A Co-operative Transferring Task by Mobile Manipulators
Kazuya Yasui, Toshiyuki Murakami, and Kouhei Ohnishi
Department of Science and Technology, Faculty of System Design Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-Ku, Yokohama 223-8522, Japan
In this paper, a method of grasping and transferring a large object by cooperative motion of multiple manipulators is introduced. To implement the task with mobile manipulators, the compliance of the grasping system between the object and end-effectors is needed. It enables us to avoid excessive internal force due to mutual positioning errors. However, the simple way of trajectory planning of the system is also required. Because the trajectory planning used to be given to each manipulator, it has been very complicated task to design the desired trajectories for each mobile manipulator. Thus this paper adopt the control algorithm with respect to objects to reduce the amount of planning tasks. The static relation between the object and end-effectors is introduced to solve the issues above. It combines the force reference of end-effectors and that of an object with static analysis of force. With this algorithm, the motion of an object is distributed to each end-effector. Then the grasping is projected to the null space of this static force relation. For confirmation of the proposed method, computational analyses are implemented and shown.
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