We discovered that the passive antennal flagellum can assume two principal mechanical states, such that the tip is either projecting backward or forward. Using a combination of behavioral and robotic experiments, we demonstrate that a switch in the antenna's state is mediated via the passive interactions between the sensor and its environment, and this switch strongly influences wall-tracking control. When the tip of the antenna is projected backward, the animals maintain greater body-to-wall distance with fewer body collisions and less leg-wall contact than when the tip is projecting forward. We hypothesized that distally pointing mechanosensory hairs at the tip of the antenna mediate the switch in state by interlocking with asperities in the wall surface. To test this hypothesis, we performed laser ablation of chemo-mechanosensory hairs and added artificial hairs to a robotic antenna. In both the natural and artificial systems, the presence of hairs categorically increased an antenna's probability of switching state. Antennal hairs, once thought to only play a role in sensing, are sufficient for mechanically reconfiguring the state of the entire antenna when coupled with forward motion. We show that the synergy between antennal mechanics, locomotion and the environment simplifies tactile sensing. PMID:24307709

  9. Par3 controls neural crest migration by promoting microtubule catastrophe during contact inhibition of locomotion.

    PubMed

    Moore, Rachel; Theveneau, Eric; Pozzi, Sara; Alexandre, Paula; Richardson, Joanna; Merks, Anne; Parsons, Maddy; Kashef, Jubin; Linker, Claudia; Mayor, Roberto

    2013-12-01

    There is growing evidence that contact inhibition of locomotion (CIL) is essential for morphogenesis and its failure is thought to be responsible for cancer invasion; however, the molecular bases of this phenomenon are poorly understood. Here we investigate the role of the polarity protein Par3 in CIL during migration of the neural crest, a highly migratory mesenchymal cell type. In epithelial cells, Par3 is localised to the cell-cell adhesion complex and is important in the definition of apicobasal polarity, but the localisation and function of Par3 in mesenchymal cells are not well characterised. We show in Xenopus and zebrafish that Par3 is localised to the cell-cell contact in neural crest cells and is essential for CIL. We demonstrate that the dynamics of microtubules are different in different parts of the cell, with an increase in microtubule catastrophe at the collision site during CIL. Par3 loss-of-function affects neural crest migration by reducing microtubule catastrophe at the site of cell-cell contact and abrogating CIL. Furthermore, Par3 promotes microtubule catastrophe by inhibiting the Rac-GEF Trio, as double inhibition of Par3 and Trio restores microtubule catastrophe at the cell contact and rescues CIL and neural crest migration. Our results demonstrate a novel role of Par3 during neural crest migration, which is likely to be conserved in other processes that involve CIL such as cancer invasion or cell dispersion.

  10. Brain-wide mapping of neural activity controlling zebrafish exploratory locomotion

    PubMed Central

    Dunn, Timothy W; Mu, Yu; Narayan, Sujatha; Randlett, Owen; Naumann, Eva A; Yang, Chao-Tsung; Schier, Alexander F

    2016-01-01

    In the absence of salient sensory cues to guide behavior, animals must still execute sequences of motor actions in order to forage and explore. How such successive motor actions are coordinated to form global locomotion trajectories is unknown. We mapped the structure of larval zebrafish swim trajectories in homogeneous environments and found that trajectories were characterized by alternating sequences of repeated turns to the left and to the right. Using whole-brain light-sheet imaging, we identified activity relating to the behavior in specific neural populations that we termed the anterior rhombencephalic turning region (ARTR). ARTR perturbations biased swim direction and reduced the dependence of turn direction on turn history, indicating that the ARTR is part of a network generating the temporal correlations in turn direction. We also find suggestive evidence for ARTR mutual inhibition and ARTR projections to premotor neurons. Finally, simulations suggest the observed turn sequences may underlie efficient exploration of local environments. DOI: http://dx.doi.org/10.7554/eLife.12741.001 PMID:27003593

  11. Compliant Synergies in Locomotion

    NASA Astrophysics Data System (ADS)

    Travers, Matthew; Choset, Howie; Goldman @ Georgia Tech. Physics Department Collaboration

    Biological systems appear to have natural mechanisms that allow them to readily compensate for unexpected environmental variations when compared to their mechanical (i.e., robotic) counterparts. We hypothesize that the basis for this discrepancy is almost innate: what biology appears to be born with, built-in mechanisms for coordinating their many degrees of freedom, we struggle to ``program.'' We therefore look toward biology for inspiration. In particular, we are interested in kinematic synergies, low-dimensional representations that explicitly encode the underlying structure of how systems coordinate their internal degrees of freedom to achieve high-level tasks. In this work, we derive parametric representations of kinematic synergies and present a new compliant locomotion control framework that enables the parameters to be directly controlled in response to external disturbances. We present results of this framework implemented on two separate platforms, a snake-like and hexapod robot. Our results show that, using synergies, the locomotion control of these very different systems can be reduced to simple, extremely capable, and common forms, thus offering new insights into both robotic as well as biological locomotion in complex terrains.

  12. Perception of gait patterns that deviate from normal and symmetric biped locomotion

    PubMed Central

    Handžić, Ismet; Reed, Kyle B.

    2015-01-01

    This study examines the range of gait patterns that are perceived as healthy and human-like with the goal of understanding how much asymmetry is allowable in a gait pattern before other people start to notice a gait impairment. Specifically, this study explores if certain abnormal walking patterns can be dismissed as unimpaired or not uncanny. Altering gait biomechanics is generally done in the fields of prosthetics and rehabilitation, however the perception of gait is often neglected. Although a certain gait can be functional, it may not be considered as normal by observers. On the other hand, an abnormally perceived gait may be more practical or necessary in some situations, such as limping after an injury or stroke and when wearing a prosthesis. This research will help to find the balance between the form and function of gait. Gait patterns are synthetically created using a passive dynamic walker (PDW) model that allows gait patterns to be systematically changed without the confounding influence from human sensorimotor feedback during walking. This standardized method allows the perception of specific changes in gait to be studied. The PDW model was used to produce walking patterns that showed a degree of abnormality in gait cadence, knee height, step length, and swing time created by changing the foot roll-over-shape, knee damping, knee location, and leg masses. The gait patterns were shown to participants who rated them according to separate scales of impairment and uncanniness. The results indicate that some pathological and asymmetric gait patterns are perceived as unimpaired and normal. Step time and step length asymmetries less than 5%, small knee location differences, and gait cadence changes of 25% do not result in a change in perception. The results also show that the parameters of a pathologically or uncanny perceived gait can be beneficially altered by increasing other independent parameters, in some sense masking the initial pathology. PMID:25774144

  13. Advanced robot locomotion.

    SciTech Connect

    Neely, Jason C.; Sturgis, Beverly Rainwater; Byrne, Raymond Harry; Feddema, John Todd; Spletzer, Barry Louis; Rose, Scott E.; Novick, David Keith; Wilson, David Gerald; Buerger, Stephen P.

    2007-01-01

    This report contains the results of a research effort on advanced robot locomotion. The majority of this work focuses on walking robots. Walking robot applications include delivery of special payloads to unique locations that require human locomotion to exo-skeleton human assistance applications. A walking robot could step over obstacles and move through narrow openings that a wheeled or tracked vehicle could not overcome. It could pick up and manipulate objects in ways that a standard robot gripper could not. Most importantly, a walking robot would be able to rapidly perform these tasks through an intuitive user interface that mimics natural human motion. The largest obstacle arises in emulating stability and balance control naturally present in humans but needed for bipedal locomotion in a robot. A tracked robot is bulky and limited, but a wide wheel base assures passive stability. Human bipedal motion is so common that it is taken for granted, but bipedal motion requires active balance and stability control for which the analysis is non-trivial. This report contains an extensive literature study on the state-of-the-art of legged robotics, and it additionally provides the analysis, simulation, and hardware verification of two variants of a proto-type leg design.

  14. Biped walking robot based on a 2-UPU+2-UU parallel mechanism

    NASA Astrophysics Data System (ADS)

    Miao, Zhihuai; Yao, Yan'an; Kong, Xianwen

    2014-03-01

    Existing biped robots mainly fall into two categories: robots with left and right feet and robots with upper and lower feet. The load carrying capability of a biped robot is quite limited since the two feet of a walking robot supports the robot alternatively during walking. To improve the load carrying capability, a novel biped walking robot is proposed based on a 2-UPU+2-UU parallel mechanism. The biped walking robot is composed of two identical platforms(feet) and four limbs, including two UPU(universal-prismatic-universal serial chain) limbs and two UU limbs. To enhance its terrain adaptability like articulated vehicles, the two feet of the biped walking robot are designed as two vehicles in detail. The conditions that the geometric parameters of the feet must satisfy are discussed. The degrees-of-freedom of the mechanism is analyzed by using screw theory. Gait analysis, kinematic analysis and stability analysis of the mechanism are carried out to verify the structural design parameters. The simulation results validate the feasibility of walking on rugged terrain. Experiments with a physical prototype show that the novel biped walking robot can walk stably on smooth terrain. Due to its unique feet design and high stiffness, the biped walking robot may adapt to rugged terrain and is suitable for load-carrying.

  15. Neuromuscular control of anguilliform locomotion: patterns of red and white muscle activity during swimming in the american eel anguilla rostrata

    PubMed

    Gillis

    1998-12-01

    Two areas that have received substantial attention in investigations of muscle activity during fish swimming are (1) patterns of fiber type recruitment with swimming speed and (2) the timing of muscle activation in relation to muscle strain. Currently, very little is known about either of these areas in eels, which represent an extreme body form among fishes and utilize a mode of locomotion found at one end of the undulatory spectrum (anguilliform locomotion). To assess how this swimming mode and body form influence the neuromuscular control of swimming, I recorded electromyographic data from red and white muscle at four positions, 0.3L, 0.45L, 0.6L and 0.75L, where L is body length, in eels (Anguilla rostrata) simultaneously video-taped (250 fields s-1) swimming at three speeds, 0.5, 0.75 and 1.0 L s-1. As in other fish, exclusively red muscle is used at slow swimming speeds and white muscle is additionally recruited at higher swimming speeds. However, this study also revealed a novel posterior-to-anterior pattern of muscle recruitment with increasing swimming speed. At slow speeds, anteriorly located muscles are never active, muscle strain is negligible and forward thrust must be generated by posterior muscles. As speed increases, more anterior muscles are additionally recruited. Electromyogram (EMG) burst durations typically occupy between 0.2 and 0.3 undulatory cycles, irrespective of speed or position. EMG burst intensity increases significantly with swimming speed. The onset of EMG activity typically occurred near the end of muscle lengthening, whereas the offset of EMG activity occurred during shortening (typically before the muscle's return to resting length). There was a significant shift in red muscle onset times such that anterior muscles were typically active later in their strain cycle than posterior muscles. When red muscle activity patterns across various fish taxa are compared, differences in propulsive wavelength among species are related to

  16. Motion synthesis and force distribution analysis for a biped robot.

    PubMed

    Trojnacki, Maciej T; Zielińska, Teresa

    2011-01-01

    In this paper, the method of generating biped robot motion using recorded human gait is presented. The recorded data were modified taking into account the velocity available for robot drives. Data includes only selected joint angles, therefore the missing values were obtained considering the dynamic postural stability of the robot, which means obtaining an adequate motion trajectory of the so-called Zero Moment Point (ZMT). Also, the method of determining the ground reaction forces' distribution during the biped robot's dynamic stable walk is described. The method was developed by the authors. Following the description of equations characterizing the dynamics of robot's motion, the values of the components of ground reaction forces were symbolically determined as well as the coordinates of the points of robot's feet contact with the ground. The theoretical considerations have been supported by computer simulation and animation of the robot's motion. This was done using Matlab/Simulink package and Simulink 3D Animation Toolbox, and it has proved the proposed method.

  17. Dopamine modulation of Ca(2+) dependent Cl(-) current regulates ciliary beat frequency controlling locomotion in Tritonia diomedea.

    PubMed

    Woodward, Owen M; Willows, A O Dennis

    2006-07-01

    The physiological mechanisms controlling ciliary beating remain largely unknown. Evidence exists supporting both hormonal control of ciliary beating and control via direct innervation. In the present study we investigated nervous control of cilia based locomotion in the nudibranch mollusc, Tritonia diomedea. Ciliated pedal epithelial (CPE) cells acting as locomotory effectors may be electrically excitable. To explore this possibility we characterized the cells' electrical properties, and found that CPE cells have large voltage dependent whole cell currents with two components. First, there is a fast activating outward Cl(-) current that is both voltage and Ca(2+) influx dependent (I(Cl(Ca))). I(Cl(Ca)) is sensitive to DIDS and 9-AC, and resembles currents of Ca(2+)-activated Cl(-) channels (CaCC). Ca(2+) dependence also suggests the presence of voltage-gated Ca(2+) channels; however, we were unable to detect these currents. The second current, a voltage dependent proton current (I(H)), activates very slowly and is sensitive to both Zn(2+) and changes in pH. In addition we identify a new cilio-excitatory substance in Tritonia, viz., dopamine. Dopamine, in the 10 mumol l(-1)-1 mmol l(-1) range, significantly increases ciliary beat frequency (CBF). We also found dopamine and Tritonia Pedal Peptide (TPep-NLS) selectively suppress I(Cl(Ca)) in CPE cells, demonstrating a link between CBF excitation and I(Cl(Ca)). It appears that dopamine and TPep-NLS inhibit I(Cl(Ca)) not through changing [Ca(2+)](in), but directly by an unknown mechanism. Coupling of I(Cl(Ca)) and CBF is further supported by our finding that DIDS and zero [Cl(-)](out) both increase CBF, mimicking dopamine and TPep-NLS excitation. These results suggest that dopamine and TPep-NLS act to inhibit I(Cl(Ca)), initiating and prolonging Ca(2+) influx, and activating CBF excitation. PMID:16809466

  18. 40 CFR 1033.335 - Remanufactured locomotives: installation audit requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Manufacturer and... ensure that all emission related components are properly installed on the locomotive and are set to the...,000 miles prior to an audit. (d) A locomotive fails if any emission related components are found to...

  19. Finite State Control of a Variable Impedance Hybrid Neuroprosthesis for Locomotion after Paralysis

    PubMed Central

    Bulea, Thomas C.; Kobetic, R.; Audu, M.L.; Schnellenberger, J.; Triolo, R.J.

    2013-01-01

    We have previously reported on a novel variable impedance knee mechanism (VIKM). The VIKM was designed as a component of a hybrid neuroprosthesis to regulate knee flexion. The hybrid neuroprosthesis is a device that uses a controllable brace to support the body against collapse while stimulation provides power for movement. The hybrid neuroprosthesis requires a control system to coordinate the actions of the VIKM with the stimulation system; the development and evaluation of such a controller is presented. Brace mounted sensors and a baseline open loop stimulation pattern are utilized as control signals to activate the VIKM during stance phase while simultaneously modulating muscle stimulation in an on-off fashion. The objective is twofold: reduce the amount of stimulation necessary for walking while simultaneously restoring more biologically correct knee motion during stance using the VIKM. Custom designed hardware and software components were developed for controller implementation. The VIKM hybrid neuroprosthesis (VIKM-HNP) was evaluated during walking in one participant with thoracic level spinal cord injury. In comparison to walking with functional neuromuscular stimulation (FNS) alone, the VIKM-HNP restored near normal stance phase knee flexion during loading response and pre-swing phases while decreasing knee extensor stimulation by up to 40%. PMID:23193320

  20. Circalunidian clocks control tidal rhythms of locomotion in the American horseshoe crab, Limulus polyphemus

    PubMed Central

    Chabot, Christopher C.; Ramberg-Pihl, Nicole C.; Watson, Winsor H.

    2016-01-01

    While many intertidal animals exhibit circatidal rhythms, the nature of the underlying endogenous clocks that control these rhythms has been controversial. In this study American horseshoe crabs, Limulus polyphemus, were used to test the circalunidian hypothesis by exposing them to four different tidal regimes. Overall, the results obtained support the circalunidian hypothesis: each of the twice-daily rhythms of activity appears to be controlled by a separate clock, each with an endogenous period of approximately 24.8h. First, spontaneous “skipping” of one of the daily bouts was observed under several different conditions. Second, the presence of two bouts of activity/day, with different periods, was observed. Lastly, we were able to separately synchronize bouts of activity to two artificial tidal regimes with different periods. These results, taken together, argue in favor of two separate circalunidian clocks in Limulus, each of which controls one of the two bouts of their daily tidal activity rhythms. PMID:27559270

  1. Neural Computation Scheme of Compound Control: Tacit Learning for Bipedal Locomotion

    NASA Astrophysics Data System (ADS)

    Shimoda, Shingo; Kimura, Hidenori

    The growing need for controlling complex behaviors of versatile robots working in unpredictable environment has revealed the fundamental limitation of model-based control strategy that requires precise models of robots and environments before their operations. This difficulty is fundamental and has the same root with the well-known frame problem in artificial intelligence. It has been a central long standing issue in advanced robotics, as well as machine intelligence, to find a prospective clue to attack this fundamental difficulty. The general consensus shared by many leading researchers in the related field is that the body plays an important role in acquiring intelligence that can conquer unknowns. In particular, purposeful behaviors emerge during body-environment interactions with the help of an appropriately organized neural computational scheme that can exploit what the environment can afford. Along this line, we propose a new scheme of neural computation based on compound control which represents a typical feature of biological controls. This scheme is based on classical neuron models with local rules that can create macroscopic purposeful behaviors. This scheme is applied to a bipedal robot and generates the rhythm of walking without any model of robot dynamics and environments.

  2. Aerial locomotion in flies and robots: kinematic control and aerodynamics of oscillating wings.

    PubMed

    Lehmann, Fritz-Olaf

    2004-07-01

    Flight in flies results from a feedback cascade in which the animal converts mechanical power produced by the flight musculature into aerodynamic forces. A major goal of flight research is to understand the functional significance of the various components in this cascade ranging from the generation of the neural code, the control of muscle mechanical power output, wing kinematics and unsteady aerodynamic mechanisms. Here, I attempted to draw a broad outline on fluid dynamic mechanisms found in flapping insect wings such as leading edge vorticity, rotational circulation and wake capture momentum transfer, as well as on the constraints of flight force control by the neuromuscular system of the fruit fly Drosophila. This system-level perspective on muscle control and aerodynamic mechanisms is thought to be a fundamental bridge in any attempt to link the function and performance of the various flight components with their particular role for wing motion and aerodynamic control in the behaving animal. Eventually, this research might facilitate the development of man-made biomimetic autonomous micro air vehicles using flapping wing motion for propulsion that are currently under construction by engineers. PMID:18089042

  3. 49 CFR 236.770 - Locomotive.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.770 Locomotive. A self... 49 Transportation 4 2010-10-01 2010-10-01 false Locomotive. 236.770 Section 236.770 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT...

  4. A feasibility study on the design and walking operation of a biped locomotor via dynamic simulation

    NASA Astrophysics Data System (ADS)

    Wang, Mingfeng; Ceccarelli, Marco; Carbone, Giuseppe

    2016-06-01

    A feasibility study on the mechanical design and walking operation of a Cassino biped locomotor is presented in this paper. The biped locomotor consists of two identical 3 degrees-of-freedom tripod leg mechanisms with a parallel manipulator architecture. Planning of the biped walking gait is performed by coordinating the motions of the two leg mechanisms and waist. A threedimensional model is elaborated in SolidWorks® environment in order to characterize a feasible mechanical design. Dynamic simulation is carried out in MSC.ADAMS® environment with the aims of characterizing and evaluating the dynamic walking performance of the proposed design. Simulation results show that the proposed biped locomotor with proper input motions of linear actuators performs practical and feasible walking on flat surfaces with limited actuation and reaction forces between its feet and the ground. A preliminary prototype of the biped locomotor is built for the purpose of evaluating the operation performance of the biped walking gait of the proposed locomotor.

  5. Anticipatory control and spatial cognition in locomotion and navigation through typical development and in cerebral palsy.

    PubMed

    Belmonti, Vittorio; Cioni, Giovanni; Berthoz, Alain

    2016-03-01

    Behavioural evidence, summarized in this narrative review, supports a developmental model of locomotor control based on increasing neural integration of spatial reference frames. Two consistent adult locomotor behaviours are head stabilization and head anticipation: the head is stabilized to gravity and leads walking direction. This cephalocaudal orienting organization aligns gaze and vestibula with a reference frame centred on the upcoming walking direction, allowing anticipatory control on body kinematics, but is not fully developed until adolescence. Walking trajectories and those of hand movements share many aspects, including power laws coupling velocity to curvature, and minimized spatial variability. In fact, the adult brain can code trajectory geometry in an allocentric reference frame, irrespective of the end effector, regulating body kinematics thereafter. Locomotor trajectory formation, like head anticipation, matures in early adolescence, indicating common neurocomputational substrates. These late-developing control mechanisms can be distinguished from biomechanical problems in children with cerebral palsy (CP). Children's performance on a novel navigation test, the Magic Carpet, indicates that typical navigation development consists of the increasing integration of egocentric and allocentric reference frames. In CP, right-brain impairment seems to reduce navigation performance due to a maladaptive left-brain sequential egocentric strategy. Spatial integration should be considered more in rehabilitation. PMID:27027604

  6. Adaptation to elastic loads and BMI robot controls during rat locomotion examined with point-process GLMs.

    PubMed

    Song, Weiguo; Cajigas, Iahn; Brown, Emery N; Giszter, Simon F

    2015-01-01

    Currently little is known about how a mechanically coupled BMI system's actions are integrated into ongoing body dynamics. We tested a locomotor task augmented with a BMI system driving a robot mechanically interacting with a rat under three conditions: control locomotion (BL), "simple elastic load" (E) and "BMI with elastic load" (BMI/E). The effect of the BMI was to allow compensation of the elastic load as a function of the neural drive. Neurons recorded here were close to one another in cortex, all within a 200 micron diameter horizontal distance of one another. The interactions of these close assemblies of neurons may differ from those among neurons at longer distances in BMI tasks and thus are important to explore. A point process generalized linear model (GLM), was used to examine connectivity at two different binning timescales (1 ms vs. 10 ms). We used GLM models to fit non-Poisson neural dynamics solely using other neurons' prior neural activity as covariates. Models at different timescales were compared based on Kolmogorov-Smirnov (KS) goodness-of-fit and parsimony. About 15% of cells with non-Poisson firing were well fitted with the neuron-to-neuron models alone. More such cells were fitted at the 1 ms binning than 10 ms. Positive connection parameters ("excitation" ~70%) exceeded negative parameters ("inhibition" ~30%). Significant connectivity changes in the GLM determined networks of well-fitted neurons occurred between the conditions. However, a common core of connections comprising at least ~15% of connections persisted between any two of the three conditions. Significantly almost twice as many connections were in common between the two load conditions (~27%), compared to between either load condition and the baseline. This local point process GLM identified neural correlation structure and the changes seen across task conditions in the rats in this neural subset may be intrinsic to cortex or due to feedback and input reorganization in adaptation.

  7. Electrokinetic Locomotion

    NASA Astrophysics Data System (ADS)

    Moran, Jeffrey Lawrence

    occurring in the interfacial layer near the particle/solution interface, which play a key role in the locomotion. The model enables one to understand how the rods' motion depends on the properties of their environment, such as hydrogen peroxide concentration, solution electrical conductivity, and solution viscosity. The numerical simulations are complemented with a scaling analysis based on the governing equations, which makes definite, verifiable predictions of these dependences. One of the most important trends that has been observed experimentally is the significant decrease in speed induced by adding sub-millimolar concentrations of inert electrolyte. It is important to understand the physical reasons for the electrolyte-induced speed decrease, in order to know whether it is fundamental to this propulsion mechanism, or if there is some feasible means to circumvent it. Successful completion of this research will result in an improved understanding of the capabilities, as well as the risks and limits of applicability, of the bimetallic nanomotors for applications in nanotechnology and nanomedicine. Potential applications of the rods include the targeted delivery of drugs in the human body, sensing of chemical impurities in drinking water, and as engines to drive fabrication of microscale structures.

  8. Investigating the potential role of TRPA1 in locomotion and cardiovascular control during hypertension

    PubMed Central

    Bodkin, Jennifer V; Thakore, Pratish; Aubdool, Aisah A; Liang, Lihuan; Fernandes, Elizabeth S; Nandi, Manasi; Spina, Domenico; Clark, James E; Aaronson, Philip I; Shattock, Michael J; Brain, Susan D

    2014-01-01

    Radiotelemetry was used to investigate the in vivo cardiovascular and activity phenotype of both TRPA1 (transient receptor potential ankyrin 1) wild-type (WT) and TRPA1 knockout (KO) mice. After baseline recording, experimental hypertension was induced using angiotensin II infusion (1.1 mg−1 kg−1 a day, for 14 days). TRPA1 WT and KO mice showed similar morphological and functional cardiovascular parameters, including similar basal blood pressure (BP), heart rate, size, and function. Similar hypertension was also displayed in response to angiotensin II (156 ± 7 and 165 ± 11 mmHg, systolic BP ± SEM, n = 5–6). TRPA1 KO mice showed increased hypertensive hypertrophy (heart weight:tibia length: 7.3 ± 1.6 mg mm−1 vs. 8.8 ± 1.7 mg mm−1) and presented with blunted interleukin 6 (IL-6) production compared with hypertensive WT mice (151 ± 24 vs. 89 ± 16 pg mL−1). TRPA1 expression in dorsal root ganglion (DRG) neurones was upregulated during hypertension (163% of baseline expression). Investigations utilizing the TRPA1 agonist cinnamaldehyde (CA) on mesenteric arterioles isolated from näive mice suggested a lack of TRPA1-dependent vasoreactivity in this vascular bed; a site with notable ability to alter total peripheral resistance. However, mesenteric arterioles isolated from TRPA1 KO hypertensive mice displayed significantly reduced ability to relax in response to nitric oxide (NO) (P < 0.05). Unexpectedly, naïve TRPA1 KO mice also displayed physical hyperactivity traits at baseline, which was exacerbated during hypertension. In conclusion, our study provides a novel cardiovascular characterization of TRPA1 KO mice in a model of hypertension. Results suggest that TRPA1 has a limited role in global cardiovascular control, but we demonstrate an unexpected capacity for TRPA1 to regulate physical activity. PMID:25505598

  9. A dynamical systems analysis of afferent control in a neuromechanical model of locomotion: II. Phase asymmetry

    NASA Astrophysics Data System (ADS)

    Spardy, Lucy E.; Markin, Sergey N.; Shevtsova, Natalia A.; Prilutsky, Boris I.; Rybak, Ilya A.; Rubin, Jonathan E.

    2011-10-01

    In this paper we analyze a closed loop neuromechanical model of locomotor rhythm generation. The model is composed of a spinal central pattern generator (CPG) and a single-joint limb, with CPG outputs projecting via motoneurons to muscles that control the limb and afferent signals from the muscles feeding back to the CPG. In a preceding companion paper (Spardy et al 2011 J. Neural Eng. 8 065003), we analyzed how the model generates oscillations in the presence or absence of feedback, identified curves in a phase plane associated with the limb that signify where feedback levels induce phase transitions within the CPG, and explained how increasing feedback strength restores oscillations in a model representation of spinal cord injury; from these steps, we derived insights about features of locomotor rhythms in several scenarios and made predictions about rhythm responses to various perturbations. In this paper, we exploit our analytical observations to construct a reduced model that retains important characteristics from the original system. We prove the existence of an oscillatory solution to the reduced model using a novel version of a Melnikov function, adapted for discontinuous systems, and also comment on the uniqueness and stability of this solution. Our analysis yields a deeper understanding of how the model must be tuned to generate oscillations and how the details of the limb dynamics shape overall model behavior. In particular, we explain how, due to the feedback signals in the model, changes in the strength of a tonic supra-spinal drive to the CPG yield asymmetric alterations in the durations of different locomotor phases, despite symmetry within the CPG itself.

  10. The intertarsal joint of the ostrich (Struthio camelus): Anatomical examination and function of passive structures in locomotion

    PubMed Central

    Schaller, Nina U; Herkner, Bernd; Villa, Rikk; Aerts, Peter

    2009-01-01

    The ostrich (Struthio camelus) is the largest extant biped. Being flightless, it exhibits advanced cursorial abilities primarily evident in its characteristic speed and endurance. In addition to the active musculoskeletal complex, its powerful pelvic limbs incorporate passive structures wherein ligaments interact with joint surfaces, cartilage and other connective tissue in their course of motion. This arrangement may enable energy conservation by providing joint stabilisation, optimised limb segment orientation and automated positioning of ground contact elements independently of direct muscle control. The intertarsal joint is of particular interest considering its position near the mid-point of the extended limb and its exposure to high load during stance with significant inertial forces during swing phase. Functional-anatomical analysis of the dissected isolated joint describes the interaction of ligaments with intertarsal joint contours through the full motion cycle. Manual manipulation identified a passive engage-disengage mechanism (EDM) that establishes joint extension, provides bi-directional resistance prior to a transition point located at 115° and contributes to rapid intertarsal flexion at toe off and full extension prior to touch down. This effect was subsequently quantified by measurement of intertarsal joint moments in prepared anatomical specimens in a neutral horizontal position and axially-loaded vertical position. Correlation with kinematic analyses of walking and running ostriches confirms the contribution of the EDM in vivo. We hypothesise that the passive EDM operates in tandem with a stringently coupled multi-jointed muscle-tendon system to conserve the metabolic cost of locomotion in the ostrich, suggesting that a complete understanding of terrestrial locomotion across extinct and extant taxa must include functional consideration of the ligamentous system. PMID:19538629

  11. Minimal feedback to a rhythm generator improves the robustness to slope variations of a compass biped.

    PubMed

    Spitz, Jonathan; Evstrachin, Alexandrina; Zacksenhouse, Miriam

    2015-10-01

    In recent years there has been a growing interest in the field of dynamic walking and bio-inspired robots. However, while walking and running on a flat surface have been studied extensively, walking dynamically over terrains with varying slope remains a challenge. Previously we developed an open loop controller based on a central pattern generator (CPG). The controller applied predefined torque patterns to a compass-gait biped, and achieved stable gaits over a limited range of slopes. In this work, this range is greatly extended by applying a once per cycle feedback to the CPG controller. The terrain's slope is measured and used to modify both the CPG frequency and the torque amplitude once per step. A multi-objective optimization algorithm was used to tune the controller parameters for a simulated CB model. The resulting controller successfully traverses terrains with slopes ranging from +7° to -8°, comparable to most slopes found in human constructed environments. Gait stability was verified by computing the linearized Poincaré Map both numerically and analytically. PMID:26291076

  12. Simulation of a Hybrid Locomotion Robot Vehicle

    NASA Astrophysics Data System (ADS)

    Aarnio, P.

    2002-10-01

    This study describes a simulation process of a mobile robot. The focus is in kinematic and dynamic behavior simulations of hybrid locomotion robot vehicles. This research is motivated by the development needs of the WorkPartner field service robot. The whole robot system consists of a mobile platform and a two-hand manipulator. The robot platform, called Hybtor, is a hybrid locomotion robot capable of walking and driving by wheels as well as combining these two locomotion modes. This study describes first the general problems and their solutions in the dynamic simulation of mobile robots. A kinematic and dynamic virtual model of the Hybtor robot was built and simulations were carried out using one commercial simulation tool. Walking, wheel driven and rolking mode locomotion, which is a special hybrid locomotion style, has been simulated and analyzed. Position and force control issues during obstacle overrun and climbing were also studied.

  13. Neuromusculoskeletal models based on the muscle synergy hypothesis for the investigation of adaptive motor control in locomotion via sensory-motor coordination.

    PubMed

    Aoi, Shinya; Funato, Tetsuro

    2016-03-01

    Humans and animals walk adaptively in diverse situations by skillfully manipulating their complicated and redundant musculoskeletal systems. From an analysis of measured electromyographic (EMG) data, it appears that despite complicated spatiotemporal properties, muscle activation patterns can be explained by a low dimensional spatiotemporal structure. More specifically, they can be accounted for by the combination of a small number of basic activation patterns. The basic patterns and distribution weights indicate temporal and spatial structures, respectively, and the weights show the muscle sets that are activated synchronously. In addition, various locomotor behaviors have similar low dimensional structures and major differences appear in the basic patterns. These analysis results suggest that neural systems use muscle group combinations to solve motor control redundancy problems (muscle synergy hypothesis) and manipulate those basic patterns to create various locomotor functions. However, it remains unclear how the neural system controls such muscle groups and basic patterns through neuromechanical interactions in order to achieve adaptive locomotor behavior. This paper reviews simulation studies that explored adaptive motor control in locomotion via sensory-motor coordination using neuromusculoskeletal models based on the muscle synergy hypothesis. Herein, the neural mechanism in motor control related to the muscle synergy for adaptive locomotion and a potential muscle synergy analysis method including neuromusculoskeletal modeling for motor impairments and rehabilitation are discussed. PMID:26616311

  14. 40 CFR 92.707 - Notification to locomotive or locomotive engine owners.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... defined in 40 CFR part 92. These standards or family emission limits, as defined in 40 CFR part 92 were established to protect the public health or welfare from the dangers of air pollution.” (2) A statement that... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES...

  15. 40 CFR 92.707 - Notification to locomotive or locomotive engine owners.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... defined in 40 CFR part 92. These standards or family emission limits, as defined in 40 CFR part 92 were established to protect the public health or welfare from the dangers of air pollution.” (2) A statement that... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES...

  16. 40 CFR 92.707 - Notification to locomotive or locomotive engine owners.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... defined in 40 CFR part 92. These standards or family emission limits, as defined in 40 CFR part 92 were... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Recall... manufacturer or remanufacturer, which may be used to report difficulty in obtaining recall repairs. (10)...

  17. 40 CFR 92.707 - Notification to locomotive or locomotive engine owners.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... defined in 40 CFR part 92. These standards or family emission limits, as defined in 40 CFR part 92 were... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Recall... manufacturer or remanufacturer, which may be used to report difficulty in obtaining recall repairs. (10)...

  18. 40 CFR 92.707 - Notification to locomotive or locomotive engine owners.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... defined in 40 CFR part 92. These standards or family emission limits, as defined in 40 CFR part 92 were... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Recall... manufacturer or remanufacturer, which may be used to report difficulty in obtaining recall repairs. (10)...

  19. Biped 4R2C six-bar mechanism with inner and outer feet

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Wang, Hao; Yao, Yan-an

    2016-01-01

    Most current biped robots are equipped with two feet arranged in the right and left which inspired by the human body system. Different from the existing configurations, a novel biped robot with inner and outer feet based on a spatial six-bar 4R2C(R and C denote revolute and cylindric joints, respectively) mechanism is proposed. It can move along a line or a curve by three walking modes that are dwell adjustment mode, limit position adjustment mode and any position adjustment mode. Kinematic, gait planning and stability analyses are performed respectively, and a prototype is developed. Lastly, a potential application is considered and two manipulating modes(sphere and cylinder manipulating modes) are carried out. This interesting mechanism feathering its single closed-chain structure and unique work performance is expected to motivate the configuration creation of biped robots.

  20. Evidence from knockout mice for distinct implications of neuropeptide-Y Y2 and Y4 receptors in the circadian control of locomotion, exploration, water and food intake.

    PubMed

    Edelsbrunner, M E; Painsipp, E; Herzog, H; Holzer, P

    2009-12-01

    Members of the neuropeptide-Y (NPY) family acting via Y2 and/or Y4 receptors have been proposed to participate in the control of ingestive behaviour and energy homeostasis. Since these processes vary between day and night, we explored the circadian patterns of locomotor, exploratory and ingestive behaviour in mice with disrupted genes for Y2 (Y2-/-) or Y4 (Y4-/-) receptors. To this end, the LabMaster system was used and its utility for the analysis of changes in circadian activity and ingestion caused by gene knockout evaluated. Female animals, aged 27weeks on average, were housed singly in cages fitted with sensors for water and food intake and two infrared frames for recording ambulation and rearing under a 12h light/dark cycle for 4days. Relative to WT animals, diurnal locomotion, exploration, drinking and feeding were reduced, whereas nocturnal locomotion was enhanced in Y2-/- mice. In contrast, Y4-/- mice moved more but ate and drank less during the photophase, while they ate more and explored less during the scotophase. Both Y2-/- and Y4-/- mice weighed more than WT mice. These findings attest to a differential role of Y2 and Y4 receptor signalling in the circadian control of behaviours that balance energy intake and energy expenditure. These phenotypic traits can be sensitively and continuously recorded by the LabMaster system.

  1. Dynamic stability and phase resetting during biped gait

    NASA Astrophysics Data System (ADS)

    Nomura, Taishin; Kawa, Kazuyoshi; Suzuki, Yasuyuki; Nakanishi, Masao; Yamasaki, Taiga

    2009-06-01

    Dynamic stability during periodic biped gait in humans and in a humanoid robot is considered. Here gait systems of human neuromusculoskeletal system and a humanoid are simply modeled while keeping their mechanical properties plausible. We prescribe periodic gait trajectories in terms of joint angles of the models as a function of time. The equations of motion of the models are then constrained by one of the prescribed gait trajectories to obtain types of periodically forced nonlinear dynamical systems. Simulated gait of the models may or may not fall down during gait, since the constraints are made only for joint angles of limbs but not for the motion of the body trunk. The equations of motion can exhibit a limit cycle solution (or an oscillatory solution that can be considered as a limit cycle practically) for each selected gait trajectory, if an initial condition is set appropriately. We analyze the stability of the limit cycle in terms of Poincaré maps and the basin of attraction of the limit cycle in order to examine how the stability depends on the prescribed trajectory. Moreover, the phase resetting of gait rhythm in response to external force perturbation is modeled. Since we always prescribe a gait trajectory in this study, reacting gait trajectories during the phase resetting are also prescribed. We show that an optimally prescribed reacting gait trajectory with an appropriate amount of the phase resetting can increase the gait stability. Neural mechanisms for generation and modulation of the gait trajectories are discussed.

  2. BIPES, a cost-effective high-throughput method for assessing microbial diversity.

    PubMed

    Zhou, Hong-Wei; Li, Dong-Fang; Tam, Nora Fung-Yee; Jiang, Xiao-Tao; Zhang, Hai; Sheng, Hua-Fang; Qin, Jin; Liu, Xiao; Zou, Fei

    2011-04-01

    Pyrosequencing of 16S rRNA (16S) variable tags has become the most popular method for assessing microbial diversity, but the method remains costly for the evaluation of large numbers of environmental samples with high sequencing depths. We developed a barcoded Illumina paired-end (PE) sequencing (BIPES) method that sequences each 16S V6 tag from both ends on the Illumina HiSeq 2000, and the PE reads are then overlapped to obtain the V6 tag. The average accuracy of Illumina single-end (SE) reads was only 97.9%, which decreased from ∼99.9% at the start of the read to less than 85% at the end of the read; nevertheless, overlapping of the PE reads significantly increased the sequencing accuracy to 99.65% by verifying the 3' end of each SE in which the sequencing quality was degraded. After the removal of tags with two or more mismatches within the medial 40-70 bases of the reads and of tags with any primer errors, the overall base sequencing accuracy of the BIPES reads was further increased to 99.93%. The BIPES reads reflected the amounts of the various tags in the initial template, but long tags and high GC tags were underestimated. The BIPES method yields 20-50 times more 16S V6 tags than does pyrosequencing in a single-flow cell run, and each of the BIPES reads costs less than 1/40 of a pyrosequencing read. As a laborsaving and cost-effective method, BIPES can be routinely used to analyze the microbial ecology of both environmental and human microbiomes.

  3. Adaptation in Human Balance Control: Lessons for Biomimetic Robotic Bipeds

    PubMed Central

    Mahboobin, Arash; Loughlin, Patrick J.; Redfern, Mark S.; Anderson, Stuart O.; Atkeson, Christopher G.; Hodgins, Jessica K.

    2008-01-01

    This paper describes mechanisms used by humans to stand on moving platforms, such as a bus or ship, and to combine body orientation and motion information from multiple sensors including vision, vestibular, and proprioception. A simple mechanism, sensory re-weighting, has been proposed to explain how human subjects learn to reduce the effects of inconsistent sensors on balance. Our goal is to replicate this robust balance behavior in bipedal robots. We review results exploring sensory re-weighting in humans and describe implementations of sensory re-weighting in simulation and on a robot. PMID:18555957

  4. Impact of locomotion training with a neurologic controlled hybrid assistive limb (HAL) exoskeleton on neuropathic pain and health related quality of life (HRQoL) in chronic SCI: a case study (.).

