A differential motion planning algorithm for controlling multi-robot systems handling a common object

Multi-robot systems have substantially increased capabilities over single-r obot systems and can handle very large or peculiar objects. This paper pres ents a differential (incremental) motion planning algorithm for an m-robot system (m greater than or equal to 2) to cooperatively transfer an object f rom an initial to a desired final position / orientation by rigidly holding it at given respective points Q(1), Q(2), ..., Qm. One of the robots plays the role of a "master" while other robots operate in the "slave" mode main taining invariant their relative positions and orieatations during the syst em motion. The method employs the differential displacements of the end-eff ector of each. robot arm. Then, the differential displacements of the joint s of the m robots are computed for the application of incremental motion co ntrol. The algorithm was tested on many examples. A representative of them is shown here, concerning the case of three STAUBLI RX-SOL robots similar t o 6-dof PUMA robots. The results obtained show the practicality and effecti veness of the method, which, however, needs particular care for completely eliminating the cumulative errors that may occur.