Adaptive force/velocity control for multi-robot cooperative manipulation under uncertain kinematic parameters

Multi-robot cooperative manipulation of a common object requires precise kinematic coordination of the attached end effectors in order to avoid excessive forces on the object and the manipulators. A manipulation task is considered successful if the desired object motion and forces are tracked accurately. In this paper we present a systematic analysis on the effect of uncertain kinematic parameters on the tracking behavior in a planar manipulation task. An adaptive control scheme is proposed, which achieves the desired control goal asymptotically. The presented scheme employs the current force/motion data of the attached end effectors without relying on a common reference frame. The algorithm is applicable to common manipulator types with wrist-mounted force/torque sensors and implementable in real-time. The performance of the proposed control scheme is evaluated experimentally with two 7DoF manipulators who cooperatively manipulate an object of uncertain length.