    PubMed

    Cruciger, Oliver; Schildhauer, Thomas A; Meindl, Renate C; Tegenthoff, Martin; Schwenkreis, Peter; Citak, Mustafa; Aach, Mirko

    2016-08-01

    Chronic neuropathic pain (CNP) is a common condition associated with spinal cord injury (SCI) and has been reported to be severe, disabling and often treatment-resistant and therefore remains a clinical challenge for the attending physicians. The treatment usually includes pharmacological and/or nonpharmacological approaches. Body weight supported treadmill training (BWSTT) and locomotion training with driven gait orthosis (DGO) have evolved over the last decades and are now considered to be an established part in the rehabilitation of SCI patients. Conventional locomotion training goes along with improvements of the patients' walking abilities in particular speed and gait pattern. The neurologic controlled hybrid assistive limb (HAL®, Cyberdyne Inc., Ibraki, Japan) exoskeleton, however, is a new tailored approach to support motor functions synchronously to the patient's voluntary drive. This report presents two cases of severe chronic and therapy resistant neuropathic pain due to chronic SCI and demonstrates the beneficial effects of neurologic controlled exoskeletal intervention on pain severity and health-related quality of life (HRQoL). Both of these patients were engaged in a 12 weeks period of daily HAL®-supported locomotion training. In addition to improvements in motor functions and walking abilities, both show significant reduction in pain severity and improvements in all HRQoL domains. Although various causal factors likely contribute to abatement of CNP, the reported results occurred due to a new approach in the rehabilitation of chronic spinal cord injury patients. These findings suggest not only the feasibility of this new approach but in conclusion, demonstrate the effectiveness of neurologic controlled locomotion training in the long-term management of refractory neuropathic pain. Implications for Rehabilitation CNP remains a challenge in the rehabilitation of chronic SCI patients. Locomotion training with the HAL exoskeleton seems to improve CNP

  5. The effects of distant and on-line visual information on the control of approach phase and step over an obstacle during locomotion.

    PubMed

    Mohagheghi, Amir A; Moraes, Renato; Patla, Aftab E

    2004-04-01

    One of the goals of this study was to examine the nature and role of distant visual information sampled during locomotion in the feedforward control of leading and trailing limb while an individual is required to step over an obstacle in the travel path. In addition we were interested in whether or not on-line visual information available while the limb (lead or trail) is stepping over the obstacle influences limb trajectory control and whether the information provided during lead limb cross would be used to calibrate movement of the trail limb. Towards this end, we manipulated availability of vision following an initial dynamic sampling period during the approach phase in proximity to the obstacle and during the lead and trail limb stepping over the obstacle. Ten participants completed 40 trials of obstacle crossing in 8 testing conditions. Initial dynamic visual sampling was sufficient to ensure successful task performance in the absence of vision in the approach phase and during both lead and trail limb stepping over the obstacle. Despite successful task performance, foot placement of the lead and trail limb before obstacle crossing and limb elevation over the obstacle were increased after withdrawal of vision in the approach area. Furthermore, the correlation between toe clearance and foot placement was diminished. While both limbs require feedforward visual information to control the step over the obstacle, only lead limb elevation was influenced by availability of on-line visual information during obstacle crossing. Results were in agreement with the notion of primacy of information inherent in the optic array over those from static samples of the environment in guiding locomotion. It is suggested that the expected proprioceptive feedback information associated with the limb posture before the obstacle, reconstructed using visual memory from dynamic sampling of the environment, mismatched with those from the actual limb position. Accordingly, participants

  6. A contribution about ferrofluid based flow manipulation and locomotion systems

    NASA Astrophysics Data System (ADS)

    Zimmermann, K.; Zeidis, I.; Bohm, V.; Popp, J.

    2009-02-01

    With the background of developing apedal bionic inspired locomotion systems for future application fields like autonomous (swarm) robots, medical engineering and inspection systems, this article presents a selection of locomotion systems with bifluidic flow control using ferrofluid. By controlling the change of shape, position and pressure of the ferrofluid in a secondary low viscous fluid by magnetic fields locomotion of objects or the ferrofluid itself can be realised. The locomotion of an object is caused in the first example by a ferrofluid generated flow of the secondary fluid and in the second and third case by the direct alteration of the ferrofluid position.

  7. 40 CFR 1033.640 - Provisions for repowered and refurbished locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Special Compliance Provisions § 1033... 3000 hp may not generate emission credits relative to the standards specified in paragraph (e)(1)(i) of...: “REFURBISHED LOCOMOTIVE EMISSION CONTROL INFORMATION.” (ii) The statement identifying when the locomotive...

  8. Lateral oscillations of the center of mass of bipeds as they walk. Inverted pendulum model with two degrees of freedom

    NASA Astrophysics Data System (ADS)

    H Goldsztein, Guillermo

    2015-10-01

    The use of inverted pendulum models to study the bio-mechanics of biped walkers is a common practice. In its simplest form, the inverted pendulum consists of a point mass, which models the center of mass of the biped, attached to two straight mass-less legs. Most works using the simplest inverted pendulum model constrain the mass and the legs to the sagittal plane (the plane that contains the direction perpendicular to the ground and the direction toward the biped is walking). In this article, we remove this constrain and use this unconstrained inverted pendulum model to study the oscillations the mass experiences in the direction perpendicular to the sagittal plane as the biped walks. While small, these oscillations are unavoidable and of importance in the understanding of balance and stability of walkers, as well as walkers induced oscillations in pedestrian bridges.

  9. Control of material strength in a fluidized bed to discover principles of animal foot impact during locomotion

    NASA Astrophysics Data System (ADS)

    Goldman, D. I.; Korff, W. L.; Full, R. J.

    2004-11-01

    We study the impact of flat disks (≈ 1 cm diameter) into a deep (800 particle diameters) bed of 250 μ m glass spheres of fixed volume fraction φ, and use a vertical flow of air (a fluidized bed) to change the material properties of the medium. By applying a series of air pulses to the bed we can achieve 0.57<φ<0.64; increasing the number of pulses increases φ, strengthening the material. A constant flow Q below the onset of bed fluidization weakens the solid: at fixed φ the penetration depth of a disk increases with increasing Q. We use this discovery to address a long-standing issue in animal locomotion -- the interaction of feet with the ground. We measure the average speed, foot impact depth, and foot contact time as a function of material strength for the desert-dwelling lizard Callisaurus draconoides (length 16 cm, mass=20 g) during rapid running on sand. The animal maintains high speed (1.4 m/sec) even when foot penetration depth varies as we manipulate material strength.

  10. 49 CFR 236.509 - Two or more locomotives coupled.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Two or more locomotives coupled. 236.509 Section..., INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Standards § 236.509 Two or more locomotives...

  11. A study of the passive gait of a compass-like biped robot: Symmetry and chaos

    SciTech Connect

    Goswami, A.; Espiau, B.; Thuilot, B.

    1998-12-01

    The focus of this work is a systematic study of the passive gait of a compass-like planar, biped robot on inclined slopes. The robot is kinematically equivalent to a double pendulum, possessing two kneeless legs with point masses and a third point mass at the hip joint. Three parameters, namely, the ground-slope angle and the normalized mass and length of the robot describe its gait. The authors show that in response to a continuous change in any one of its parameters, the symmetric and steady stable gait of the unpowered robot gradually evolves through a regime of bifurcations characterized by progressively complicated asymmetric gaits, eventually arriving at an apparently chaotic gait where not two steps are identical. The robot can maintain this gait indefinitely. A necessary (but not sufficient) condition for the stability of such gaits is the contraction of the phase-fluid volume. For this frictionless robot, the volume contraction, which the authors compute, is caused by the dissipative effects of the ground-impact model. In the chaotic regime, the fractal dimension of the robot`s strange attractor (2.07) compared to its state-space dimension (4) also reveals strong contraction. The authors present a novel graphical technique based on the first return map that compactly captures the entire evolution of the gait, from symmetry to chaos. Additional passive dissipative elements in the robot joint results in a significant improvement in the stability and the versatility of the gait, and provide a rich repertoire for simple controls laws.

  12. Axial dynamics during locomotion in vertebrates lesson from the salamander.

    PubMed

    Cabelguen, Jean-Marie; Ijspeert, Auke; Lamarque, Stéphanie; Ryczko, Dimitri

    2010-01-01

    Much of what we know about the flexibility of the locomotor networks in vertebrates is derived from studies examining the adaptation of limb movements during stepping in various conditions. However, the body movements play important roles during locomotion: they produce the thrust during undulatory locomotion and they help to increase the stride length during legged locomotion. In this chapter, we review our current knowledge about the flexibility in the neuronal circuits controlling the body musculature during locomotion. We focus especially on salamander because, as an amphibian, this animal is able to display a rich repertoire of aquatic and terrestrial locomotor modes.

  13. 40 CFR 1033.420 - Maintenance, procurement and testing of in-use locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES In-use Testing § 1033.420... recommended emission-related maintenance requirements. (1) When procuring locomotives for in-use testing, ask... adjustments. (c) If the locomotive selected for testing is equipped with emission diagnostics meeting...

  14. The Need for Speed in Rodent Locomotion Analyses

    PubMed Central

    Batka, Richard J.; Brown, Todd J.; Mcmillan, Kathryn P.; Meadows, Rena M.; Jones, Kathryn J.; Haulcomb, Melissa M.

    2016-01-01

    Locomotion analysis is now widely used across many animal species to understand the motor defects in disease, functional recovery following neural injury, and the effectiveness of various treatments. More recently, rodent locomotion analysis has become an increasingly popular method in a diverse range of research. Speed is an inseparable aspect of locomotion that is still not fully understood, and its effects are often not properly incorporated while analyzing data. In this hybrid manuscript, we accomplish three things: (1) review the interaction between speed and locomotion variables in rodent studies, (2) comprehensively analyze the relationship between speed and 162 locomotion variables in a group of 16 wild-type mice using the CatWalk gait analysis system, and (3) develop and test a statistical method in which locomotion variables are analyzed and reported in the context of speed. Notable results include the following: (1) over 90% of variables, reported by CatWalk, were dependent on speed with an average R2 value of 0.624, (2) most variables were related to speed in a nonlinear manner, (3) current methods of controlling for speed are insufficient, and (4) the linear mixed model is an appropriate and effective statistical method for locomotion analyses that is inclusive of speed-dependent relationships. Given the pervasive dependency of locomotion variables on speed, we maintain that valid conclusions from locomotion analyses cannot be made unless they are analyzed and reported within the context of speed. PMID:24890845

  15. 40 CFR 92.104 - Locomotive and engine testing; overview.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... restriction within 1 inch of water of the upper limit of a typical engine as installed with clean air filters...; overview. 92.104 Section 92.104 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures §...

  16. 40 CFR 92.104 - Locomotive and engine testing; overview.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... restriction within 1 inch of water of the upper limit of a typical engine as installed with clean air filters...; overview. 92.104 Section 92.104 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures §...

  17. Operation analysis of a Chebyshev-Pantograph leg mechanism for a single DOF biped robot

    NASA Astrophysics Data System (ADS)

    Liang, Conghui; Ceccarelli, Marco; Takeda, Yukio

    2012-12-01

    In this paper, operation analysis of a Chebyshev-Pantograph leg mechanism is presented for a single degree of freedom (DOF) biped robot. The proposed leg mechanism is composed of a Chebyshev four-bar linkage and a pantograph mechanism. In contrast to general fully actuated anthropomorphic leg mechanisms, the proposed leg mechanism has peculiar features like compactness, low-cost, and easy-operation. Kinematic equations of the proposed leg mechanism are formulated for a computer oriented simulation. Simulation results show the operation performance of the proposed leg mechanism with suitable characteristics. A parametric study has been carried out to evaluate the operation performance as function of design parameters. A prototype of a single DOF biped robot equipped with two proposed leg mechanisms has been built at LARM (Laboratory of Robotics and Mechatronics). Experimental test shows practical feasible walking ability of the prototype, as well as drawbacks are discussed for the mechanical design.

  18. Suppression of dinoflagellate Peridinium bipes bloom in a reservoir by ultraviolet radiation

    SciTech Connect

    Iseri, Yasushi; Tano, Johichiro; Kawabata, Zen`ichiro

    1995-12-31

    The effect of ultraviolet (UV) radiation with a 253.7 nm wave length on the survival of Peridinium bipes was investigated in a laboratory culture system and in a mesocosm placed in a reservoir. According to the results obtained from those experiments, a boat with UV lamps was developed and optimum operating conditions were examined in situ. This boat could treat a maximum of about 700 m{sup 3} h{sup -1} of lake water and required 5 hours to treat 2.0 x 10{sup 4} m{sup 2} of surface are of lake water containing 1.0 x 10{sup 3} to 5.0 10{sup 4} P. bipes cells ml{sup -1}. The quantity of water treated per hour was 10 times as much as the long hair filtration method which is commonly used.

  19. Fuelcell Prototype Locomotive

    SciTech Connect

    David L. Barnes

    2007-09-28

    An international industry-government consortium is developing a fuelcell hybrid switcher locomotive for commercial railway applications and power-to-grid generation applications. The current phase of this on-going project addresses the practicalities of on-board hydrogen storage, fuelcell technology, and hybridity, all with an emphasis on commercially available products. Through practical evaluation using designs from Vehicle Projects’ Fuelcell-Powered Underground Mine Loader Project, the configuration of the fuelcell switcher locomotive changed from using metal-hydride hydrogen storage and a pure fuelcell power plant to using compressed hydrogen storage, a fuelcell-battery hybrid power plant, and fuelcell stack modules from Ballard Power Systems that have been extensively used in the Citaro bus program in Europe. The new overall design will now use a RailPower battery hybrid Green Goat™ as the locomotive platform. Keeping the existing lead-acid batteries, we will replace the 205 kW diesel gen-set with 225 kW of net fuelcell power, remove the diesel fuel tank, and place 14 compressed hydrogen cylinders, capable of storing 70 kg of hydrogen at 350 bar, on the roof. A detailed design with associated CAD models will allow a complete build of the fuelcell-battery hybrid switcher locomotive in the next funded phase.

  20. Human locomotion and heat loss: an evolutionary perspective.

    PubMed

    Lieberman, Daniel E

    2015-01-01

    Humans are unique in many respects including being furless, striding bipeds that excel at walking and running long distances in hot conditions. This review summarizes what we do and do not know about the evolution of these characteristics, and how they are related. Although many details remain poorly known, the first hominins (species more closely related to humans than to chimpanzees) apparently diverged from the chimpanzee lineage because of selection for bipedal walking, probably because it improved their ability to forage efficiently. However, because bipedal hominins are necessarily slow runners, early hominins in open habitats likely benefited from improved abilities to dump heat in order to forage safely during times of peak heat when predators were unable to hunt them. Endurance running capabilities evolved later, probably as adaptations for scavenging and then hunting. If so, then there would have been strong selection for heat-loss mechanisms, especially sweating, to persistence hunt, in which hunters combine endurance running and tracking to drive their prey into hyperthermia. As modern humans dispersed into a wide range of habitats over the last few hundred thousand years, recent selection has helped populations cope better with a broader range of locomotor and thermoregulatory challenges, but all humans remain essentially adapted for long distance locomotion rather than speed, and to dump rather than retain heat.

  1. Novel locomotion via biological inspiration

    NASA Astrophysics Data System (ADS)

    Quinn, Roger D.; Boxerbaum, Alexander; Palmer, Luther; Chiel, Hillel; Diller, Eric; Hunt, Alexander; Bachmann, Richard

    2011-05-01

    Animal behavioral, physiological and neurobiological studies are providing a wealth of inspirational data for robot design and control. Several very different biologically inspired mobile robots will be reviewed. A robot called DIGbot is being developed that moves independent of the direction of gravity using Distributed Inward Gripping (DIG) as a rapid and robust attachment mechanism observed in climbing animals. DIGbot is an 18 degree of freedom hexapod with onboard power and control systems. Passive compliance in its feet, which is inspired by the flexible tarsus of the cockroach, increases the robustness of the adhesion strategy and enables DIGbot to execute large steps and stationary turns while walking on mesh screens. A Whegs™ robot, inspired by insect locomotion principles, is being developed that can be rapidly reconfigured between tracks and wheel-legs and carry GeoSystems Zipper Mast. The mechanisms that cause it to passively change its gait on irregular terrain have been integrated into its hubs for a compact and modular design. The robot is designed to move smoothly on moderately rugged terrain using its tracks and run on irregular terrain and stairs using its wheel-legs. We are also developing soft bodied robots that use peristalsis, the same method of locomotion earthworms use. We present a technique of using a braided mesh exterior to produce fluid waves of motion along the body of the robot that increase the robot's speed relative to previous designs. The concept is highly scalable, for endoscopes to water, oil or gas line inspection.

  2. Judgments of Path, Not Heading, Guide Locomotion

    ERIC Educational Resources Information Center

    Wilkie, Richard M.; Wann, John P.

    2006-01-01

    To steer a course through the world, people are almost entirely dependent on visual information, of which a key component is optic flow. In many models of locomotion, heading is described as the fundamental control variable; however, it has also been shown that fixating points along or near one's future path could be the basis of an efficient…

  3. 40 CFR 1033.650 - Incidental use exemption for Canadian and Mexican locomotives.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Special Compliance... the United States and that enter the United States temporarily from Canada or Mexico. We will...

  4. A Review of Locomotion Systems for Capsule Endoscopy.

    PubMed

    Liu, Lejie; Towfighian, Shahrzad; Hila, Amine

    2015-01-01

    Wireless capsule endoscopy for gastrointestinal (GI) tract is a modern technology that has the potential to replace conventional endoscopy techniques. Capsule endoscopy is a pill-shaped device embedded with a camera, a coin battery, and a data transfer. Without a locomotion system, this capsule endoscopy can only passively travel inside the GI tract via natural peristalsis, thus causing several disadvantages such as inability to control and stop, and risk of capsule retention. Therefore, a locomotion system needs to be added to optimize the current capsule endoscopy. This review summarizes the state-of-the-art locomotion methods along with the desired locomotion features such as size, speed, power, and temperature and compares the properties of different methods. In addition, properties and motility mechanisms of the GI tract are described. The main purpose of this review is to understand the features of GI tract and diverse locomotion methods in order to create a future capsule endoscopy compatible with GI tract properties. PMID:26292162

  5. Reduction and identification for hybrid dynamical models of terrestrial locomotion

    NASA Astrophysics Data System (ADS)

    Burden, Samuel A.; Sastry, S. Shankar

    2013-06-01

    The study of terrestrial locomotion has compelling applications ranging from design of legged robots to development of novel prosthetic devices. From a first-principles perspective, the dynamics of legged locomotion seem overwhelmingly complex as nonlinear rigid body dynamics couple to a granular substrate through viscoelastic limbs. However, a surfeit of empirical data demonstrates that animals use a small fraction of their available degrees-of-freedom during locomotion on regular terrain, suggesting that a reduced-order model can accurately describe the dynamical variation observed during steady-state locomotion. Exploiting this emergent phenomena has the potential to dramatically simplify design and control of micro-scale legged robots. We propose a paradigm for studying dynamic terrestrial locomotion using empirically-validated reduced{order models.

  6. Evolution and development of neural controllers for locomotion, gradient-following, and obstacle-avoidance in artificial insects.

    PubMed

    Kodjabachian, J; Meyer, J A

    1998-01-01

    This paper describes how the SGOCE paradigm has been used to evolve developmental programs capable of generating recurrent neural networks that control the behavior of simulated insects. This paradigm is characterized by an encoding scheme, by an evolutionary algorithm, by syntactic constraints, and by an incremental strategy that are described in turn. The additional use of an insect model equipped with six legs and two antennae made it possible to generate control modules that allowed it to successively add gradient-following and obstacle-avoidance capacities to walking behavior. The advantages of this evolutionary approach, together with directions for future work, are discussed.

  7. Passive mechanics in jellyfish-like locomotion

    NASA Astrophysics Data System (ADS)

    Wilson, Megan; Eldredge, Jeff

    2008-11-01

    The aim of this work is to identify possible benefits of passive flexibility in biologically-inspired locomotion. Substantial energy savings are likely achieved in natural locomotion by allowing a mix of actively controlled and passively responsive deformation. The jellyfish is a useful target of study, due to its relatively simple structure and the availability of recent kinematics and flow-field measurements. In this investigation, the jellyfish consists of a two-dimensional articulated system of rigid bodies linked by hinges. The kinematics -- expressed via the hinge angles -- are adapted from experimentally measured motion. The free swimming system is explored via high-fidelity numerical simulation with a viscous vortex particle method with coupled body dynamics. The computational tool allows the arbitrary designation of individual hinges as ``active'' or ``passive,'' to introduce a mix of flexibility into the system. In some cases, replacing an active hinge with a passive spring can enhance the mean swimming speed, thus reducing the power requirements of the system. Varying the stiffness and damping coefficients of the spring yield different locomotive results. The numerical solution is used to compute the finite-time Lyapunov exponents (FTLE) throughout the field. The FTLE fields reveal manifolds in the flow that act as transport barriers, uncovering otherwise unseen geometric characteristics of the flow field that add new insight into the locomotion mechanics.

  8. Locomotion: Dealing with friction

    PubMed Central

    Radhakrishnan, V.

    1998-01-01

    To move on land, in water, or in the air, even at constant speed and at the same level, always requires an expenditure of energy. The resistance to motion that has to be overcome is of many different kinds depending on size, speed, and the characteristics of the medium, and is a fascinating subject in itself. Even more interesting are nature’s stratagems and solutions toward minimizing the effort involved in the locomotion of different types of living creatures, and humans’ imitations and inventions in an attempt to do at least as well. PMID:9576902

  9. Forcing contact inhibition of locomotion.

    PubMed

    Roycroft, Alice; Mayor, Roberto

    2015-07-01

    Contact inhibition of locomotion drives a variety of biological phenomenon, from cell dispersion to collective cell migration and cancer invasion. New imaging techniques have allowed contact inhibition of locomotion to be visualised in vivo for the first time, helping to elucidate some of the molecules and forces involved in this phenomenon.

  10. Forcing contact inhibition of locomotion

    PubMed Central

    Roycroft, Alice; Mayor, Roberto

    2015-01-01

    Contact inhibition of locomotion drives a variety of biological phenomenon, from cell dispersion to collective cell migration and cancer invasion. New imaging techniques have allowed contact inhibition of locomotion to be visualised in vivo for the first time, helping to elucidate some of the molecules and forces involved in this phenomenon. PMID:25981318

  11. Locomotion in caterpillars.

    PubMed

    van Griethuijsen, L I; Trimmer, B A

    2014-08-01

    Most species of caterpillar move around by inching or crawling. Their ability to navigate in branching three-dimensional structures makes them particularly interesting biomechanical subjects. The mechanism of inching has not been investigated in detail, but crawling is now well understood from studies on caterpillar neural activity, dynamics and structural mechanics. Early papers describe caterpillar crawling as legged peristalsis, but recent work suggests that caterpillars use a tension-based mechanism that helps them to exploit arboreal niches. Caterpillars are not obligate hydrostats but instead use their strong grip to the substrate to transmit forces, in effect using their environment as a skeleton. In addition, the gut which accounts for a substantial part of the caterpillar's weight, moves independently of the body wall during locomotion and may contribute to crawling dynamics. Work-loop analysis of caterpillar muscles shows that they are likely to act both as actuators and energy dissipaters during crawling. Because caterpillar tissues are pseudo-elastic, and locomotion involves large body deformations, moving is energetically inefficient. Possession of a soft body benefits caterpillars by allowing them to grow quickly and to access remote food sources safely.

  12. Legless locomotion in lattices

    NASA Astrophysics Data System (ADS)

    Schiebel, Perrin; Dai, Jin; Gong, Chaohui; Serrano, Miguel M.; Mendelson, Joseph R., III; Choset, Howie; Goldman, Daniel I.

    2015-03-01

    By propagating waves from head to tail, limbless organisms like snakes can traverse terrain composed of rocks, foliage, soil and sand. Previous research elucidated how rigid obstacles influence snake locomotion by studying a model terrain-symmetric lattices of pegs placed in hard ground. We want to understand how different substrate-body interaction modes affect performance in desert-adapted snakes during transit of substrates composed of both rigid obstacles and granular media (GM). We tested Chionactis occipitalis, the Mojave shovel-nosed snake, in two laboratory treatments: lattices of 0 . 64 cm diameter obstacles arrayed on both a hard, slick substrate and in a GM of ~ 0 . 3 mm diameter glass particles. For all lattice spacings, d, speed through the hard ground lattices was less than that in GM lattices. However, maximal undulation efficiencies ηu (number of body lengths advanced per undulation cycle) in both treatments were comparable when d was intermediate. For other d, ηu was lower than this maximum in hard ground lattices, while on GM, ηu was insensitive to d. To systematically explore such locomotion, we tested a physical robot model of the snake; performance depended sensitively on base substrate, d and body wave parameters.

  13. Activity of motor cortex neurons during backward locomotion.

    PubMed

    Zelenin, P V; Deliagina, T G; Orlovsky, G N; Karayannidou, A; Stout, E E; Sirota, M G; Beloozerova, I N

    2011-06-01

    Forward walking (FW) and backward walking (BW) are two important forms of locomotion in quadrupeds. Participation of the motor cortex in the control of FW has been intensively studied, whereas cortical activity during BW has never been investigated. The aim of this study was to analyze locomotion-related activity of the motor cortex during BW and compare it with that during FW. For this purpose, we recorded activity of individual neurons in the cat during BW and FW. We found that the discharge frequency in almost all neurons was modulated in the rhythm of stepping during both FW and BW. However, the modulation patterns during BW and FW were different in 80% of neurons. To determine the source of modulating influences (forelimb controllers vs. hindlimb controllers), the neurons were recorded not only during quadrupedal locomotion but also during bipedal locomotion (with either forelimbs or hindlimbs walking), and their modulation patterns were compared. We found that during BW (like during FW), modulation in some neurons was determined by inputs from limb controllers of only one girdle, whereas the other neurons received inputs from both girdles. The combinations of inputs could depend on the direction of locomotion. Most often (in 51% of forelimb-related neurons and in 34% of the hindlimb-related neurons), the neurons received inputs only from their own girdle when this girdle was leading and from both girdles when this girdle was trailing. This reconfiguration of inputs suggests flexibility of the functional roles of individual cortical neurons during different forms of locomotion.

  14. A Locomotion Intent Prediction System Based on Multi-Sensor Fusion

    PubMed Central

    Chen, Baojun; Zheng, Enhao; Wang, Qining

    2014-01-01

    Locomotion intent prediction is essential for the control of powered lower-limb prostheses to realize smooth locomotion transitions. In this research, we develop a multi-sensor fusion based locomotion intent prediction system, which can recognize current locomotion mode and detect locomotion transitions in advance. Seven able-bodied subjects were recruited for this research. Signals from two foot pressure insoles and three inertial measurement units (one on the thigh, one on the shank and the other on the foot) are measured. A two-level recognition strategy is used for the recognition with linear discriminate classifier. Six kinds of locomotion modes and ten kinds of locomotion transitions are tested in this study. Recognition accuracy during steady locomotion periods (i.e., no locomotion transitions) is 99.71% ± 0.05% for seven able-bodied subjects. During locomotion transition periods, all the transitions are correctly detected and most of them can be detected before transiting to new locomotion modes. No significant deterioration in recognition performance is observed in the following five hours after the system is trained, and small number of experiment trials are required to train reliable classifiers. PMID:25014097

  15. Postural stability of biped robots and the foot-rotation indicator (FRI) point

    SciTech Connect

    Goswami, A.

    1999-06-01

    The focus of this paper is the problem of foot rotation in biped robots during the single-support phase. Foot rotation is an indication of postural instability, which should be carefully treated in a dynamically stable walk and avoided altogether in a statically stable walk. The author introduces the foot-rotation indicator (FRI) point, which is a point on the foot/ground-contact surface where the net ground-reaction force would have to act to keep the foot stationary. To ensure no foot rotation, the FRI point must remain within the convex hull of the foot-support area. In contrast with the ground projection of the center of mass (GCoM), which is a static criterion, the FRI point incorporates robot dynamics. As opposed to the center of pressure (CoP) -- better known as the zero-moment point (ZMP) in the robotics literature -- which may not leave the support area, the FRI point may leave the area. In fact, the position of the FRI point outside the footprint indicates the direction of the impending rotation and the magnitude of rotational moment acting on the foot. Owing to these important properties, the FRI point helps not only to monitor the state of postural stability of a biped robot during the entire gait cycle, but indicates the severity of instability of the gait as well. In response to a recent need, the paper also resolves the misconceptions surrounding the CoP/ZMP equivalence.

  16. Mechanics of peristaltic locomotion and role of anchoring

    PubMed Central

    Tanaka, Yoshimi; Ito, Kentaro; Nakagaki, Toshiyuki; Kobayashi, Ryo

    2012-01-01

    Limbless crawling is a fundamental form of biological locomotion adopted by a wide variety of species, including the amoeba, earthworm and snake. An interesting question from a biomechanics perspective is how limbless crawlers control their flexible bodies in order to realize directional migration. In this paper, we discuss the simple but instructive problem of peristalsis-like locomotion driven by elongation–contraction waves that propagate along the body axis, a process frequently observed in slender species such as the earthworm. We show that the basic equation describing this type of locomotion is a linear, one-dimensional diffusion equation with a time–space-dependent diffusion coefficient and a source term, both of which express the biological action that drives the locomotion. A perturbation analysis of the equation reveals that adequate control of friction with the substrate on which locomotion occurs is indispensable in order to translate the internal motion (propagation of the elongation–contraction wave) into directional migration. Both the locomotion speed and its direction (relative to the wave propagation) can be changed by the control of friction. The biological relevance of this mechanism is discussed. PMID:21831891

  17. Scaling macroscopic aquatic locomotion

    NASA Astrophysics Data System (ADS)

    Gazzola, Mattia; Argentina, Médéric; Mahadevan, L.

    2014-10-01

    Inertial aquatic swimmers that use undulatory gaits range in length L from a few millimetres to 30 metres, across a wide array of biological taxa. Using elementary hydrodynamic arguments, we uncover a unifying mechanistic principle characterizing their locomotion by deriving a scaling relation that links swimming speed U to body kinematics (tail beat amplitude A and frequency ω) and fluid properties (kinematic viscosity ν). This principle can be simply couched as the power law Re ~ Swα, where Re = UL/ν >> 1 and Sw = ωAL/ν, with α = 4/3 for laminar flows, and α = 1 for turbulent flows. Existing data from over 1,000 measurements on fish, amphibians, larvae, reptiles, mammals and birds, as well as direct numerical simulations are consistent with our scaling. We interpret our results as the consequence of the convergence of aquatic gaits to the performance limits imposed by hydrodynamics.

  18. Scaling macroscopic aquatic locomotion

    NASA Astrophysics Data System (ADS)

    Gazzola, Mattia; Argentina, Mederic; Mahadevan, Lakshminarayanan

    2014-11-01

    Inertial aquatic swimmers that use undulatory gaits range in length L from a few millimeters to 30 meters, across a wide array of biological taxa. Using elementary hydrodynamic arguments, we uncover a unifying mechanistic principle characterizing their locomotion by deriving a scaling relation that links swimming speed U to body kinematics (tail beat amplitude A and frequency ω) and fluid properties (kinematic viscosity ν). This principle can be simply couched as the power law Re ~ Swα , where Re = UL / ν >> 1 and Sw = ωAL / ν , with α = 4 / 3 for laminar flows, and α = 1 for turbulent flows. Existing data from over 1000 measurements on fish, amphibians, larvae, reptiles, mammals and birds, as well as direct numerical simulations are consistent with our scaling. We interpret our results as the consequence of the convergence of aquatic gaits to the performance limits imposed by hydrodynamics.

  19. Locomotion Speeds of Various Dinosaurs

    NASA Astrophysics Data System (ADS)

    Dougherty, M. T.; Lee, S. A.

    2009-04-01

    A methodology for estimating the locomotion speed of an animal based upon their footprint tracks is developed. Using this technique, an analysis of the locomotion speeds of various dinosaurs is performed. The tracks studied include 28 theropods (meat-eating dinosaurs), 23 sauropods (the ``long-necked'' herbivores), 28 non-armored, non-sauropod herbivores and 10 armored, non-sauropod herbivores. The theropods show the fastest locomotion speed as well as the greatest variety of speeds while the armored dinosaurs are the slowest.

  20. Locomotion speeds of various dinosaurs

    NASA Astrophysics Data System (ADS)

    Dougherty, Mary; Lee, Scott

    2009-03-01

    Most students have a passing curiosity about dinosaurs. Piquing this interest is an excellent tool to engage students. A methodology for estimating the locomotion speed of an animal based upon their footprint tracks is developed. Using this technique, an analysis of the locomotion speeds of various dinosaurs is performed. The tracks studied include 28 theropods (meat-eating dinosaurs), 23 sauropods (the ``long-necked'' herbivores), 28 non-armored, non-sauropod herbivores and 10 armored, non-sauropod herbivores. The theropods show the fastest locomotion speed as well as the greatest variety of speeds while the armored dinosaurs are the slowest.

  1. Robot locomotion on weak ground

    NASA Astrophysics Data System (ADS)

    Qian, Feifei; Li, Chen; Umbanhowar, Paul; Goldman, Daniel

    2012-11-01

    Natural substrates like sand, soil, and leaf litter vary widely in penetration resistance. Little is known about how animals (and increasingly robots) respond to this variation. To address this deficit, we built an air fluidized bed trackway, in which we control penetration resistance of 1mm granular substrates down to zero by increasing the upward flow rate, Q , to the fluidization transition. Using a 2 . 5 kg bio-inspired hexapedal robot as our model locomotor, we systematically study how locomotion performance (average forward speed, v) varies with penetration resistance, limb kinematics, and foot morphology. Average robot speed decreases with increasing Q, and decreases faster for robots with higher leg frequency or narrower leg width. A previously developed model, which captured the robot's performance on granular media with Q = 0 , also captures the observed performance for weakened states with Q > 0 . A single dimensionless control parameter from the model, which combines gait and ground parameters, determines v for all penetration resistances. Our ground control technique and modeling approach provide a way to probe and understand the limits of locomotor performance on yielding substrates.

  2. Disparity and convergence in bipedal archosaur locomotion

    PubMed Central

    Bates, K. T.; Schachner, E. R.

    2012-01-01

    This study aims to investigate functional disparity in the locomotor apparatus of bipedal archosaurs. We use reconstructions of hindlimb myology of extant and extinct archosaurs to generate musculoskeletal biomechanical models to test hypothesized convergence between bipedal crocodile-line archosaurs and dinosaurs. Quantitative comparison of muscle leverage supports the inference that bipedal crocodile-line archosaurs and non-avian theropods had highly convergent hindlimb myology, suggesting similar muscular mechanics and neuromuscular control of locomotion. While these groups independently evolved similar musculoskeletal solutions to the challenges of parasagittally erect bipedalism, differences also clearly exist, particularly the distinct hip and crurotarsal ankle morphology characteristic of many pseudosuchian archosaurs. Furthermore, comparative analyses of muscle design in extant archosaurs reveal that muscular parameters such as size and architecture are more highly adapted or optimized for habitual locomotion than moment arms. The importance of these aspects of muscle design, which are not directly retrievable from fossils, warns against over-extrapolating the functional significance of anatomical convergences. Nevertheless, links identified between posture, muscle moments and neural control in archosaur locomotion suggest that functional interpretations of osteological changes in limb anatomy traditionally linked to postural evolution in Late Triassic archosaurs could be constrained through musculoskeletal modelling. PMID:22112652

  3. [Evolution of tetrapod locomotion].

    PubMed

    Gambarian, P P

    2002-01-01

    Fish-like ancestors of tetrapods did not need strong limb musculature because they inhabited waters and were practically imponderable. In the primitive tetrapods, principal function of the limbs was initially restricted to passive anchoring in the course of animal movements on the substrate by means of lateral bending of the body (undulation). However, progressive development of carrying function of tetrapod limbs lead to clearing the body off the substrate which reduced friction costs and made the tetrapods less dependent on the substrate properties. Along with this, the limbs became more important as the active locomotory organs. But at the beginning, this diminished locomotory speed as the momentum caused by undulation could no longer provide additional forward sliding. Locomotory function of the tetrapod limb could be carried out due to both retraction and pronation at the shoulder joint. Relatively short humerus of the primitive tetrapods made it indifferent which of these two particular actions lead to elongation of the steps. In most of the recent tetrapods with sprawling limbs (Urodela, Lacertilia Sphenodontia, Crocodilia), step elongation was carried out mainly by retraction at the shoulder joint. Contrary to this, in Tachyglossidae (Mammalia: Monotremata) retraction is absent while pronation at the shoulder joint becomes the most important component of step elongation. This made it possible to recognize two principal types, pronatory and retractory, of locomotion on the basis of the main movement in the phase of support. A mathematical model describing changes in step length during the phase of support in both of these types is elaborated. It takes into account relative sizes of stylopodium and zeugopodium, the angles of pronation and retraction at the shoulder joint, the angle of adduction at the elbow joint, and the angle of body undulation arc. It is shown on the basis of this model, varying of which of the above parameters is advantageous and which is

  4. Kinetics of bipedal locomotion during load carrying in capuchin monkeys.

    PubMed

    Hanna, Jandy B; Schmitt, Daniel; Wright, Kristin; Eshchar, Yonat; Visalberghi, Elisabetta; Fragaszy, Dorothy

    2015-08-01

    Facultative bipedalism during load transport in nonhuman primates has been argued to be an important behavior potentially leading to the evolution of obligate, extended limb bipedalism. Understanding the biomechanics of such behavior may lead to insights about associated morphology, which may translate to interpretation of features in the fossil record. Some populations of bearded capuchin monkeys (Sapajus libidinosus) spontaneously carry heavy loads bipedally during foraging activities. This study provides the first data on all three components of ground reaction force for spontaneous bipedalism during load carriage in a nonhuman primate. Five individual S. libidinosus (mean body mass = 2.4 kg ± 0.96) were videorecorded during bipedalism while carrying a stone (0.93 kg) under natural conditions. A force plate was embedded in the path of the monkeys. Spatiotemporal and force data for all three components of the ground reaction force were recorded for 28 steps. Capuchins exhibited a mean vertical peak force per total weight (Vpk) for the hindlimb of 1.19 (sd = 0.13), consistent with those of unloaded capuchins in the laboratory and for other bipedal primates, including humans. Vertical force records suggest that capuchins, along with most nonhuman primates, maintain a relatively compliant leg during both unloaded and loaded locomotion. Like all other primates, loaded capuchins maintained laterally (outward) directed medio-lateral forces, presumably to stabilize side-to-side movements of the center of mass. Medio-lateral forces suggest that at near-running speeds dynamic stability diminishes the need to generate high lateral forces. Vertical force traces exhibited a measurable impact spike at foot contact in 85% of the steps recorded. An impact spike is common in human walking and running but has not been reported in other bipedal primates. This spike in humans is thought to lead to bone and cartilage damage. The earliest biped may have experienced similar

  5. Interaction of ARF-1.1 and neuronal calcium sensor-1 in the control of the temperature-dependency of locomotion in Caenorhabditis elegans

    PubMed Central

    Todd, Paul A. C.; McCue, Hannah V.; Haynes, Lee P.; Barclay, Jeff W.; Burgoyne, Robert D.

    2016-01-01

    Neuronal calcium sensor-1 (NCS-1) mediates changes in cellular function by regulating various target proteins. Many potential targets have been identified but the physiological significance of only a few has been established. Upon temperature elevation, Caenorhabditis elegans exhibits reversible paralysis. In the absence of NCS-1, worms show delayed onset and a shorter duration of paralysis. This phenotype can be rescued by re-expression of ncs-1 in AIY neurons. Mutants with defects in four potential NCS-1 targets (arf-1.1, pifk-1, trp-1 and trp-2) showed qualitatively similar phenotypes to ncs-1 null worms, although the effect of pifk-1 mutation on time to paralysis was considerably delayed. Inhibition of pifk-1 also resulted in a locomotion phenotype. Analysis of double mutants showed no additive effects between mutations in ncs-1 and trp-1 or trp-2. In contrast, double mutants of arf-1.1 and ncs-1 had an intermediate phenotype, consistent with NCS-1 and ARF-1.1 acting in the same pathway. Over-expression of arf-1.1 in the AIY neurons was sufficient to rescue partially the phenotype of both the arf-1.1 and the ncs-1 null worms. These findings suggest that ARF-1.1 interacts with NCS-1 in AIY neurons and potentially pifk-1 in the Ca2+ signaling pathway that leads to inhibited locomotion at an elevated temperature. PMID:27435667

  6. Legless locomotion in lattices

    NASA Astrophysics Data System (ADS)

    Schiebel, Perrin; Goldman, Daniel I.

