COORDINATED CONTROL OF MULTIPLE ROBOTIC MANIPULATORS HANDLING A COMMON OBJECT - THEORY AND EXPERIMENTS

A general framework for the analysis and design of the control system with multiple robots handling a common object is presented, based on t he decomposition of the combined system dynamics into motion-control a nd internal force-control subsystems. It is found that, under the infi nite-rigidity assumption, the motion-control subsystem is independent of the internal force control, and has the same form and possesses the same properties as those of a single manipulator. This allows for any advanced motion-control law, developed for the control of a single ma nipulator, to be applied directly to the motion control of the multipl e manipulators. In particular, a decentralised adaptive-control law is incorporated to form the motion-control law for the co-operative syst em. With the definition of the internal force and introduction of a lo ad-sharing criterion, an internal-force-control strategy is analysed a nd formulated together with an internal-force-estimation algorithm so that the internal-force-control strategy may be implemented without us ing direct force feedback. The effectiveness of this approach to the m ultiple-arm co-operation is validated through a set of experimental te sts.