Coordinative object-transportation by multiple industrial mobile robots using coupler with mechanical compliance

This paper proposes an approach to the motion coordination of multiple industrial mobile robots (AGVs). The task of the robots is to cooperatively transport a common object. An ordinary mobile robot has uncertain dynamics, and its motion is constrained by a non-holonomic constraint. Furthermore, multiple robots with a common object form a closed-chain structure which would cause the severe dynamical interactions. The authors´ approach overcomes the inherent problems by introducing a robot-mounted coupler with mechanical compliance which provides compliance between each robot and the object. The hierarchical coordinative control scheme is presented to perform accurate object-transportation based on the synchronous motions of the robots. Simulation and fundamental experiment by using a commercially available AGV demonstrate the effectiveness of the authors´ approach