Object impedance control for cooperative manipulation: theory and experimental results

The dynamic control module of the Dynamic and Strategic Control of Cooperating Manipulators (DASCCOM) project for aerospace robotics is presented. The cooperative manipulation problem is analyzed from a systems perspective, and the desirable features of a control system for cooperative manipulation are discussed. A control policy is developed that enforces a controlled impedance not of the individual arm endpoints, but of the manipulated object itself. A parallel implementation for a multiprocessor system is presented. The controller fully compensates for the system dynamics and directly controls the object internal forces. Most importantly, it presents a simple, powerful, intuitive interface to higher level strategic control modules. Experimental results from a dual two-link-arm robotic system show the effectiveness of the object impedance controller compared to other strategies, both for free-motion slews and environmental contact