Observer-Based Impedance Control in Robotics

This paper presents theoretical and experimental results onobserver-based impedance control. Impedance control is a technique for robot force control, which is often used to deal with geometric uncertainty. The aim of this technique is to obtain a dynamic relation between position and force in interaction similar to Newton's second law. Here the velocity is used to modify the damping of the impedance relation.Since the velocity is not measurable, which is often the case for industrial robots, an observer is designed to reconstruct it. A good model of the robot joint used is obtained by system identification. Results on observer-based SPR feedback are applied in the design, and the stability issue is approached by a modified Popov criterion.The experiments are carried out on an ABB industrial robot 2000 at the Department of Automatic Control in Lund, Sweden