    2014-11-01

    Little is known about interactions between an animal body and complex terrestrial terrain like sand and boulders during legless, undulatory travel (e.g. snake locomotion). We study the locomotor performance of Mojave shovel-nosed snakes (Chionactisoccipitalis , ~ 35 cm long) using a simplified model of heterogeneous terrain: symmetric lattices of obstacles. To quantify performance we measure mean forward speed and slip angle, βs, defined as the angle between the instantaneous velocity and tangent vectors at each point on the body. We find that below a critical peg density the presence of granular media results in high speed (~ 60 cm/s), low average slip (βs ~6°) snake performance as compared to movement in the same peg densities on hard ground (~ 25 cm/s and βs ~15°). Above this peg density, performance on granular and hard substrates converges. Speed on granular media decreases with increasing peg density to that of the speed on hard ground, while speed on hard ground remains constant. Conversely, βs on hard ground trends toward that on granular media as obstacle density increases.

  7. Chaotic exploration and learning of locomotion behaviors.

    PubMed

    Shim, Yoonsik; Husbands, Phil

    2012-08-01

    We present a general and fully dynamic neural system, which exploits intrinsic chaotic dynamics, for the real-time goal-directed exploration and learning of the possible locomotion patterns of an articulated robot of an arbitrary morphology in an unknown environment. The controller is modeled as a network of neural oscillators that are initially coupled only through physical embodiment, and goal-directed exploration of coordinated motor patterns is achieved by chaotic search using adaptive bifurcation. The phase space of the indirectly coupled neural-body-environment system contains multiple transient or permanent self-organized dynamics, each of which is a candidate for a locomotion behavior. The adaptive bifurcation enables the system orbit to wander through various phase-coordinated states, using its intrinsic chaotic dynamics as a driving force, and stabilizes on to one of the states matching the given goal criteria. In order to improve the sustainability of useful transient patterns, sensory homeostasis has been introduced, which results in an increased diversity of motor outputs, thus achieving multiscale exploration. A rhythmic pattern discovered by this process is memorized and sustained by changing the wiring between initially disconnected oscillators using an adaptive synchronization method. Our results show that the novel neurorobotic system is able to create and learn multiple locomotion behaviors for a wide range of body configurations and physical environments and can readapt in realtime after sustaining damage. PMID:22509965

  8. 40 CFR 1033.615 - Voluntarily subjecting locomotives to the standards of this part.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Voluntarily subjecting locomotives to the standards of this part. 1033.615 Section 1033.615 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Special...

  9. 49 CFR 236.512 - Cab signal indication when locomotive enters block where restrictive conditions obtain.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Cab signal indication when locomotive enters block... TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Standards § 236.512 Cab signal indication when locomotive enters block where...

  10. Locomotion in ornithischian dinosaurs: an assessment using three-dimensional computational modelling.

    PubMed

    Maidment, Susannah C R; Bates, Karl T; Falkingham, Peter L; VanBuren, Collin; Arbour, Victoria; Barrett, Paul M

    2014-08-01

    Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the

  11. Locomotion in ornithischian dinosaurs: an assessment using three-dimensional computational modelling.

    PubMed

    Maidment, Susannah C R; Bates, Karl T; Falkingham, Peter L; VanBuren, Collin; Arbour, Victoria; Barrett, Paul M

    2014-08-01

    Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the

  12. Bipedal locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Kingsbury, Mark; Zhang, Tingnan; Goldman, Daniel

    Bipedal walking, locomotion characterized by alternating swing and double support phase, is well studied on ground where feet do not penetrate the substrate. On granular media like sand however, intrusion and extrusion phases also occur. In these phases, relative motion of the two feet requires that one or both feet slip through the material, degrading performance. To study walking in these phases, we designed and studied a planarized bipedal robot (1.6 kg, 42 cm) that walked in a fluidized bed of poppy seeds. We also simulated the robot in a multibody software environment (Chrono) using granular resistive force theory (RFT) to calculate foot forces. In experiment and simulation, the robot experienced slip during the intrusion phase, with the experiment presenting additional slip due to motor control error during the double support phase. This exaggerated slip gave insight (through analysis of ground reaction forces in simulation) into how slip occurs when relative motion exists between the two feet in the granular media, where the foot with higher relative drag forces (from its instantaneous orientation, rotation, relative direction of motion, and depth) remains stationary. With this relationship, we generated walking gaits for the robot to walk with minimal slip.

  13. The mechanics of slithering locomotion

    PubMed Central

    Hu, David L.; Nirody, Jasmine; Scott, Terri; Shelley, Michael J.

    2009-01-01

    In this experimental and theoretical study, we investigate the slithering of snakes on flat surfaces. Previous studies of slithering have rested on the assumption that snakes slither by pushing laterally against rocks and branches. In this study, we develop a theoretical model for slithering locomotion by observing snake motion kinematics and experimentally measuring the friction coefficients of snakeskin. Our predictions of body speed show good agreement with observations, demonstrating that snake propulsion on flat ground, and possibly in general, relies critically on the frictional anisotropy of their scales. We have also highlighted the importance of weight distribution in lateral undulation, previously difficult to visualize and hence assumed uniform. The ability to redistribute weight, clearly of importance when appendages are airborne in limbed locomotion, has a much broader generality, as shown by its role in improving limbless locomotion. PMID:19506255

  14. 49 CFR 236.505 - Proper operative relation between parts along roadway and parts on locomotive.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... roadway and parts on locomotive. 236.505 Section 236.505 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Standards § 236.505 Proper operative relation between parts along roadway and parts on locomotive....

  15. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Test... the provisions of 40 CFR part 1065, subpart F for general pre-test procedures (including engine and... way you choose to warm it up prior to beginning the sample preconditioning specified in 40 CFR...

  16. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Test... the provisions of 40 CFR part 1065, subpart F for general pre-test procedures (including engine and... way you choose to warm it up prior to beginning the sample preconditioning specified in 40 CFR...

  17. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Test... the provisions of 40 CFR part 1065, subpart F for general pre-test procedures (including engine and... way you choose to warm it up prior to beginning the sample preconditioning specified in 40 CFR...

  18. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Test... the provisions of 40 CFR part 1065, subpart F for general pre-test procedures (including engine and... way you choose to warm it up prior to beginning the sample preconditioning specified in 40 CFR...

  19. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Test... the provisions of 40 CFR part 1065, subpart F for general pre-test procedures (including engine and... way you choose to warm it up prior to beginning the sample preconditioning specified in 40 CFR...

  20. Insects Use Two Distinct Classes of Steps during Unrestrained Locomotion

    PubMed Central

    Theunissen, Leslie M.; Dürr, Volker

    2013-01-01

    Background Adaptive, context-dependent control of locomotion requires modulation of centrally generated rhythmic motor patterns through peripheral control loops and postural reflexes. Thus assuming that the modulation of rhythmic motor patterns accounts for much of the behavioural variability observed in legged locomotion, investigating behavioural variability is a key to the understanding of context-dependent control mechanisms in locomotion. To date, the variability of unrestrained locomotion is poorly understood, and virtually nothing is known about the features that characterise the natural statistics of legged locomotion. In this study, we quantify the natural variability of hexapedal walking and climbing in insects, drawing from a database of several thousand steps recorded over two hours of walking time. Results We show that the range of step length used by unrestrained climbing stick insects is large, showing that step length can be changed substantially for adaptive locomotion. Step length distributions were always bimodal, irrespective of leg type and walking condition, suggesting the presence of two distinct classes of steps: short and long steps. Probability density of step length was well-described by a gamma distribution for short steps, and a logistic distribution for long steps. Major coefficients of these distributions remained largely unaffected by walking conditions. Short and long steps differed concerning their spatial occurrence on the walking substrate, their timing within the step sequence, and their prevalent swing direction. Finally, ablation of structures that serve to improve foothold increased the ratio of short to long steps, indicating a corrective function of short steps. Conclusions Statistical and functional differences suggest that short and long steps are physiologically distinct classes of leg movements that likely reflect distinct control mechanisms at work. PMID:24376877

  1. Proprioceptive Actuation Design for Dynamic Legged locomotion

    NASA Astrophysics Data System (ADS)

    Kim, Sangbae; Wensing, Patrick; Biomimetic Robotics Lab Team

    Designing an actuator system for highly-dynamic legged locomotion exhibited by animals has been one of the grand challenges in robotics research. Conventional actuators designed for manufacturing applications have difficulty satisfying challenging requirements for high-speed locomotion, such as the need for high torque density and the ability to manage dynamic physical interactions. It is critical to introduce a new actuator design paradigm and provide guidelines for its incorporation in future mobile robots for research and industry. To this end, we suggest a paradigm called proprioceptive actuation, which enables highly- dynamic operation in legged machines. Proprioceptive actuation uses collocated force control at the joints to effectively control contact interactions at the feet under dynamic conditions. In the realm of legged machines, this paradigm provides a unique combination of high torque density, high-bandwidth force control, and the ability to mitigate impacts through backdrivability. Results show that the proposed design provides an impact mitigation factor that is comparable to other quadruped designs with series springs to handle impact. The paradigm is shown to enable the MIT Cheetah to manage the application of contact forces during dynamic bounding, with results given down to contact times of 85ms and peak forces over 450N. As a result, the MIT Cheetah achieves high-speed 3D running up to 13mph and jumping over an 18-inch high obstacle. The project is sponsored by DARPA M3 program.

  2. Railroad and locomotive technology roadmap.

    SciTech Connect

    Stodolsky, F.; Gaines, L.; Energy Systems

    2003-02-24

    Railroads are important to the U.S. economy. They transport freight efficiently, requiring less energy and emitting fewer pollutants than other modes of surface transportation. While the railroad industry has steadily improved its fuel efficiency--by 16% over the last decade--more can, and needs to, be done. The ability of locomotive manufacturers to conduct research into fuel efficiency and emissions reduction is limited by the small number of locomotives manufactured annually. Each year for the last five years, the two North American locomotive manufacturers--General Electric Transportation Systems and the Electro-Motive Division of General Motors--have together sold about 800 locomotives in the United States. With such a small number of units over which research costs can be spread, outside help is needed to investigate all possible ways to reduce fuel usage and emissions. Because fuel costs represent a significant portion of the total operating costs of a railroad, fuel efficiency has always been an important factor in the design of locomotives and in the operations of a railroad. However, fuel efficiency has recently become even more critical with the introduction of strict emission standards by the U.S. Environmental Protection Agency, to be implemented in stages (Tiers 0, 1, and 2) between 2000 and 2005. Some of the technologies that could be employed to meet the emission standards may negatively affect fuel economy--by as much as 10-15% when emissions are reduced to Tier 1 levels. Lowering fuel economy by that magnitude would have a serious impact on the cost to the consumer of goods shipped by rail, on the competitiveness of the railroad industry, and on this country's dependence on foreign oil. Clearly, a joint government/industry R&D program is needed to help catalyze the development of advanced technologies that will substantially reduce locomotive engine emissions while also improving train system energy efficiency. DOE convened an industry

  3. 21st Century Locomotive Technology: 2003 Annual Technical Status Report DOE/AL68284-TSR03

    SciTech Connect

    Lembit Salasoo

    2004-01-09

    The 21st Century Locomotive program objective is to develop 25% more efficient freight locomotives by 2010. Diesel engine-related research addresses advanced fuel injection, electric turbocharger and abradable seals. Assembly of a common rail fuel injection test system is underway, and a CFD combustion model has been validated. An electrically assisted turbocharger has been constructed and operated, meeting the generator mode design rating. System characterization and optimization is ongoing. Candidate abradable seal materials have been identified and test coupons prepared. Locomotive system-related research addresses capturing, storing and utilizing regenerative braking energy in a hybrid locomotive, and fuel optimization control. Hybrid locomotive energy storage requirements have been identified and studies on specific energy storage solutions are in progress. Energy management controls have been defined and testing initiated. Train and track parameter identification necessary for fuel optimization has been demonstrated.

  4. Guiding locomotion in complex, dynamic environments

    PubMed Central

    Fajen, Brett R.

    2013-01-01

    Locomotion in complex, dynamic environments is an integral part of many daily activities, including walking in crowded spaces, driving on busy roadways, and playing sports. Many of the tasks that humans perform in such environments involve interactions with moving objects—that is, they require people to coordinate their own movement with the movements of other objects. A widely adopted framework for research on the detection, avoidance, and interception of moving objects is the bearing angle model, according to which observers move so as to keep the bearing angle of the object constant for interception and varying for obstacle avoidance. The bearing angle model offers a simple, parsimonious account of visual control but has several significant limitations and does not easily scale up to more complex tasks. In this paper, I introduce an alternative account of how humans choose actions and guide locomotion in the presence of moving objects. I show how the new approach addresses the limitations of the bearing angle model and accounts for a variety of behaviors involving moving objects, including (1) choosing whether to pass in front of or behind a moving obstacle, (2) perceiving whether a gap between a pair of moving obstacles is passable, (3) avoiding a collision while passing through single or multiple lanes of traffic, (4) coordinating speed and direction of locomotion during interception, (5) simultaneously intercepting a moving target while avoiding a stationary or moving obstacle, and (6) knowing whether to abandon the chase of a moving target. I also summarize data from recent studies that support the new approach. PMID:23885238

  5. Guiding locomotion in complex, dynamic environments.

    PubMed

    Fajen, Brett R

    2013-01-01

    Locomotion in complex, dynamic environments is an integral part of many daily activities, including walking in crowded spaces, driving on busy roadways, and playing sports. Many of the tasks that humans perform in such environments involve interactions with moving objects-that is, they require people to coordinate their own movement with the movements of other objects. A widely adopted framework for research on the detection, avoidance, and interception of moving objects is the bearing angle model, according to which observers move so as to keep the bearing angle of the object constant for interception and varying for obstacle avoidance. The bearing angle model offers a simple, parsimonious account of visual control but has several significant limitations and does not easily scale up to more complex tasks. In this paper, I introduce an alternative account of how humans choose actions and guide locomotion in the presence of moving objects. I show how the new approach addresses the limitations of the bearing angle model and accounts for a variety of behaviors involving moving objects, including (1) choosing whether to pass in front of or behind a moving obstacle, (2) perceiving whether a gap between a pair of moving obstacles is passable, (3) avoiding a collision while passing through single or multiple lanes of traffic, (4) coordinating speed and direction of locomotion during interception, (5) simultaneously intercepting a moving target while avoiding a stationary or moving obstacle, and (6) knowing whether to abandon the chase of a moving target. I also summarize data from recent studies that support the new approach. PMID:23885238

  6. Quantifying coordination between the head and the trunk during locomotion

    NASA Astrophysics Data System (ADS)

    Mulavara, Ajitkumar P.

    This study developed unique measures of coordination between the head and the trunk during the combined tasks of locomotion and gaze fixation of visual targets. These measures will be used to determine the effects of long-duration space flight on sensorimotor function. This will enable evaluation of the efficacy of countermeasures and postflight rehabilitation programs. Indices were proposed as composite measures reflecting the functional aspects of the control system involved in gaze fixation during locomotion. The stiffness index (Nm/deg) was calculated as the ratio between the change in the magnitude of the net relative moments to the change in magnitude of the relative angular motion. The viscosity index (Nm-sec/deg) was calculated as the ratio between the change in the magnitude of the net relative moments to the change in magnitude of the relative angular velocity. These coordination measures were used to evaluate the normal dynamic pattern of coordination between the head and the trunk with respect to the events occurring in a gait cycle. The indices were evaluated for three discrete speeds of locomotion for the same gaze fixation task and for three discrete gaze fixation tasks at the same speed of locomotion. The indices were found to be repeatable measures reflecting inter-segmental coordination strategies while performing an activity of daily living. These indices showed that the coordination of the head with respect to the trunk was significantly different between the events of heel strike and swing phases during the gait cycle. These indices showed no significant differences between the different gaze fixation tasks. The speed of locomotion had a significant effect on the magnitude of these indices. The results indicate that the CNS dynamically modulates head motion with respect to the trunk dependent on the events occurring during the gait cycle. This modulation is appropriate for stabilizing gaze during locomotion. The results support the hypothesis

  7. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion

    ERIC Educational Resources Information Center

    Lee, Scott

    2015-01-01

    In our first article on scaling in theropod dinosaurs, the longitudinal stress in the leg bones due to supporting the weight of the animal was studied and found not to control the dimensions of the femur. As a continuation of our study of elasticity in dinosaur bones, we now examine the transverse stress in the femur due to locomotion and find…

  8. 40 CFR 92.511 - Remanufactured locomotives: installation audit requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in complete conformance with all applicable regulations under 40 CFR part 92. No emission-related...: installation audit requirements. 92.511 Section 92.511 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND...

  9. Differential gating of thalamo-cortical signals by reticular nucleus of thalamus during locomotion

    PubMed Central

    Marlinski, Vladimir; Sirota, Mikhail G.; Beloozerova, Irina N.

    2012-01-01

    SUMMARY The thalamic reticular nucleus (RE) provides inhibition to the dorsal thalamus, and forms a crucial interface between thalamo-cortical and cortico-thalamic signals. Whereas there has been significant interest in the role of the RE in organizing thalamo-cortical signaling, information on the activity of the RE in the awake animal is scant. Here we investigated the activity of neurons within the ‘motor’ compartment of the RE in the awake, unrestrained cat during simple locomotion on a flat surface and complex locomotion along a horizontal ladder that required visual control of stepping. The activity of 88% of neurons in this region was modulated during locomotion. Neurons with receptive fields on the shoulder were located dorsally in the nucleus and had regular discharges; during locomotion they had relatively low activity and modest magnitudes of stride-related modulation, and their group activity was distributed over the stride. In contrast, neurons with receptive fields on the wrist/paw were located more ventrally, often discharged sleep-type bursts during locomotion, were very active and profoundly modulated, and their group activity was concentrated in the swing and end of stance. 75% of RE neurons had different activity during the two locomotion tasks. We conclude that during locomotion the RE differentially gates thalamo-cortical signals transmitted during different phases of the stride, in relation to different parts of the limb, and the type of locomotion task. PMID:23136421

  10. Reversibility in locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Savoie, William; Goldman, Daniel

    2013-11-01

    A recent study of a self-deforming robot [Hatton et al., PRL, 2013] demonstrated that slow movement in dry granular media resembles locomotion in low Re fluids, in part because inertia is dominated by friction. The study indicated that granular swimming was kinematically reversible, a surprise because yielding in granular flow is irreversible. To investigate if reciprocal motions lead to net displacements in granular swimmers, in laboratory experiments, we study the locomotion of a robotic ``scallop'' consisting of a square body with two flipper-like limbs controlled to flap forward and backward symmetrically (a flap cycle). The body is constrained by linear bearings to allow motion in only one dimension. We vary the the flapping frequency f, the body/flipper burial depth d, and the number of flaps N in a deep bed of 6 mm diameter plastic spheres. Over a range of f and d, the N = 1 cycle produces net translation of the body; however for large N, a cycle produces no net translation. We conclude that symmetric strokes in granular swimming are irreversible at the onset of self-deformation, but become asymptotically reversible. work supported by NSF and ARL.

  11. Lizard locomotion on weak sand

    NASA Astrophysics Data System (ADS)

    Goldman, Daniel

    2005-03-01

    Terrestrial animal locomotion in the natural world can involve complex foot-ground interaction; for example, running on sand probes the solid and fluid behaviors of the medium. We study locomotion of desert-dwelling lizard Callisaurus draconoides (length 16 cm, mass=20 g) during rapid running on sand. To explore the role of foot-ground interaction on locomotion, we study the impact of flat disks ( 2 cm diameter, 10 grams) into a deep (800 particle diameters) bed of 250 μm glass spheres of fixed volume fraction φ 0.59, and use a vertical flow of air (a fluidized bed) to change the material properties of the medium. A constant flow Q below the onset of bed fluidization weakens the solid: at fixed φ the penetration depth and time of a disk increases with increasing Q. We measure the average speed, foot impact depth, and foot contact time as a function of material strength. The animal maintains constant penetration time (30 msec) and high speed (1.4 m/sec) even when foot penetration depth varies as we manipulate material strength. The animals compensate for decreasing propulsion by increasing stride frequency.

  12. Locomotive Emission and Engine Idle Reduction Technology Demonstration Project

    SciTech Connect

    John R. Archer

    2005-03-14

    In response to a United States Department of Energy (DOE) solicitation, the Maryland Energy Administration (MEA), in partnership with CSX Transportation, Inc. (CSXT), submitted a proposal to DOE to support the demonstration of Auxiliary Power Unit (APU) technology on fifty-six CSXT locomotives. The project purpose was to demonstrate the idle fuel savings, the Nitrous Oxide (NOX) emissions reduction and the noise reduction capabilities of the APU. Fifty-six CSXT Baltimore Division locomotives were equipped with APUs, Engine Run Managers (ERM) and communications equipment to permit GPS tracking and data collection from the locomotives. Throughout the report there is mention of the percent time spent in the State of Maryland. The fifty-six locomotives spent most of their time inside the borders of Maryland and some spent all their time inside the state borders. Usually when a locomotive traveled beyond the Maryland State border it was into an adjoining state. They were divided into four groups according to assignment: (1) Power Unit/Switcher Mate units, (2) Remote Control units, (3) SD50 Pusher units and (4) Other units. The primary data of interest were idle data plus the status of the locomotive--stationary or moving. Also collected were main engine off, idling or working. Idle data were collected by county location, by locomotive status (stationary or moving) and type of idle (Idle 1, main engine idling, APU off; Idle 2, main engine off, APU on; Idle 3, main engine off, APU off; Idle 4, main engine idle, APU on). Desirable main engine idle states are main engine off and APU off or main engine off and APU on. Measuring the time the main engine spends in these desirable states versus the total time it could spend in an engine idling state allows the calculation of Percent Idle Management Effectiveness (%IME). IME is the result of the operation of the APU plus the implementation of CSXT's Warm Weather Shutdown Policy. It is difficult to separate the two. The units

  13. Fish locomotion: insights from both simple and complex mechanical models

    NASA Astrophysics Data System (ADS)

    Lauder, George

    2015-11-01

    Fishes are well-known for their ability to swim and maneuver effectively in the water, and recent years have seen great progress in understanding the hydrodynamics of aquatic locomotion. But studying freely-swimming fishes is challenging due to difficulties in controlling fish behavior. Mechanical models of aquatic locomotion have many advantages over studying live animals, including the ability to manipulate and control individual structural or kinematic factors, easier measurement of forces and torques, and the ability to abstract complex animal designs into simpler components. Such simplifications, while not without their drawbacks, facilitate interpretation of how individual traits alter swimming performance and the discovery of underlying physical principles. In this presentation I will discuss the use of a variety of mechanical models for fish locomotion, ranging from simple flexing panels to complex biomimetic designs incorporating flexible, actively moved, fin rays on multiple fins. Mechanical devices have provided great insight into the dynamics of aquatic propulsion and, integrated with studies of locomotion in freely-swimming fishes, provide new insights into how fishes move through the water.

  14. 49 CFR 229.209 - Alternative locomotive crashworthiness designs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Alternative locomotive crashworthiness designs... Locomotive Crashworthiness Design Requirements § 229.209 Alternative locomotive crashworthiness designs. (a... locomotive crashworthiness designs which are not consistent with any FRA-approved locomotive...

  15. 49 CFR 238.209 - Forward end structure of locomotives, including cab cars and MU locomotives.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... locomotives, including cab cars and MU locomotives. (a)(1) The skin covering the forward-facing end of each... “skin” does not include forward-facing windows and doors. (b) The forward end structure of a cab car...

  16. 49 CFR 238.209 - Forward end structure of locomotives, including cab cars and MU locomotives.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Forward end structure of locomotives, including... SAFETY STANDARDS Specific Requirements for Tier I Passenger Equipment § 238.209 Forward end structure of... locomotive, including a cab car and an MU locomotive, shall be: (i) Equivalent to a 1/2-inch steel plate...

  17. 49 CFR 238.209 - Forward end structure of locomotives, including cab cars and MU locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Forward end structure of locomotives, including... SAFETY STANDARDS Specific Requirements for Tier I Passenger Equipment § 238.209 Forward end structure of... locomotive, including a cab car and an MU locomotive, shall be: (i) Equivalent to a 1/2-inch steel plate...

  18. 49 CFR 238.209 - Forward end structure of locomotives, including cab cars and MU locomotives.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Forward end structure of locomotives, including... SAFETY STANDARDS Specific Requirements for Tier I Passenger Equipment § 238.209 Forward end structure of... locomotive, including a cab car and an MU locomotive, shall be: (i) Equivalent to a 1/2-inch steel plate...

  19. Human locomotion and workload for simulated lunar and Martian environments.

    PubMed

    Newman, D J; Alexander, H L

    1993-08-01

    Human locomotion in simulated lunar and Martian environments is investigated. A unique human-rated underwater treadmill and an adjustable ballasting harness simulate partial gravity in order to better understand how gravity determines the biomechanics and energetics of human locomotion. This study has two research aspects, biomechanics and energetics. The fundamental biomechanics measurements are continuously recorded vertical forces as exerted by subjects of the treadmill which is instrumented with a force platform. Experimental results indicate that peak vertical force and stride frequency decrease as the gravity level is reduced. Foot contact time is independent of gravity level. Oxygen uptake measurements, VO2, constitute the energetics, or workload, data for this study. As theory predicts, locomotion energy requirements for lunar (1/6-g) and Martian (3/8-g) gravity levels are significantly less than at 1-g. The observed variation in workload with gravity level is nonmonotonic, however, in over half the subject population. The hypothesis is offered that energy expenditure increases for lunar, as compared with Martian, locomotion due to the subject "wasting energy" for stability and posture control in simulated lunar gravity. Biomechanics data could influence advanced spacesuit design and planetary habitat design, while workload data will help define oxygen requirements for planetary life support systems.

  20. Regulation of two motor patterns enables the gradual adjustment of locomotion strategy in Caenorhabditis elegans.

    PubMed

    Hums, Ingrid; Riedl, Julia; Mende, Fanny; Kato, Saul; Kaplan, Harris S; Latham, Richard; Sonntag, Michael; Traunmüller, Lisa; Zimmer, Manuel

    2016-01-01

    In animal locomotion a tradeoff exists between stereotypy and flexibility: fast long-distance travelling (LDT) requires coherent regular motions, while local sampling and area-restricted search (ARS) rely on flexible movements. We report here on a posture control system in C. elegans that coordinates these needs. Using quantitative posture analysis we explain worm locomotion as a composite of two modes: regular undulations versus flexible turning. Graded reciprocal regulation of both modes allows animals to flexibly adapt their locomotion strategy under sensory stimulation along a spectrum ranging from LDT to ARS. Using genetics and functional imaging of neural activity we characterize the counteracting interneurons AVK and DVA that utilize FLP-1 and NLP-12 neuropeptides to control both motor modes. Gradual regulation of behaviors via this system is required for spatial navigation during chemotaxis. This work shows how a nervous system controls simple elementary features of posture to generate complex movements for goal-directed locomotion strategies. PMID:27222228

  1. Regulation of two motor patterns enables the gradual adjustment of locomotion strategy in Caenorhabditis elegans.

    PubMed

    Hums, Ingrid; Riedl, Julia; Mende, Fanny; Kato, Saul; Kaplan, Harris S; Latham, Richard; Sonntag, Michael; Traunmüller, Lisa; Zimmer, Manuel

    2016-05-25

    In animal locomotion a tradeoff exists between stereotypy and flexibility: fast long-distance travelling (LDT) requires coherent regular motions, while local sampling and area-restricted search (ARS) rely on flexible movements. We report here on a posture control system in C. elegans that coordinates these needs. Using quantitative posture analysis we explain worm locomotion as a composite of two modes: regular undulations versus flexible turning. Graded reciprocal regulation of both modes allows animals to flexibly adapt their locomotion strategy under sensory stimulation along a spectrum ranging from LDT to ARS. Using genetics and functional imaging of neural activity we characterize the counteracting interneurons AVK and DVA that utilize FLP-1 and NLP-12 neuropeptides to control both motor modes. Gradual regulation of behaviors via this system is required for spatial navigation during chemotaxis. This work shows how a nervous system controls simple elementary features of posture to generate complex movements for goal-directed locomotion strategies.

  2. 49 CFR 212.215 - Locomotive inspector.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... applicable sections of the Safety Glazing Standards (49 CFR part 223), Locomotive Safety Standards (49 CFR part 229), Safety Appliance Standards (49 CFR part 231) and Power Brake Standards (49 CFR part 232), to... four years of experience in locomotive construction or maintenance. A bachelor's degree in...

  3. 49 CFR 212.215 - Locomotive inspector.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... applicable sections of the Safety Glazing Standards (49 CFR part 223), Locomotive Safety Standards (49 CFR part 229), Safety Appliance Standards (49 CFR part 231) and Power Brake Standards (49 CFR part 232), to... four years of experience in locomotive construction or maintenance. A bachelor's degree in...

  4. 49 CFR 212.215 - Locomotive inspector.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... applicable sections of the Safety Glazing Standards (49 CFR part 223), Locomotive Safety Standards (49 CFR part 229), Safety Appliance Standards (49 CFR part 231) and Power Brake Standards (49 CFR part 232), to... four years of experience in locomotive construction or maintenance. A bachelor's degree in...

  5. 77 FR 21311 - Locomotive Safety Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-09

    .... Alerters are currently required on passenger locomotives pursuant to Sec. 238.237 (67 FR 19991), and are..., 2007 (72 FR 59216). FRA continued to utilize the RSAC process to address additional locomotive safety... text for these issues with minor clarifying modifications on January 12, 2011. See 76 FR 2199. The...

  6. 76 FR 8699 - Locomotive Safety Standards; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... NPRM related to locomotive safety standards. See 76 FR 2200. The NPRM established a public docket to... the proposed rule published January 12, 2011, at 76 FR 2200, remains March 14, 2011. FOR FURTHER... Federal Railroad Administration 49 CFR Parts 229 and 238 RIN 2130-AC16 Locomotive Safety...

  7. 49 CFR 229.129 - Locomotive horn.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... defectives equal to an AQL of 1% or less, as set forth in 7 CFR part 43. (2) Each locomotive built before.... The locomotive shall be positioned on straight, level track. (6) Measurements shall be taken only when... between 20 percent and 95 percent inclusively; wind velocity is not more than 12 miles per hour and...

  8. 49 CFR 229.129 - Locomotive horn.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... defectives equal to an AQL of 1% or less, as set forth in 7 CFR part 43. (2) Each locomotive built before.... The locomotive shall be positioned on straight, level track. (6) Measurements shall be taken only when... between 20 percent and 95 percent inclusively; wind velocity is not more than 12 miles per hour and...

  9. 49 CFR 212.215 - Locomotive inspector.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... applicable sections of the Safety Glazing Standards (49 CFR part 223), Locomotive Safety Standards (49 CFR part 229), Safety Appliance Standards (49 CFR part 231) and Power Brake Standards (49 CFR part 232), to... four years of experience in locomotive construction or maintenance. A bachelor's degree in...

  10. Trunk orientation causes asymmetries in leg function in small bird terrestrial locomotion.

    PubMed

    Andrada, Emanuel; Rode, Christian; Sutedja, Yefta; Nyakatura, John A; Blickhan, Reinhard

    2014-12-22

    In contrast to the upright trunk in humans, trunk orientation in most birds is almost horizontal (pronograde). It is conceivable that the orientation of the heavy trunk strongly influences the dynamics of bipedal terrestrial locomotion. Here, we analyse for the first time the effects of a pronograde trunk orientation on leg function and stability during bipedal locomotion. For this, we first inferred the leg function and trunk control strategy applied by a generalized small bird during terrestrial locomotion by analysing synchronously recorded kinematic (three-dimensional X-ray videography) and kinetic (three-dimensional force measurement) quail locomotion data. Then, by simulating quail gaits using a simplistic bioinspired numerical model which made use of parameters obtained in in vivo experiments with real quail, we show that the observed asymmetric leg function (left-skewed ground reaction force and longer leg at touchdown than at lift-off) is necessary for pronograde steady-state locomotion. In addition, steady-state locomotion becomes stable for specific morphological parameters. For quail-like parameters, the most common stable solution is grounded running, a gait preferred by quail and most of the other small birds. We hypothesize that stability of bipedal locomotion is a functional demand that, depending on trunk orientation and centre of mass location, constrains basic hind limb morphology and function, such as leg length, leg stiffness and leg damping.

  11. Locomotion concerns with moral usefulness: When liberals endorse binding moral foundations.

    PubMed

    Cornwell, James F M; Higgins, E Tory

    2014-01-01

    Moral Foundations Theory has provided a framework for understanding the endorsement of different moral beliefs. Our research investigated whether there are other reasons to endorse moral foundations in addition to epistemic concerns; specifically, the perceived social usefulness of moral foundations. In Study 1, we demonstrate that those showing stronger locomotion concerns for controlling movement tend toward a higher endorsement of binding foundations, and that this effect is stronger among political liberals who otherwise do not typically endorse these foundations. In Study 2, we show that priming participants with assessment concerns (emphasizing truth) rather than locomotion concerns (emphasizing control) reduces the response variance among liberals and also removes the association between locomotion and the binding foundations. In Study 3, we directly ask participants to focus on moral truth versus moral usefulness, with moral truth replicating the Study 2 effect of assessment priming, and moral usefulness replicating the effect of locomotion priming.

  12. Locomotion concerns with moral usefulness: When liberals endorse binding moral foundations.

    PubMed

    Cornwell, James F M; Higgins, E Tory

    2014-01-01

    Moral Foundations Theory has provided a framework for understanding the endorsement of different moral beliefs. Our research investigated whether there are other reasons to endorse moral foundations in addition to epistemic concerns; specifically, the perceived social usefulness of moral foundations. In Study 1, we demonstrate that those showing stronger locomotion concerns for controlling movement tend toward a higher endorsement of binding foundations, and that this effect is stronger among political liberals who otherwise do not typically endorse these foundations. In Study 2, we show that priming participants with assessment concerns (emphasizing truth) rather than locomotion concerns (emphasizing control) reduces the response variance among liberals and also removes the association between locomotion and the binding foundations. In Study 3, we directly ask participants to focus on moral truth versus moral usefulness, with moral truth replicating the Study 2 effect of assessment priming, and moral usefulness replicating the effect of locomotion priming. PMID:24347681

  13. Locomotion concerns with moral usefulness: When liberals endorse binding moral foundations

    PubMed Central

    Cornwell, James F. M.; Higgins, E. Tory

    2013-01-01

    Moral Foundations Theory has provided a framework for understanding the endorsement of different moral beliefs. Our research investigated whether there are other reasons to endorse moral foundations in addition to epistemic concerns; specifically, the perceived social usefulness of moral foundations. In Study 1, we demonstrate that those showing stronger locomotion concerns for controlling movement tend toward a higher endorsement of binding foundations, and that this effect is stronger among political liberals who otherwise do not typically endorse these foundations. In Study 2, we show that priming participants with assessment concerns (emphasizing truth) rather than locomotion concerns (emphasizing control) reduces the response variance among liberals and also removes the association between locomotion and the binding foundations. In Study 3, we directly ask participants to focus on moral truth versus moral usefulness, with moral truth replicating the Study 2 effect of assessment priming, and moral usefulness replicating the effect of locomotion priming. PMID:24347681

  14. Electrical stimulation of motor cortex in the uninjured hemisphere after chronic unilateral injury promotes recovery of skilled locomotion through ipsilateral control.

    PubMed

    Carmel, Jason B; Kimura, Hiroki; Martin, John H

    2014-01-01

    Partial injury to the corticospinal tract (CST) causes sprouting of intact axons at their targets, and this sprouting correlates with functional improvement. Electrical stimulation of motor cortex augments sprouting of intact CST axons and promotes functional recovery when applied soon after injury. We hypothesized that electrical stimulation of motor cortex in the intact hemisphere after chronic lesion of the CST in the other hemisphere would restore function through ipsilateral control. To test motor skill, rats were trained and tested to walk on a horizontal ladder with irregularly spaced rungs. Eight weeks after injury, produced by pyramidal tract transection, half of the rats received forelimb motor cortex stimulation of the intact hemisphere. Rats with injury and stimulation had significantly improved forelimb control compared with rats with injury alone and achieved a level of proficiency similar to uninjured rats. To test whether recovery of forelimb function was attributable to ipsilateral control, we selectively inactivated the stimulated motor cortex using the GABA agonist muscimol. The dose of muscimol we used produces strong contralateral but no ipsilateral impairments in naive rats. In rats with injury and stimulation, but not those with injury alone, inactivation caused worsening of forelimb function; the initial deficit was reinstated. These results demonstrate that electrical stimulation can promote recovery of motor function when applied late after injury and that motor control can be exerted from the ipsilateral motor cortex. These results suggest that the uninjured motor cortex could be targeted for brain stimulation in people with large unilateral CST lesions. PMID:24403146

  15. Kinematics of treadmill locomotion in mice raised in hypergravity.

    PubMed

    Bojados, Mickael; Herbin, Marc; Jamon, Marc

    2013-05-01

    The study compared the motor performance of adult C57Bl/6J mice previously exposed to a 2G gravity environment during different periods of their development. 12 mice were housed in a large diameter centrifuge from the conception to Postnatal day 10 (P10). Another group of 10 mice was centrifuged form P10 to P30, and a third group of 9 mice was centrifuged from conception to P30. Their gait parameters, and kinematics of joint excursions were compared with 11 control mice, at the age of 2 months using a video-radiographic apparatus connected to a motorized treadmill. The mice that returned to Earth gravity level at the age of P10 showed a motor pattern similar to control mice. At variance the two groups that were centrifuged from P10 to P30 showed a different motor pattern with smaller and faster strides to walk at the same velocity as controls. On the other hand all the centrifuged mice showed significant postural changes, particularly with a more extended ankle joint, but the mice centrifuged during the whole experimental period differed even more. Our results showed that the exposure to hypergravity before P10 sufficed to modify the posture, suggesting that postural control starts before the onset of locomotion, whereas the gravity constraint perceived between P10 and P30 conditioned the tuning of quadruped locomotion with long term consequences. These results support the existence of a critical period in the acquisition of locomotion in mice. PMID:23352767

  16. 21st Century Locomotive Technology: Quarterly Technical Status Report 8 DOE/AL68284-TSR08

    SciTech Connect

    Lembit Salasoo; Jennifer Topinka; Anthony Furman; Raj Bharadwaj

    2005-02-16

    Completed high pressure common rail system performance mapping at notch 8 to establish advanced fuel injection fuel savings entitlement. Investigated performance differences of several abradable coatings between full-scale tests and rub test coupons using post-run micrographic analysis. Demonstrated implementation of advanced energy management controls on hybrid locomotive. Began advanced energy storage detailed design; continued life-cycle subscale energy storage testing. Formulated trip optimization problem with hybrid locomotive, and evaluated first implementation to produce an optimal driving plan.

  17. Central pattern generator for locomotion: anatomical, physiological, and pathophysiological considerations.

    PubMed

    Guertin, Pierre A

    2012-01-01

    This article provides a perspective on major innovations over the past century in research on the spinal cord and, specifically, on specialized spinal circuits involved in the control of rhythmic locomotor pattern generation and modulation. Pioneers such as Charles Sherrington and Thomas Graham Brown have conducted experiments in the early twentieth century that changed our views of the neural control of locomotion. Their seminal work supported subsequently by several decades of evidence has led to the conclusion that walking, flying, and swimming are largely controlled by a network of spinal neurons generally referred to as the central pattern generator (CPG) for locomotion. It has been subsequently demonstrated across all vertebrate species examined, from lampreys to humans, that this CPG is capable, under some conditions, to self-produce, even in absence of descending or peripheral inputs, basic rhythmic, and coordinated locomotor movements. Recent evidence suggests, in turn, that plasticity changes of some CPG elements may contribute to the development of specific pathophysiological conditions associated with impaired locomotion or spontaneous locomotor-like movements. This article constitutes a comprehensive review summarizing key findings on the CPG as well as on its potential role in Restless Leg Syndrome, Periodic Leg Movement, and Alternating Leg Muscle Activation. Special attention will be paid to the role of the CPG in a recently identified, and uniquely different neurological disorder, called the Uner Tan Syndrome.

