Distributed impedance control of multiple robot systems

This paper proposes the distributed impedance approach as a new formulation of multiple robot systems control. In this approach, each cooperating manipulator is provided with its own independent impedance controller. In addition, along selected degrees of freedom, force control is achieved through an external loop, in order to improve control of the object's internal loading. Extensive stability analysis is performed based on a realistic model that includes robots impedance and object dynamics. Experiments are performed using two cooperating industrial robots holding an object through point contacts. Force and position control actions are suitably dispatched to achieve both internal loading control and object position control. The performance of the system is demonstrated for transporting tasks.