La locomotion des robots humanoides est essentielle pour le developpement de nouveaux systemes de... more La locomotion des robots humanoides est essentielle pour le developpement de nouveaux systemes de transport. Elle doit satisfaire des contraintes de moindre consommation d’energie afin d’accroitre l’autonomie energetique, et de respect des conditions de contact unilateral. Il faut aussi assurer la stabilite orbitale de la marche malgre les perturbations telles que les incertitudes de modele, les irregularites du sol, ou les interactions avec l’environnement. Pour rejeter ces perturbations, nous considerons des strategies de commande qui sont associees a la definition des mouvements de reference. Quelques strategies de commande de base et des elements d’analyse de la stabilite orbitale d’une marche cyclique de robots bipedes planaires et 3D sont presentes dans cet article.
In this paper, optimal cyclic reference trajectories are designed for three walking gaits of a qu... more In this paper, optimal cyclic reference trajectories are designed for three walking gaits of a quadruped robot, the curvet, the amble, the trot, taking into account the actuators characteristics and for a given motion robot velocity. The objectives of this study are multiple: • Automatic design of admissible reference trajectories, • Definition of the maximal speed of the robot for given actuators, • Study of the evolution of the torque cost for various motion velocities, • Comparison of three different gaits with respect to a sthenic criterion. For the gaits studied, during some phases the system is underactuated. The design of the cyclic gaits takes this fact into account. The optimization problem is solved with an algebraic optimization technique. The actuated joint evolution is chosen as a polynomial function of time. The coefficients of the polynomial functions are optimization parameters. The evolution of the passive joint is defined using the dynamic model to have admissible trajectory. During the optimization process, the constraints on the ground reactions, the validity of impact, the torques, the joints velocities of the robot are taken into account. Simulation results are presented for the three gaits. All motions are realistics. Curvet is the less efficient gait with respect to the criterion studied. For slow motion, trot is the more efficient gait. But amble permits the fastest motion with the same actuators.
Underactuated robotic hands are becoming popular in complex robotic designs where mass and size a... more Underactuated robotic hands are becoming popular in complex robotic designs where mass and size are yet limited. Such designs require a tradeoff between versatility and simplicity. This is the case for prosthetic robotic hands, which need to imitate the human hand both in functionality and dimensions as closely as possible to achieve a natural feeling solution for the patient. This paper presents the initial mechanical analysis of the design of an anthropomorphic hand with 15 degrees of freedom using six electric motor actuators. A transmission system of cables and pulleys is used as the underactuated mechanism in order to propagate the motor torque over the three joints of each finger, and springs are used to provide the passive return actuation. The design has been validated according to its ability to stably grasp different cylindrical objects. The stability of the grasp has been judged according to the criterion of positive or zero contact forces being present at all points of contact between the hand and the object in a static case. A simulation of the grasping procedure where the contact forces are modeled over time has been developed in Matlab®. It has been shown that the design process requires iterative steps, as multiple factors such as spring stiffness, pulley radii, and motor torques will affect the stability of grasping of the hand and its effectiveness as a prosthetic device.
The paper aim is to show theoretically the feasibility and efficiency of a passive exoskeleton fo... more The paper aim is to show theoretically the feasibility and efficiency of a passive exoskeleton for human carrying a load. Human is modeled using a mathematical model of a planar bipedal five-link anthropomorphic mechanism. This mechanism consists of a trunk and two identical legs; each leg consists of a thigh and shin with point-foot. The exoskeleton is considered also as a five-link anthropomorphic mechanism. The shape and the degrees of freedom of the exoskeleton are identical to biped (to human). If the biped is equipped with an exoskeleton, then the links of this exoskeleton are attached to the corresponding links of the biped and the corresponding hip-, knee-, and ankle-joints coincide. We compare the walking of a biped alone (without exoskeleton) and of a biped equipped with exoskeleton; both models are with a load. A ballistic walking gait is designed in both cases. During the ballistic walking of the biped with exoskeleton the knee of the stance leg of the exoskeleton (and as a consequence of the biped) is locked. The locking can be realized in the knee of each leg of the exoskeleton by any mechanical brake device with no energy consumption. There are not any actuators in our exoskeleton. Therefore, we call it passive exoskeleton. The walking of the biped consists of alternating single- and double-support phases. In our study, the double-support phase is assumed as instantaneous. At the instant of this phase, the knee of the previous swing leg is locked and the knee of the previous stance leg is unlocked. Numerical results show that during the load transport the human with the exoskeleton spends less energy than human alone.
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 ...