  18. Central Pattern Generator for Locomotion: Anatomical, Physiological, and Pathophysiological Considerations

    PubMed Central

    Guertin, Pierre A.

    2013-01-01

    This article provides a perspective on major innovations over the past century in research on the spinal cord and, specifically, on specialized spinal circuits involved in the control of rhythmic locomotor pattern generation and modulation. Pioneers such as Charles Sherrington and Thomas Graham Brown have conducted experiments in the early twentieth century that changed our views of the neural control of locomotion. Their seminal work supported subsequently by several decades of evidence has led to the conclusion that walking, flying, and swimming are largely controlled by a network of spinal neurons generally referred to as the central pattern generator (CPG) for locomotion. It has been subsequently demonstrated across all vertebrate species examined, from lampreys to humans, that this CPG is capable, under some conditions, to self-produce, even in absence of descending or peripheral inputs, basic rhythmic, and coordinated locomotor movements. Recent evidence suggests, in turn, that plasticity changes of some CPG elements may contribute to the development of specific pathophysiological conditions associated with impaired locomotion or spontaneous locomotor-like movements. This article constitutes a comprehensive review summarizing key findings on the CPG as well as on its potential role in Restless Leg Syndrome, Periodic Leg Movement, and Alternating Leg Muscle Activation. Special attention will be paid to the role of the CPG in a recently identified, and uniquely different neurological disorder, called the Uner Tan Syndrome. PMID:23403923

  19. Control of a three-dimensional magnetic force generated from a magnetic navigation system to precisely manipulate the locomotion of a magnetic microrobot

    NASA Astrophysics Data System (ADS)

    Nam, J. K.; Jeon, S. M.; Lee, W. S.; Jang, G. H.

    2015-05-01

    We propose a method to generate a three-dimensional (3D) magnetic force to manipulate a magnetic microrobot in various environments by using a magnetic navigation system. The proposed method is based on the control of the magnetic force with respect to the change in the magnetization direction of the microrobot and an external magnetic flux gradient. We derived the nonlinear constraint equations which can determine the required direction of the uniform magnetic fields and magnetic gradients to generate the 3D magnetic force of a microrobot. The solutions of the equations were calculated using a geometrical analysis of the equations without any singular point. The proposed methodology was verified on 3D planar environments considering gravitational force, and we also conducted an experiment in a 3D water-filled tubular environment to verify the possibility of the clinical application in human blood vessels.

  20. Visual Exploration during Locomotion Limited by Fear of Heights

    PubMed Central

    Kugler, Günter; Huppert, Doreen; Eckl, Maria; Schneider, Erich; Brandt, Thomas

    2014-01-01

    Background Visual exploration of the surroundings during locomotion at heights has not yet been investigated in subjects suffering from fear of heights. Methods Eye and head movements were recorded separately in 16 subjects susceptible to fear of heights and in 16 non-susceptible controls while walking on an emergency escape balcony 20 meters above ground level. Participants wore mobile infrared eye-tracking goggles with a head-fixed scene camera and integrated 6-degrees-of-freedom inertial sensors for recording head movements. Video recordings of the subjects were simultaneously made to correlate gaze and gait behavior. Results Susceptibles exhibited a limited visual exploration of the surroundings, particularly the depth. Head movements were significantly reduced in all three planes (yaw, pitch, and roll) with less vertical head oscillations, whereas total eye movements (saccade amplitudes, frequencies, fixation durations) did not differ from those of controls. However, there was an anisotropy, with a preference for the vertical as opposed to the horizontal direction of saccades. Comparison of eye and head movement histograms and the resulting gaze-in-space revealed a smaller total area of visual exploration, which was mainly directed straight ahead and covered vertically an area from the horizon to the ground in front of the feet. This gaze behavior was associated with a slow, cautious gait. Conclusions The visual exploration of the surroundings by susceptibles to fear of heights differs during locomotion at heights from the earlier investigated behavior of standing still and looking from a balcony. During locomotion, anisotropy of gaze-in-space shows a preference for the vertical as opposed to the horizontal direction during stance. Avoiding looking into the abyss may reduce anxiety in both conditions; exploration of the “vertical strip” in the heading direction is beneficial for visual control of balance and avoidance of obstacles during locomotion. PMID

  1. Warning system against locomotive driving wheel flaccidity

    NASA Astrophysics Data System (ADS)

    Luo, Peng

    2014-09-01

    Causes of locomotive relaxation are discussed. Alarm system against locomotive driving wheel flaccidity is designed by means of techniques of infrared temperature measurement and Hall sensor measurement. The design scheme of the system, the principle of detecting locomotive driving wheel flaccidity with temperature and Hall sensor is introduced, threshold temperature of infrared alarm is determined. The circuit system is designed by microcontroller technology and the software is designed with the assembly language. The experiment of measuring the flaccid displacement with Hall sensor measurement is simulated. The results show that the system runs well with high reliability and low cost, which has a wide prospect of application and popularization.

  2. 49 CFR 229.121 - Locomotive cab noise.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Locomotive cab noise. 229.121 Section 229.121... § 229.121 Locomotive cab noise. (a) Performance standards for locomotives. (1) When tested for static noise in accordance with paragraph (a)(3) of this section, all locomotives of each design or model...

  3. 49 CFR 230.21 - Steam locomotive number change.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Steam locomotive number change. 230.21 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS General Recordkeeping Requirements § 230.21 Steam locomotive number change. When a steam locomotive number is...

  4. 49 CFR 230.106 - Steam locomotive frame.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Steam locomotive frame. 230.106 Section 230.106..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.106 Steam locomotive frame. (a) Maintenance...

  5. 49 CFR 230.106 - Steam locomotive frame.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive frame. 230.106 Section 230.106..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.106 Steam locomotive frame. (a) Maintenance...

  6. 49 CFR 230.21 - Steam locomotive number change.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive number change. 230.21 Section 230... Recordkeeping Requirements § 230.21 Steam locomotive number change. When a steam locomotive number is changed, the steam locomotive owner and/or operator must reflect the change in the upper right-hand corner...

  7. 49 CFR 230.106 - Steam locomotive frame.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Steam locomotive frame. 230.106 Section 230.106..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.106 Steam locomotive frame. (a) Maintenance...

  8. 49 CFR 230.106 - Steam locomotive frame.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Steam locomotive frame. 230.106 Section 230.106..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.106 Steam locomotive frame. (a) Maintenance...

  9. 49 CFR 230.21 - Steam locomotive number change.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Steam locomotive number change. 230.21 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS General Recordkeeping Requirements § 230.21 Steam locomotive number change. When a steam locomotive number is...

  10. 49 CFR 230.21 - Steam locomotive number change.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Steam locomotive number change. 230.21 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS General Recordkeeping Requirements § 230.21 Steam locomotive number change. When a steam locomotive number is...

  11. 49 CFR 230.106 - Steam locomotive frame.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Steam locomotive frame. 230.106 Section 230.106..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.106 Steam locomotive frame. (a) Maintenance...

  12. 49 CFR 230.21 - Steam locomotive number change.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Steam locomotive number change. 230.21 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS General Recordkeeping Requirements § 230.21 Steam locomotive number change. When a steam locomotive number is...

  13. 49 CFR 238.223 - Locomotive fuel tanks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Locomotive fuel tanks. 238.223 Section 238.223... Equipment § 238.223 Locomotive fuel tanks. Locomotive fuel tanks shall comply with either the following or....21: (a) External fuel tanks. External locomotive fuel tanks shall comply with the...

  14. The Kinematics of Treadmill Locomotion in Space

    NASA Technical Reports Server (NTRS)

    Thornton, W. E.; Cavanagh, P. R.; Buczek, F. L.; Burgess-Milliron, M. J.; Davis, B. L.

    1997-01-01

    Locomotion on a treadmill in 0 G will probably remain a centerpiece of NASA's exercise countermeasures programme. This form of physical activity has the potential to cause large bone and muscle forces as well as loading during a period of continuous treadmill exercise. A critical concern is the provision of a treadmill which can approximate 1 G performance in space. At this point, no adequate objective measurements of in-flight treadmill kinetics or of the human response to this activity have been made. Interpretation of the results obtained in the present study is limited by the following: (1) bungee tensions were not measured; (2) ground reaction forces were not measured in parallel with the kinematic measurements; and (3) the instrumentation used to film the astronauts could itself have been affected by microgravity. Despite these shortcomings, what is apparent is that exercise during NASA missions STS 7 and STS 8 resulted in leg motions that were similar to those found during 1 G locomotion on an inclined passive treadmill and on an active treadmill at an even steeper grade. In addition, it was apparent that the majority of the loads were transmitted through the forefoot, and one can surmise that this style of running would result in physiologically significant tensions in the calf musculature and resultant ankle compressive loading. Further speculation regarding limb loading is complicated by the fact that varying amounts of force are transmitted through (1) the treadmill handle and (2) bungee cords that act as a tether. New generations of treadmills are being manufactured that could provide I important information for planners of long-duration space missions. If these types of treadmill are flown on future missions, it will be possible to control bungee tensions more precisely, control for grade and speed, and, most importantly, provide data on the rates and magnitudes of limb loading. These data could then be incorporated into biomechanical models of the

  15. Push-Pull Locomotion for Vehicle Extrication

    NASA Technical Reports Server (NTRS)

    Creager, Colin M.; Johnson, Kyle A.; Plant, Mark; Moreland, Scott J.; Skonieczny, Krzysztof

    2014-01-01

    For applications in which unmanned vehicles must traverse unfamiliar terrain, there often exists the risk of vehicle entrapment. Typically, this risk can be reduced by using feedback from on-board sensors that assess the terrain. This work addressed the situations where a vehicle has already become immobilized or the desired route cannot be traversed using conventional rolling. Specifically, the focus was on using push-pull locomotion in high sinkage granular material. Push-pull locomotion is an alternative mode of travel that generates thrust through articulated motion, using vehicle components as anchors to push or pull against. It has been revealed through previous research that push-pull locomotion has the capacity for generating higher net traction forces than rolling, and a unique optical flow technique indicated that this is the result of a more efficient soil shearing method. It has now been found that pushpull locomotion results in less sinkage, lower travel reduction, and better power efficiency in high sinkage material as compared to rolling. Even when starting from an "entrapped" condition, push-pull locomotion was able to extricate the test vehicle. It is the authors' recommendation that push-pull locomotion be considered as a reliable back-up mode of travel for applications where terrain entrapment is a possibility.

  16. Characteristics of undulatory locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn J.

    2016-03-01

    Undulatory locomotion is ubiquitous in nature and observed in different media, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Despite the similarity in the undulating pattern, the swimming characteristics depend on the rheological properties of different media. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but recently a resistive force theory in granular media has been proposed and shown useful in studying the locomotion of a sand-swimming lizard. Here we employ the proposed model to investigate the swimming characteristics of a slender filament, of both finite and infinite length, undulating in a granular medium and compare the results with swimming in viscous fluids. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. We also find that, similar to Lighthill's results using resistive force theory in viscous fluids, the sawtooth swimmer is the optimal waveform for propulsion speed at a given power consumption in granular media. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

  17. Characterization of undulatory locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn

    2015-11-01

    Undulatory locomotion is ubiquitous in nature, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but a recently proposed resistive force theory (RFT) in granular media has been shown useful in studying the locomotion of a sand-swimming lizard. Here we employ this model to investigate the swimming characteristics of an undulating slender filament of both finite and infinite length. For infinite swimmers, similar to results in viscous fluids, the sawtooth waveform is found to be optimal for propulsion speed at a given power consumption. We also compare the swimming characteristics of sinusoidal and sawtooth swimmers with swimming in viscous fluids. More complex swimming dynamics emerge when the assumption of an infinite swimmer is removed. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

  18. Reversal of the late phase of spike frequency adaptation in cat spinal motoneurons during fictive locomotion

    PubMed Central

    Brownstone, Robert M.; Krawitz, Sherry; Jordan, Larry M.

    2016-01-01

    In spinal motoneurons, late spike frequency adaptation (SFA) is defined as the slowing of the firing rate over tens of seconds and can be seen during sustained or intermittent current injection. Although the function of late SFA is not known, it may result in a decrease in force production over time, or muscle fatigue. Because locomotion can persist for long periods of time without fatigue, late SFA was studied using intracellular recordings from adult cat motoneurons during fictive locomotion. Of eight lumbar motoneurons studied, all showed late adaptation during control conditions, but none demonstrated late adaptation during locomotor activity. The most consistent properties that correlated with the presence or absence of late SFA were those related to availability of fast, inactivating sodium channels, particularly action potential rate of rise. Evidence of the reversal of late SFA during locomotion was present for several minutes following locomotor trials, consistent with the suggestion that SFA is modulated through slow metabotropic pathways. The abolition of late adaptation in spinal motoneurons during fictive locomotion is an example of a state-dependent change in the “intrinsic” properties of mammalian motoneurons. This change contributes to increased excitability of motoneurons during locomotion and results in robust firing during sustained locomotion. PMID:21177992

  19. Reversal of the late phase of spike frequency adaptation in cat spinal motoneurons during fictive locomotion.

    PubMed

    Brownstone, Robert M; Krawitz, Sherry; Jordan, Larry M

    2011-03-01

    In spinal motoneurons, late spike frequency adaptation (SFA) is defined as the slowing of the firing rate over tens of seconds and can be seen during sustained or intermittent current injection. Although the function of late SFA is not known, it may result in a decrease in force production over time, or muscle fatigue. Because locomotion can persist for long periods of time without fatigue, late SFA was studied using intracellular recordings from adult cat motoneurons during fictive locomotion. Of eight lumbar motoneurons studied, all showed late adaptation during control conditions, but none demonstrated late adaptation during locomotor activity. The most consistent properties that correlated with the presence or absence of late SFA were those related to availability of fast, inactivating sodium channels, particularly action potential rate of rise. Evidence of the reversal of late SFA during locomotion was present for several minutes following locomotor trials, consistent with the suggestion that SFA is modulated through slow metabotropic pathways. The abolition of late adaptation in spinal motoneurons during fictive locomotion is an example of a state-dependent change in the "intrinsic" properties of mammalian motoneurons. This change contributes to increased excitability of motoneurons during locomotion and results in robust firing during sustained locomotion. PMID:21177992

  20. Vertebral function during tadpole locomotion.

    PubMed

    Azizi, Emanuel; Landberg, Tobias; Wassersug, Richard J

    2007-01-01

    Most anuran larvae show large lateral oscillations at both the tip of the tail and the snout while swimming in a straight line. Although the lateral deflections at the snout have long been considered an inefficient aspect of tadpole locomotion, a recent hydrodynamic model suggests that they may in fact help generate thrust. It is not clear though exactly where this bending takes place. The vertebral column is extremely short and seemingly inflexible in anurans, and any axial flexion that might occur there is hidden within the globose body of the tadpole. Here we test the hypothesis that lateral deflections of the snout correlate with bending of the vertebral column within the torso of tadpoles. To quantify vertebral curvature, three sonomicrometry crystals were surgically implanted along the dorsal midline in locations corresponding to the anterior, middle, and posterior region of the presacral vertebral column. Swimming trials were conducted in a flume where synchronized video recordings were collected in dorsal view. Our results confirm that cyclic lateral bending occurs along the vertebral column during swimming and indicate that vertebral curvature is temporally in phase with lateral oscillation of the snout. Lateral oscillation of the snout increased significantly with increasing vertebral curvature. Similarly, tail beat amplitude also increases significantly with increasing vertebral curvature. Our results suggest that cyclic lateral flexion of the vertebral column, activated by the axial muscle within the torso of tadpoles contributes to snout oscillations and the generation of thrust during undulatory swimming in anuran larvae.

  1. Locomotive wheel 3D reconstruction

    NASA Astrophysics Data System (ADS)

    Guan, Xin; Luo, Zhisheng; Gao, Xiaorong; Wu, Jianle

    2010-08-01

    In the article, a system, which is used to reconstruct locomotive wheels, is described, helping workers detect the condition of a wheel through a direct view. The system consists of a line laser, a 2D camera, and a computer. We use 2D camera to capture the line-laser light reflected by the object, a wheel, and then compute the final coordinates of the structured light. Finally, using Matlab programming language, we transform the coordinate of points to a smooth surface and illustrate the 3D view of the wheel. The article also proposes the system structure, processing steps and methods, and sets up an experimental platform to verify the design proposal. We verify the feasibility of the whole process, and analyze the results comparing to standard date. The test results show that this system can work well, and has a high accuracy on the reconstruction. And because there is still no such application working in railway industries, so that it has practical value in railway inspection system.

  2. Gravitational Effects upon Locomotion Posture

    NASA Technical Reports Server (NTRS)

    DeWitt, John K.; Bentley, Jason R.; Edwards, W. Brent; Perusek, Gail P.; Samorezov, Sergey

    2008-01-01

    Researchers use actual microgravity (AM) during parabolic flight and simulated microgravity (SM) obtained with horizontal suspension analogs to better understand the effect of gravity upon gait. In both environments, the gravitational force is replaced by an external load (EL) that returns the subject to the treadmill. However, when compared to normal gravity (N), researchers consistently find reduced ground reaction forces (GRF) and subtle kinematic differences (Schaffner et al., 2005). On the International Space Station, the EL is applied by elastic bungees attached to a waist and shoulder harness. While bungees can provide EL approaching body weight (BW), their force-length characteristics coupled with vertical oscillations of the body during gait result in a variable load. However, during locomotion in N, the EL is consistently equal to 100% body weight. Comparisons between AM and N have shown that during running, GRF are decreased in AM (Schaffner et al, 2005). Kinematic evaluations in the past have focussed on joint range of motion rather than joint posture at specific instances of the gait cycle. The reduced GRF in microgravity may be a result of differing hip, knee, and ankle positions during contact. The purpose of this investigation was to compare joint angles of the lower extremities during walking and running in AM, SM, and N. We hypothesized that in AM and SM, joints would be more flexed at heel strike (HS), mid-stance (MS) and toe-off (TO) than in N.

  3. Locomotion in a turbulent world

    NASA Astrophysics Data System (ADS)

    Koehl, M.

    2014-11-01

    When organisms swim or crawl in aquatic habitats, the water through which they travel is usually moving. Therefore, an important part of understanding how aquatic organisms locomote is determining how they interact with the fluctuating turbulent water currents through which they move. The research systems we have been using to address this question are microscopic marine animals swimming in turbulent, wavy water flow or crawling on surfaces in spatially-complex habitats exposed to such flow. Using a combination of field studies, wave-flume experiments, experiments in fluidic devices, and mathematical modeling, we have discovered that small organisms swimming or crawling in turbulent flow are not subjected to steady velocities. The shears, accelerations, and odor concentrations encountered by small swimmers and crawlers fluctuate rapidly, with peaks much higher than mean values. Although microscopic organisms swim slowly relative to ambient water flow, their locomotory behavior in response to the rapidly-fluctuating shears and odors they encounter can affect where they are transported by ambient water movement. Furthermore, the ability of small organisms to walk on surfaces without being dislodged by pulses of rapid flow constrains the microhabitats in which they can forage. Supported by NSF Grant #IOS-0842685.

  4. Dynamic primitives in the control of locomotion

    PubMed Central

    Hogan, Neville; Sternad, Dagmar

    2013-01-01

    Humans achieve locomotor dexterity that far exceeds the capability of modern robots, yet this is achieved despite slower actuators, imprecise sensors, and vastly slower communication. We propose that this spectacular performance arises from encoding motor commands in terms of dynamic primitives. We propose three primitives as a foundation for a comprehensive theoretical framework that can embrace a wide range of upper- and lower-limb behaviors. Building on previous work that suggested discrete and rhythmic movements as elementary dynamic behaviors, we define submovements and oscillations: as discrete movements cannot be combined with sufficient flexibility, we argue that suitably-defined submovements are primitives. As the term “rhythmic” may be ambiguous, we define oscillations as the corresponding class of primitives. We further propose mechanical impedances as a third class of dynamic primitives, necessary for interaction with the physical environment. Combination of these three classes of primitive requires care. One approach is through a generalized equivalent network: a virtual trajectory composed of simultaneous and/or sequential submovements and/or oscillations that interacts with mechanical impedances to produce observable forces and motions. Reliable experimental identification of these dynamic primitives presents challenges: identification of mechanical impedances is exquisitely sensitive to assumptions about their dynamic structure; identification of submovements and oscillations is sensitive to their assumed form and to details of the algorithm used to extract them. Some methods to address these challenges are presented. Some implications of this theoretical framework for locomotor rehabilitation are considered. PMID:23801959

  5. A strategy for identifying locomotion modes using surface electromyography.

    PubMed

    Huang, He; Kuiken, Todd A; Lipschutz, Robert D

    2009-01-01

    This study investigated the use of surface electromyography (EMG) combined with pattern recognition (PR) to identify user locomotion modes. Due to the nonstationary characteristics of leg EMG signals during locomotion, a new phase-dependent EMG PR strategy was proposed for classifying the user's locomotion modes. The variables of the system were studied for accurate classification and timely system response. The developed PR system was tested on EMG data collected from eight able-bodied subjects and two subjects with long transfemoral (TF) amputations while they were walking on different terrains or paths. The results showed reliable classification for the seven tested modes. For eight able-bodied subjects, the average classification errors in the four defined phases using ten electrodes located over the muscles above the knee (simulating EMG from the residual limb of a TF amputee) were 12.4% +/- 5.0%, 6.0% +/- 4.7%, 7.5% +/- 5.1%, and 5.2% +/- 3.7%, respectively. Comparable results were also observed in our pilot study on the subjects with TF amputations. The outcome of this investigation could promote the future design of neural-controlled artificial legs.

  6. Union Pacific Railroad`s LNG locomotive test program

    SciTech Connect

    Grimaila, B.

    1995-12-31

    Union Pacific Railroad is testing LNG in six locomotives through 1997 to determine if the liquefied natural gas technology is right for them. Two of the six LNG test locomotives are switch, or yard, locomotives. These 1,350 horsepower locomotives are the industry`s first locomotives totally fueled by natural gas. They`re being tested in the yard in the Los Angeles area. The other four locomotives are long-haul locomotives fueled by two tenders. These units are duel-fueled, operating on a mixture of LNG and diesel and are being tested primarily on the Los Angeles to North Platte, Nebraska corridor. All the information concerning locomotive emissions, locomotive performance, maintenance requirements, the overall LNG system design and the economic feasibility of the project will be analyzed to determine if UPR should expand, or abandon, the LNG technology.

  7. Visualizing the spinal neuronal dynamics of locomotion

    NASA Astrophysics Data System (ADS)

    Subramanian, Kalpathi R.; Bashor, D. P.; Miller, M. T.; Foster, J. A.

    2004-06-01

    Modern imaging and simulation techniques have enhanced system-level understanding of neural function. In this article, we present an application of interactive visualization to understanding neuronal dynamics causing locomotion of a single hip joint, based on pattern generator output of the spinal cord. Our earlier work visualized cell-level responses of multiple neuronal populations. However, the spatial relationships were abstract, making communication with colleagues difficult. We propose two approaches to overcome this: (1) building a 3D anatomical model of the spinal cord with neurons distributed inside, animated by the simulation and (2) adding limb movements predicted by neuronal activity. The new system was tested using a cat walking central pattern generator driving a pair of opposed spinal motoneuron pools. Output of opposing motoneuron pools was combined into a single metric, called "Net Neural Drive", which generated angular limb movement in proportion to its magnitude. Net neural drive constitutes a new description of limb movement control. The combination of spatial and temporal information in the visualizations elegantly conveys the neural activity of the output elements (motoneurons), as well as the resulting movement. The new system encompasses five biological levels of organization from ion channels to observed behavior. The system is easily scalable, and provides an efficient interactive platform for rapid hypothesis testing.

  8. Legged-locomotion on inclined granular media

    NASA Astrophysics Data System (ADS)

    Rieser, Jennifer; Qian, Feifei; Goldman, Daniel

    Animals traverse a wide variety of complex environments, including situations in which the ground beneath them can yield (e.g. dry granular media in desert dunes). Locomotion strategies that are effective on level granular media can fail when traversing a granular slope. Taking inspiration from successful legged-locomotors in sandy, uneven settings, we explore the ability of a small (15 cm long, 100 g), six-c-shaped legged robot to run uphill in a bed of 1-mm-diameter poppy seeds, using an alternating tripod gait. Our fully automated experiments reveal that locomotor performance can depend sensitively on both environmental parameters such as the inclination angle and volume fraction of the substrate, and robot morphology and control parameters like leg shape, step frequency, and the friction between the feet of the robot and the substrate. We assess performance by measuring the average speed of the robot, and we find that the robot tends to perform better at higher step frequency and lower inclination angles, and that average speed decreases more rapidly with increasing angle for higher step frequency.

  9. Locomotion of an all-terrain mobile robot

    NASA Astrophysics Data System (ADS)

    Iagolnitzer, M.; Richard, F.; Samson, J. F.; Tournassoud, P.

    The authors introduce a framework and prospective solutions for intelligent locomotion, defined as the ability for a mobile robot to cross over obstacles along a path roughly determined either through teleoperation or by a navigation path-finder. Then, they present a simple but efficient control scheme derived from these concepts, taking into account ground clearance, vehicle safety, and possible occlusions in the vision field. This control scheme is applied to Rami, a four tiltable track robot equipped with force sensors, an inertial reference system, a laser-stripe range finder, and extensive real-time computing facilities based on a decentralized architecture.

  10. Advantage of straight walk instability in turning maneuver of multilegged locomotion: a robotics approach

    NASA Astrophysics Data System (ADS)

    Aoi, Shinya; Tanaka, Takahiro; Fujiki, Soichiro; Funato, Tetsuro; Senda, Kei; Tsuchiya, Kazuo

    2016-07-01

    Multilegged locomotion improves the mobility of terrestrial animals and artifacts. Using many legs has advantages, such as the ability to avoid falling and to tolerate leg malfunction. However, many intrinsic degrees of freedom make the motion planning and control difficult, and many contact legs can impede the maneuverability during locomotion. The underlying mechanism for generating agile locomotion using many legs remains unclear from biological and engineering viewpoints. The present study used a centipede-like multilegged robot composed of six body segments and twelve legs. The body segments are passively connected through yaw joints with torsional springs. The dynamic stability of the robot walking in a straight line changes through a supercritical Hopf bifurcation due to the body axis flexibility. We focused on a quick turning task of the robot and quantitatively investigated the relationship between stability and maneuverability in multilegged locomotion by using a simple control strategy. Our experimental results show that the straight walk instability does help the turning maneuver. We discuss the importance and relevance of our findings for biological systems and propose a design principle for a simple control scheme to create maneuverable locomotion of multilegged robots.

  11. Advantage of straight walk instability in turning maneuver of multilegged locomotion: a robotics approach.

    PubMed

    Aoi, Shinya; Tanaka, Takahiro; Fujiki, Soichiro; Funato, Tetsuro; Senda, Kei; Tsuchiya, Kazuo

    2016-01-01

    Multilegged locomotion improves the mobility of terrestrial animals and artifacts. Using many legs has advantages, such as the ability to avoid falling and to tolerate leg malfunction. However, many intrinsic degrees of freedom make the motion planning and control difficult, and many contact legs can impede the maneuverability during locomotion. The underlying mechanism for generating agile locomotion using many legs remains unclear from biological and engineering viewpoints. The present study used a centipede-like multilegged robot composed of six body segments and twelve legs. The body segments are passively connected through yaw joints with torsional springs. The dynamic stability of the robot walking in a straight line changes through a supercritical Hopf bifurcation due to the body axis flexibility. We focused on a quick turning task of the robot and quantitatively investigated the relationship between stability and maneuverability in multilegged locomotion by using a simple control strategy. Our experimental results show that the straight walk instability does help the turning maneuver. We discuss the importance and relevance of our findings for biological systems and propose a design principle for a simple control scheme to create maneuverable locomotion of multilegged robots. PMID:27444746

  12. Advantage of straight walk instability in turning maneuver of multilegged locomotion: a robotics approach

    PubMed Central

    Aoi, Shinya; Tanaka, Takahiro; Fujiki, Soichiro; Funato, Tetsuro; Senda, Kei; Tsuchiya, Kazuo

    2016-01-01

    Multilegged locomotion improves the mobility of terrestrial animals and artifacts. Using many legs has advantages, such as the ability to avoid falling and to tolerate leg malfunction. However, many intrinsic degrees of freedom make the motion planning and control difficult, and many contact legs can impede the maneuverability during locomotion. The underlying mechanism for generating agile locomotion using many legs remains unclear from biological and engineering viewpoints. The present study used a centipede-like multilegged robot composed of six body segments and twelve legs. The body segments are passively connected through yaw joints with torsional springs. The dynamic stability of the robot walking in a straight line changes through a supercritical Hopf bifurcation due to the body axis flexibility. We focused on a quick turning task of the robot and quantitatively investigated the relationship between stability and maneuverability in multilegged locomotion by using a simple control strategy. Our experimental results show that the straight walk instability does help the turning maneuver. We discuss the importance and relevance of our findings for biological systems and propose a design principle for a simple control scheme to create maneuverable locomotion of multilegged robots. PMID:27444746

  13. The Role of Adaptation in Body Load-Regulating Mechanisms During Locomotion

    NASA Technical Reports Server (NTRS)

    Ruttley, Tara; Holt, Christopher; Mulavara, Ajitkumar; Bloomberg, Jacob

    2010-01-01

    Body loading is a fundamental parameter that modulates motor output during locomotion, and is especially important for controlling the generation of stepping patterns, dynamic balance, and termination of locomotion. Load receptors that regulate and control posture and stance in locomotion include the Golgi tendon organs and muscle spindles at the hip, knee, and ankle joints, and the Ruffini endings and the Pacinian corpuscles in the soles of the feet. Increased body weight support (BWS) during locomotion results in an immediate reorganization of locomotor control, such as a reduction in stance and double support duration and decreased hip, ankle, and knee angles during the gait cycle. Previous studies on the effect during exposure to increased BWS while walking showed a reduction in lower limb joint angles and gait cycle timing that represents a reorganization of locomotor control. Until now, no studies have investigated how locomotor control responds after a period of exposure to adaptive modification in the body load sensing system. The goal of this research was to determine the adaptive properties of body load-regulating mechanisms in locomotor control during locomotion. We hypothesized that body load-regulating mechanisms contribute to locomotor control, and adaptive changes in these load-regulating mechanisms require reorganization to maintain forward locomotion. Head-torso coordination, lower limb movement patterns, and gait cycle timing were evaluated before and after a 30-minute adaptation session during which subjects walked on a treadmill at 5.4 km/hr with 40% body weight support (BWS). Before and after the adaptation period, head-torso and lower limb 3D kinematic data were obtained while performing a goal directed task during locomotion with 0% BWS using a video-based motion analysis system, and gait cycle timing parameters were collected by foot switches positioned under the heel and toe of the subjects shoes. Subjects showed adaptive modification in

  14. Locomotion gaits of a rotating cylinder pair

    NASA Astrophysics Data System (ADS)

    van Rees, Wim M.; Novati, Guido; Koumoutsakos, Petros; Mahadevan, L.

    2015-11-01

    Using 2D numerical simulations of the Navier-Stokes equations, we demonstrate that a simple pair of rotating cylinders can display a range of locomotion patterns of biological and engineering interest. Steadily counter-rotating the cylinders causes the pair to move akin to a vortex dipole for low rotation rates, but as the rotational velocity is increased the direction of motion reverses. Unsteady rotations lead to different locomotion gaits that resemble jellyfish (for in-phase rotations) and undulating swimmers (for out-of-phase rotations). The small number of parameters for this simple system allows us to systematically map the phase space of these gaits, and allows us to understand the underlying physical mechanisms using a minimal model with implications for biological locomotion and engineered analogs.

  15. Passive appendages aid locomotion through symmetry breaking

    NASA Astrophysics Data System (ADS)

    Bagheri, Shervin; Lacis, Ugis; Mazzino, Andrea; Kellay, Hamid; Brosse, Nicolas; Lundell, Fredrik; Ingremeau, Francois

    2014-11-01

    Plants and animals use plumes, barbs, tails, feathers, hairs, fins, and other types of appendages to aid locomotion. Despite their enormous variation, passive appendages may contribute to locomotion by exploiting the same physical mechanism. We present a new mechanism that applies to body appendages surrounded by a separated flow, which often develops behind moving bodies larger than a few millimeters. We use theory, experiments, and numerical simulations to show that bodies with protrusions turn and drift by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in flowing fluid is unstable and how it stabilizes either to the left or right of the incoming fluid flow direction. The discovery suggests a new mechanism of locomotion that may be relevant for certain organisms; for example, how plumed seeds may drift without wind and how motile animals may passively reorient themselves.

  16. Analysis of fuel cell hybrid locomotives

    NASA Astrophysics Data System (ADS)

    Miller, Arnold R.; Peters, John; Smith, Brian E.; Velev, Omourtag A.

    Led by Vehicle Projects LLC, an international industry-government consortium is developing a 109 t, 1.2 MW road-switcher locomotive for commercial and military railway applications. As part of the feasibility and conceptual-design analysis, a study has been made of the potential benefits of a hybrid power plant in which fuel cells comprise the prime mover and a battery or flywheel provides auxiliary power. The potential benefits of a hybrid power plant are: (i) enhancement of transient power and hence tractive effort; (ii) regenerative braking; (iii) reduction of capital cost. Generally, the tractive effort of a locomotive at low speed is limited by wheel adhesion and not by available power. Enhanced transient power is therefore unlikely to benefit a switcher locomotive, but could assist applications that require high acceleration, e.g. subway trains with all axles powered. In most cases, the value of regeneration in locomotives is minimal. For low-speed applications such as switchers, the available kinetic energy and the effectiveness of traction motors as generators are both minimal. For high-speed heavy applications such as freight, the ability of the auxiliary power device to absorb a significant portion of the available kinetic energy is low. Moreover, the hybrid power plant suffers a double efficiency penalty, namely, losses occur in both absorbing and then releasing energy from the auxiliary device, which result in a net storage efficiency of no more than 50% for present battery technology. Capital cost in some applications may be reduced. Based on an observed locomotive duty cycle, a cost model shows that a hybrid power plant for a switcher may indeed reduce capital cost. Offsetting this potential benefit are the increased complexity, weight and volume of the power plant, as well as 20-40% increased fuel consumption that results from lower efficiency. Based on this analysis, the consortium has decided to develop a pure fuel cell road-switcher locomotive

  17. Energy balance of human locomotion in water.

    PubMed

    Pendergast, D; Zamparo, P; di Prampero, P E; Capelli, C; Cerretelli, P; Termin, A; Craig, A; Bushnell, D; Paschke, D; Mollendorf, J

    2003-10-01

    In this paper a complete energy balance for water locomotion is attempted with the aim of comparing different modes of transport in the aquatic environment (swimming underwater with SCUBA diving equipment, swimming at the surface: leg kicking and front crawl, kayaking and rowing). On the basis of the values of metabolic power (E), of the power needed to overcome water resistance (Wd) and of propelling efficiency (etaP=Wd/Wtot, where Wtot is the total mechanical power) as reported in the literature for each of these forms of locomotion, the energy cost per unit distance (C=E/v, where v is the velocity), the drag (performance) efficiency (etad=Wd/E) and the overall efficiency (etao=Wtot/E=etad/etaP) were calculated. As previously found for human locomotion on land, for a given metabolic power (e.g. 0.5 kW=1.43 l.min(-1) VO2) the decrease in C (from 0.88 kJ.m(-1) in SCUBA diving to 0.22 kJ.m(-1) in rowing) is associated with an increase in the speed of locomotion (from 0.6 m.s(-1) in SCUBA diving to 2.4 m.s(-1) in rowing). At variance with locomotion on land, however, the decrease in C is associated with an increase, rather than a decrease, of the total mechanical work per unit distance (Wtot, kJ.m(-1)). This is made possible by the increase of the overall efficiency of locomotion (etao=Wtot/E=Wtot/C) from the slow speeds (and loads) of swimming to the high speeds (and loads) attainable with hulls and boats (from 0.10 in SCUBA diving to 0.29 in rowing).

  18. Energy balance of human locomotion in water.

    PubMed

    Pendergast, D; Zamparo, P; di Prampero, P E; Capelli, C; Cerretelli, P; Termin, A; Craig, A; Bushnell, D; Paschke, D; Mollendorf, J

    2003-10-01

    In this paper a complete energy balance for water locomotion is attempted with the aim of comparing different modes of transport in the aquatic environment (swimming underwater with SCUBA diving equipment, swimming at the surface: leg kicking and front crawl, kayaking and rowing). On the basis of the values of metabolic power (E), of the power needed to overcome water resistance (Wd) and of propelling efficiency (etaP=Wd/Wtot, where Wtot is the total mechanical power) as reported in the literature for each of these forms of locomotion, the energy cost per unit distance (C=E/v, where v is the velocity), the drag (performance) efficiency (etad=Wd/E) and the overall efficiency (etao=Wtot/E=etad/etaP) were calculated. As previously found for human locomotion on land, for a given metabolic power (e.g. 0.5 kW=1.43 l.min(-1) VO2) the decrease in C (from 0.88 kJ.m(-1) in SCUBA diving to 0.22 kJ.m(-1) in rowing) is associated with an increase in the speed of locomotion (from 0.6 m.s(-1) in SCUBA diving to 2.4 m.s(-1) in rowing). At variance with locomotion on land, however, the decrease in C is associated with an increase, rather than a decrease, of the total mechanical work per unit distance (Wtot, kJ.m(-1)). This is made possible by the increase of the overall efficiency of locomotion (etao=Wtot/E=Wtot/C) from the slow speeds (and loads) of swimming to the high speeds (and loads) attainable with hulls and boats (from 0.10 in SCUBA diving to 0.29 in rowing). PMID:12955519

  19. 40 CFR 1033.15 - Other regulation parts that apply for locomotives.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Overview and Applicability § 1033.15 Other... specifications for testing engines to measure exhaust emissions. Subpart F of this part 1033 describes how to... exhaust emission standards in this part. (b) The requirements and prohibitions of part 1068 of...

  20. 40 CFR 1033.15 - Other regulation parts that apply for locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Overview and Applicability § 1033.15 Other... specifications for testing engines to measure exhaust emissions. Subpart F of this part 1033 describes how to... exhaust emission standards in this part. (b) The requirements and prohibitions of part 1068 of...

  1. 40 CFR 1033.625 - Special certification provisions for non-locomotive-specific engines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Special Compliance... useful life. (iii) The emission data submitted under 40 CFR part 1039 (or part 89). (2) You may... engines included in engine families certified under 40 CFR part 1039 (or part 89) in limited...

  2. 49 CFR 236.927 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... following elements must be addressed: (1) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or...

  3. 49 CFR 236.1047 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or enter data to, the system, such as consist data, and...

  4. 49 CFR 236.1047 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or enter data to, the system, such as consist data, and...

  5. 49 CFR 236.927 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... following elements must be addressed: (1) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or...

  6. 49 CFR 236.927 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... following elements must be addressed: (1) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or...

  7. 49 CFR 236.1047 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or enter data to, the system, such as consist data, and...

  8. 49 CFR 236.1047 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or enter data to, the system, such as consist data, and...

  9. 49 CFR 236.927 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... following elements must be addressed: (1) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or...

  10. 49 CFR 236.927 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... following elements must be addressed: (1) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or...

  11. 49 CFR 236.1047 - Training specific to locomotive engineers and other operating personnel.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Familiarization with train control equipment onboard the locomotive and the functioning of that equipment as part of the system and in relation to other onboard systems under that person's control; (2) Any actions required of the onboard personnel to enable, or enter data to, the system, such as consist data, and...

  12. A novel device for studying weight supported, quadrupedal overground locomotion in spinal cord injured rats

    PubMed Central

    Hamlin, Marvin; Traughber, Terrance; Reinkensmeyer, David J.; de Leon, Ray D.

