Optimal grasping poses of manipulators for cooperative manipulation with passive joints

摘要

This paper discusses an object handling system using three position-controlled manipulators. Mechanical compliance units are installed between each manipulator tip and its hand in order not to generate an excessive inner forces among manipulators caused by mutual positioning errors. From our previous studies, the kinematic conditions of the compliance units necessary for the position control based coordination are made clear and four passive joints are used here for each compliance unit to satisfy the conditions. In the system, the loads distributed to each manipulator tip are changed according to both the passive joint angles and the grasping points of the handled object. Therefore we firstly obtain the relationship between the grasping points and the distributed loads to each hand and then analyze the relationship between the passive joint angles and the loads given to each manipulator tip. Using these relationships we propose the searching scheme for the optimal grasping poses and passive joint angles. The effectiveness of the proposed scheme and the developed system are verified by a fundamental experiment and simulations.