La locomotion des robots humanoides est essentielle pour le developpement de nouveaux systemes de... more La locomotion des robots humanoides est essentielle pour le developpement de nouveaux systemes de transport. Elle doit satisfaire des contraintes de moindre consommation d’energie afin d’accroitre l’autonomie energetique, et de respect des conditions de contact unilateral. Il faut aussi assurer la stabilite orbitale de la marche malgre les perturbations telles que les incertitudes de modele, les irregularites du sol, ou les interactions avec l’environnement. Pour rejeter ces perturbations, nous considerons des strategies de commande qui sont associees a la definition des mouvements de reference. Quelques strategies de commande de base et des elements d’analyse de la stabilite orbitale d’une marche cyclique de robots bipedes planaires et 3D sont presentes dans cet article.
In this paper, optimal cyclic reference trajectories are designed for three walking gaits of a qu... more In this paper, optimal cyclic reference trajectories are designed for three walking gaits of a quadruped robot, the curvet, the amble, the trot, taking into account the actuators characteristics and for a given motion robot velocity. The objectives of this study are multiple: • Automatic design of admissible reference trajectories, • Definition of the maximal speed of the robot for given actuators, • Study of the evolution of the torque cost for various motion velocities, • Comparison of three different gaits with respect to a sthenic criterion. For the gaits studied, during some phases the system is underactuated. The design of the cyclic gaits takes this fact into account. The optimization problem is solved with an algebraic optimization technique. The actuated joint evolution is chosen as a polynomial function of time. The coefficients of the polynomial functions are optimization parameters. The evolution of the passive joint is defined using the dynamic model to have admissible trajectory. During the optimization process, the constraints on the ground reactions, the validity of impact, the torques, the joints velocities of the robot are taken into account. Simulation results are presented for the three gaits. All motions are realistics. Curvet is the less efficient gait with respect to the criterion studied. For slow motion, trot is the more efficient gait. But amble permits the fastest motion with the same actuators.
Underactuated robotic hands are becoming popular in complex robotic designs where mass and size a... more Underactuated robotic hands are becoming popular in complex robotic designs where mass and size are yet limited. Such designs require a tradeoff between versatility and simplicity. This is the case for prosthetic robotic hands, which need to imitate the human hand both in functionality and dimensions as closely as possible to achieve a natural feeling solution for the patient. This paper presents the initial mechanical analysis of the design of an anthropomorphic hand with 15 degrees of freedom using six electric motor actuators. A transmission system of cables and pulleys is used as the underactuated mechanism in order to propagate the motor torque over the three joints of each finger, and springs are used to provide the passive return actuation. The design has been validated according to its ability to stably grasp different cylindrical objects. The stability of the grasp has been judged according to the criterion of positive or zero contact forces being present at all points of contact between the hand and the object in a static case. A simulation of the grasping procedure where the contact forces are modeled over time has been developed in Matlab®. It has been shown that the design process requires iterative steps, as multiple factors such as spring stiffness, pulley radii, and motor torques will affect the stability of grasping of the hand and its effectiveness as a prosthetic device.
The paper aim is to show theoretically the feasibility and efficiency of a passive exoskeleton fo... more The paper aim is to show theoretically the feasibility and efficiency of a passive exoskeleton for human carrying a load. Human is modeled using a mathematical model of a planar bipedal five-link anthropomorphic mechanism. This mechanism consists of a trunk and two identical legs; each leg consists of a thigh and shin with point-foot. The exoskeleton is considered also as a five-link anthropomorphic mechanism. The shape and the degrees of freedom of the exoskeleton are identical to biped (to human). If the biped is equipped with an exoskeleton, then the links of this exoskeleton are attached to the corresponding links of the biped and the corresponding hip-, knee-, and ankle-joints coincide. We compare the walking of a biped alone (without exoskeleton) and of a biped equipped with exoskeleton; both models are with a load. A ballistic walking gait is designed in both cases. During the ballistic walking of the biped with exoskeleton the knee of the stance leg of the exoskeleton (and as a consequence of the biped) is locked. The locking can be realized in the knee of each leg of the exoskeleton by any mechanical brake device with no energy consumption. There are not any actuators in our exoskeleton. Therefore, we call it passive exoskeleton. The walking of the biped consists of alternating single- and double-support phases. In our study, the double-support phase is assumed as instantaneous. At the instant of this phase, the knee of the previous swing leg is locked and the knee of the previous stance leg is unlocked. Numerical results show that during the load transport the human with the exoskeleton spends less energy than human alone.
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 ...
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Papers by Yannick Aoustin