    2015-01-01

    Background Providing weight support facilitates locomotion in spinal cord injured animals. To control weight support, robotic systems have been developed for treadmill stepping and more recently for overground walking. New Method We developed a novel device, the body weight supported ambulatory rodent trainer (i.e. BART). It has a small pneumatic cylinder that moves along a linear track above the rat. When air is supplied to the cylinder, the rats are lifted as they perform overground walking. We tested the BART device in rats that received a moderate spinal cord contusion injury and in normal rats. Locomotor training with the BART device was not performed. Results All of the rats learned to walk in the BART device. In the contused rats, significantly greater paw dragging and dorsal stepping occurred in the hindlimbs compared to normal. Providing weight support significantly raised hip position and significantly reduced locomotor deficits. Hindlimb stepping was tightly coupled to forelimb stepping but only when the contused rats stepped without weight support. Three weeks after the contused rats received a complete spinal cord transection, significantly fewer hindlimb steps were performed. Comparison with Existing Methods Relative to rodent robotic systems, the BART device is a simpler system for studying overground locomotion. The BART device lacks sophisticated control and sensing capability, but it can be assembled relatively easily and cheaply. Conclusions These findings suggest that the BART device is a useful tool for assessing quadrupedal, overground locomotion which is a more natural form of locomotion relative to treadmill locomotion. PMID:25794460

  13. 7. Detail of the Grant Locomotive Works Erecting Shop looking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail of the Grant Locomotive Works Erecting Shop looking southwest showing ruined wall and entrance of a single story addition. - Grant Locomotive Works, Market & Spruce Streets, Paterson, Passaic County, NJ

  14. 22. AERIAL VIEW LOOKING EAST SHOWING GRANT LOCOMOTIVE WORKS, UNION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. AERIAL VIEW LOOKING EAST SHOWING GRANT LOCOMOTIVE WORKS, UNION WORKS (ROSEN MILL), ROGERS LOCOMOTIVE AND MACHINE COMPANY AND IVANHOE MILL WHEELHOUSE UNDER RESTORATION. - Great Falls S. U. M. Historic District, Oliver Street, Paterson, Passaic County, NJ

  15. Locomotion of Paramecium in patterned environments

    NASA Astrophysics Data System (ADS)

    Park, Eun-Jik; Eddins, Aja; Kim, Junil; Yang, Sung; Jana, Saikat; Jung, Sunghwan

    2011-10-01

    Ciliary organisms like Paramecium Multimicronucleatum locomote by synchronized beating of cilia that produce metachronal waves over their body. In their natural environments they navigate through a variety of environments especially surfaces with different topology. We study the effects of wavy surfaces patterned on the PDMS channels on the locomotive abilities of Paramecium by characterizing different quantities like velocity amplitude and wavelength of the trajectories traced. We compare this result with the swimming characteristics in straight channels and draw conclusions about the effects of various patterned surfaces.

  16. Optimizing snake locomotion on an inclined plane.

    PubMed

    Wang, Xiaolin; Osborne, Matthew T; Alben, Silas

    2014-01-01

    We develop a model to study the locomotion of snakes on inclined planes. We determine numerically which snake motions are optimal for two retrograde traveling-wave body shapes, triangular and sinusoidal waves, across a wide range of frictional parameters and incline angles. In the regime of large transverse friction coefficients, we find power-law scalings for the optimal wave amplitudes and corresponding costs of locomotion. We give an asymptotic analysis to show that the optimal snake motions are traveling waves with amplitudes given by the same scaling laws found in the numerics.

  17. Bio-inspired Optimal Locomotion Reconfigurability of Quadruped Rovers using Central Pattern Generators

    NASA Astrophysics Data System (ADS)

    Bohra, Murtaza

    Legged rovers are often considered as viable solutions for traversing unknown terrain. This work addresses the optimal locomotion reconfigurability of quadruped rovers, which consists of obtaining optimal locomotion modes, and transitioning between them. A 2D sagittal plane rover model is considered based on a domestic cat. Using a Genetic Algorithm, the gait, pose and control variables that minimize torque or maximize speed are found separately. The optimization approach takes into account the elimination of leg impact, while considering the entire variable spectrum. The optimal solutions are consistent with other works on gait optimization, and are similar to gaits found in quadruped animals as well. An online model-free gait planning framework is also implemented, that is based on Central Pattern Generators is implemented. It is used to generate joint and control trajectories for any arbitrarily varying speed profile, and shown to regulate locomotion transition and speed modulation, both endogenously and continuously.

  18. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion

    NASA Astrophysics Data System (ADS)

    Lee, Scott

    2015-02-01

    In our first article1 on scaling in theropod dinosaurs, the longitudinal stress in the leg bones due to supporting the weight of the animal was studied and found not to control the dimensions of the femur. As a continuation of our study of elasticity in dinosaur bones, we now examine the transverse stress in the femur due to locomotion and find that this effect is important for the geometry of the bone. We find that larger theropods (including Tyrannosaurus rex) were less athletic than smaller theropods.

  19. 49 CFR 230.101 - Steam locomotive driving journal boxes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not...

  20. 49 CFR 231.29 - Road locomotives with corner stairways.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Road locomotives with corner stairways. 231.29... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.29 Road locomotives with corner stairways. After September 30, 1979, road locomotives with corner stairway openings must...

  1. 49 CFR 231.29 - Road locomotives with corner stairways.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Road locomotives with corner stairways. 231.29... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.29 Road locomotives with corner stairways. After September 30, 1979, road locomotives with corner stairway openings must...

  2. 49 CFR 231.29 - Road locomotives with corner stairways.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Road locomotives with corner stairways. 231.29... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.29 Road locomotives with corner stairways. After September 30, 1979, road locomotives with corner stairway openings must...

  3. 49 CFR 231.29 - Road locomotives with corner stairways.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Road locomotives with corner stairways. 231.29... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.29 Road locomotives with corner stairways. After September 30, 1979, road locomotives with corner stairway openings must...

  4. 49 CFR 223.11 - Requirements for existing locomotives.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Requirements for existing locomotives. 223.11... be equipped with certified glazing in all locomotive cab windows after June 30, 1984. (d) Each... vandalism has a locomotive cab window that is broken or damaged so that the window fails to permit...

  5. 49 CFR 223.11 - Requirements for existing locomotives.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Requirements for existing locomotives. 223.11... be equipped with certified glazing in all locomotive cab windows after June 30, 1984. (d) Each... vandalism has a locomotive cab window that is broken or damaged so that the window fails to permit...

  6. 49 CFR 229.141 - Body structure, MU locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Body structure, MU locomotives. 229.141 Section... Design Requirements § 229.141 Body structure, MU locomotives. (a) MU locomotives built new after April 1... body structure designed to meet or exceed the following minimum specifications: (1) The body...

  7. 49 CFR 229.141 - Body structure, MU locomotives.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Body structure, MU locomotives. 229.141 Section... Design Requirements § 229.141 Body structure, MU locomotives. (a) MU locomotives built new after April 1... body structure designed to meet or exceed the following minimum specifications: (1) The body...

  8. 49 CFR 231.29 - Road locomotives with corner stairways.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.29 Road locomotives with corner stairways. After September 30, 1979, road locomotives with corner stairway openings must be... 49 Transportation 4 2010-10-01 2010-10-01 false Road locomotives with corner stairways....

  9. 49 CFR 230.101 - Steam locomotive driving journal boxes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not...

  10. 49 CFR 230.101 - Steam locomotive driving journal boxes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not...

  11. 49 CFR 230.101 - Steam locomotive driving journal boxes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not...

  12. 49 CFR 230.101 - Steam locomotive driving journal boxes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not...

  13. Metastable legged locomotion: methods to quantify and optimize reliability

    NASA Astrophysics Data System (ADS)

    Saglam, Cenk O.; Byl, Katie

    2015-05-01

    Measuring the stability of highly-dynamic bipedal locomotion is a challenging but essential task for more capable human-like walking. By discretizing the walking dynamics, we treat the system as a Markov chain, which lends itself to an easy quantification of failure rates by the expected number of steps before falling. This meaningful and intuitive metric is then used for optimizing and benchmarking given controllers. While this method is applicable to any controller scheme, we illustrate the results with two case demonstrations. One scheme is the now-familiar hybrid zero dynamics approach and the other is a method using piece-wise reference trajectories with a sliding mode control. We optimize low-level controllers, to minimize failure rates for any one gait, and we adopt a hierarchical control structure to switch among low-level gaits, providing even more dramatic improvements on the system performance.

  14. From the ethology of unicellular eukaryotes to the locomotion of the living beings: meaning and evolution of the phenomenon.

    PubMed

    Banchetti, Rosalba

    2005-01-01

    A comparative reappraisal of the general problem of evolutionary trends and constraints of the locomotion phenomenon from prokaryotes to protozoa to metazoa was carried on. They elaborated different propulsive systems, different control systems of motion and different analysis systems of the stimuli. A general understanding of the locomotion phenomenon was reached and ciliate behaviour was positioned within the wider context of the evolution of biological displacement.

  15. 49 CFR 210.9 - Movement of a noise defective locomotive, rail car, or consist of a locomotive and rail cars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Movement of a noise defective locomotive, rail car, or consist of a locomotive and rail cars. 210.9 Section 210.9 Transportation Other Regulations... locomotive, rail car, or consist of a locomotive and rail cars. A locomotive, rail car, or consist of...

  16. 49 CFR 210.9 - Movement of a noise defective locomotive, rail car, or consist of a locomotive and rail cars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Movement of a noise defective locomotive, rail car, or consist of a locomotive and rail cars. 210.9 Section 210.9 Transportation Other Regulations... locomotive, rail car, or consist of a locomotive and rail cars. A locomotive, rail car, or consist of...

  17. Hybrid magnetic mechanism for active locomotion based on inchworm motion

    NASA Astrophysics Data System (ADS)

    Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2013-02-01

    Magnetic robots have been studied in the past. Insect-type micro-robots are used in various biomedical applications; researchers have developed inchworm micro-robots for endoscopic use. A biological inchworm has a looping locomotion gait. However, most inchworm micro-robots depend on a general bending, or bellows, motion. In this paper, we introduce a new robotic mechanism using magnetic force and torque control in a rotating magnetic field for a looping gait. The proposed robot is controlled by the magnetic torque, attractive force, and body mechanisms (two stoppers, flexible body, and different frictional legs). The magnetic torque generates a general bending motion. In addition, the attractive force and body mechanisms produce the robot’s looping motion within a rotating magnetic field and without the use of an algorithm for field control. We verified the device’s performance and analyzed the motion through simulations and various experiments. The robot mechanism can be applied to active locomotion for various medical robots, such as wireless endoscopes.

  18. 49 CFR 229.129 - Locomotive horn.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... defectives equal to an AQL of 1% or less, as set forth in 7 CFR part 43. (2) Each locomotive built before... Electrotechnical Commission (IEC) Standard 61672-1 (2002-05) for a Class 2 instrument. (2) An acoustic calibrator... with the acoustic calibrator immediately before and after compliance tests. Any change in the...

  19. Lizard locomotion in heterogeneous granular media

    NASA Astrophysics Data System (ADS)

    Schiebel, Perrin; Goldman, Daniel

    2014-03-01

    Locomotion strategies in heterogeneous granular environments (common substrates in deserts), are relatively unexplored. The zebra-tailed lizard (C. draconoides) is a useful model organism for such studies owing to its exceptional ability to navigate a variety of desert habitats at impressive speed (up to 50 body-lengths per second) using both quadrapedal and bidepal gaits. In laboratory experiments, we challenge the lizards to run across a field of boulders (2.54 cm diameter glass spheres or 3.8 cm 3D printed spheres) placed in a lattice pattern and embedded in a loosely packed granular medium of 0.3 mm diameter glass particles. Locomotion kinematics of the lizard are recorded using high speed cameras, with and without the scatterers. The data reveals that unlike the lizard's typical quadrupedal locomotion using a diagonal gait, when scatterers are present the lizard is most successful when using a bipedal gait, with a raised center of mass (CoM). We propose that the kinematics of bipedal running in conjunction with the lizard's long toes and compliant hind foot are the keys to this lizard's successful locomotion in the presence of such obstacles. NSF PoLS

  20. 49 CFR 229.129 - Locomotive horn.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... defectives equal to an AQL of 1% or less, as set forth in 7 CFR part 43. (2) Each locomotive built before... Electrotechnical Commission (IEC) Standard 61672-1 (2002-05) for a Class 2 instrument. (2) An acoustic calibrator... with the acoustic calibrator immediately before and after compliance tests. Any change in the...

  1. 49 CFR 229.129 - Locomotive horn.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... defectives equal to an AQL of 1% or less, as set forth in 7 CFR part 43. (2) Each locomotive built before... Electrotechnical Commission (IEC) Standard 61672-1 (2002-05) for a Class 2 instrument. (2) An acoustic calibrator... with the acoustic calibrator immediately before and after compliance tests. Any change in the...

  2. 77 FR 23159 - Locomotive Safety Standards; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... rule related to locomotive safety standards. See 77 FR 21312. The final rule established a public... safety standards and comments on such petitions. That final rule mistakenly lists FR-2009- 0095... is FRA-2009-0094. The final rule issued on April 9, 2012, incorrectly identified docket number...

  3. Evidence for Motor Simulation in Imagined Locomotion

    ERIC Educational Resources Information Center

    Kunz, Benjamin R.; Creem-Regehr, Sarah H.; Thompson, William B.

    2009-01-01

    A series of experiments examined the role of the motor system in imagined movement, finding a strong relationship between imagined walking performance and the biomechanical information available during actual walking. Experiments 1 through 4 established the finding that real and imagined locomotion differ in absolute walking time. We then tested…

  4. Muscle spindle and fusimotor activity in locomotion.

    PubMed

    Ellaway, Peter H; Taylor, Anthony; Durbaba, Rade

    2015-08-01

    Mammals may exhibit different forms of locomotion even within a species. A particular form of locomotion (e.g. walk, run, bound) appears to be selected by supraspinal commands, but the precise pattern, i.e. phasing of limbs and muscles, is generated within the spinal cord by so-called central pattern generators. Peripheral sense organs, particularly the muscle spindle, play a crucial role in modulating the central pattern generator output. In turn, the feedback from muscle spindles is itself modulated by static and dynamic fusimotor (gamma) neurons. The activity of muscle spindle afferents and fusimotor neurons during locomotion in the cat is reviewed here. There is evidence for some alpha-gamma co-activation during locomotion involving static gamma motoneurons. However, both static and dynamic gamma motoneurons show patterns of modulation that are distinct from alpha motoneuron activity. It has been proposed that static gamma activity may drive muscle spindle secondary endings to signal the intended movement to the central nervous system. Dynamic gamma motoneuron drive appears to prime muscle spindle primary endings to signal transitions in phase of the locomotor cycle. These findings come largely from reduced animal preparations (decerebrate) and require confirmation in freely moving intact animals. PMID:26047022

  5. Muscle spindle and fusimotor activity in locomotion.

    PubMed

    Ellaway, Peter H; Taylor, Anthony; Durbaba, Rade

    2015-08-01

    Mammals may exhibit different forms of locomotion even within a species. A particular form of locomotion (e.g. walk, run, bound) appears to be selected by supraspinal commands, but the precise pattern, i.e. phasing of limbs and muscles, is generated within the spinal cord by so-called central pattern generators. Peripheral sense organs, particularly the muscle spindle, play a crucial role in modulating the central pattern generator output. In turn, the feedback from muscle spindles is itself modulated by static and dynamic fusimotor (gamma) neurons. The activity of muscle spindle afferents and fusimotor neurons during locomotion in the cat is reviewed here. There is evidence for some alpha-gamma co-activation during locomotion involving static gamma motoneurons. However, both static and dynamic gamma motoneurons show patterns of modulation that are distinct from alpha motoneuron activity. It has been proposed that static gamma activity may drive muscle spindle secondary endings to signal the intended movement to the central nervous system. Dynamic gamma motoneuron drive appears to prime muscle spindle primary endings to signal transitions in phase of the locomotor cycle. These findings come largely from reduced animal preparations (decerebrate) and require confirmation in freely moving intact animals.

  6. Diencephalic regulation of respiration and arterial pressure during actual and fictive locomotion in cat.

    PubMed

    Millhorn, D E; Eldridge, F L; Waldrop, T G; Kiley, J P

    1987-10-01

    The purpose of this study was to examine by experimentation the hypothesis that the respiratory and circulatory responses during exercise are attributable to command signals that emanate from the suprapontine brain. We studied the relations between locomotion (exercise) and phrenic nerve activity and arterial pressure in cats that walked or ran on a treadmill and in animals during fictive locomotion, i.e., locomotor activity in motor nerves to legs. Anesthetized cats with intact brains and unanesthetized decorticated cats were used. All preparations exhibited spontaneous actual and fictive locomotion. Electrical stimulation or microinjection of picrotoxin, a GABA antagonist, of the subthalamic locomotor areas always caused locomotion to develop. Phrenic nerve activity and arterial pressure increased in proportion to the level of locomotor activity despite control or ablation of feedback signals from chemoreceptors and vagal receptors. Similar relations were measured during fictive locomotion despite the absence of muscular contraction and limb movement and the lack of change in metabolic rate. These findings provide experimental support for the central command hypothesis for the genesis of the respiratory hyperpnea and increased cardiovascular function that occur during exercise. We believe that the command signals emanate from the subthalamic locomotor area of the diencephalon. PMID:3652403

  7. 49 CFR 1242.60 - Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 9 2014-10-01 2014-10-01 false Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives (accounts XX-51-67, XX-51-68 and XX-51-69). 1242.60 Section...-Transportation § 1242.60 Locomotive fuel, electric power purchased/produced for motive power and...

  8. 49 CFR 1242.60 - Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 9 2013-10-01 2013-10-01 false Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives (accounts XX-51-67, XX-51-68 and XX-51-69). 1242.60 Section...-Transportation § 1242.60 Locomotive fuel, electric power purchased/produced for motive power and...

  9. 49 CFR 1242.60 - Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 9 2012-10-01 2012-10-01 false Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives (accounts XX-51-67, XX-51-68 and XX-51-69). 1242.60 Section...-Transportation § 1242.60 Locomotive fuel, electric power purchased/produced for motive power and...

  10. 49 CFR 1242.60 - Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 9 2011-10-01 2011-10-01 false Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives (accounts XX-51-67, XX-51-68 and XX-51-69). 1242.60 Section...-Transportation § 1242.60 Locomotive fuel, electric power purchased/produced for motive power and...

  11. Discordance in recovery between altered locomotion and muscle atrophy induced by simulated microgravity in rats.

    PubMed

    Tajino, Junichi; Ito, Akira; Nagai, Momoko; Zhang, Xiangkai; Yamaguchi, Shoki; Iijima, Hirotaka; Aoyama, Tomoki; Kuroki, Hiroshi

    2015-01-01

    Exposure to a microgravity environment leads to adverse effects in motion and musculoskeletal properties. However, few studies have investigated the recovery of altered locomotion and muscle atrophy simultaneously. The authors investigated altered locomotion in rats submitted to simulated microgravity by hindlimb unloading for 2 weeks. Motion deficits were characterized by hyperextension of the knees and ankle joints and forward-shifted limb motion. Furthermore, these locomotor deficits did not revert to their original form after a 2-week recovery period, although muscle atrophy in the hindlimbs had recovered, implying discordance in recovery between altered locomotion and muscle atrophy, and that other factors such as neural drives might control behavioral adaptations to microgravity. PMID:25789843

  12. Climbing, falling, and jamming during ant locomotion in confined environments

    PubMed Central

    Gravish, Nick; Monaenkova, Daria; Goodisman, Michael A. D.; Goldman, Daniel I.

    2013-01-01

    Locomotion emerges from effective interactions of an individual with its environment. Principles of biological terrestrial locomotion have been discovered on unconfined vertical and horizontal substrates. However, a diversity of organisms construct, inhabit, and move within confined spaces. Such animals are faced with locomotor challenges including limited limb range of motion, crowding, and visual sensory deprivation. Little is known about how these organisms accomplish their locomotor tasks, and such environments challenge human-made devices. To gain insight into how animals move within confined spaces, we study the locomotion of the fire ant Solenopsis invicta, which constructs subterranean tunnel networks (nests). Laboratory experiments reveal that ants construct tunnels with diameter, D, comparable to body length, L = 3.5 ± 0.5 mm. Ants can move rapidly (> 9 bodylengths per s) within these environments; their tunnels allow for effective limb, body, and antennae interaction with walls, which facilitate rapid slip-recovery during ascending and descending climbs. To examine the limits of slip-recovery in artificial tunnels, we perform perturbations consisting of rapid downward accelerations of the tunnels, which induce falls. Below a critical tunnel diameter, Ds = 1.31 ± 0.02 L, falls are always arrested through rapid interaction of appendages and antennae with tunnel walls to jam the falls. Ds is comparable to the size of incipient nest tunnels (D = 1.06 ± 0.23 L), supporting our hypothesis that fire ants construct environments that simplify their control task when moving through the nest, likely without need for rapid nervous system intervention. PMID:23690589

  13. Locomotion in the rat after 5-hydroxy-L-tryptophan.

    PubMed

    Clarke, K A; Parker, A J; Stirk, G C

    1984-02-17

    Previous work has shown that administration of 5HTP in amounts substantially less than those required to elicit 'serotonin syndrome' to rats pretreated witha peripheral decarboxylase inhibitor, produced increases in locomotion, measured by whole body movements. The purpose of the present work was to study the cyclic shifts of weights from side to side which underly the progress of locomotion and to see whether these change after 5HTP. From the reciprocal of the interval for one complete cycle was calculated the weight transferral frequency (WTF). The modal WTF for control and treated rats were in the ranges 1-1.49 and 2-2.49 Hz respectively, while the medians were in the ranges 2-2.49 and 2.5-2.99 Hz respectively. Testing of goodness of fit between the frequency distribution curves in control and treated animals showed significant differences. It is concluded that after 5HTP treatment, basic locomotor patterns are shifted towards higher frequencies. PMID:6609078

  14. 49 CFR 236.1006 - Equipping locomotives operating in PTC territory.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... segment equipped with a PTC system shall be controlled by a locomotive equipped with an onboard PTC... shall include in its PTCIP specific goals for progressive implementation of onboard systems and... operative PTC onboard equipment. The PTCIP shall include a brief but sufficient explanation of how...

  15. 49 CFR 236.1006 - Equipping locomotives operating in PTC territory.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... segment equipped with a PTC system shall be controlled by a locomotive equipped with an onboard PTC... shall include in its PTCIP specific goals for progressive implementation of onboard systems and... operative PTC onboard equipment. The PTCIP shall include a brief but sufficient explanation of how...

  16. 49 CFR 236.1006 - Equipping locomotives operating in PTC territory.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... segment equipped with a PTC system shall be controlled by a locomotive equipped with an onboard PTC... shall include in its PTCIP specific goals for progressive implementation of onboard systems and... operative PTC onboard equipment. The PTCIP shall include a brief but sufficient explanation of how...

  17. 49 CFR 236.1006 - Equipping locomotives operating in PTC territory.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... segment equipped with a PTC system shall be controlled by a locomotive equipped with an onboard PTC... shall include in its PTCIP specific goals for progressive implementation of onboard systems and... operative PTC onboard equipment. The PTCIP shall include a brief but sufficient explanation of how...

  18. 49 CFR 236.1006 - Equipping locomotives operating in PTC territory.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... segment equipped with a PTC system shall be controlled by a locomotive equipped with an onboard PTC... shall include in its PTCIP specific goals for progressive implementation of onboard systems and... operative PTC onboard equipment. The PTCIP shall include a brief but sufficient explanation of how...

  19. Feedback Control of Floor Reaction Force Based on Force-Reflecting-Type Multilateral Control

    NASA Astrophysics Data System (ADS)

    Nagase, Kazuki; Katsura, Seiichiro

    Real-world haptics is being studied not only for improving feedback on real-world haptic information in teleoperation but also for developing key technologies for future human support. For the remote operating of systems at distant places, haptic information is required in addition to visual information. The haptic information around a work environment can be the floor reaction force, which can be obtained using a movement-type haptic device. The floor reaction force from the environment that the mobile haptic device touches is fed back accurately to the operator. First, this paper proposes a general force-reflecting-type multilateral control. Second, this paper extends the control to feedback control of the floor reaction force by using force-reflecting-type multilateral control and a novel haptic device employing a biped robot with a slave system. The position response of a master system is transformed to a leg tip position command for the biped-type haptic device. In addition, the floor reaction force determined by the biped-type haptic device is fed back to the master system. The proposed method can determine the force feedback to the sole of the foot, which is not possible with a conventional stationary system. As a result, the floor reaction force from a large area can be obtained, and the operability of the control system is improved by using the proposed system.

  20. Locomotion of Amorphous Surface Robots

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T. (Inventor)

    2016-01-01

    An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

  1. Locomotion of Amorphous Surface Robots

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T. (Inventor)

    2014-01-01

    An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

  2. Pyramidal tract neurons receptive to different forelimb joints act differently during locomotion

    PubMed Central

    Stout, Erik E.

    2012-01-01

    During locomotion, motor cortical neurons projecting to the pyramidal tract (PTNs) discharge in close relation to strides. How their discharges vary based on the part of the body they influence is not well understood. We addressed this question with regard to joints of the forelimb in the cat. During simple and ladder locomotion, we compared the activity of four groups of PTNs with somatosensory receptive fields involving different forelimb joints: 1) 45 PTNs receptive to movements of shoulder, 2) 30 PTNs receptive to movements of elbow, 3) 40 PTNs receptive to movements of wrist, and 4) 30 nonresponsive PTNs. In the motor cortex, a relationship exists between the location of the source of afferent input and the target for motor output. On the basis of this relationship, we inferred the forelimb joint that a PTN influences from its somatosensory receptive field. We found that different PTNs tended to discharge differently during locomotion. During simple locomotion shoulder-related PTNs were most active during late stance/early swing, and upon transition from simple to ladder locomotion they often increased activity and stride-related modulation while reducing discharge duration. Elbow-related PTNs were most active during late swing/early stance and typically did not change activity, modulation, or discharge duration on the ladder. Wrist-related PTNs were most active during swing and upon transition to the ladder often decreased activity and increased modulation while reducing discharge duration. These data suggest that during locomotion the motor cortex uses distinct mechanisms to control the shoulder, elbow, and wrist. PMID:22236716

  3. Regulation of two motor patterns enables the gradual adjustment of locomotion strategy in Caenorhabditis elegans

    PubMed Central

    Hums, Ingrid; Riedl, Julia; Mende, Fanny; Kato, Saul; Kaplan, Harris S; Latham, Richard; Sonntag, Michael; Traunmüller, Lisa; Zimmer, Manuel

    2016-01-01

    In animal locomotion a tradeoff exists between stereotypy and flexibility: fast long-distance travelling (LDT) requires coherent regular motions, while local sampling and area-restricted search (ARS) rely on flexible movements. We report here on a posture control system in C. elegans that coordinates these needs. Using quantitative posture analysis we explain worm locomotion as a composite of two modes: regular undulations versus flexible turning. Graded reciprocal regulation of both modes allows animals to flexibly adapt their locomotion strategy under sensory stimulation along a spectrum ranging from LDT to ARS. Using genetics and functional imaging of neural activity we characterize the counteracting interneurons AVK and DVA that utilize FLP-1 and NLP-12 neuropeptides to control both motor modes. Gradual regulation of behaviors via this system is required for spatial navigation during chemotaxis. This work shows how a nervous system controls simple elementary features of posture to generate complex movements for goal-directed locomotion strategies. DOI: http://dx.doi.org/10.7554/eLife.14116.001 PMID:27222228

  4. Using entropy measures to characterize human locomotion.

    PubMed

    Leverick, Graham; Szturm, Tony; Wu, Christine Q

    2014-12-01

    Entropy measures have been widely used to quantify the complexity of theoretical and experimental dynamical systems. In this paper, the value of using entropy measures to characterize human locomotion is demonstrated based on their construct validity, predictive validity in a simple model of human walking and convergent validity in an experimental study. Results show that four of the five considered entropy measures increase meaningfully with the increased probability of falling in a simple passive bipedal walker model. The same four entropy measures also experienced statistically significant increases in response to increasing age and gait impairment caused by cognitive interference in an experimental study. Of the considered entropy measures, the proposed quantized dynamical entropy (QDE) and quantization-based approximation of sample entropy (QASE) offered the best combination of sensitivity to changes in gait dynamics and computational efficiency. Based on these results, entropy appears to be a viable candidate for assessing the stability of human locomotion.

  5. Locomotion in complex fluids: Integral theorems

    NASA Astrophysics Data System (ADS)

    Lauga, Eric

    2014-08-01

    The biological fluids encountered by self-propelled cells display complex microstructures and rheology. We consider here the general problem of low-Reynolds number locomotion in a complex fluid. Building on classical work on the transport of particles in viscoelastic fluids, we demonstrate how to mathematically derive three integral theorems relating the arbitrary motion of an isolated organism to its swimming kinematics in a non-Newtonian fluid. These theorems correspond to three situations of interest, namely, (1) squirming motion in a linear viscoelastic fluid, (2) arbitrary surface deformation in a weakly non-Newtonian fluid, and (3) small-amplitude deformation in an arbitrarily non-Newtonian fluid. Our final results, valid for a wide-class of swimmer geometry, surface kinematics, and constitutive models, at most require mathematical knowledge of a series of Newtonian flow problems, and will be useful to quantity the locomotion of biological and synthetic swimmers in complex environments.

  6. Locomotion of chemically powered autonomous nanowire motors

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Li, Longqiu; Li, Tianlong; Zhang, Guangyu; Sun, Qian

    2015-08-01

    Physical insights on the hydrodynamics and locomotion of self-propelled nanowire motor under nonequilibrium steady state are investigated using finite element method in accordance with hybrid molecular dynamics/multiparticle collision dynamics and rigid body dynamics. Nanowire motor is discretized into finite segments, and forces of solvent molecule acting on the motor are assumed to be the sum of forces acting on all segments of the motor. We show that the locomotion of nanowire motor is mainly determined by the imbalance forces acting on the catalytic and noncatalytic segments. The average velocity along the axis increases significantly as a function of time prior to reaching equilibrium. The length of nanowire motor shows negligible effect on the velocity of the motor. Preliminary experimental results are provided to validate the current model.

  7. Azimut: a multimodal locomotion robotic platform

    NASA Astrophysics Data System (ADS)

    Michaud, Francois; Letourneau, Dominic; Arsenault, Martin; Bergeron, Yann; Cadrin, Richard; Gagnon, Frederic; Legault, Marc-Antoine; Millette, Mathieu; Pare, Jean-Francois; Tremblay, Marie-Christine; Lepage, Pierre; Morin, Yan; Caron, Serge

    2003-09-01

    Other than from its sensing and processing capabilities, a mobile robotic platform can be limited in its use by its ability to move in the environment. A wheeled robot works well on flat surfaces. Tracks are useful over rough terrains, while legs allow a robot to move over obstacles. In this paper we present a new concept of mobile robot with the objective of combining different locomotion mechanisms on the same platform to increase its locomotion capabilities. After presenting a review of multi-modal robotic platforms, we describe the design of our robot called AZIMUT. AZIMUT combines wheels, legs and tracks to move in three-dimensional environments. The robot is symmetrical and is made of four independent leg-track-wheel articulations. It can move with its articulations up, down or straight, or move sideways without changing the robot's orientation. The robot could be used in surveillance and rescue missions, exploration or operation in hazardous environments.

  8. Differences in gaze anticipation for locomotion with and without vision

    PubMed Central

    Authié, Colas N.; Hilt, Pauline M.; N'Guyen, Steve; Berthoz, Alain; Bennequin, Daniel

    2015-01-01

    Previous experimental studies have shown a spontaneous anticipation of locomotor trajectory by the head and gaze direction during human locomotion. This anticipatory behavior could serve several functions: an optimal selection of visual information, for instance through landmarks and optic flow, as well as trajectory planning and motor control. This would imply that anticipation remains in darkness but with different characteristics. We asked 10 participants to walk along two predefined complex trajectories (limaçon and figure eight) without any cue on the trajectory to follow. Two visual conditions were used: (i) in light and (ii) in complete darkness with eyes open. The whole body kinematics were recorded by motion capture, along with the participant's right eye movements. We showed that in darkness and in light, horizontal gaze anticipates the orientation of the head which itself anticipates the trajectory direction. However, the horizontal angular anticipation decreases by a half in darkness for both gaze and head. In both visual conditions we observed an eye nystagmus with similar properties (frequency and amplitude). The main difference comes from the fact that in light, there is a shift of the orientations of the eye nystagmus and the head in the direction of the trajectory. These results suggest that a fundamental function of gaze is to represent self motion, stabilize the perception of space during locomotion, and to simulate the future trajectory, regardless of the vision condition. PMID:26106313

  9. Multi-limbed locomotion systems for space construction and maintenance

    NASA Technical Reports Server (NTRS)

    Waldron, K. J.; Klein, C. A.

    1987-01-01

    A well developed technology of coordination of multi-limbed locomotory systems is now available. Results from a NASA sponsored study of several years ago are presented. This was a simulation study of a three-limbed locomotion/manipulation system. Each limb had six degrees of freedom and could be used either as a locomotory grasping hand-holds, or as a manipulator. The focus of the study was kinematic coordination algorithms. The presentation will also include very recent results from the Adaptive Suspension Vehicle Project. The Adaptive Suspension Vehicle (ASV) is a legged locomotion system designed for terrestrial use which is capable of operating in completely unstructured terrain in either a teleoperated or operator-on-board mode. Future development may include autonomous operation. The ASV features a very advanced coordination and control system which could readily be adapted to operation in space. An inertial package with a vertical gyro, and rate gyros and accelerometers on three orthogonal axes provides body position information at high bandwidth. This is compared to the operator's commands, injected via a joystick to provide a commanded force system on the vehicle's body. This system is, in turn, decomposed by a coordination algorithm into force commands to those legs which are in contact with the ground.

  10. Different forms of locomotion in the spinal lamprey.

    PubMed

    Hsu, Li-Ju; Orlovsky, Grigori N; Zelenin, Pavel V

    2014-06-01

    Forward locomotion has been extensively studied in different vertebrate animals, and the principal role of spinal mechanisms in the generation of this form of locomotion has been demonstrated. Vertebrate animals, however, are capable of other forms of locomotion, such as backward walking and swimming, sideward walking, and crawling. Do the spinal mechanisms play a principal role in the generation of these forms of locomotion? We addressed this question in lampreys, which are capable of five different forms of locomotion - fast forward swimming, slow forward swimming, backward swimming, forward crawling, and backward crawling. To induce locomotion in lampreys spinalised at the second gill level, we used either electrical stimulation of the spinal cord at different rostrocaudal levels, or tactile stimulation of specific cutaneous receptive fields from which a given form of locomotion could be evoked in intact lampreys. We found that any of the five forms of locomotion could be evoked in the spinal lamprey by electrical stimulation of the spinal cord, and some of them by tactile stimulation. These results suggest that spinal mechanisms in the lamprey, in the absence of phasic supraspinal commands, are capable of generating the basic pattern for all five forms of locomotion observed in intact lampreys. In spinal lampreys, the direction of swimming did not depend on the site of spinal cord stimulation, but on the stimulation strength. The direction of crawling strongly depended on the body configuration. The spinal structures presumably activated by spinal cord stimulation and causing different forms of locomotion are discussed.

  11. Gait transitions during unrestrained locomotion in dogs.

    PubMed

    Blaszczyk, J W

    2001-04-01

    Gait transitions during long distance, unrestrained locomotion were studied in 22 mongrel dogs. Spatial and temporal limb movement parameters were collected and the phase relationships between limb movements based upon a 2-dimensional (2-D) gait diagram were computed. During most of the trials, the dogs trotted within a relatively narrow velocity range. Gait transitions were observed during radical changes of the movement velocity. In most cases the gait switches were abrupt and completed within 2 strides of the gait cycle. The dogs walked, depending on the animal size, within the upper velocity range of 0.93-1.21 m/s. Most of the walk-trot transitions were observed within this range. All of them had a typical pattern that involved changes of the phase shift between diagonal limb movements from 0.31 +/- 0.02 (a typical value for a walking dog) down to 0.02 +/- 0.03. These changes appeared abruptly within one stride cycle for each diagonal pair of limbs; therefore, the transition was completed in 2 strides of the gait cycle. The switch involved momentary shortening of the hindlimb amplitudes. During the next gait cycle, all limb movement amplitudes were reduced with a concomitant increase in limb movement frequencies. In contrast to the clear border between the symmetrical gaits, the dogs switched to gallop at any speed within the trot range (most frequently between 1.5-2.6 m/s). The transitions were usually completed within one stride of the diagonal limbs. In most cases, the switch from trot to gallop had a similar pattern; while maintaining synchronous movement of one diagonal pair of limbs, the other pair movement control was modified accordingly. The typical transition pattern involved the shortening of the swing phase in the front limb with simultaneous lengthening of the swing phase in the diagonal hindlimb. These transient modifications had their equivalent in the analogous limb movement amplitude changes. A mirror-image pattern of phase changes was observed

  12. Network interneurons underlying ciliary locomotion in Hermissenda.

    PubMed

    Crow, Terry; Jin, Nan Ge; Tian, Lian-Ming

    2013-02-01

    In the nudibranch mollusk Hermissenda, ciliary locomotion contributes to the generation of two tactic behaviors. Light elicits a positive phototaxis, and graviceptive stimulation evokes a negative gravitaxis. Two classes of light-responsive premotor interneurons in the network contributing to ciliary locomotion have been recently identified in the cerebropleural ganglia. Aggregates of type I interneurons receive monosynaptic excitatory (I(e)) or inhibitory (I(i)) input from identified photoreceptors. Type II interneurons receive polysynaptic excitatory (II(e)) or inhibitory (II(i)) input from photoreceptors. The ciliary network also includes type III inhibitory (III(i)) interneurons, which form monosynaptic inhibitory connections with ciliary efferent neurons (CENs). Illumination of the eyes evokes a complex inhibitory postsynaptic potential, a decrease of I(i) spike activity, a complex excitatory postsynaptic potential, and an increase of I(e) spike activity. Here, we characterized the contribution of identified I, II, and III(i) interneurons to the neural network supporting visually guided locomotion. In dark-adapted preparations, light elicited an increase in the tonic spike activity of II(e) interneurons and a decrease in the tonic spike activity of II(i) interneurons. Fluorescent dye-labeled type II interneurons exhibited diverse projections within the circumesophageal nervous system. However, a subclass of type II interneurons, II(e(cp)) and II(i(cp)) interneurons, were shown to terminate within the ipsilateral cerebropleural ganglia and indirectly modulate the activity of CENs. Type II interneurons form monosynaptic or polysynaptic connections with previously identified components of the ciliary network. The identification of a monosynaptic connection between I(e) and III(i) interneurons shown here suggest that they provide a major role in the light-dependent modulation of CEN spike activity underlying ciliary locomotion. PMID:23155173

  13. Exotendons for assistance of human locomotion

    PubMed Central

    van den Bogert, Antonie J

    2003-01-01

    Background Powered robotic exoskeletons for assistance of human locomotion are currently under development for military and medical applications. The energy requirements for such devices are excessive, and this has become a major obstacle for practical applications. Legged locomotion in many animals, however, is very energy efficient. We propose that poly-articular elastic mechanisms are a major contributor to the economy of locomotion in such specialized animals. Consequently, it should be possible to design unpowered assistive devices that make effective use of similar mechanisms. Methods A passive assistive technology is presented, based on long elastic cords attached to an exoskeleton and guided by pulleys placed at the joints. A general optimization procedure is described for finding the best geometrical arrangement of such "exotendons" for assisting a specific movement. Optimality is defined either as minimal residual joint moment or as minimal residual joint power. Four specific exotendon systems with increasing complexity are considered. Representative human gait data were used to optimize each of these four systems to achieve maximal assistance for normal walking. Results The most complex exotendon system, with twelve pulleys per limb, was able to reduce the joint moments required for normal walking by 71% and joint power by 74%. A simpler system, with only three pulleys per limb, could reduce joint moments by 46% and joint power by 47%. Conclusion It is concluded that unpowered passive elastic devices can substantially reduce the muscle forces and the metabolic energy needed for walking, without requiring a change in movement. When optimally designed, such devices may allow independent locomotion in patients with large deficits in muscle function. PMID:14613503

  14. Period-three route to chaos induced by a cyclic-fold bifurcation in passive dynamic walking of a compass-gait biped robot

    NASA Astrophysics Data System (ADS)

    Gritli, Hassène; Khraief, Nahla; Belghith, Safya

    2012-11-01

    This paper presents a study of the passive dynamic walking of a compass-gait biped robot as it goes down an inclined plane. This biped robot is a two-degrees-of-freedom mechanical system modeled by an impulsive hybrid nonlinear dynamics with unilateral constraints. It is well-known to possess periodic as well as chaotic gaits and to possess only one stable gait for a given set of parameters. The main contribution of this paper is the finding of a window in the parameters space of the compass-gait model where there is multistability. Using constraints of a grazing bifurcation on the basis of a shooting method and the Davidchack-Lai scheme, we show that, depending on initial conditions, new passive walking patterns can be observed besides those already known. Through bifurcation diagrams and Floquet multipliers, we show that a pair of stable and unstable period-three gait patterns is generated through a cyclic-fold bifurcation. We show also that the stable period-three orbit generates a route to chaos.

