Cooperative Control Of Three PID Position- Controlled Robots With Passive Joint Mechanisms

A simple method of handling objects by cooperation of three PID positioncontrolled robots is proposed. In order to handle single object by multiple position-controlled robots, mechanical compliance is installed into each robot to avoid excessive inner forces due to the mutual positioning errors. First, necessary kinematic conditions required for installed mechanical compliance is reviewed. Then, a passive joint mechanism for cooperation among three popular industrial robots is designed as mechanical compliance. Since the cooperative system including the installed passive joint mechanisms has kinematic redundancy, robot motions in the redundant space are analyzed. After the redundant joint angles are set to initial values satisfying the desirable conditions, each robot is controlled so as to keep the initial joint values during the trucking of planned object trajectories. Some fundamental experiments done by three industrial robots verify the effectiveness of the proposed system.