A Decoupling Scheme for Force Control in Cooperative Multi-Robot Manipulation Tasks

The internal forces and torques arising in cooperative manipulators ensembles are the grasp forces/torques and it is obviously desirable to control them. We present a novel approach that describes the internal loading as the interaction forces/torques arising in a multi-body system formed by multiple manipulators that behave like a formation of robots. We show that these quantities belong to the null space of the grasp matrix, thus they do not affect the dynamics of the object. The main contribution of this paper is a decoupling control scheme for tracking the internal and the motion-inducing forces and torques in a physically consistent way. The scheme is based on a physically and mathematically consistent model of the dynamics of the constrained interaction.