  15. Testosterone attenuates and the selective estrogen receptor modulator, raloxifene, potentiates amphetamine-induced locomotion in male rats.

    PubMed

    Purves-Tyson, Tertia D; Boerrigter, Danny; Allen, Katherine; Zavitsanou, Katerina; Karl, Tim; Djunaidi, Vanezha; Double, Kay L; Desai, Reena; Handelsman, David J; Weickert, Cynthia Shannon

    2015-04-01

    Although sex steroids are known to modulate brain dopamine, it is still unclear how testosterone modifies locomotor behaviour controlled, at least in part, by striatal dopamine in adolescent males. Our previous work suggests that increasing testosterone during adolescence may bias midbrain neurons to synthesise more dopamine. We hypothesised that baseline and amphetamine-induced locomotion would differ in adult males depending on testosterone exposure during adolescence. We hypothesised that concomitant stimulation of estrogen receptor signaling, through a selective estrogen receptor modulator (SERM), raloxifene, can counter testosterone effects on locomotion. Male Sprague-Dawley rats at postnatal day 45 were gonadectomised (G) or sham-operated (S) prior to the typical adolescent testosterone increase. Gonadectomised rats were either given testosterone replacement (T) or blank implants (B) for six weeks and sham-operated (i.e. intact or endogenous testosterone group) were given blank implants. Subgroups of sham-operated, gonadectomised and gonadectomised/testosterone-replaced rats were treated with raloxifene (R, 5mg/kg) or vehicle (V), daily for the final four weeks. There were six groups (SBV, GBV, GTV, SBR, GBR, GTR). Saline and amphetamine-induced (1.25mg/kg) locomotion in the open field was measured at PND85. Gonadectomy increased amphetamine-induced locomotion compared to rats with endogenous or with exogenous testosterone. Raloxifene increased amphetamine-induced locomotion in rats with either endogenous or exogenous testosterone. Amphetamine-induced locomotion was negatively correlated with testosterone and this relationship was abolished by raloxifene. Lack of testosterone during adolescence potentiates and testosterone exposure during adolescence attenuates amphetamine-induced locomotion. Treatment with raloxifene appears to potentiate amphetamine-induced locomotion and to have an opposite effect to that of testosterone in male rats.

  16. Trackways Produced by Lungfish During Terrestrial Locomotion

    PubMed Central

    Falkingham, Peter L.; Horner, Angela M.

    2016-01-01

    Some primarily aquatic vertebrates make brief forays onto land, creating traces as they do. A lack of studies on aquatic trackmakers raises the possibility that such traces may be ignored or misidentified in the fossil record. Several terrestrial Actinopterygian and Sarcopterygian species have previously been proposed as possible models for ancestral tetrapod locomotion, despite extant fishes being quite distinct from Devonian fishes, both morphologically and phylogenetically. Although locomotion has been well-studied in some of these taxa, trackway production has not. We recorded terrestrial locomotion of a 35 cm African lungfish (Protopterus annectens; Dipnoi: Sarcopterygii) on compliant sediment. Terrestrial movement in the lungfish is accomplished by planting the head and then pivoting the trunk. Impressions are formed where the head impacts the substrate, while the body and fins produce few traces. The head leaves a series of alternating left-right impressions, where each impact can appear as two separate semi-circular impressions created by the upper and lower jaws, bearing some similarity to fossil traces interpreted as footprints. Further studies of trackways of extant terrestrial fishes are necessary to understand the behavioural repertoire that may be represented in the fossil track record. PMID:27670758

  17. Rhythms of locomotion expressed by Limulus polyphemus, the American horseshoe crab: II. Relationship to circadian rhythms of visual sensitivity.

    PubMed

    Watson, Winsor H; Bedford, Lisa; Chabot, Christopher C

    2008-08-01

    In the laboratory, horseshoe crabs express a circadian rhythm of visual sensitivity as well as daily and circatidal rhythms of locomotion. The major goal of this investigation was to determine whether the circadian clock underlying changes in visual sensitivity also modulates locomotion. To address this question, we developed a method for simultaneously recording changes in visual sensitivity and locomotion. Although every animal (24) expressed consistent circadian rhythms of visual sensitivity, rhythms of locomotion were more variable: 44% expressed a tidal rhythm, 28% were most active at night, and the rest lacked statistically significant rhythms. When exposed to artificial tides, 8 of 16 animals expressed circatidal rhythms of locomotion that continued after tidal cycles were stopped. However, rhythms of visual sensitivity remained stable and showed no tendency to be influenced by the imposed tides or locomotor activity. These results indicate that horseshoe crabs possess at least two biological clocks: one circadian clock primarily used for modulating visual sensitivity, and one or more clocks that control patterns of locomotion. This arrangement allows horseshoe crabs to see quite well while mating during both daytime and nighttime high tides.

  18. System Design and Locomotion of Superball, an Untethered Tensegrity Robot

    NASA Technical Reports Server (NTRS)

    Sabelhaus, Andrew P.; Bruce, Jonathan; Caluwaerts, Ken; Manovi, Pavlo; Firoozi, Roya Fallah; Dobi, Sarah; Agogino, Alice M.; Sunspiral, Vytas

    2015-01-01

    The Spherical Underactuated Planetary Exploration Robot ball (SUPERball) is an ongoing project within NASA Ames Research Center's Intelligent Robotics Group and the Dynamic Tensegrity Robotics Lab (DTRL). The current SUPERball is the first full prototype of this tensegrity robot platform, eventually destined for space exploration missions. This work, building on prior published discussions of individual components, presents the fully-constructed robot. Various design improvements are discussed, as well as testing results of the sensors and actuators that illustrate system performance. Basic low-level motor position controls are implemented and validated against sensor data, which show SUPERball to be uniquely suited for highly dynamic state trajectory tracking. Finally, SUPERball is shown in a simple example of locomotion. This implementation of a basic motion primitive shows SUPERball in untethered control.

  19. Twisting and bending: the functional role of salamander lateral hypaxial musculature during locomotion.

    PubMed

    Bennett, W O; Simons, R S; Brainerd, E L

    2001-06-01

    support. However, unlike the EMG pattern reported for D. ensatus, a second, lower-intensity burst of EMG activity ('beta-burst') was sometimes recorded from the lateral hypaxial muscles in A. tigrinum. As seen in other muscle systems, these beta-bursts of hypaxial muscle coactivation may function to provide fine motor control during locomotion. The presence of asynchronous, relatively high-intensity alpha-bursts indicates that the lateral hypaxial muscles generate torsional moments during terrestrial locomotion, but it is possible that the balance of forces from both alpha- and beta-bursts may allow the lateral hypaxial muscles to contribute to lateral bending of the body as well.

  20. Locomotion with flexible propulsors: I. Experimental analysis of pectoral fin swimming in sunfish.

    PubMed

    Lauder, George V; Madden, Peter G A; Mittal, Rajat; Dong, Haibo; Bozkurttas, Meliha

    2006-12-01

    A full understanding of the mechanics of locomotion can be achieved by incorporating descriptions of (1) three-dimensional kinematics of propulsor movement, (2) material properties of the propulsor, (3) power input and control and (4) the fluid dynamics effects of propulsor motion into (5) a three-dimensional computational framework that models the complexity of propulsors that deform and change area. In addition, robotic models would allow for further experimental investigation of changes to propulsor design and for testing of hypothesized relationships between movement and force production. Such a comprehensive suite of data is not yet available for any flexible propulsor. In this paper, we summarize our research program with the goal of producing a comprehensive data set for each of the five components noted above through a study of pectoral fin locomotion in one species of fish: the bluegill sunfish Lepomis macrochirus. Many fish use pectoral fins exclusively for locomotion, and pectoral fins in most fish are integral to generating force during maneuvering. Pectoral fins are complex structures composed of jointed bony supports that are under active control via pectoral fin musculature. During propulsion in sunfish, the fin deforms considerably, has two leading edges, and sunfish can rotate the whole fin or just control individual sections to vector thrust. Fin material properties vary along the length of fin rays and among rays. Experimental fluid dynamic analysis of sunfish pectoral fin locomotion reveals that the fin generates thrust throughout the fin beat cycle, and that the upper and lower edges each produce distinct simultaneous leading edge vortices. The following companion paper provides data on the computational approach taken to understand locomotion using flexible pectoral fins. PMID:17671315

  1. From Beetles in Nature to the Laboratory: Actuating Underwater Locomotion on Hydrophobic Surfaces.

    PubMed

    Pinchasik, Bat-El; Steinkühler, Jan; Wuytens, Pieter; Skirtach, Andre G; Fratzl, Peter; Möhwald, Helmuth

    2015-12-29

    The controlled wetting and dewetting of surfaces is a primary mechanism used by beetles in nature, such as the ladybird and the leaf beetle for underwater locomotion.1 Their adhesion to surfaces underwater is enabled through the attachment of bubbles trapped in their setae-covered legs. Locomotion, however, is performed by applying mechanical forces in order to move, attach, and detach the bubbles in a controlled manner. Under synthetic conditions, however, when a bubble is bound to a surface, it is nearly impossible to maneuver without the use of external stimuli. Thus, actuated wetting and dewetting of surfaces remain challenges. Here, electrowetting-on-dielectric (EWOD) is used for the manipulation of bubble-particle complexes on unpatterned surfaces. Bubbles nucleate on catalytic Janus disks adjacent to a hydrophobic surface. By changing the wettability of the surface through electrowetting, the bubbles show a variety of reactions, depending on the shape and periodicity of the electrical signal. Time-resolved (μs) imaging of bubble radial oscillations reveals possible mechanisms for the lateral mobility of bubbles on a surface under electrowetting: bubble instability is induced when electric pulses are carefully adjusted. This instability is used to control the surface-bound bubble locomotion and is described in terms of the change in surface energy. It is shown that a deterministic force applied normal can lead to a random walk of micrometer-sized bubbles by exploiting the phenomenon of contact angle hysteresis. Finally, bubble use in nature for underwater locomotion and the actuated bubble locomotion presented in this study are compared.

  2. From Beetles in Nature to the Laboratory: Actuating Underwater Locomotion on Hydrophobic Surfaces.

    PubMed

    Pinchasik, Bat-El; Steinkühler, Jan; Wuytens, Pieter; Skirtach, Andre G; Fratzl, Peter; Möhwald, Helmuth

    2015-12-29

    The controlled wetting and dewetting of surfaces is a primary mechanism used by beetles in nature, such as the ladybird and the leaf beetle for underwater locomotion.1 Their adhesion to surfaces underwater is enabled through the attachment of bubbles trapped in their setae-covered legs. Locomotion, however, is performed by applying mechanical forces in order to move, attach, and detach the bubbles in a controlled manner. Under synthetic conditions, however, when a bubble is bound to a surface, it is nearly impossible to maneuver without the use of external stimuli. Thus, actuated wetting and dewetting of surfaces remain challenges. Here, electrowetting-on-dielectric (EWOD) is used for the manipulation of bubble-particle complexes on unpatterned surfaces. Bubbles nucleate on catalytic Janus disks adjacent to a hydrophobic surface. By changing the wettability of the surface through electrowetting, the bubbles show a variety of reactions, depending on the shape and periodicity of the electrical signal. Time-resolved (μs) imaging of bubble radial oscillations reveals possible mechanisms for the lateral mobility of bubbles on a surface under electrowetting: bubble instability is induced when electric pulses are carefully adjusted. This instability is used to control the surface-bound bubble locomotion and is described in terms of the change in surface energy. It is shown that a deterministic force applied normal can lead to a random walk of micrometer-sized bubbles by exploiting the phenomenon of contact angle hysteresis. Finally, bubble use in nature for underwater locomotion and the actuated bubble locomotion presented in this study are compared. PMID:26633751

  3. Stable Gait Generation of a Quasi-Passive Biped Walking Robot Based on Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Matsumoto, Itaru

    A passive walker is a robot which can walk down a shallow slope without active control or energy input, being powered only by gravity. This paper proposes a control law that can stabilize the gait of a quasi-passive walker by manipulating torque at the hip joint. The motion of the quasi-passive walker is divided into two modes: one is a sinusoidal mode and the other a hyperbolic sinusoidal mode. The controller is designed with a servo system which forces the motion of the sinusoidal mode to track the reference input signal obtained from the phase-plane trajectory of the hyperbolic sinusoidal mode. The generated gait is quite natural, because the input of the servo system is made based on the system dynamics. The results of simulations have demonstrated the effectiveness of the proposed control law.

  4. Industry review: Locomotive dynamic characterization test-analysis

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Data are given relative to tests performed on locomotive components. Dynamic characteristics related to safety are described. Suspension systems, shock absorbers, data processing, bearings, and damping are discussed.

  5. Memorial stone (R. Norris and Son Locomotive Works), level 270 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Memorial stone (R. Norris and Son Locomotive Works), level 270 - Washington Monument, High ground West of Fifteenth Street, Northwest, between Independence & Constitution Avenues, Washington, District of Columbia, DC

  6. Continuous Locomotion-Mode Identification for Prosthetic Legs Based on Neuromuscular–Mechanical Fusion

    PubMed Central

    Zhang, Fan; Hargrove, Levi J.; Dou, Zhi; Rogers, Daniel R.; Englehart, Kevin B.

    2011-01-01

    In this study, we developed an algorithm based on neuromuscular–mechanical fusion to continuously recognize a variety of locomotion modes performed by patients with transfemoral (TF) amputations. Electromyographic (EMG) signals recorded from gluteal and residual thigh muscles and ground reaction forces/moments measured from the prosthetic pylon were used as inputs to a phase-dependent pattern classifier for continuous locomotion-mode identification. The algorithm was evaluated using data collected from five patients with TF amputations. The results showed that neuromuscular–mechanical fusion outperformed methods that used only EMG signals or mechanical information. For continuous performance of one walking mode (i.e., static state), the interface based on neuromuscular–mechanical fusion and a support vector machine (SVM) algorithm produced 99% or higher accuracy in the stance phase and 95% accuracy in the swing phase for locomotion-mode recognition. During mode transitions, the fusion-based SVM method correctly recognized all transitions with a sufficient predication time. These promising results demonstrate the potential of the continuous locomotion-mode classifier based on neuromuscular–mechanical fusion for neural control of prosthetic legs. PMID:21768042

  7. Quadrupedal Robot Locomotion: A Biologically Inspired Approach and Its Hardware Implementation.

    PubMed

    Espinal, A; Rostro-Gonzalez, H; Carpio, M; Guerra-Hernandez, E I; Ornelas-Rodriguez, M; Puga-Soberanes, H J; Sotelo-Figueroa, M A; Melin, P

    2016-01-01

    A bioinspired locomotion system for a quadruped robot is presented. Locomotion is achieved by a spiking neural network (SNN) that acts as a Central Pattern Generator (CPG) producing different locomotion patterns represented by their raster plots. To generate these patterns, the SNN is configured with specific parameters (synaptic weights and topologies), which were estimated by a metaheuristic method based on Christiansen Grammar Evolution (CGE). The system has been implemented and validated on two robot platforms; firstly, we tested our system on a quadruped robot and, secondly, on a hexapod one. In this last one, we simulated the case where two legs of the hexapod were amputated and its locomotion mechanism has been changed. For the quadruped robot, the control is performed by the spiking neural network implemented on an Arduino board with 35% of resource usage. In the hexapod robot, we used Spartan 6 FPGA board with only 3% of resource usage. Numerical results show the effectiveness of the proposed system in both cases. PMID:27436997

  8. Reducing the Noise in Behavioral Assays: Sex and Age in Adult Zebrafish Locomotion

    PubMed Central

    Philpott, Catelyn; Donack, Corey J.; Cousin, Margot A.

    2012-01-01

    Abstract Many assays are used in animal model systems to measure specific human disease-related behaviors. The use of both adult and larval zebrafish as a behavioral model is gaining popularity. As this work progresses and potentially translates into new treatments, we must do our best to improve the sensitivity of these assays by reducing confounding factors. Scientists who use the mouse model system have demonstrated that sex and age can influence a number of behaviors. As a community, they have moved to report the age and sex of all animals used in their studies. Zebrafish work does not yet carry the same mandate. In this study, we evaluated sex and age differences in locomotion behavior. We found that age was a significant factor in locomotion, as was sex within a given age group. In short, as zebrafish age, they appear to show less base level locomotion. With regard to sex, younger (10 months) zebrafish showed more locomotion in males, while older zebrafish (22 months) showed more movement in females. These findings have led us to suggest that those using the zebrafish for behavioral studies control for age and sex within their experimental design and report these descriptors in their methods. PMID:23244690

  9. Reducing the noise in behavioral assays: sex and age in adult zebrafish locomotion.

    PubMed

    Philpott, Catelyn; Donack, Corey J; Cousin, Margot A; Pierret, Chris

    2012-12-01

    Many assays are used in animal model systems to measure specific human disease-related behaviors. The use of both adult and larval zebrafish as a behavioral model is gaining popularity. As this work progresses and potentially translates into new treatments, we must do our best to improve the sensitivity of these assays by reducing confounding factors. Scientists who use the mouse model system have demonstrated that sex and age can influence a number of behaviors. As a community, they have moved to report the age and sex of all animals used in their studies. Zebrafish work does not yet carry the same mandate. In this study, we evaluated sex and age differences in locomotion behavior. We found that age was a significant factor in locomotion, as was sex within a given age group. In short, as zebrafish age, they appear to show less base level locomotion. With regard to sex, younger (10 months) zebrafish showed more locomotion in males, while older zebrafish (22 months) showed more movement in females. These findings have led us to suggest that those using the zebrafish for behavioral studies control for age and sex within their experimental design and report these descriptors in their methods.

  10. Quadrupedal Robot Locomotion: A Biologically Inspired Approach and Its Hardware Implementation

    PubMed Central

    Espinal, A.; Rostro-Gonzalez, H.; Carpio, M.; Guerra-Hernandez, E. I.; Ornelas-Rodriguez, M.; Puga-Soberanes, H. J.; Sotelo-Figueroa, M. A.; Melin, P.

    2016-01-01

    A bioinspired locomotion system for a quadruped robot is presented. Locomotion is achieved by a spiking neural network (SNN) that acts as a Central Pattern Generator (CPG) producing different locomotion patterns represented by their raster plots. To generate these patterns, the SNN is configured with specific parameters (synaptic weights and topologies), which were estimated by a metaheuristic method based on Christiansen Grammar Evolution (CGE). The system has been implemented and validated on two robot platforms; firstly, we tested our system on a quadruped robot and, secondly, on a hexapod one. In this last one, we simulated the case where two legs of the hexapod were amputated and its locomotion mechanism has been changed. For the quadruped robot, the control is performed by the spiking neural network implemented on an Arduino board with 35% of resource usage. In the hexapod robot, we used Spartan 6 FPGA board with only 3% of resource usage. Numerical results show the effectiveness of the proposed system in both cases. PMID:27436997

  11. Quadrupedal Robot Locomotion: A Biologically Inspired Approach and Its Hardware Implementation.

    PubMed

    Espinal, A; Rostro-Gonzalez, H; Carpio, M; Guerra-Hernandez, E I; Ornelas-Rodriguez, M; Puga-Soberanes, H J; Sotelo-Figueroa, M A; Melin, P

    2016-01-01

    A bioinspired locomotion system for a quadruped robot is presented. Locomotion is achieved by a spiking neural network (SNN) that acts as a Central Pattern Generator (CPG) producing different locomotion patterns represented by their raster plots. To generate these patterns, the SNN is configured with specific parameters (synaptic weights and topologies), which were estimated by a metaheuristic method based on Christiansen Grammar Evolution (CGE). The system has been implemented and validated on two robot platforms; firstly, we tested our system on a quadruped robot and, secondly, on a hexapod one. In this last one, we simulated the case where two legs of the hexapod were amputated and its locomotion mechanism has been changed. For the quadruped robot, the control is performed by the spiking neural network implemented on an Arduino board with 35% of resource usage. In the hexapod robot, we used Spartan 6 FPGA board with only 3% of resource usage. Numerical results show the effectiveness of the proposed system in both cases.

  12. Deficits in memory-guided limb movements impair obstacle avoidance locomotion in Alzheimer's disease mouse model

    PubMed Central

    Setogawa, Susumu; Yamaura, Hiroshi; Arasaki, Tomoko; Endo, Shogo; Yanagihara, Dai

    2014-01-01

    Memory function deficits induced by Alzheimer's disease (AD) are believed to be one of the causes of an increased risk of tripping in patients. Working memory contributes to accurate stepping over obstacles during locomotion, and AD-induced deficits of this memory function may lead to an increased risk of contact with obstacles. We used the triple transgenic (3xTg) mice to examine the effects of memory deficits in terms of tripping and contact with obstacles. We found that the frequency of contact of the hindlimbs during an obstacle avoidance task increased significantly in 10–13 month-old 3xTg (Old-3xTg) mice compared with control mice. However, no changes in limb kinematics during unobstructed locomotion or successful obstacle avoidance locomotion were observed in the Old-3xTg mice. Furthermore, we found that memory-based movements in stepping over an obstacle were impaired in these mice. Our findings suggest that working memory deficits as a result of AD are associated with an increased risk of tripping during locomotion. PMID:25427820

  13. Optimal locomotion of mechanical rectifier systems

    NASA Astrophysics Data System (ADS)

    Blair, Justin T.

    Vehicles utilizing animal locomotion mechanisms may possess increased performance parameters and the ability to overcome more difficult terrain than conventional wheel or propeller driven vehicles. The essential mechanism underlying animal locomotion can be viewed as mechanical rectification that converts periodic body movements to thrust force through interactions with the environment. This dissertation defines a general class of mechanical rectifiers as multi-body systems equipped with such thrust generation mechanisms. A general model is developed from the Euler-Lagrange equation and simplified by assuming small body oscillations around a given nominal posture. The model reveals that the rectifying dynamics can be captured by a bilinear (but not linear) term of body shape variables. An optimal gait problem is formulated for the bilinear rectifier model as a minimization of a quadratic cost function over the set of periodic functions subject to a constraint on the average locomotion velocity. We prove that a globally optimal solution is given by a harmonic gait that can be found by generalized eigenvalue computation with a line search over cycle frequencies. We verify the solution method through case studies of a two dimensional chain of links for which snake-like undulations and jellyfish-like flapping gaits are found to be optimal, and obtain analytical insights into determinants of optimal gaits from a simple disk-mass rectifier system. Lastly, we develop a dynamic model for batoid swimming featuring a 6 degree-of-freedom main body (position and orientation), with independent wing deformation (described as the motion of many discrete points in the body-fixed coordinate frame), and calculate various gaits. Multiple wing shapes and optimality criteria are considered, such as the maximum thrust to deflection ratio or minimum input power, and the resulting gaits are compared.

  14. Locomotive and reptation motion induced by internal force and friction.

    PubMed

    Sakaguchi, Hidetsugu; Ishihara, Taisuke

    2011-06-01

    We propose a simple mechanical model of locomotion induced by internal force and friction. We first construct a system of two elements as an analog of the bipedal motion. The internal force does not induce a directional motion by itself because of the action-reaction law, but a directional motion becomes possible by the control of the frictional force. The efficiency of these model systems is studied using an analogy to the heat engine. As a modified version of the two-element model, we construct a model that exhibits a bipedal motion similar to kinesin's motion of molecular motor. Next, we propose a linear chain model and a ladder model as an extension of the original two-element model. We find a transition from a straight to a snake-like motion in a ladder model by changing the strength of the internal force. PMID:21797399

  15. Structured variability in Purkinje cell activity during locomotion

    PubMed Central

    Sauerbrei, Britton A.; Lubenov, Evgueniy V.; Siapas, Athanassios G.

    2015-01-01

    Summary The cerebellum is a prominent vertebrate brain structure that is critically involved in sensorimotor function. During locomotion, cerebellar Purkinje cells are rhythmically active, shaping descending signals and coordinating commands from higher brain areas with the step cycle. However, the variation in this activity across steps has not been studied, and its statistical structure, afferent mechanisms, and relationship to behavior remain unknown. Here, using multi-electrode recordings in freely moving rats, we show that behavioral variables systematically influence the shape of the step-locked firing rate. This effect depends strongly on the phase of the step cycle and reveals a functional clustering of Purkinje cells. Furthermore, we find a pronounced disassociation between patterns of variability driven by the parallel and climbing fibers. These results suggest that Purkinje cell activity not only represents step phase within each cycle, but is also shaped by behavior across steps, facilitating control of movement under dynamic conditions. PMID:26291165

  16. Scaling Relations for Wheeled Locomotion in Granular Media

    NASA Astrophysics Data System (ADS)

    Slonaker, James; Kamrin, Ken

    Vehicular wheel design for use on granular material has not currently been perfected. Resistive Force Theory (RFT) is a reduced-order empirical model for granular drag, which shows promise to help simulate and understand locomotion processes to design more efficient wheels. Here we explore the fundamental scaling relations derived from RFT and their experimental validation. Similar to the non-dimensional scaling relations in fluid mechanics, the relative simplicity of RFT asserts that only one material parameter, the ''grain-structure coefficient'', is required, which reduces the complexity of the non-dimensional groups implied by the system. Therefore, wheels with differing input design parameters like size, mass, shape and even gravity, can be tested and their performance related to each other in predictable ways. We experimentally confirmed these relations by testing with 3D printed wheel geometries in a controlled sand bed.

  17. Elastic mesh braided worm robot for locomotive endoscopy.

    PubMed

    Manwell, Thomas; Vítek, Tomáš; Ranzani, Tommaso; Menciassi, Arianna; Althoefer, Kaspar; Liu, Hongbin

    2014-01-01

    This paper presents a new design of worm robot whose body is constructed using a novel crimped elastic mesh braid inspired by the earthworm. The proposed worm robot is intended for inspection within the human body via natural orifices. The design and fabrication procedure of the worm robot are given in the paper. The imitation of peristalsis, used by natural worms, is used to control the worm robot for the purpose of producing motion while causing minimal trauma to biological tissue. The forward locomotive function of the worm robot has been tested on both a flat surface and in a rubber tube. It is shown that the worm robot is capable of propagating forwards for both test conditions in a form similar to the earthworm. The test results indicate the proposed worm robot design has promising application for natural tube inspection, like the colon and the esophagus.

  18. Biomedical perspectives on locomotion in null gravity

    NASA Technical Reports Server (NTRS)

    Cavanagh, Peter R.

    1989-01-01

    A number of important features of various locomotor activities are discussed, and approaches to the study of these activities in the context of space flight are suggested. In particular, the magnitude of peak forces and the rates of change of force during terrestrial cycling, walking, and running are compared. It is shown that subtle changes in the conditions and techniques of locomotion can have a major influence on the biomechanical consequences to the skeleton. The various hypotheses that identify locomotor exercise as a countermeasure to bone demineralization during weightlessness deserve to be tested with some degree of biomechanical rigor. Various approaches for achieving such scrutiny are discussed.

  19. Direct dynamics simulation of FES-assisted locomotion

    NASA Astrophysics Data System (ADS)

    Gerritsen, Karin G.; van den Bogert, Anton J.; Hulliger, Manuel

    1996-05-01

    Using functional electrical stimulation (FES), muscles of spinal-cord injured patients can be activated by externally generated electrical currents in order to restore function. As for gait, the question arises when during the gait cycle and two what extent individual muscles should be stimulated. Computer simulation provides the designer with a tool to evaluate the performance of different muscle stimulation patterns without the need to test patients at every stage of system development. The goals of this paper are: first, to identify, using computer simulation, multi-channel stimulation patterns that are capable of reproducing normal gait kinematics for a full gait cycle, without relying on sensory feedback (open-loop control); second, to briefly assess the stability of the gait obtained. A two-dimensional musculo-skeletal model was developed, based on mathematical representations of muscle properties (including force-length and force velocity characteristics and muscle activation dynamics). A visco-elastic model, including non-linear heel-pad properties, was used to describe the foot-ground interaction. A seven segment skeletal model was actuated by 8 major muscle groups in each leg. Rectangular muscle stimulation patterns were defined by 3 parameters: onset, termination and level of stimulation. Thus, the minimization of the differences between simulated and measured normal gait kinematics was a 24 (3 by 8) parameter optimization problem. Although a good agrement was found between simulated and measured kinematics (rms difference equals 6.5 degrees), stable cyclic locomotion was not achieved. At this point it is concluded that muscle properties do not provide sufficient stability to permit cyclic locomotion with sixteen channels of muscle stimulation, and that incorporation of sensory feedback control will be necessary to achieve this goal.

  20. Intelligent mobility research for robotic locomotion in complex terrain

    NASA Astrophysics Data System (ADS)

    Trentini, Michael; Beckman, Blake; Digney, Bruce; Vincent, Isabelle; Ricard, Benoit

    2006-05-01

    The objective of the Autonomous Intelligent Systems Section of Defence R&D Canada - Suffield is best described by its mission statement, which is "to augment soldiers and combat systems by developing and demonstrating practical, cost effective, autonomous intelligent systems capable of completing military missions in complex operating environments." The mobility requirement for ground-based mobile systems operating in urban settings must increase significantly if robotic technology is to augment human efforts in these roles and environments. The intelligence required for autonomous systems to operate in complex environments demands advances in many fields of robotics. This has resulted in large bodies of research in areas of perception, world representation, and navigation, but the problem of locomotion in complex terrain has largely been ignored. In order to achieve its objective, the Autonomous Intelligent Systems Section is pursuing research that explores the use of intelligent mobility algorithms designed to improve robot mobility. Intelligent mobility uses sensing, control, and learning algorithms to extract measured variables from the world, control vehicle dynamics, and learn by experience. These algorithms seek to exploit available world representations of the environment and the inherent dexterity of the robot to allow the vehicle to interact with its surroundings and produce locomotion in complex terrain. The primary focus of the paper is to present the intelligent mobility research within the framework of the research methodology, plan and direction defined at Defence R&D Canada - Suffield. It discusses the progress and future direction of intelligent mobility research and presents the research tools, topics, and plans to address this critical research gap. This research will create effective intelligence to improve the mobility of ground-based mobile systems operating in urban settings to assist the Canadian Forces in their future urban operations.

  1. A neural circuitry that emphasizes spinal feedback generates diverse behaviours of human locomotion

    PubMed Central

    Song, Seungmoon; Geyer, Hartmut

    2015-01-01

    Neural networks along the spinal cord contribute substantially to generating locomotion behaviours in humans and other legged animals. However, the neural circuitry involved in this spinal control remains unclear. We here propose a specific circuitry that emphasizes feedback integration over central pattern generation. The circuitry is based on neurophysiologically plausible muscle-reflex pathways that are organized in 10 spinal modules realizing limb functions essential to legged systems in stance and swing. These modules are combined with a supraspinal control layer that adjusts the desired foot placements and selects the leg that is to transition into swing control during double support. Using physics-based simulation, we test the proposed circuitry in a neuromuscular human model that includes neural transmission delays, musculotendon dynamics and compliant foot–ground contacts. We find that the control network is sufficient to compose steady and transitional 3-D locomotion behaviours including walking and running, acceleration and deceleration, slope and stair negotiation, turning, and deliberate obstacle avoidance. The results suggest feedback integration to be functionally more important than central pattern generation in human locomotion across behaviours. In addition, the proposed control architecture may serve as a guide in the search for the neurophysiological origin and circuitry of spinal control in humans. PMID:25920414

  2. A Multi-Sample Investigation of the Assessment and Locomotion Scales in a Population of Secondary School Students

    ERIC Educational Resources Information Center

    Hodis, Flaviu A.

    2015-01-01

    Understanding human motivation requires gauging individuals' strivings to be effective in controlling goal pursuits and establishing the truth about themselves and their experiences. Two constructs, assessment and locomotion, capture well truth and control strivings, respectively. The validation process of the instruments measuring assessment…

  3. 49 CFR 229.141 - Body structure, MU locomotives.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... structure. (2) An anti-climbing arrangement shall be applied at each end that is designed so that coupled MU locomotives under full compression shall mate in a manner that will resist one locomotive from climbing the.... (2) An anti-climbing arrangement shall be applied at each end that is designed so that...

  4. Job Grading Standard for Locomotive Engineer WG-6004.

    ERIC Educational Resources Information Center

    Civil Service Commission, Washington, DC. Bureau of Policies and Standards.

    The standard is used to grade the nonsupervisory work of operating all types of locomotives and trains to transport supplies, equipment, conveyances, and personnel. The work involves skill in operating locomotives under various conditions, and knowledge of the layout of a track system and the safety, signalling, and track use requirements or…

  5. 49 CFR 223.11 - Requirements for existing locomotives.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... of the Secretary of Transportation, 49 CFR 1.49(m)) ... be equipped with certified glazing in all locomotive cab windows after June 30, 1984. (d) Each... vandalism has a locomotive cab window that is broken or damaged so that the window fails to permit...

  6. Economic assessment of coal-burning locomotives: Topical report

    SciTech Connect

    Not Available

    1986-02-01

    The General Electric Company embarked upon a study to evaluate various alternatives for the design and manufacture a coal fired locomotive considering various prime movers, but retaining the electric drive transmission. The initial study was supported by the Burlington-Northern and Norfolk-Southern railroads, and included the following alternatives: coal fired diesel locomotive; direct fired gas turbine locomotives; direct fired gas turbine locomotive with steam injection; raw coal gasifier gas turbine locomotive; and raw coal fluid bed steam turbine locomotive. All alternatives use the electric drive transmission and were selected for final evaluation. The first three would use a coal water slurry as a fuel, which must be produced by new processing plants. Therefore, use of a slurry would require a significant plant capital investment. The last two would use classified run-of-the-mine (ROM) coal with much less capital expenditure. Coal fueling stations would be required but are significantly lower in capital cost than a coal slurry plant. For any coal fired locomotive to be commercially viable, it must pass the following criteria: be technically feasible and environmentally acceptable; meet railroads' financial expectations; and offer an attractive return to the locomotive manufacturer. These three criteria are reviewed in the report.

  7. 49 CFR 229.121 - Locomotive cab noise.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) of this section, a railroad shall not make any alterations that cause the average sound level for that locomotive design or model to exceed: (i) 82 dB(A) if the average sound level for a locomotive design or model is less than 82 dB(A); or (ii) 85 dB(A) if the average sound level for a...

  8. 40 CFR Appendix A to Subpart A of... - Switcher Locomotives

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Switcher Locomotives A Appendix A to Subpart A of Part 201 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE... Provisions Pt. 201, Subpt. A, App. A Appendix A to Subpart A of Part 201—Switcher Locomotives Type...

  9. Looking north toward Locomotive Shop (2 tracks on left), Car ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking north toward Locomotive Shop (2 tracks on left), Car Shop on right, and flat car in foreground. Note locomotive and car tires leaning on stock shed at left - East Broad Top Railroad & Coal Company, State Route 994, West of U.S. Route 522, Rockhill Furnace, Huntingdon County, PA

  10. Locomotion Induced by Spatial Restriction in Adult Drosophila

    PubMed Central

    Xiao, Chengfeng; Robertson, R. Meldrum

    2015-01-01

    Drosophila adults display an unwillingness to enter confined spaces but the behaviors induced by spatial restriction in Drosophila are largely unknown. We developed a protocol for high-throughput analysis of locomotion and characterized features of locomotion in a restricted space. We observed intense and persistent locomotion of flies in small circular arenas (diameter 1.27 cm), whereas locomotion was greatly reduced in large circular arenas (diameter 3.81 cm). The increased locomotion induced by spatial restriction was seen in male flies but not female flies, indicating sexual dimorphism of the response to spatial restriction. In large arenas, male flies increased locomotion in arenas previously occupied by male but not female individuals. In small arenas, such pre-conditioning had no effect on male flies, which showed intense and persistent locomotion similar to that seen in fresh arenas. During locomotion with spatial restriction, wildtype Canton-S males traveled slower and with less variation in speed than the mutant w1118 carrying a null allele of white gene. In addition, wildtype flies showed a stronger preference for the boundary than the mutant in small arenas. Genetic analysis with a series of crosses revealed that the white gene was not associated with the phenotype of boundary preference in wildtype flies. PMID:26351842

  11. 49 CFR 229.213 - Locomotive manufacturing information.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Locomotive manufacturing information. 229.213 Section 229.213 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Design Requirements § 229.213 Locomotive manufacturing information. (a) Each railroad operating...

  12. 49 CFR 229.213 - Locomotive manufacturing information.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Locomotive manufacturing information. 229.213 Section 229.213 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Design Requirements § 229.213 Locomotive manufacturing information. (a) Each railroad operating...

  13. 49 CFR 229.213 - Locomotive manufacturing information.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Locomotive manufacturing information. 229.213 Section 229.213 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Design Requirements § 229.213 Locomotive manufacturing information. (a) Each railroad operating...

  14. 49 CFR 229.213 - Locomotive manufacturing information.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locomotive manufacturing information. 229.213 Section 229.213 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Design Requirements § 229.213 Locomotive manufacturing information. (a) Each railroad operating...

  15. 49 CFR 229.213 - Locomotive manufacturing information.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Locomotive manufacturing information. 229.213 Section 229.213 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Design Requirements § 229.213 Locomotive manufacturing information. (a) Each railroad operating...

  16. 77 FR 30047 - Petition for Alternative Locomotive Crashworthiness Design

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-21

    ... Federal Railroad Administration Petition for Alternative Locomotive Crashworthiness Design In accordance... design for an electric locomotive, Model ACS-64, built by Siemens Industry, Inc. This request is made in...-0036. The alternative design incorporates crash energy management features, detailed in the...

  17. 49 CFR 232.105 - General requirements for locomotives.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-49A or suitably stenciled or tagged on the locomotive. (d) The amount of leakage from the equalizing... leakage is detected en route, the train may be moved only to the nearest forward location where the equalizing-reservoir leakage can be corrected. On locomotives equipped with electronic brakes, if the...

  18. 49 CFR 232.105 - General requirements for locomotives.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-49A or suitably stenciled or tagged on the locomotive. (d) The amount of leakage from the equalizing... leakage is detected en route, the train may be moved only to the nearest forward location where the equalizing-reservoir leakage can be corrected. On locomotives equipped with electronic brakes, if the...

  19. 49 CFR 232.105 - General requirements for locomotives.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-49A or suitably stenciled or tagged on the locomotive. (d) The amount of leakage from the equalizing... leakage is detected en route, the train may be moved only to the nearest forward location where the equalizing-reservoir leakage can be corrected. On locomotives equipped with electronic brakes, if the...

  20. 49 CFR 232.105 - General requirements for locomotives.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-49A or suitably stenciled or tagged on the locomotive. (d) The amount of leakage from the equalizing... leakage is detected en route, the train may be moved only to the nearest forward location where the equalizing-reservoir leakage can be corrected. On locomotives equipped with electronic brakes, if the...

  1. 49 CFR 232.105 - General requirements for locomotives.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-49A or suitably stenciled or tagged on the locomotive. (d) The amount of leakage from the equalizing... leakage is detected en route, the train may be moved only to the nearest forward location where the equalizing-reservoir leakage can be corrected. On locomotives equipped with electronic brakes, if the...

