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Résumé

Les humains construisent des machines de plus en plus évolués pour se faciliter la vie. La prochaine étape de cette évolution sera la construction de robots capables de choisir, définir et enfin accomplir une tâche de manière autonome au milieu des humains. Pour atteindre ce but, des outils de planification et de contrôle pour des tâches de manipulation sont présentés. La notion de mouvements souples constitués de suites de fonctions cubiques permet, dune part, de planifier des trajectoires en prenant en compte le temps et les contraintes de confort et de sécurité des utilisateurs, et dautre part, de faire le lien entre planification et commande. La planification de prises et létude de leurs stabilités constitue un élément clé de la planification de tâches de manipulation. Létude de la dynamique et des frottements sont indispensables à la compréhension de la manipulation. Linteraction entre humains et robots est abordée à partir de létude de léchange dun objet équipé de capteurs pour mesurer les forces dinteraction.

Abstract

Humans build more and more evolved machines to facilitate their life. The next stage of this evolution will be the construction of robots capable of choosing, defining and finally achieving a task autonomously in the middle of humans. To accomplish this objective, planning and control tools for manipulation tasks are presented. The concept of soft motions that are constituted by cubic functions enables, on the one hand, to plan trajectories that take into account time, and security and comfort constraints for users, and on the other hand, to do a link between planning and control. The grasp planning and the study of the stability of grasps constitute a key element of the manipulation planning. The study of dynamic and friction are indispensable to the understanding of manipulation. Interaction between humans and robots is tackled from the study of the hand over of an object that is equipped with sensors to measure interaction forces.

Mots-Clés / Keywords

Robotique; Manipulation; Planification; Commande; Saisie d'objets; Interaction; Frottements; Dynamique; Robotics; Planning; Control; Grasping; Friction; Dynamic;

Mots-Clés / Keywords

Force closure; Grasping; Multifingered hands;

Abstract

Human interaction introduces two main constraints: Safety and Comfort. Therefore service robot manipulator can't be controlled like industrial robotic manipulator where personnel is isolated from the robot's work envelope. In this paper, we present a soft motion trajectory planner to try to ensure that these constraints are satisfied. This planner can be used on-line to establish visual and force control loop suitable in presence of human. The cubic trajectories build by this planner are good candidates as output of a manipulation task planner. The obtained system is then homogeneous from task planning to robot control. The soft motion trajectory planner limits jerk, acceleration and velocity in cartesian space using quaternion. Experimental results carried out on a Mitsubishi PA10-6CE arm are presented.

Abstract

In this paper, we propose a new approach for computing force-closure grasps of two-dimensional and three-dimensional objects. Assuming n hard-finger contact with Coulomb friction model and based on central axes of the grasp wrench (i.e., force and torque), we develop a new necessary and sufficient condition for n-finger grasps to achieve force-closure. We demonstrate that a grasp is force-closure if and only if, its wrench can generate any arbitrary central axis. According to this condition, we reformulate the force-closure test as a linear programming problem without computing the convex hull of the primitive contact wrenches. Therefore, we present an efficient algorithm for computing n-finger force-closure grasps. Finally, we have implemented the proposed algorithm and verified its efficiency through some examples.

Mots-Clés / Keywords

Multifingered robotic hand; Force-closure grasp; Grasp optimization;