Design of cooperative system consisting of multiple position controlled robots

A simple strategy for carrying a large object with the cooperation of multi ple position-controlled robots is proposed. In cooperative systems handling single objects, compliance is necessary for each robot to avoid excessive inner forces caused by mutual positioning errors. However, since the majori ty of commercial industrial robots have PID position controllers, the neces sary compliance cannot be achieved by servo systems. Thus, mechanisms consi sting of passive joints are installed in a cooperative system as mechanical compliance. First, the mechanical compliance required for the cooperation of position-controlled robots is derived, From the theoretical results, it is determined that the maximum number of robots that can directly support a single object is six. Second, the statics and error characteristics of coo perative systems including compliant mechanisms are analyzed. An example of the cooperation of three mobile robots is designed using passive joint mec hanisms. Finally, the strategy is extended to cooperation among an arbitrar y number of mobile robots by building hierarchical structures with passive joints.