  2. EXTERIOR VIEW, RIGHT SIDE OF LOCOMOTIVE SHOWING WHEEL ASSEMBLY WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    EXTERIOR VIEW, RIGHT SIDE OF LOCOMOTIVE SHOWING WHEEL ASSEMBLY WITH BIG END OF MAIN ROD (TOP), ECCENTRIC CRANK (CENTER), AND BIG END CONCENTRIC ROD (BOTTOM). - Norfolk & Southern Steam Locomotive No. 611, Norris Yards, East of Ruffner Road, Irondale, Jefferson County, AL

  3. Underwater locomotion strategy by a benthic pennate diatom Navicula sp.

    PubMed

    Wang, Jiadao; Cao, Shan; Du, Chuan; Chen, Darong

    2013-10-01

    The mechanism of diatom locomotion has been widely researched but still remains a hypothesis. There are several questionable points on the prevailing model proposed by Edgar, and some of the observed phenomena cannot be completely explained by this model. In this paper, we undertook detailed investigations of cell structures, locomotion, secreted mucilage, and bending deformation for a benthic pennate diatom Navicula species. According to these broad evidences, an updated locomotion model is proposed. For Navicula sp., locomotion is realized via two or more pseudopods or stalks protruded out of the frustules. The adhesion can be produced due to the pull-off of one pseudopod or stalk from the substratum through extracellular polymeric substances. And the positive pressure is generated to balance the adhesion because of the push-down of another pseudopod or stalk onto the substratum. Because of the positive pressure, friction is generated, acting as a driving force of locomotion, and the other pseudopod or stalk can detach from the substratum, resulting in the locomotion. Furthermore, this model is validated by the force evaluation and can better explain observed phenomena. This updated model would provide a novel aspect on underwater locomotion strategy, hence can be useful in terms of artificial underwater locomotion devices.

  4. Instability-induced hierarchy in bipedal locomotion

    NASA Astrophysics Data System (ADS)

    Ohgane, Kunishige; Ueda, Kei-Ichi

    2008-05-01

    One of the important features of human locomotion is its instant adaptability to various unpredictable changes of physical and environmental conditions. This property is known as flexibility. Modeling the bipedal locomotion system, we show that initial-state coordination by a global variable which encodes the attractor basins of the system can yield flexibility. This model is based on the following hypotheses: (i) the walking velocity is a global variable, and (ii) the leg posture at the beginning of the stance phase is the initial state of the gait. Moreover, we confirm these hypotheses. We investigate the regions near the neutral states between walking and falling phases using numerical experiments and demonstrate that global variables can be defined as the dominant unstable directions of the system dynamics near the neutral states. We propose the concept of an “instability-induced hierarchy.” In this hierarchy, global variables govern other variables near neutral states; i.e., they become elements of a higher level.

  5. Turning and maneuverability during sidewinding locomotion

    NASA Astrophysics Data System (ADS)

    Astley, Henry; Goldman, Daniel; Hu, David

    2014-03-01

    Sidewinding is an unusual form of snake locomotion used to move rapidly on yielding substrates such as desert sands. Posteriorly propagating waves alternate between static contact with the substrate and elevated motion, resulting in a ``stepping'' motion of body segments. Unlike lateral undulation, the direction of travel is not collinear with the axis of the body wave, and posterior body segments do not follow the path of anterior segments. Field observations indicate that sidewinding snakes are highly maneuverable, but the mechanisms by which these snakes change direction during this complex movement are unknown. Motion capture data from three Colorado Desert sidewinder rattlesnakes (Crotalus cerastes laterorepens) shows a variety of turn magnitudes and behaviors. Additionally, sidewinders are capable of ``reversals'' in which the snakes halts forward progress and begins locomotion in the opposite direction without rotation of the body. Because the head is re-oriented with respect to the body during these reversals, the snake is able to reverse direction without rotation yet continue moving in the new direction without impediment to perception or mechanics, a rare level of maneuverability in animals.

  6. Predictability of visual perturbation during locomotion: implications for corrective efference copy signaling.

    PubMed

    Chagnaud, Boris P; Simmers, John; Straka, Hans

    2012-12-01

    In guiding adaptive behavior, efference copy signals or corollary discharge are traditionally considered to serve as predictors of self-generated sensory inputs and by interfering with their central processing are able to counter unwanted consequences of an animal's own actions. Here, in a speculative reflection on this issue, we consider a different functional role for such intrinsic predictive signaling, namely in stabilizing gaze during locomotion where resultant changes in head orientation in space require online compensatory eye movements in order to prevent retinal image slip. The direct activation of extraocular motoneurons by locomotor-related efference copies offers a prospective substrate for assisting self-motion derived sensory feedback, rather than being subtracted from the sensory signal to eliminate unwanted reafferent information. However, implementing such a feed-forward mechanism would be critically dependent on an appropriate phase coupling between rhythmic propulsive movement and resultant head/visual image displacement. We used video analyzes of actual locomotor behavior and basic theoretical modeling to evaluate head motion during stable locomotion in animals as diverse as Xenopus laevis tadpoles, teleost fish and horses in order to assess the potential suitability of spinal efference copies to the stabilization of gaze during locomotion. In all three species, and therefore regardless of aquatic or terrestrial environment, the head displacements that accompanied locomotor action displayed a strong correlative spatio-temporal relationship in correspondence with a potential predictive value for compensatory eye adjustments. Although spinal central pattern generator-derived efference copies offer appropriately timed commands for extraocular motor control during self-generated motion, it is likely that precise image stabilization requires the additional contributions of sensory feedback signals. Nonetheless, the predictability of the visual

  7. Delayed and lasting effects of deep brain stimulation on locomotion in Parkinson's disease

    NASA Astrophysics Data System (ADS)

    Beuter, Anne; Modolo, Julien

    2009-06-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by a variety of motor signs affecting gait, postural stability, and tremor. These symptoms can be improved when electrodes are implanted in deep brain structures and electrical stimulation is delivered chronically at high frequency (>100 Hz). Deep brain stimulation (DBS) onset or cessation affects PD signs with different latencies, and the long-term improvements of symptoms affecting the body axis and those affecting the limbs vary in duration. Interestingly, these effects have not been systematically analyzed and modeled. We compare these timing phenomena in relation to one axial (i.e., locomotion) and one distal (i.e., tremor) signs. We suggest that during DBS, these symptoms are improved by different network mechanisms operating at multiple time scales. Locomotion improvement may involve a delayed plastic reorganization, which takes hours to develop, whereas rest tremor is probably alleviated by an almost instantaneous desynchronization of neural activity in subcortical structures. Even if all PD patients develop both distal and axial symptoms sooner or later, current computational models of locomotion and rest tremor are separate. Furthermore, a few computational models of locomotion focus on PD and none exploring the effect of DBS was found in the literature. We, therefore, discuss a model of a neuronal network during DBS, general enough to explore the subcircuits controlling locomotion and rest tremor simultaneously. This model accounts for synchronization and plasticity, two mechanisms that are believed to underlie the two types of symptoms analyzed. We suggest that a hysteretic effect caused by DBS-induced plasticity and synchronization modulation contributes to the different therapeutic latencies observed. Such a comprehensive, generic computational model of DBS effects, incorporating these timing phenomena, should assist in developing a more efficient, faster, durable treatment of

  8. Patterns of white muscle activity during terrestrial locomotion in the American eel (Anguilla rostrata).

    PubMed

    Gillis, G B

    2000-02-01

    Eels (Anguilla rostrata) are known to make occasional transitory excursions into the terrestrial environment. While on land, their locomotor kinematics deviate drastically from that observed during swimming. In this study, electromyographic (EMG) recordings were made from white muscle at various longitudinal positions in eels performing undulatory locomotion on land to determine the muscle activity patterns underlying these terrestrial movements. As during swimming, eels propagate a wave of muscle activity from anterior to posterior during terrestrial locomotion. However, the intensity of EMG bursts is much greater on land (on average approximately five times greater than in water). In addition, anteriorly located musculature has higher-intensity EMG bursts than posteriorly located muscle during locomotion on land. EMG duty cycle (burst duration relative to undulatory cycle time) is significantly affected by longitudinal position during terrestrial locomotion, and duty cycles are significantly greater on land (0.4-0.5 cycles) than in water (0. 2-0.3 cycles). Finally, as in swimming, a phase shift in the timing of muscle activity exists such that posteriorly located muscle fibers become activated earlier in their strain cycle than do more anteriorly located fibers. However, fibers become activated much later in their muscle strain cycle on land than in water. Therefore, it is clear that, while eels propagate a wave of muscle activity posteriorly to generate backward-traveling waves that generate propulsive thrust both in water and on land, the specific patterns of timing and the intensity of muscle activity are substantially altered depending upon the environment. This suggests that physical differences in an animal's external environment can play a substantial role in affecting the motor control of locomotion, even when similar structures are used to generate the propulsive forces.

  9. PSO-SVM-Based Online Locomotion Mode Identification for Rehabilitation Robotic Exoskeletons.

    PubMed

    Long, Yi; Du, Zhi-Jiang; Wang, Wei-Dong; Zhao, Guang-Yu; Xu, Guo-Qiang; He, Long; Mao, Xi-Wang; Dong, Wei

    2016-01-01

    Locomotion mode identification is essential for the control of a robotic rehabilitation exoskeletons. This paper proposes an online support vector machine (SVM) optimized by particle swarm optimization (PSO) to identify different locomotion modes to realize a smooth and automatic locomotion transition. A PSO algorithm is used to obtain the optimal parameters of SVM for a better overall performance. Signals measured by the foot pressure sensors integrated in the insoles of wearable shoes and the MEMS-based attitude and heading reference systems (AHRS) attached on the shoes and shanks of leg segments are fused together as the input information of SVM. Based on the chosen window whose size is 200 ms (with sampling frequency of 40 Hz), a three-layer wavelet packet analysis (WPA) is used for feature extraction, after which, the kernel principal component analysis (kPCA) is utilized to reduce the dimension of the feature set to reduce computation cost of the SVM. Since the signals are from two types of different sensors, the normalization is conducted to scale the input into the interval of [0, 1]. Five-fold cross validation is adapted to train the classifier, which prevents the classifier over-fitting. Based on the SVM model obtained offline in MATLAB, an online SVM algorithm is constructed for locomotion mode identification. Experiments are performed for different locomotion modes and experimental results show the effectiveness of the proposed algorithm with an accuracy of 96.00% ± 2.45%. To improve its accuracy, majority vote algorithm (MVA) is used for post-processing, with which the identification accuracy is better than 98.35% ± 1.65%. The proposed algorithm can be extended and employed in the field of robotic rehabilitation and assistance. PMID:27598160

  10. A noncontact capacitive sensing system for recognizing locomotion modes of transtibial amputees.

    PubMed

    Zheng, Enhao; Wang, Long; Wei, Kunlin; Wang, Qining

    2014-12-01

    This paper presents a noncontact capacitive sensing system (C-Sens) for locomotion mode recognition of transtibial amputees. C-Sens detects changes in physical distance between the residual limb and the prosthesis. The sensing front ends are built into the prosthetic socket without contacting the skin. This novel signal source improves the usability of locomotion mode recognition systems based on electromyography (EMG) signals and systems based on capacitance signals obtained from skin contact. To evaluate the performance of C-Sens, we carried out experiments among six transtibial amputees with varying levels of amputation when they engaged in six common locomotive activities. The capacitance signals were consistent and stereotypical for different locomotion modes. Importantly, we were able to obtain sufficiently informative signals even for amputees with severe muscle atrophy (i.e., amputees lacking of quality EMG from shank muscles for mode classification). With phase-dependent quadratic classifier and selected feature set, the proposed system was capable of making continuous judgments about locomotion modes with an average accuracy of 96.3% and 94.8% for swing phase and stance phase, respectively (Experiment 1). Furthermore, the system was able to achieve satisfactory recognition performance after the subjects redonned the socket (Experiment 2). We also validated that C-Sens was robust to load bearing changes when amputees carried 5-kg weights during activities (Experiment 3). These results suggest that noncontact capacitive sensing is capable of circumventing practical problems of EMG systems without sacrificing performance and it is, thus, promising for automatic recognition of human motion intent for controlling powered prostheses.

  11. PSO-SVM-Based Online Locomotion Mode Identification for Rehabilitation Robotic Exoskeletons

    PubMed Central

    Long, Yi; Du, Zhi-Jiang; Wang, Wei-Dong; Zhao, Guang-Yu; Xu, Guo-Qiang; He, Long; Mao, Xi-Wang; Dong, Wei

    2016-01-01

    Locomotion mode identification is essential for the control of a robotic rehabilitation exoskeletons. This paper proposes an online support vector machine (SVM) optimized by particle swarm optimization (PSO) to identify different locomotion modes to realize a smooth and automatic locomotion transition. A PSO algorithm is used to obtain the optimal parameters of SVM for a better overall performance. Signals measured by the foot pressure sensors integrated in the insoles of wearable shoes and the MEMS-based attitude and heading reference systems (AHRS) attached on the shoes and shanks of leg segments are fused together as the input information of SVM. Based on the chosen window whose size is 200 ms (with sampling frequency of 40 Hz), a three-layer wavelet packet analysis (WPA) is used for feature extraction, after which, the kernel principal component analysis (kPCA) is utilized to reduce the dimension of the feature set to reduce computation cost of the SVM. Since the signals are from two types of different sensors, the normalization is conducted to scale the input into the interval of [0, 1]. Five-fold cross validation is adapted to train the classifier, which prevents the classifier over-fitting. Based on the SVM model obtained offline in MATLAB, an online SVM algorithm is constructed for locomotion mode identification. Experiments are performed for different locomotion modes and experimental results show the effectiveness of the proposed algorithm with an accuracy of 96.00% ± 2.45%. To improve its accuracy, majority vote algorithm (MVA) is used for post-processing, with which the identification accuracy is better than 98.35% ± 1.65%. The proposed algorithm can be extended and employed in the field of robotic rehabilitation and assistance. PMID:27598160

  12. Intrathecal application of cyproheptadine impairs locomotion in intact rats.

    PubMed

    Majczyński, Henryk; Cabaj, Anna; Górska, Teresa

    In intact adult rats, cyproheptadine, a 5-HT2 antagonist, administered intrathecally at the midlumbar segments was found to impair hindlimb locomotor movements during overground locomotion. These effects were dose-dependent; they varied from transient complete hindlimb paraplegia seen at doses of 300 microg/20 microl, to short-lasting trunk instability at doses of 100 microg/20 microl. After the return of overground locomotion, transient abduction of one of the hindlimbs was observed in some animals. These findings demonstrate that the blockade of 5-HT2 receptors affects locomotion in intact rats. Our results provide support for the hypothesis of serotonergic involvement in rat locomotion, which, so far, has been based mainly on the effects of 5-HT2 agonists on the recovery of locomotion in spinal rats.

  13. [A theoretical model of the transition phase in human locomotion].

    PubMed

    Beuter, A; Lefebvre, R

    1988-12-01

    In this study we examine the bifurcation of the transition between walking and running. Beuter and Lalonde (1986) have conjectured that the pertinent parameters separating walking and running can be described by a cusp singularity (Thom, 1972). In this model, the unidimensional state space is characterized by support duration and the bidimensional parameter space is characterized by the subject's weight and speed. To test this model eight males walked and ran on a motor driven treadmill at an increasing or decreasing speed with or without additional loads corresponding to 0%, 7% and 14% of their body weight. Velocities corresponding to transitions between the two modes of locomotion indicate that on the average the walk-run transition occurs at higher speed than the run-walk transition illustrating an hysteresis effect. In addition, the average difference between the transitions decreases as the load increases [mean 0 = 0.235 m/s, +/- 0.09 m/s, mean 7 = 0.104 m/s, +/- 0.07 m/s and mean 14 = 0.041 m/s, +/- 0.06 m/s] corresponding to an F ratio of F = 2.72, 0.05 less than p less than 0.1. A comparison of the differences in transition velocity at 0% and 14% is statistically different (t = 2.8, p less than 0.025). These results tend to support the existence of an elementary cusp singularity separating the two locomotion modes and suggest that the mechanisms controlling these transitions can be described by a hysterisis cycle and a small number of parameters. PMID:3219673

  14. 49 CFR 1242.60 - Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Locomotive fuel, electric power purchased/produced for motive power and servicing locomotives (accounts XX-51-67, XX-51-68 and XX-51-69). 1242.60 Section 1242.60 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION...

  15. Whole-body vibration and ergonomic study of US railroad locomotives

    NASA Astrophysics Data System (ADS)

    Johanning, Eckardt; Landsbergis, Paul; Fischer, Siegfried; Christ, Eberhard; Göres, Benno; Luhrman, Raymond

    2006-12-01

    US locomotive operators have exposure to multi-axis whole-body vibration (WBV) and shocks while seated. This study assessed operator-related and ergonomic seating design factors that may have confounding or mitigating influence on WBV exposure and its effects. Vibration exposure was measured according to international guidelines (ISO 2631-1; 1997); ergonomic work place factors and vibration effects were studied with a cross-sectional survey instrument distributed to a randomly selected group of railroad engineers ( n=2546) and a control group; and during vehicle inspections. The survey response rate was 47% for the RR engineers ( n=1195) and 41% for the controls ( n=323). Results of the mean basic vibration measurements were for the x, y, z-direction and vector sum 0.14, 0.22, 0.28 and 0.49 m/s 2 respectively; almost all crest factors (CF), MTVV and VDV values were above the critical ratios given in ISO 2631-1. The prevalence of serious neck and lower back disorders among locomotive engineers was found to be nearly double that of the sedentary control group without such exposure. Railroad engineers rated their seats mostly unacceptable regarding different adjustment and comfort aspects (3.02-3.51; scale 1=excellent to 4=unacceptable), while the control group rated their chairs more favorably (1.96-3.44). Existing cab and seat design in locomotives can result in prolonged forced awkward spinal posture of the operator combined with WBV exposure. In a logistic regression analysis, time at work being bothered by vibration (h/day) was significantly associated with an increased risk of low back pain, shoulder and neck pain, and sciatic pain among railroad engineers. Customized vibration attenuation seats and improved cab design of the locomotive controls should be further investigated.

  16. A predictive model of muscle excitations based on muscle modularity for a large repertoire of human locomotion conditions

    PubMed Central

    Gonzalez-Vargas, Jose; Sartori, Massimo; Dosen, Strahinja; Torricelli, Diego; Pons, Jose L.; Farina, Dario

    2015-01-01

    Humans can efficiently walk across a large variety of terrains and locomotion conditions with little or no mental effort. It has been hypothesized that the nervous system simplifies neuromuscular control by using muscle synergies, thus organizing multi-muscle activity into a small number of coordinative co-activation modules. In the present study we investigated how muscle modularity is structured across a large repertoire of locomotion conditions including five different speeds and five different ground elevations. For this we have used the non-negative matrix factorization technique in order to explain EMG experimental data with a low-dimensional set of four motor components. In this context each motor components is composed of a non-negative factor and the associated muscle weightings. Furthermore, we have investigated if the proposed descriptive analysis of muscle modularity could be translated into a predictive model that could: (1) Estimate how motor components modulate across locomotion speeds and ground elevations. This implies not only estimating the non-negative factors temporal characteristics, but also the associated muscle weighting variations. (2) Estimate how the resulting muscle excitations modulate across novel locomotion conditions and subjects. The results showed three major distinctive features of muscle modularity: (1) the number of motor components was preserved across all locomotion conditions, (2) the non-negative factors were consistent in shape and timing across all locomotion conditions, and (3) the muscle weightings were modulated as distinctive functions of locomotion speed and ground elevation. Results also showed that the developed predictive model was able to reproduce well the muscle modularity of un-modeled data, i.e., novel subjects and conditions. Muscle weightings were reconstructed with a cross-correlation factor greater than 70% and a root mean square error less than 0.10. Furthermore, the generated muscle excitations matched

  17. A Capillarity Mechanism for Diatom Gliding Locomotion

    PubMed Central

    Gordon, Richard; Drum, Ryan W.

    1970-01-01

    It is proposed that the diatom raphe is a parallel-plate capillary containing a fluid which reacts at the trailing end, turning into a form which no longer „wets” the raphe walls, and which is left behind as a trail. More unreacted raphe fluid is drawn by capillary pressure from a source near the leading end of the raphe. This fluid sticks out from the raphe along its length, adhering to surfaces, thus causing gliding locomotion. Formulae are given for the maximum velocity and force of a moving diatom in terms of the raphe dimensions and the surface tension and viscosity of the fluid. An a priori estimate of the force exerted by a moving diatom, 1-50 millidynes, agrees with measured values. Five experimental tests of the theory are proposed. PMID:16591861

  18. Fish Locomotion: Recent Advances and New Directions

    NASA Astrophysics Data System (ADS)

    Lauder, George V.

    2015-01-01

    Research on fish locomotion has expanded greatly in recent years as new approaches have been brought to bear on a classical field of study. Detailed analyses of patterns of body and fin motion and the effects of these movements on water flow patterns have helped scientists understand the causes and effects of hydrodynamic patterns produced by swimming fish. Recent developments include the study of the center-of-mass motion of swimming fish and the use of volumetric imaging systems that allow three-dimensional instantaneous snapshots of wake flow patterns. The large numbers of swimming fish in the oceans and the vorticity present in fin and body wakes support the hypothesis that fish contribute significantly to the mixing of ocean waters. New developments in fish robotics have enhanced understanding of the physical principles underlying aquatic propulsion and allowed intriguing biological features, such as the structure of shark skin, to be studied in detail.

  19. Undulatory Locomotion of Magnetic Multilink Nanoswimmers.

    PubMed

    Jang, Bumjin; Gutman, Emiliya; Stucki, Nicolai; Seitz, Benedikt F; Wendel-García, Pedro D; Newton, Taylor; Pokki, Juho; Ergeneman, Olgaç; Pané, Salvador; Or, Yizhar; Nelson, Bradley J

    2015-07-01

    Micro- and nanorobots operating in low Reynolds number fluid environments require specialized swimming strategies for efficient locomotion. Prior research has focused on designs mimicking the rotary corkscrew motion of bacterial flagella or the planar beating motion of eukaryotic flagella. These biologically inspired designs are typically of uniform construction along their flagellar axis. This work demonstrates for the first time planar undulations of composite multilink nanowire-based chains (diameter 200 nm) induced by a planar-oscillating magnetic field. Those chains comprise an elastic eukaryote-like polypyrrole tail and rigid magnetic nickel links connected by flexible polymer bilayer hinges. The multilink design exhibits a high swimming efficiency. Furthermore, the manufacturing process enables tuning the geometrical and material properties to specific applications.

  20. Force-sensitive afferents recruited during stance encode sensory depression in the contralateral swinging limb during locomotion.

    PubMed

    Hochman, Shawn; Hayes, Heather Brant; Speigel, Iris; Chang, Young-Hui

    2013-03-01

    Afferent feedback alters muscle activity during locomotion and must be tightly controlled. As primary afferent depolarization-induced presynaptic inhibition (PAD-PSI) regulates afferent signaling, we investigated hindlimb PAD-PSI during locomotion in an in vitro rat spinal cord-hindlimb preparation. We compared the relation of PAD-PSI, measured as dorsal root potentials (DRPs), to observed ipsilateral and contralateral limb endpoint forces. Afferents activated during stance-phase force strongly and proportionately influenced DRP magnitude in the swinging limb. Responses increased with locomotor frequency. Electrical stimulation of contralateral afferents also preferentially evoked DRPs in the opposite limb during swing (flexion). Nerve lesioning, in conjunction with kinematic results, support a prominent contribution from toe Golgi tendon organ afferents. Thus, force-dependent afferent feedback during stance binds interlimb sensorimotor state to a proportional PAD-PSI in the swinging limb, presumably to optimize interlimb coordination. These results complement known actions of ipsilateral afferents on PAD-PSI during locomotion.

  1. Locomotion in simulated microgravity: gravity replacement loads

    NASA Technical Reports Server (NTRS)

    McCrory, Jean L.; Baron, Heidi A.; Balkin, Sandy; Cavanagh, Peter R.

    2002-01-01

    BACKGROUND: When an astronaut walks or runs on a treadmill in microgravity, a subject load device (SLD) is used to return him or her back to the treadmill belt. The gravity replacement load (GRL) in the SLD is transferred, via a harness, to the pelvis and/or the shoulders. This research compared comfort and ground reaction forces during treadmill running in a microgravity locomotion simulator at GRLs of 60%, 80%, and 100% of body weight (BW). Two harness designs (shoulder springs only (SSO) and waist and shoulder springs (WSS)) were used. HYPOTHESES: 1) The 100% BW gravity replacement load conditions would be comfortably tolerated and would result in larger ground reaction forces and loading rates than the lower load conditions, and 2) the WSS harness would be more comfortable than the SSO harness. METHODS: Using the Penn State Zero Gravity Locomotion Simulator (ZLS), 8 subjects ran at 2.0 m x s(-1) (4.5 mph) for 3 min at each GRL setting in each harness. Subjective ratings of harness comfort, ground reaction forces, and GRL data were collected during the final minute of exercise. RESULTS: The 100% BW loading conditions were comfortably tolerated (2.3 on a scale of 0-10), although discomfort increased as the GRL increased. There were no overall differences in perceived comfort between the two harnesses. The loading rates (27.1, 33.8, 39.1 BW x s(-1)) and the magnitudes of the first (1.0, 1.4, 1.6 BW) and second (1.3, 1.7, 1.9 BW) peaks of the ground reaction force increased with increasing levels (60, 80, 100% BW respectively) of GRL. CONCLUSIONS: Subjects were able to tolerate a GRL of 100% BW well. The magnitude of the ground reaction force peaks and the loading rate is directly related to the magnitude of the GRL.

  2. The Effect of Increasing Mass upon Locomotion

    NASA Technical Reports Server (NTRS)

    DeWitt, John; Hagan, Donald

    2007-01-01

    The purpose of this investigation was to determine if increasing body mass while maintaining bodyweight would affect ground reaction forces and joint kinetics during walking and running. It was hypothesized that performing gait with increased mass while maintaining body weight would result in greater ground reaction forces, and would affect the net joint torques and work at the ankle, knee and hip when compared to gait with normal mass and bodyweight. Vertical ground reaction force was measured for ten subjects (5M/5F) during walking (1.34 m/s) and running (3.13 m/s) on a treadmill. Subjects completed one minute of locomotion at normal mass and bodyweight and at four added mass (AM) conditions (10%, 20%, 30% and 40% of body mass) in random order. Three-dimensional joint position data were collected via videography. Walking and running were analyzed separately. The addition of mass resulted in several effects. Peak impact forces and loading rates increased during walking, but decreased during running. Peak propulsive forces decreased during walking and did not change during running. Stride time increased and hip extensor angular impulse and positive work increased as mass was added for both styles of locomotion. Work increased at a greater rate during running than walking. The adaptations to additional mass that occur during walking are different than during running. Increasing mass during exercise in microgravity may be beneficial to increasing ground reaction forces during walking and strengthening hip musculature during both walking and running. Future study in true microgravity is required to determine if the adaptations found would be similar in a weightless environment.

  3. Mutually opposing forces during locomotion can eliminate the tradeoff between maneuverability and stability

    NASA Astrophysics Data System (ADS)

    Cowan, Noah; Sefati, Shahin; Neveln, Izaak; Roth, Eatai; Mitchell, Terence; Snyder, James; Maciver, Malcolm; Fortune, Eric

    A surprising feature of animal locomotion is that organisms typically produce substantial forces in directions other than what is necessary to move the animal through its environment, such as perpendicular to, or counter to, the direction of travel. The effect of these forces has been difficult to observe because they are often mutually opposing and therefore cancel out. Using a combination of robotic physical modeling, computational modeling, and biological experiments, we discovered that these forces serve an important role: to simplify and enhance the control of locomotion. Specifically, we examined a well-suited model system, the glass knifefish Eigenmannia virescens, which produces mutually opposing forces during a hovering behavior. By systematically varying the locomotor parameters of our biomimetic robot, and measuring the resulting forces and kinematics, we demonstrated that the production and differential control of mutually opposing forces is a strategy that generates passive stabilization while simultaneously enhancing maneuverability. Mutually opposing forces during locomotion are widespread across animal taxa, and these results indicate that such forces can eliminate the tradeoff between stability and maneuverability, thereby simplifying robotic and neural control.

  4. Calcium/calmodulin-dependent protein kinase II regulates Caenorhabditis elegans locomotion in concert with a G(o)/G(q) signaling network.

    PubMed Central

    Robatzek, M; Thomas, J H

    2000-01-01

    Caenorhabditis elegans locomotion is a complex behavior generated by a defined set of motor neurons and interneurons. Genetic analysis shows that UNC-43, the C. elegans Ca(2+)/calmodulin protein kinase II (CaMKII), controls locomotion rate. Elevated UNC-43 activity, from a gain-of-function mutation, causes severely lethargic locomotion, presumably by inappropriate phosphorylation of targets. In a genetic screen for suppressors of this phenotype, we identified multiple alleles of four genes in a G(o)/G(q) G-protein signaling network, which has been shown to regulate synaptic activity via diacylglycerol. Mutations in goa-1, dgk-1, eat-16, or eat-11 strongly or completely suppressed unc-43(gf) lethargy, but affected other mutants with reduced locomotion only weakly. We conclude that CaMKII and G(o)/G(q) pathways act in concert to regulate synaptic activity, perhaps through a direct interaction between CaMKII and G(o). PMID:11063685

  5. Impaired H-Reflex Gain during Postural Loaded Locomotion in Individuals Post-Stroke

    PubMed Central

    Liang, Jing Nong; Brown, David A.

    2015-01-01

    Objective Successful execution of upright locomotion requires coordinated interaction between controllers for locomotion and posture. Our earlier research supported this model in the non-impaired and found impaired interaction in the post-stroke nervous system during locomotion. In this study, we sought to examine the role of the Ia afferent spinal loop, via the H-reflex response, under postural influence during a locomotor task. We tested the hypothesis that the ability to increase stretch reflex gain in response to postural loads during locomotion would be reduced post-stroke. Methods Fifteen individuals with chronic post-stroke hemiparesis and 13 non-impaired controls pedaled on a motorized cycle ergometer with specialized backboard support system under (1) seated supported, and (2) non-seated postural-loaded conditions, generating matched pedal force outputs of two levels. H-reflexes were elicited at 90°crank angle. Results We observed increased H-reflex gain with postural influence in non-impaired individuals, but a lack of increase in individuals post-stroke. Furthermore, we observed decreased H-reflex gain at higher postural loads in the stroke-impaired group. Conclusion These findings suggest an impaired Ia afferent pathway potentially underlies the defects in the interaction between postural and locomotor control post-stroke and may explain reduced ability of paretic limb support during locomotor weight-bearing in individuals post-stroke. Significance These results support the judicious use of bodyweight support training when first helping individuals post-stroke to regain locomotor pattern generation and weight-bearing capability. PMID:26629996

  6. A study to explore locomotion patterns in partial gravity environments

    NASA Technical Reports Server (NTRS)

    Rajulu, Sudhakar L.; Klute, Glenn K.; Moore, Nathan R.

    1992-01-01

    An effort is made to ascertain the factors affecting stability during locomotion in lunar and Martian gravity environments, as well as to establish criteria for the enhancement of stability and traction. The effects of changing both the speed and the pattern of locomotion under three different gravity conditions were investigated. As gravity level increased, vertical and horizontal forces significantly declined; similarities were noted across gravity levels, however, with respect to locomotion speed and pattern changes, where increasing speed enhanced both vertical and horizontal forces. With decreasing gravity, the ratio of horizontal to vertical forces increased significantly.

  7. 49 CFR 230.108 - Steam locomotive leading and trailing trucks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Steam locomotive leading and trailing trucks. 230... RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.108 Steam locomotive...

  8. 49 CFR 230.108 - Steam locomotive leading and trailing trucks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Steam locomotive leading and trailing trucks. 230... RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.108 Steam locomotive...

  9. 49 CFR 230.108 - Steam locomotive leading and trailing trucks.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Steam locomotive leading and trailing trucks. 230... RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.108 Steam locomotive...

  10. 49 CFR 230.108 - Steam locomotive leading and trailing trucks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Steam locomotive leading and trailing trucks. 230... RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.108 Steam locomotive...

  11. 49 CFR 230.108 - Steam locomotive leading and trailing trucks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive leading and trailing trucks. 230... RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Trucks, Frames and Equalizing System § 230.108 Steam locomotive...

  12. 49 CFR 230.20 - Alteration and repair report for steam locomotive boilers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... boilers. (a) Alterations. When an alteration is made to a steam locomotive boiler, the steam locomotive... steam locomotive boiler, the steam locomotive owner and/or operator shall file with the FRA Regional... the boiler. Whenever welded or riveted repairs are performed on stayed portions of a steam...

  13. 49 CFR 230.20 - Alteration and repair report for steam locomotive boilers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... boilers. (a) Alterations. When an alteration is made to a steam locomotive boiler, the steam locomotive... steam locomotive boiler, the steam locomotive owner and/or operator shall file with the FRA Regional... the boiler. Whenever welded or riveted repairs are performed on stayed portions of a steam...

  14. 49 CFR 230.20 - Alteration and repair report for steam locomotive boilers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... boilers. (a) Alterations. When an alteration is made to a steam locomotive boiler, the steam locomotive... steam locomotive boiler, the steam locomotive owner and/or operator shall file with the FRA Regional... the boiler. Whenever welded or riveted repairs are performed on stayed portions of a steam...

  15. 49 CFR 230.20 - Alteration and repair report for steam locomotive boilers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... boilers. (a) Alterations. When an alteration is made to a steam locomotive boiler, the steam locomotive... steam locomotive boiler, the steam locomotive owner and/or operator shall file with the FRA Regional... the boiler. Whenever welded or riveted repairs are performed on stayed portions of a steam...

  16. 49 CFR 230.20 - Alteration and repair report for steam locomotive boilers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... boilers. (a) Alterations. When an alteration is made to a steam locomotive boiler, the steam locomotive... steam locomotive boiler, the steam locomotive owner and/or operator shall file with the FRA Regional... the boiler. Whenever welded or riveted repairs are performed on stayed portions of a steam...

  17. Reinforcement learning of periodical gaits in locomotion robots

    NASA Astrophysics Data System (ADS)

    Svinin, Mikhail; Yamada, Kazuyaki; Ushio, S.; Ueda, Kanji

    1999-08-01

    Emergence of stable gaits in locomotion robots is studied in this paper. A classifier system, implementing an instance- based reinforcement learning scheme, is used for sensory- motor control of an eight-legged mobile robot. Important feature of the classifier system is its ability to work with the continuous sensor space. The robot does not have a prior knowledge of the environment, its own internal model, and the goal coordinates. It is only assumed that the robot can acquire stable gaits by learning how to reach a light source. During the learning process the control system, is self-organized by reinforcement signals. Reaching the light source defines a global reward. Forward motion gets a local reward, while stepping back and falling down get a local punishment. Feasibility of the proposed self-organized system is tested under simulation and experiment. The control actions are specified at the leg level. It is shown that, as learning progresses, the number of the action rules in the classifier systems is stabilized to a certain level, corresponding to the acquired gait patterns.

  18. A Survey of Phase Variable Candidates of Human Locomotion

    PubMed Central

    Villarreal, Dario J.; Gregg, Robert D.

    2014-01-01

    Studies show that the human nervous system is able to parameterize gait cycle phase using sensory feedback. In the field of bipedal robots, the concept of a phase variable has been successfully used to mimic this behavior by parameterizing the gait cycle in a time-independent manner. This approach has been applied to control a powered transfemoral prosthetic leg, but the proposed phase variable was limited to the stance period of the prosthesis only. In order to achieve a more robust controller, we attempt to find a new phase variable that fully parameterizes the gait cycle of a prosthetic leg. The angle with respect to a global reference frame at the hip is able to monotonically parameterize both the stance and swing periods of the gait cycle. This survey looks at multiple phase variable candidates involving the hip angle with respect to a global reference frame across multiple tasks including level-ground walking, running, and stair negotiation. In particular, we propose a novel phase variable candidate that monotonically parameterizes the whole gait cycle across all tasks, and does so particularly well across level-ground walking. In addition to furthering the design of robust robotic prosthetic leg controllers, this survey could help neuroscientists and physicians study human locomotion across tasks from a time-independent perspective. PMID:25570873

  19. Development of Self-Produced Locomotion in the First Year: Changes in Parent Perceptions and Infant Behaviour

    ERIC Educational Resources Information Center

    Hendrix, Rebecca R.; Thompson, Ross A.

    2011-01-01

    Self-produced locomotion is regarded as a setting event for other developmental transitions in infancy with important implications for socioemotional development and parent-child interaction. Using an age-held-constant design, this study examined changes in reported infant behaviour and maternal proactive/reactive control and compared them with…

  20. Theta oscillations regulate the speed of locomotion via a hippocampus to lateral septum pathway.

    PubMed

    Bender, Franziska; Gorbati, Maria; Cadavieco, Marta Carus; Denisova, Natalia; Gao, Xiaojie; Holman, Constance; Korotkova, Tatiana; Ponomarenko, Alexey

    2015-10-12

    Hippocampal theta oscillations support encoding of an animal's position during spatial navigation, yet longstanding questions about their impact on locomotion remain unanswered. Combining optogenetic control of hippocampal theta oscillations with electrophysiological recordings in mice, we show that hippocampal theta oscillations regulate locomotion. In particular, we demonstrate that their regularity underlies more stable and slower running speeds during exploration. More regular theta oscillations are accompanied by more regular theta-rhythmic spiking output of pyramidal cells. Theta oscillations are coordinated between the hippocampus and its main subcortical output, the lateral septum (LS). Chemo- or optogenetic inhibition of this pathway reveals its necessity for the hippocampal regulation of running speed. Moreover, theta-rhythmic stimulation of LS projections to the lateral hypothalamus replicates the reduction of running speed induced by more regular hippocampal theta oscillations. These results suggest that changes in hippocampal theta synchronization are translated into rapid adjustment of running speed via the LS.

  1. Towards Development of Robotic Aid for Rehabilitation of Locomotion-Impaired Subjects

    NASA Technical Reports Server (NTRS)

    Bejczy, Antal K.

    2000-01-01

    Manual assistance of therapists to help movement of legs of spinal cord injured (SCI) subjects during stepping on a treadmill for locomotion rehabilitation has severe economic and technical limitations. Scientists at the Department of Physiological Science at the University of California Los Angeles (UCLA) and roboticists at the Jet Propulsion Laboratory (JPL) initiated a joint effort to develop a robotic mechanism capable of performing controlled motions equivalent to the arm and hand motions of therapists assisting the stepping of locomotion impaired subjects on a treadmill, while the subjects' body weight is partially supported by an overhead harness. A first necessary technical step towards this development is to measure and understand the kinematics and dynamics of the therapists' arm and hand motions as they are reflected on the subjects' leg movement. This paper describes an initial measurement system developed for this purpose together with the related measurement results, and outlines the planned future technical work.

  2. Theta oscillations regulate the speed of locomotion via a hippocampus to lateral septum pathway

    PubMed Central

    Bender, Franziska; Gorbati, Maria; Cadavieco, Marta Carus; Denisova, Natalia; Gao, Xiaojie; Holman, Constance; Korotkova, Tatiana; Ponomarenko, Alexey

    2015-01-01

    Hippocampal theta oscillations support encoding of an animal's position during spatial navigation, yet longstanding questions about their impact on locomotion remain unanswered. Combining optogenetic control of hippocampal theta oscillations with electrophysiological recordings in mice, we show that hippocampal theta oscillations regulate locomotion. In particular, we demonstrate that their regularity underlies more stable and slower running speeds during exploration. More regular theta oscillations are accompanied by more regular theta-rhythmic spiking output of pyramidal cells. Theta oscillations are coordinated between the hippocampus and its main subcortical output, the lateral septum (LS). Chemo- or optogenetic inhibition of this pathway reveals its necessity for the hippocampal regulation of running speed. Moreover, theta-rhythmic stimulation of LS projections to the lateral hypothalamus replicates the reduction of running speed induced by more regular hippocampal theta oscillations. These results suggest that changes in hippocampal theta synchronization are translated into rapid adjustment of running speed via the LS. PMID:26455912

  3. Matching visual and nonvisual signals: evidence for a mechanism to discount optic flow during locomotion

    NASA Astrophysics Data System (ADS)

    Thurrell, Adrian; Pelah, Adar

    2005-03-01

    We report on recent experiments to investigate the Arthrovisual Locomotor Effect (ALE), a mechanism based on non-visual signals postulated to discount or remove the self-generated visual motion signals during locomotion. It is shown that perceptual matches made by standing subjects to a constant motion optic flow stimulus that is viewed while walking on a treadmill are linearly reduced by walking speed, a measure of the reported ALE. The degree of reduction in perceived speed depends on the similarity of the motor activity to natural locomotion, thus for the four activities tested, ALE strength is ranked as follows: Walking > Cycling > Hand Pedalling > Finger Tapping = 0. Other variations and important controls for the ALE are described.

