Papers by C. Chevallereau
The development of an algorithm to achieve optimal cyclic gaits in space for a thirteen-link bipe... more The development of an algorithm to achieve optimal cyclic gaits in space for a thirteen-link biped and twelve actuated joints is proposed. The cyclic walking gait is composed of successive single support phases and impulsive impacts with full contact between the sole of the feet and the ground. The evolution of the joints are chosen as spline functions. The parameters to define the spline functions are determined using an optimization under constraints on the dynamic balance, on the ground reactions, on the validity of impact, on the torques and on the joints velocities. The criterion considered is represented by the integral of the torque norm. The algorithm is tested for a biped robot whose numerical walking results are presented.
Computer Methods in Biomechanics and Biomedical Engineering, 2019
Mechanisms and Machine Science, 2016
The possibility of developing increasingly sophisticated robots, and the availability of cloud-co... more The possibility of developing increasingly sophisticated robots, and the availability of cloud-connected resources, have boosted the interest in the study of real world applications of service robotics. However, in order to operate under natural or less structured conditions, and given the information processing bottleneck and the reactivity required for a secure execution of the task, it is desirable that the agent can exploit more efficiently the local information available, so that being more autonomous, and relying less on remote computation. This study explores a strategy for obtaining reliable approach tasks. It considers the anticipation of perception, by taking into account the statistical regularities and the information redundancies induced in the sensorymotor coupling. From an initial perception of the object assisted by remote computation, contextual features are defined for capturing bodily sensations emerging in the task. The observations based on proprioceptive and visual data are fused in a Bayesian Network, which is in charge of assessing the saliency during the object approach, thus constituing a local discriminative processing of the object. The strategy proposed reduces dependency on context-free models of behavior, while providing an estimate on the degree of confidence in the progress of the task.
Cet ouvrage traite de différentes techniques pour la modélisation, la conception, la synthèse de ... more Cet ouvrage traite de différentes techniques pour la modélisation, la conception, la synthèse de la marche et la commande de robots marcheurs bipèdes. Des données générales sur la marche humaine sont accompagnées d'une brève présentation des réalisations actuelles ...
Proceedings 2000 ICRA. Millennium Conference. IEEE International Conference on Robotics and Automation. Symposia Proceedings (Cat. No.00CH37065)
ABSTRACT Several French laboratories, joint in the CNRS Project “Control of Legged Robots”, have ... more ABSTRACT Several French laboratories, joint in the CNRS Project “Control of Legged Robots”, have defined a biped robot intended to experiment walking and running gaits. This biped is made of one trunk and two legs without feet, animated by means of four active articulations. This paper describes the design of the prototype, closely combining technological considerations and dynamics ones. The geometrical parameters and actuation characteristics are defined with the aim of generating walking and running gaits with rather large velocities. Each gait is synthesised with optimization criterion including the energy consideration with respect to actuator performances. During the single support phase and the flight phase, the biped is under-actuated. The synthesis of the corresponding trajectories is carried out by means of a local optimization method, and the cyclic constraints being handled as equality constraints. The optimal gear ratio of the speed reducers is computed
Nature-Inspired Mobile Robotics, 2013
IEEE Control Systems Magazine, 2003
Proceedings of the First Workshop on Robot Motion and Control. RoMoCo'99 (Cat. No.99EX353), 1999
ABSTRACT The objective of this study is to generate optimal gait cycles for the walking of a plan... more ABSTRACT The objective of this study is to generate optimal gait cycles for the walking of a planar biped robot without an actuated ankle joint and four actuators. The evolution of four joint variables is assumed to be polynomial functions of the fourth order. The evolution of the other variable is deduced from the dynamic model of the biped. The coefficients of the polynomial functions are chosen to optimize the criteria and insure cyclic motion of the biped. The criteria chosen are maximal motion velocity, minimal torque, and minimal energy. These criteria are functions of some parameters, which define the configurations of the biped, its step length, and duration of the step. To minimize these functions means to find the optimal motion. Also, the optimal gait is defined with respect to given performances of actuators: the torques and velocities at the output of the gear are bounded. For this study, the physical parameters of a prototype are used
9th IEEE International Workshop on Advanced Motion Control, 2006.
Page 1. Impulsive control for a thirteen-link biped Yannick AOUSTIN, David TLALOLINI ROMERO, Chri... more Page 1. Impulsive control for a thirteen-link biped Yannick AOUSTIN, David TLALOLINI ROMERO, Christine CHEVALLEREAU and Sebastien AUBIN \lRCCyN, Unité mixte CNRS 6957 Université dp Nantes - Ernie Centrale, de. ...
