Decentralized control of robots for dynamic coordination

We propose a coordinated motion control algorithm of manipulators, by which each manipulator is controlled by its own controller in a decentralized way. We select a manipulator as a leader and a task is described by the motion of the leader and the motions of the other manipulators relative to the motion of the leader. The latter manipulators are referred to the followers. First we consider the problem of manipulation of a single object by multiple manipulators. In this task, the motion of the object is given to the leader. To execute the task in a decentralized way, we propose an algorithm for each follower to estimate the motion of the leader based on the information from its own force sensor. Using the algorithm, the manipulation of a single object is executed in a decentralized way. We consider the parts-mating problem, next, by two manipulators in coordination. An assembly task is described by the motion of a part manipulated by the leader and the relative motion between two parts given to the follower. The relative motion is observed and controlled by a vision sensor attached to the follower and the assembly task is executed independently of the motion of the leader. Experimental results using two industrial robots will illustrate the validity of the proposed control system.