  4. Inertia of amoebic cell locomotion as an emergent collective property of the cellular dynamics

    NASA Astrophysics Data System (ADS)

    Nishimura, Shin I.; Sasai, Masaki

    2005-01-01

    Amoebic cells are ubiquitous in many species and have been used as model systems to study the eukaryotic cellular locomotion. We construct a model of amoebic cells on two-dimensional grids, which describes sensing, cell status, and locomotion in a unified way. We show that the averaged position of simulated cells is described by a second-order differential equation of motion and that the mechanical pushing at the initial moment boosts the cell movement, which continues after the cell is released from the pushing. These “inertialike” features suggest the possibility of Newtonian-type motions in chemical distributions of the signaling molecule. We show, as an example, the possibility of rotating motion in a “centripetal” distribution. The observed inertial motion is an emergent collective dynamics, which is controlled by diffusive and chemical processes in the cell.

  5. Theta oscillations regulate the speed of locomotion via a hippocampus to lateral septum pathway.

    PubMed

    Bender, Franziska; Gorbati, Maria; Cadavieco, Marta Carus; Denisova, Natalia; Gao, Xiaojie; Holman, Constance; Korotkova, Tatiana; Ponomarenko, Alexey

    2015-01-01

    Hippocampal theta oscillations support encoding of an animal's position during spatial navigation, yet longstanding questions about their impact on locomotion remain unanswered. Combining optogenetic control of hippocampal theta oscillations with electrophysiological recordings in mice, we show that hippocampal theta oscillations regulate locomotion. In particular, we demonstrate that their regularity underlies more stable and slower running speeds during exploration. More regular theta oscillations are accompanied by more regular theta-rhythmic spiking output of pyramidal cells. Theta oscillations are coordinated between the hippocampus and its main subcortical output, the lateral septum (LS). Chemo- or optogenetic inhibition of this pathway reveals its necessity for the hippocampal regulation of running speed. Moreover, theta-rhythmic stimulation of LS projections to the lateral hypothalamus replicates the reduction of running speed induced by more regular hippocampal theta oscillations. These results suggest that changes in hippocampal theta synchronization are translated into rapid adjustment of running speed via the LS. PMID:26455912

  6. Autonomous undulatory serpentine locomotion utilizing body dynamics of a fluidic soft robot.

    PubMed

    Onal, Cagdas D; Rus, Daniela

    2013-06-01

    Soft robotics offers the unique promise of creating inherently safe and adaptive systems. These systems bring man-made machines closer to the natural capabilities of biological systems. An important requirement to enable self-contained soft mobile robots is an on-board power source. In this paper, we present an approach to create a bio-inspired soft robotic snake that can undulate in a similar way to its biological counterpart using pressure for actuation power, without human intervention. With this approach, we develop an autonomous soft snake robot with on-board actuation, power, computation and control capabilities. The robot consists of four bidirectional fluidic elastomer actuators in series to create a traveling curvature wave from head to tail along its body. Passive wheels between segments generate the necessary frictional anisotropy for forward locomotion. It takes 14 h to build the soft robotic snake, which can attain an average locomotion speed of 19 mm s(-1).

  7. Development of an Environment-Aware Locomotion Mode Recognition System for Powered Lower Limb Prostheses.

    PubMed

    Liu, Ming; Wang, Ding; Helen Huang, He

    2016-04-01

    This paper aimed to develop and evaluate an environment-aware locomotion mode recognition system for volitional control of powered artificial legs. A portable terrain recognition (TR) module, consisting of an inertia measurement unit and a laser distance meter, was built to identify the type of terrain in front of the wearer while walking. A decision tree was used to classify the terrain types and provide either coarse or refined information about the walking environment. Then, the obtained environmental information was modeled as a priori probability and was integrated with a neuromuscular-mechanical-fusion-based locomotion mode (LM) recognition system. The designed TR module and environmental-aware LM recognition system was evaluated separately on able-bodied subjects and a transfemoral amputee online. The results showed that the TR module provided high quality environmental information: TR accuracy is above 98% and terrain transitions are detected over 500 ms before the time required to switch the prosthesis control mode. This enabled smooth locomotion mode transitions for the wearers. The obtained environmental information further improved the performance of LM recognition system, regardless of whether coarse or refined information was used. In addition, the environment-aware LM recognition system produced reliable online performance when the TR output was relatively noisy, which indicated the potential of this system to operate in unconstructed environment. This paper demonstrated that environmental information should be considered for operating wearable lower limb robotic devices, such as prosthetics and orthotics.

  8. A 3D undulatory locomotion system inspired by nematode C. elegans.

    PubMed

    Deng, Xin; Xu, Jian-Xin

    2014-01-01

    This paper provides an undulatory locomotion model inspired by C. elegans, whose nervous system and muscular structure are well studied. C. elegans is divided into 11 muscle segments according to its anatomical structure, and represented as a multi-joint rigid link model in this work. In each muscle segment, there are four pieces of muscles located in four quadrants. The muscles change their lengths according to the outputs of nervous system. In this work, the dynamic neural networks (DNN) are adopted to represent the nervous system. The DNN are divided into the head DNN and the body DNN. The head DNN produces the sinusoid waves to generate the forward and backward undulatory movements. The body DNN with 11 segments is responsible for passing the sinusoid wave and creating the phase lag. The 3D locomotion of this system are implemented by using the DNN to control the muscle lengths, and then using the muscle lengths to control the angles between two consecutive links on both horizontal and vertical planes. The test results show good performances of this model in both forward and backward locomotion in 3D, which could serve as a prototype of the micro-robot for clinical use. PMID:24211936

  9. Analysis of emotionality and locomotion in radio-frequency electromagnetic radiation exposed rats.

    PubMed

    Narayanan, Sareesh Naduvil; Kumar, Raju Suresh; Paval, Jaijesh; Kedage, Vivekananda; Bhat, M Shankaranarayana; Nayak, Satheesha; Bhat, P Gopalakrishna

    2013-07-01

    In the current study the modulatory role of mobile phone radio-frequency electromagnetic radiation (RF-EMR) on emotionality and locomotion was evaluated in adolescent rats. Male albino Wistar rats (6-8 weeks old) were randomly assigned into the following groups having 12 animals in each group. Group I (Control): they remained in the home cage throughout the experimental period. Group II (Sham exposed): they were exposed to mobile phone in switch-off mode for 28 days, and Group III (RF-EMR exposed): they were exposed to RF-EMR (900 MHz) from an active GSM (Global system for mobile communications) mobile phone with a peak power density of 146.60 μW/cm(2) for 28 days. On 29th day, the animals were tested for emotionality and locomotion. Elevated plus maze (EPM) test revealed that, percentage of entries into the open arm, percentage of time spent on the open arm and distance travelled on the open arm were significantly reduced in the RF-EMR exposed rats. Rearing frequency and grooming frequency were also decreased in the RF-EMR exposed rats. Defecation boli count during the EPM test was more with the RF-EMR group. No statistically significant difference was found in total distance travelled, total arm entries, percentage of closed arm entries and parallelism index in the RF-EMR exposed rats compared to controls. Results indicate that mobile phone radiation could affect the emotionality of rats without affecting the general locomotion.

  10. A 3D undulatory locomotion system inspired by nematode C. elegans.

    PubMed

    Deng, Xin; Xu, Jian-Xin

    2014-01-01

    This paper provides an undulatory locomotion model inspired by C. elegans, whose nervous system and muscular structure are well studied. C. elegans is divided into 11 muscle segments according to its anatomical structure, and represented as a multi-joint rigid link model in this work. In each muscle segment, there are four pieces of muscles located in four quadrants. The muscles change their lengths according to the outputs of nervous system. In this work, the dynamic neural networks (DNN) are adopted to represent the nervous system. The DNN are divided into the head DNN and the body DNN. The head DNN produces the sinusoid waves to generate the forward and backward undulatory movements. The body DNN with 11 segments is responsible for passing the sinusoid wave and creating the phase lag. The 3D locomotion of this system are implemented by using the DNN to control the muscle lengths, and then using the muscle lengths to control the angles between two consecutive links on both horizontal and vertical planes. The test results show good performances of this model in both forward and backward locomotion in 3D, which could serve as a prototype of the micro-robot for clinical use.

  11. A bioinspired autonomous swimming robot as a tool for studying goal-directed locomotion.

    PubMed

    Manfredi, L; Assaf, T; Mintchev, S; Marrazza, S; Capantini, L; Orofino, S; Ascari, L; Grillner, S; Wallén, P; Ekeberg, O; Stefanini, C; Dario, P

    2013-10-01

    The bioinspired approach has been key in combining the disciplines of robotics with neuroscience in an effective and promising fashion. Indeed, certain aspects in the field of neuroscience, such as goal-directed locomotion and behaviour selection, can be validated through robotic artefacts. In particular, swimming is a functionally important behaviour where neuromuscular structures, neural control architecture and operation can be replicated artificially following models from biology and neuroscience. In this article, we present a biomimetic system inspired by the lamprey, an early vertebrate that locomotes using anguilliform swimming. The artefact possesses extra- and proprioceptive sensory receptors, muscle-like actuation, distributed embedded control and a vision system. Experiments on optimised swimming and on goal-directed locomotion are reported, as well as the assessment of the performance of the system, which shows high energy efficiency and adaptive behaviour. While the focus is on providing a robotic platform for testing biological models, the reported system can also be of major relevance for the development of engineering system applications. PMID:24030051

  12. A bioinspired autonomous swimming robot as a tool for studying goal-directed locomotion.

    PubMed

    Manfredi, L; Assaf, T; Mintchev, S; Marrazza, S; Capantini, L; Orofino, S; Ascari, L; Grillner, S; Wallén, P; Ekeberg, O; Stefanini, C; Dario, P

    2013-10-01

    The bioinspired approach has been key in combining the disciplines of robotics with neuroscience in an effective and promising fashion. Indeed, certain aspects in the field of neuroscience, such as goal-directed locomotion and behaviour selection, can be validated through robotic artefacts. In particular, swimming is a functionally important behaviour where neuromuscular structures, neural control architecture and operation can be replicated artificially following models from biology and neuroscience. In this article, we present a biomimetic system inspired by the lamprey, an early vertebrate that locomotes using anguilliform swimming. The artefact possesses extra- and proprioceptive sensory receptors, muscle-like actuation, distributed embedded control and a vision system. Experiments on optimised swimming and on goal-directed locomotion are reported, as well as the assessment of the performance of the system, which shows high energy efficiency and adaptive behaviour. While the focus is on providing a robotic platform for testing biological models, the reported system can also be of major relevance for the development of engineering system applications.

  13. Synaptic representation of locomotion in single cerebellar granule cells

    PubMed Central

    Powell, Kate; Mathy, Alexandre; Duguid, Ian; Häusser, Michael

    2015-01-01

    The cerebellum plays a crucial role in the regulation of locomotion, but how movement is represented at the synaptic level is not known. Here, we use in vivo patch-clamp recordings to show that locomotion can be directly read out from mossy fiber synaptic input and spike output in single granule cells. The increase in granule cell spiking during locomotion is enhanced by glutamate spillover currents recruited during movement. Surprisingly, the entire step sequence can be predicted from input EPSCs and output spikes of a single granule cell, suggesting that a robust gait code is present already at the cerebellar input layer and transmitted via the granule cell pathway to downstream Purkinje cells. Thus, synaptic input delivers remarkably rich information to single neurons during locomotion. DOI: http://dx.doi.org/10.7554/eLife.07290.001 PMID:26083712

  14. 10. Locomotive smoke flue coming through Roundhouse roof with gable ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Locomotive smoke flue coming through Roundhouse roof with gable end of Machine Shop in background. - Central of Georgia Railway, Savannah Repair Shops & Terminal Facilities, Roundhouse, Site Bounded by West Broad, Jones, West Boundary & Hull, Savannah, Chatham County, GA

  15. EXTERIOR VIEW WITH HEART OF DIXIE MUSEUM'S HISTORIC LOCOMOTIVE IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    EXTERIOR VIEW WITH HEART OF DIXIE MUSEUM'S HISTORIC LOCOMOTIVE IN MUSEUM'S POWELL AVENUE YARD (BOTTOM) AND SOUTHERN RAILWAY BOXCAR ON ACTIVE TRACKAGE (ABOVE). - Heart of Dixie Railroad, Rolling Stock, 1800 Block Powell Avenue, Birmingham, Jefferson County, AL

  16. Breathing and locomotion: comparative anatomy, morphology and function.

    PubMed

    Klein, Wilfried; Codd, Jonathan R

    2010-08-31

    Using specialized respiratory structures such as gills, lungs and or a tracheal system, animals take up oxygen and release carbon dioxide. The efficiency of gas exchange, however, may be constrained by the morphology of the respiratory organ itself as well as by other aspects of an animal's physiology such as feeding, circulation or locomotion. Herein we discuss some aspects of the functional link between the respiratory and locomotor systems, such as gill morphology of sharks as a factor limiting maximum aerobic scope, respiratory constraints among legless lizards, lung morphology of testudines, trade-offs between locomotion and respiration among birds, reconstruction of the respiratory system of sauropods, respiration of mice during locomotion as well as some aspects of gas exchange among insects. Data covering such a broad spectrum of interactions between the locomotor and respiratory systems shall allow us to place breathing and locomotion into a wider context of evolution of oxygen.

  17. 6. Photocopy of drawing, January 28, 1920. LOCOMOTIVE: ELEVATIONS AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of drawing, January 28, 1920. LOCOMOTIVE: ELEVATIONS AND TYPICAL SECTION. Watertown Arsenal Engineering Division, Drawing Number 10453. (Original: AMTL Engineering Division, Watertown). - Watertown Arsenal, Building No. 97, Wooley Avenue, Watertown, Middlesex County, MA

  18. 7. STRUCTURAL DETAILS AT ENTRANCE OF LOCOMOTIVE ROUNDHOUSE, SHEET NO. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. STRUCTURAL DETAILS AT ENTRANCE OF LOCOMOTIVE ROUNDHOUSE, SHEET NO. 1-9-2/89.1 (DRAWING DATED 1942). - Oakland Army Base, Railroad Engine Shop, Engineer Road & Wake Avenue, Oakland, Alameda County, CA

  19. "Shower head" water connection for servicing railroad locomotives, perspective view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "Shower head" water connection for servicing railroad locomotives, perspective view looking NW across ATSF railyard. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  20. Locomotion in Lymphocytes is Altered by Differential PKC Isoform Expression

    NASA Technical Reports Server (NTRS)

    Sundaresan, A.; Risin, D.; Pellis, N. R.

    1999-01-01

    Lymphocyte locomotion is critical for proper elicitation of the immune response. Locomotion of immune cells via the interstitium is essential for optimal immune function during wound healing, inflammation and infection. There are conditions which alter lymphocyte locomotion and one of them is spaceflight. Lymphocyte locomotion is severely inhibited in true spaceflight (true microgravity) and in rotating wall vessel culture (modeled microgravity). When lymphocytes are activated prior to culture in modeled microgravity, locomotion is not inhibited and the levels are comparable to those of static cultured lymphocytes. When a phorbol ester (PMA) is used in modeled microgravity, lymphocyte locomotion is restored by 87%. This occurs regardless if PMA is added after culture in the rotating wall vessel or during culture. Inhibition of DNA synthesis also does not alter restoration of lymphocyte locomotion by PMA. PMA is a direct activator of (protein kinase C) PKC . When a calcium ionophore, ionomycin is used it does not possess any restorative properties towards locomotion either alone or collectively with PMA. Since PMA brings about restoration without help from calcium ionophores (ionomycin), it is infer-red that calcium independent PKC isoforms are involved. Changes were perceived in the protein levels of PKC 6 where levels of the protein were downregulated at 24,72 and 96 hours in untreated rotated cultures (modeled microgravity) compared to untreated static (1g) cultures. At 48 hours there is an increase in the levels of PKC & in the same experimental set up. Studies on transcriptional and translational patterns of calcium independent isoforms of PKC such as 8 and E are presented in this study.

  1. EXTERIOR VIEW WITH HISTORIC LOCOMOTIVES, COAL AND PASSENGER CARS INCLUDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    EXTERIOR VIEW WITH HISTORIC LOCOMOTIVES, COAL AND PASSENGER CARS INCLUDING THE WOODWARD IRON COMPANY NO. 38 LOCOMOTIVE AND TENDER LOCATED IN THE HEART OF DIXIE MUSEUM'S POWELL AVENUE YARD AND SOUTHERN RAILROAD BOXCARS ON ACTIVE TRACKS OF BIRMINGHAM'S RAILROAD RESERVATION. IN BACKGROUND AT RIGHT AND CENTER IS THE BIRMINGHAM CITY CENTER. - Heart of Dixie Railroad, Rolling Stock, 1800 Block Powell Avenue, Birmingham, Jefferson County, AL

  2. The Geometry of Locomotive Behavioral States in C. elegans

    PubMed Central

    Bjorness, Theresa; Greene, Robert; You, Young-Jai

    2013-01-01

    We develop a new hidden Markov model-based method to analyze C elegans locomotive behavior and use this method to quantitatively characterize behavioral states. In agreement with previous work, we find states corresponding to roaming, dwelling, and quiescence. However, we also find evidence for a continuum of intermediate states. We suggest that roaming, dwelling, and quiescence may best be thought of as extremes which, mixed in any proportion, define the locomotive repertoire of C elegans foraging and feeding behavior. PMID:23555813

  3. Expression of emotion in the kinematics of locomotion.

    PubMed

    Barliya, Avi; Omlor, Lars; Giese, Martin A; Berthoz, Alain; Flash, Tamar

    2013-03-01

    Here, we examine how different emotions-happiness, fear, sadness and anger-affect the kinematics of locomotion. We focus on a compact representation of locomotion properties using the intersegmental law of coordination (Borghese et al. in J Physiol 494(3):863-879, 1996), which states that, during the gait cycle of human locomotion, the elevation angles of the thigh, shank and foot do not evolve independently of each other but form a planar pattern of co-variation. This phenomenon is highly robust and has been extensively studied. The orientation of the plane has been correlated with changes in the speed of locomotion and with reduction in energy expenditure as speed increases. An analytical model explaining the conditions underlying the emergence of this plane and predicting its orientation reveals that it suffices to examine the amplitudes of the elevation angles of the different segments along with the phase shifts between them (Barliya et al. in Exp Brain Res 193:371-385, 2009). We thus investigated the influence of different emotions on the parameters directly determining the orientation of the intersegmental plane and on the angular rotation profiles of the leg segments, examining both the effect of changes in walking speed and effects independent of speed. Subjects were professional actors and naïve subjects with no training in acting. As expected, emotions were found to strongly affect the kinematics of locomotion, particularly walking speed. The intersegmental coordination patterns revealed that emotional expression caused additional modifications to the locomotion patterns that could not be explained solely by a change in speed. For all emotions except sadness, the amplitude of thigh elevation angles changed from those in neutral locomotion. The intersegmental plane was also differently oriented, especially during anger. We suggest that, while speed is the dominant variable allowing discrimination between different emotional gaits, emotion can be

  4. Compensatory plasticity restores locomotion after chronic removal of descending projections

    PubMed Central

    Harley, Cynthia M.; Reilly, Melissa G.; Stewart, Christopher; Schlegel, Chantel; Morley, Emma; Puhl, Joshua G.; Nagel, Christian; Crisp, Kevin M.

    2015-01-01

    Homeostatic plasticity is an important attribute of neurons and their networks, enabling functional recovery after perturbation. Furthermore, the directed nature of this plasticity may hold a key to the restoration of locomotion after spinal cord injury. Here we studied the recovery of crawling in the leech Hirudo verbana after descending cephalic fibers were surgically separated from crawl central pattern generators shown previously to be regulated by dopamine. We observed that immediately after nerve cord transection leeches were unable to crawl, but remarkably, after a day to weeks, animals began to show elements of crawling and intersegmental coordination. Over a similar time course, excessive swimming due to the loss of descending inhibition returned to control levels. Additionally, removal of the brain did not prevent crawl recovery, indicating that connectivity of severed descending neurons was not essential. After crawl recovery, a subset of animals received a second transection immediately below the anterior-most ganglion remaining. Similar to their initial transection, a loss of crawling with subsequent recovery was observed. These data, in recovered individuals, support the idea that compensatory plasticity directly below the site of injury is essential for the initiation and coordination of crawling. We maintain that the leech provides a valuable model to understand the neural mechanisms underlying locomotor recovery after injury because of its experimental accessibility, segmental organization, and dependence on higher-order control involved in the initiation, modulation, and coordination of locomotor behavior. PMID:25787951

  5. Rapid signalling in distinct dopaminergic axons during locomotion and reward.

    PubMed

    Howe, M W; Dombeck, D A

    2016-07-28

    Dopaminergic projection axons from the midbrain to the striatum are crucial for motor control, as their degeneration in Parkinson disease results in profound movement deficits. Paradoxically, most recording methods report rapid phasic dopamine signalling (~100-ms bursts) in response to unpredicted rewards, with little evidence for movement-related signalling. The leading model posits that phasic signalling in striatum-targeting dopamine neurons drives reward-based learning, whereas slow variations in firing (tens of seconds to minutes) in these same neurons bias animals towards or away from movement. However, current methods have provided little evidence to support or refute this model. Here, using new optical recording methods, we report the discovery of rapid phasic signalling in striatum-targeting dopaminergic axons that is associated with, and capable of triggering, locomotion in mice. Axons expressing these signals were largely distinct from those that responded to unexpected rewards. These results suggest that dopaminergic neuromodulation can differentially impact motor control and reward learning with sub-second precision, and indicate that both precise signal timing and neuronal subtype are important parameters to consider in the treatment of dopamine-related disorders. PMID:27398617

  6. Rapid signalling in distinct dopaminergic axons during locomotion and reward.

    PubMed

    Howe, M W; Dombeck, D A

    2016-07-28

    Dopaminergic projection axons from the midbrain to the striatum are crucial for motor control, as their degeneration in Parkinson disease results in profound movement deficits. Paradoxically, most recording methods report rapid phasic dopamine signalling (~100-ms bursts) in response to unpredicted rewards, with little evidence for movement-related signalling. The leading model posits that phasic signalling in striatum-targeting dopamine neurons drives reward-based learning, whereas slow variations in firing (tens of seconds to minutes) in these same neurons bias animals towards or away from movement. However, current methods have provided little evidence to support or refute this model. Here, using new optical recording methods, we report the discovery of rapid phasic signalling in striatum-targeting dopaminergic axons that is associated with, and capable of triggering, locomotion in mice. Axons expressing these signals were largely distinct from those that responded to unexpected rewards. These results suggest that dopaminergic neuromodulation can differentially impact motor control and reward learning with sub-second precision, and indicate that both precise signal timing and neuronal subtype are important parameters to consider in the treatment of dopamine-related disorders.

  7. Universality in legged locomotion on low-resistance ground

    NASA Astrophysics Data System (ADS)

    Qian, Feifei; Korff, Wyatt; Umbanhowar, Paul; Full, Robert; Goldman, Daniel

    2014-03-01

    Natural substrates like sand, snow, leaf litter and soil vary widely in penetration resistance, but little is known about how legged locomotors respond to this variation. To address this deficit, we built an air-fluidized trackway filled with granular material to control ground resistance. Resistance can be reduced to zero by increasing the upward flow of air through the bed. Using a hexapedal robot as our model locomotor, we systematically study how locomotion performance varies with penetration resistance, limb kinematics and foot morphology. A universal model, which combines robot kinematics and ground parameters, determines robot speed for all penetration resistances and captures the dependence of performance sensitivity on foot pressure and ground resistance. Expanding the scope of locomotors to include five organisms, we find that their performance on low-resistance ground is also well captured by the universal model. The model suggests that both increasing foot size and decreasing gait frequency reduce the performance loss as ground resistance decreases. Organisms may minimize the inertial effects of the granular media by maintaining maximum foot impact shear stresses through passive structures, e.g. long flexible toes, and active mechanisms, e.g. gait frequency control.

  8. Serotonin influences locomotion in the nudibranch mollusc Melibe leonina.

    PubMed

    Lewis, Stefanie L; Lyons, Deborah E; Meekins, Tiffanie L; Newcomb, James M

    2011-06-01

    Serotonin (5-HT) influences locomotion in many animals, from flatworms to mammals. This study examined the effects of 5-HT on locomotion in the nudibranch mollusc Melibe leonina (Gould, 1852). M. leonina exhibits two modes of locomotion, crawling and swimming. Animals were bath-immersed in a range of concentrations of 5-HT or injected with various 5-HT solutions into the hemolymph and then monitored for locomotor activity. In contrast to other gastropods studied, M. leonina showed no significant effect of 5-HT on the distance crawled or the speed of crawling. However, the highest concentration (10(-3) mol l(-1) for bath immersion and 10(-5) mol l(-1) for injection) significantly increased the time spent swimming and the swimming speed. The 5-HT receptor antagonist methysergide inhibited the influence of 5-HT on the overall amount of swimming but not on swimming speed. These results suggest that 5-HT influences locomotion at the behavioral level in M. leonina. In conjunction with previous studies on the neural basis of locomotion in M. leonina, these results also suggest that this species is an excellent model system for investigating the 5-HT modulation of locomotion. PMID:21712224

  9. Stokesian locomotion in elastic fluids: Experiments

    NASA Astrophysics Data System (ADS)

    Zenit, Roberto; Lauga, Eric

    2010-11-01

    In many instances of biological relevance, self-propelled cells have to swim through non-Newtonian fluids. In order to provide fundamental understanding on the effect of such non-Newtonian stresses on locomotion, we have studied the motion an oscillating magnetic swimmer immersed in both Newtonian and non-Newtonian liquids at small Reynolds numbers. The swimmer is made with a small rare earth (Neodymium-Iron-Boron) magnetic rod (3 mm) to which a flexible tail was glued. This array was immersed in cylindrical container (50 mm diameter) in which the test fluid was contained. A nearly uniform oscillating magnetic field was created with a Helmholtz coil (R=200mm) and a AC power supply. For the Newtonian case, a 30,000 cSt silicon oil was used. In the non-Newtonian case, a fluid with nearly constant viscosity and large first normal stress difference (highly elastic) was used; this fluid was made with Corn syrup with a small amount of polyacrylamide. The swimming speed was measured, for different amplitudes and frequencies, using a digital image analysis. The objective of the present investigation is to determine whether the elastic effects of the fluid improve or not the swimming performance. Some preliminary results will be presented and discussed.

  10. Incidental sounds of locomotion in animal cognition.

    PubMed

    Larsson, Matz

    2012-01-01

    The highly synchronized formations that characterize schooling in fish and the flight of certain bird groups have frequently been explained as reducing energy expenditure. I present an alternative, or complimentary, hypothesis that synchronization of group movements may improve hearing perception. Although incidental sounds produced as a by-product of locomotion (ISOL) will be an almost constant presence to most animals, the impact on perception and cognition has been little discussed. A consequence of ISOL may be masking of critical sound signals in the surroundings. Birds in flight may generate significant noise; some produce wing beats that are readily heard on the ground at some distance from the source. Synchronization of group movements might reduce auditory masking through periods of relative silence and facilitate auditory grouping processes. Respiratory locomotor coupling and intermittent flight may be other means of reducing masking and improving hearing perception. A distinct border between ISOL and communicative signals is difficult to delineate. ISOL seems to be used by schooling fish as an aid to staying in formation and avoiding collisions. Bird and bat flocks may use ISOL in an analogous way. ISOL and interaction with animal perception, cognition, and synchronized behavior provide an interesting area for future study. PMID:21748447

  11. Incidental sounds of locomotion in animal cognition.

    PubMed

    Larsson, Matz

    2012-01-01

    The highly synchronized formations that characterize schooling in fish and the flight of certain bird groups have frequently been explained as reducing energy expenditure. I present an alternative, or complimentary, hypothesis that synchronization of group movements may improve hearing perception. Although incidental sounds produced as a by-product of locomotion (ISOL) will be an almost constant presence to most animals, the impact on perception and cognition has been little discussed. A consequence of ISOL may be masking of critical sound signals in the surroundings. Birds in flight may generate significant noise; some produce wing beats that are readily heard on the ground at some distance from the source. Synchronization of group movements might reduce auditory masking through periods of relative silence and facilitate auditory grouping processes. Respiratory locomotor coupling and intermittent flight may be other means of reducing masking and improving hearing perception. A distinct border between ISOL and communicative signals is difficult to delineate. ISOL seems to be used by schooling fish as an aid to staying in formation and avoiding collisions. Bird and bat flocks may use ISOL in an analogous way. ISOL and interaction with animal perception, cognition, and synchronized behavior provide an interesting area for future study.

  12. Leg intramuscular pressures during locomotion in humans

    NASA Technical Reports Server (NTRS)

    Ballard, R. E.; Watenpaugh, D. E.; Breit, G. A.; Murthy, G.; Holley, D. C.; Hargens, A. R.

    1998-01-01

    To assess the usefulness of intramuscular pressure (IMP) measurement for studying muscle function during gait, IMP was recorded in the soleus and tibialis anterior muscles of 10 volunteers during treadmill walking and running by using transducer-tipped catheters. Soleus IMP exhibited single peaks during late-stance phase of walking [181 +/- 69 (SE) mmHg] and running (269 +/- 95 mmHg). Tibialis anterior IMP showed a biphasic response, with the largest peak (90 +/- 15 mmHg during walking and 151 +/- 25 mmHg during running) occurring shortly after heel strike. IMP magnitude increased with gait speed in both muscles. Linear regression of soleus IMP against ankle joint torque obtained by a dynamometer produced linear relationships (n = 2, r = 0.97 for both). Application of these relationships to IMP data yielded estimated peak soleus moment contributions of 0.95-1.65 N . m/kg during walking, and 1.43-2.70 N . m/kg during running. Phasic elevations of IMP during exercise are probably generated by local muscle tissue deformations due to muscle force development. Thus profiles of IMP provide a direct, reproducible index of muscle function during locomotion in humans.

  13. Locomotion of granulocytes on an inclined plane.

    PubMed

    Doroszewski, J; Lewandowska, K; Wierzbicki, W

    1986-01-01

    The paper presents a quantitative study of the trajectories of rat granulocytes (PMNs) migrating on a glass surface inclined at various angles, i.e. under the action of gravitational force component parallel to the plane. The action of the force of the order of 5 X 10(-13) N (component parallel to the plane inclined at 80 degrees) accompanied by the decrease of a gravitational component perpendicular to the surface does not disrupt the adhesion contact of migrating PMNs with the serum coated glass surface. Under the action of the external force parallel to the surface, the PMNs exhibit a tendency to migrate in the direction of the force vector and the angles between elementary segments (steps) of cell trajectories are smaller in comparison with migration on a horizontal plane (0 degrees inclination). It has been found that the mean velocity of motion of PMNs locomoting on a steep slope (70 degrees and 80 degrees) is greater in comparison with the migration velocity on a horizontal surface. The increase of velocity concerns not only cells migrating in the downward direction, but also those which move upwards. Possible mechanisms of the influence of external force on direction and rate of migration of granulocytes are discussed, namely modification of adhesion force, stimulation of cell motile activity, individual variability of cell adhesive and migration properties, shortening of transient locomotory adhesions.

  14. Stability versus maneuverability in aquatic locomotion.

    PubMed

    Weihs, Daniel

    2002-02-01

    The dictionary definition of stability as "Firmly established, not easily to be changed" immediately indicates the conflict between stability and maneuverability in aquatic locomotion. The present paper addresses several issues resulting from these opposing requirements. Classical stability theory for bodies moving in fluids is based on developments in submarine and airship motions. These have lateral symmetry, in common with most animals. This enables the separation of the equations of motion into two sets of 3 each. The vertical (longitudinal) set, which includes motions in the axial (surge), normal (heave) and pitching directions, can thus be separated from the lateral-horizontal plane which includes yaw, roll and sideslip motions. This has been found useful in the past for longitudinal stability studies based on coasting configurations but is not applicable to the analysis of turning, fast starts and vigorous swimming, where the lateral symmetry of the fish body is broken by bending motions. The present paper will also examine some of the aspects of the stability vs. maneuverability tradeoff for these asymmetric motions. An analysis of the conditions under which the separation of equations of motions into vertical and horizontal planes is justified, and a definition of the equations to be used in cases where this separation is not accurate enough is presented. PMID:21708701

  15. Intramuscular Pressure Measurement During Locomotion in Humans

    NASA Technical Reports Server (NTRS)

    Ballard, Ricard E.

    1996-01-01

    To assess the usefulness of intramuscular pressure (IMP) measurement for studying muscle function during gait, IMP was recorded in the soleus and tibialis anterior muscles of ten volunteers during, treadmill walking, and running using transducer-tipped catheters. Soleus IMP exhibited single peaks during late-stance phase of walking (181 +/- 69 mmHg, mean +/- S.E.) and running (269 +/- 95 mmHg). Tibialis anterior IMP showed a biphasic response, with the largest peak (90 +/- 15 mmHg during walking and 151 +/- 25 mmHg during running) occurring shortly after heel strike. IMP magnitude increased with gait speed in both muscles. Linear regression of soleus IMP against ankle joint torque obtained by a dynamometer in two subjects produced linear relationships (r = 0.97). Application of these relationships to IMP data yielded estimated peak soleus moment contributions of 0.95-165 Nm/Kg during walking, and 1.43-2.70 Nm/Kg during running. IMP results from local muscle tissue deformations caused by muscle force development and thus, provides a direct, practical index of muscle function during locomotion in humans.

  16. Nematode locomotion in unconfined and confined fluids

    NASA Astrophysics Data System (ADS)

    Bilbao, Alejandro; Wajnryb, Eligiusz; Vanapalli, Siva A.; Blawzdziewicz, Jerzy

    2013-08-01

    The millimeter-long soil-dwelling nematode Caenorhabditis elegans propels itself by producing undulations that propagate along its body and turns by assuming highly curved shapes. According to our recent study [V. Padmanabhan et al., PLoS ONE 7, e40121 (2012), 10.1371/journal.pone.0040121] all these postures can be accurately described by a piecewise-harmonic-curvature model. We combine this curvature-based description with highly accurate hydrodynamic bead models to evaluate the normalized velocity and turning angles for a worm swimming in an unconfined fluid and in a parallel-wall cell. We find that the worm moves twice as fast and navigates more effectively under a strong confinement, due to the large transverse-to-longitudinal resistance-coefficient ratio resulting from the wall-mediated far-field hydrodynamic coupling between body segments. We also note that the optimal swimming gait is similar to the gait observed for nematodes swimming in high-viscosity fluids. Our bead models allow us to determine the effects of confinement and finite thickness of the body of the nematode on its locomotion. These effects are not accounted for by the classical resistive-force and slender-body theories.

  17. Vestibular compensation and orientation during locomotion

    NASA Technical Reports Server (NTRS)

    Raphan, T.; Imai, T.; Moore, S. T.; Cohen, B.

    2001-01-01

    Body, head, and eye movements were studied in three dimensions while walking and turning to determine the role of the vestibular system in directing gaze and maintaining spatial orientation. The body, head, and eyes were represented as three-dimensional coordinate frames, and the movement of these frames was related to a trajectory frame that described the motion of the body on a terrestrial plane. The axis-angle of the body, head, and eye rotation were then compared to the axis-angle of the rotation of the gravitoinertial acceleration (GIA). We inferred the role of the vestibular system during locomotion and the contributions of the VCR and VOR by examining the interrelationship between these coordinate frames. Straight walking induced head and eye rotations in a compensatory manner to the linear accelerations, maintaining head pointing and gaze along the direction of forward motion. Turning generated a combination of compensation and orientation responses. The head leads and steers the turn while the eyes compensate to maintain stable horizontal gaze in space. Saccades shift horizontal gaze as the turn is executed. The head pitches, as during straight walking. It also rolls so that the head tends to align with the orientation of the GIA. Head orientation changes anticipate orientation changes of the GIA. Eye orientation follows the changes in GIA orientation so that the net orientation gaze is closer to the orientation of the GIA. The study indicates that the vestibular system utilizes compensatory and orienting mechanisms to stabilize spatial orientation and gaze during walking and turning.

  18. The Behavioral Space of Zebrafish Locomotion and Its Neural Network Analog.

    PubMed

    Girdhar, Kiran; Gruebele, Martin; Chemla, Yann R

    2015-01-01

    How simple is the underlying control mechanism for the complex locomotion of vertebrates? We explore this question for the swimming behavior of zebrafish larvae. A parameter-independent method, similar to that used in studies of worms and flies, is applied to analyze swimming movies of fish. The motion itself yields a natural set of fish "eigenshapes" as coordinates, rather than the experimenter imposing a choice of coordinates. Three eigenshape coordinates are sufficient to construct a quantitative "postural space" that captures >96% of the observed zebrafish locomotion. Viewed in postural space, swim bouts are manifested as trajectories consisting of cycles of shapes repeated in succession. To classify behavioral patterns quantitatively and to understand behavioral variations among an ensemble of fish, we construct a "behavioral space" using multi-dimensional scaling (MDS). This method turns each cycle of a trajectory into a single point in behavioral space, and clusters points based on behavioral similarity. Clustering analysis reveals three known behavioral patterns-scoots, turns, rests-but shows that these do not represent discrete states, but rather extremes of a continuum. The behavioral space not only classifies fish by their behavior but also distinguishes fish by age. With the insight into fish behavior from postural space and behavioral space, we construct a two-channel neural network model for fish locomotion, which produces strikingly similar postural space and behavioral space dynamics compared to real zebrafish.

  19. EphA4-Mediated Ipsilateral Corticospinal Tract Misprojections Are Necessary for Bilateral Voluntary Movements But Not Bilateral Stereotypic Locomotion

    PubMed Central

    Serradj, Najet; Paixão, Sónia; Sobocki, Tomasz; Feinberg, Mitchell; Klein, Rüdiger; Kullander, Klas

    2014-01-01

    In this study, we took advantage of the reported role of EphA4 in determining the contralateral spinal projection of the corticospinal tract (CST) to investigate the effects of ipsilateral misprojections on voluntary movements and stereotypic locomotion. Null EphA4 mutations produce robust ipsilateral CST misprojections, resulting in bilateral corticospinal tracts. We hypothesize that a unilateral voluntary limb movement, not a stereotypic locomotor movement, will become a bilateral movement in EphA4 knock-out mice with a bilateral CST. However, in EphA4 full knock-outs, spinal interneurons also develop bilateral misprojections. Aberrant bilateral spinal circuits could thus transform unilateral corticospinal control signals into bilateral movements. We therefore studied mice with conditional forebrain deletion of the EphA4 gene under control by Emx1, a gene expressed in the forebrain that affects the developing CST but spares brainstem motor pathways and spinal motor circuits. We examined two conditional knock-outs targeting forebrain EphA4 during performance of stereotypic locomotion and voluntary movement: adaptive locomotion over obstacles and exploratory reaching. We found that the conditional knock-outs used alternate stepping, not hopping, during overground locomotion, suggesting normal central pattern generator function and supporting our hypothesis of minimal CST involvement in the moment-to-moment control of stereotypic locomotion. In contrast, the conditional knock-outs showed bilateral voluntary movements under conditions when single limb movements are normally produced and, as a basis for this aberrant control, developed a bilateral motor map in motor cortex that is driven by the aberrant ipsilateral CST misprojections. Therefore, a specific change in CST connectivity is associated with and explains a change in voluntary movement. PMID:24719100

  20. A highly adaptive magnetorheological fluid robotic leg for efficient terrestrial locomotion

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Sun, Shuaishuai; Ouyang, Yiming; Xu, Min; Li, Weihua; Zhang, Shiwu

    2016-09-01

    To survive in nature, animals adjust the characteristics of their legs or fins to adapt the motion to their environment. Inspired by the locomotion of animals, a study on the tunable stiffness and damping of a leg will help in the development of intelligent locomotion robots. In this paper we report on the development and experiment of a novel and simple robotic leg that can be adapted to the environment via a smart magnetorheological fluid (MRF). The robotic leg consists of a rotation MRF damper, a torsional spring, a ‘foot’ and a ‘leg’. The curved part of the ‘foot’ makes contact with the grounds while the other end is linked to an outer cylinder of the MRF damper with an inelastic cable. The variable force arm rising from the MRF damper and the torsional spring can help the leg adapt to a changing environment. The characteristics of the MRF damper have been investigated and a model is built to describe its mechanical features when different currents are applied to the MRF damper. A test on a linear dynamic test instrument has been conducted to verify the accuracy of the model. The robotic leg is installed in a locomotion platform to investigate the speed of its locomotion and the cost of the transport; the result demonstrated the feasibility and adaptability of the leg when walking on hard terrain. Its simple structure, high adaptability, and easy control of the MRF leg helped in the design and development of a high performance field robot that can adapt to various environments.