Proceedings of the 2005 IEEE International Conference on Robotics and Automation
ABSTRACT The objective of this study is to obtain optimal cyclic gaits for a biped without actuat... more ABSTRACT The objective of this study is to obtain optimal cyclic gaits for a biped without actuated ankle. For the walking, the gait is composed of successive single support phases and instantaneous double support phases that are modeled by passive impact equations. The legs swap their roles from one single support phase to the next one. During each phase the evolution of the joints variables is assumed to be polynomial functions of a scalar path parameter. The coefficients of the polynomial functions are chosen to optimise a torque criterion and to insure a cyclic motion for the biped. Furthermore, the optimal gait is defined with respect to given performances of actuators. The torques and velocities at the output of the gearbox are bounded. For this study, the physical parameters of a prototype are used. Initial starting motions that are composed of a double support and a transitional single support are also defined.
Robotica, 2004
This paper presents a control law for the tracking of a cyclic reference path by an under-actuate... more This paper presents a control law for the tracking of a cyclic reference path by an under-actuated biped robot. The robot studied is a five-link planar biped. The degree of under-actuation is one during the single support phase. The control law is defined in such a way that only the geometric evolution of the biped configuration is controlled, but not the temporal evolution. To achieve this objective, we consider a parametrized control. When a joint path is given, a five degree of freedom biped in single support becomes similar to a one degree of freedom inverted pendulum. The temporal evolution during the geometric tracking is completely defined and can be analyzed through the study of a model with one degree of freedom. Simple analytical conditions, which guarantee the existence of a cyclic motion and the convergence towards this motion, are deduced. These conditions are defined on the reference trajectory path. The analytical considerations are illustrated with some simulation re...
Multibody System Dynamics, 2009
IEEE/ASME Transactions on Mechatronics, 2011
Fast human walking includes a phase where the stance heel rises from the ground and the stance fo... more Fast human walking includes a phase where the stance heel rises from the ground and the stance foot rotates about the stance toe. This phase where the biped becomes underactuated is not present during the walk of humanoid robots. The objective of this study is to determine if the introduction of this phase for a 3D biped robot is useful to reduce the energy consumed in the walking. In order to study the efficiency of this new gait, two cyclic gaits are presented. The first cyclic motion is composed of successive single support phases with flat stance foot on the ground, the stance foot does not rotate. The second cyclic motion is composed of single support phases that includes a sub-phase of rotation of the supporting foot about the toe. The single support phases are separated by a double support phase. For simplicity this double support phase is considered as instantaneous (passive impact). For these two gaits, optimal motions are designed by minimizing a functional torques cost. The given performances of actuators are taken into account. It is shown that for fast motion a foot rotation sub-phase is useful to reduce the functional cost. These gaits are illustrated with simulation results.
2008 47th IEEE Conference on Decision and Control, 2008
This paper presents a within-stride feedback controller that achieves an exponentially stable, pe... more This paper presents a within-stride feedback controller that achieves an exponentially stable, periodic, and fast walking gait for a 3D bipedal robot consisting of a torso, revolute knees, and passive (unactuated) point feet. The walking surface is assumed to be rigid and flat; the contact between the robot and the walking surface is assumed to inhibit yaw rotation. The studied robot has 8 DOF in the single support phase and 6 actuators. In addition to the reduced number of actuators, the interest of studying robots with point feet is that the feedback control solution must explicitly account for the robot's natural dynamics in order to achieve balance while walking. We use an extension of the method of virtual constraints and hybrid zero dynamics (HZD), a very successful method for planar bipeds, in order to determine a periodic orbit and an autonomous feedback controller that realizes the orbit, for a 3D (spatial) bipedal walking robot. The effect of output selection on the zero dynamics is highlighted and a pertinent choice of outputs is proposed, leading to stabilization without the use of a supplemental event-based controller.
New Trends in Medical and Service Robots, 2016
Volume 2: 32nd Mechanisms and Robotics Conference, Parts A and B, 2008
ABSTRACT Fast human walking includes a phase where the stance heel rises from the ground and the ... more ABSTRACT Fast human walking includes a phase where the stance heel rises from the ground and the stance foot rotates about the stance toe. This phase where the biped becomes under-actuated is not present during the walk of humanoid robots. The objective of this study is to determine if the introduction of this phase for a biped robot is useful to reduce the energy consumed in the walking. For simplicity only a planar biped is considered. In order to study the efficiency of this phase, four cyclic gaits are presented. For these gaits optimal motions with respect to the torque cost are defined for given performances of actuators. It is shown that for fast motions a foot rotation sub-phase is useful to reduce the criteria cost. In the optimization process, under-actuated phase (foot rotation phase), fully-actuated phase (flat foot phase) and over-actuated phase (double support phase) are considered.
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Papers by C. Chevallereau