Robotic force control using observer-based strict positive real impedance control

This paper presents theoretical and experimental results on observer-based impedance control for force control without velocity feedback. As the velocity may not available to measurement, which is often the case for industrial robots, an observer was designed to reconstruct velocity in such a way that it be useful for stabilizing feedback control and to modification of the damping in the impedance relationship. A good model of the robot joint used was obtained by system identification. Experiments were carried out on an ABB industrial robot 2000 to demonstrate results on observer-based SPR feedback applied in the design. Stability was shown via a modified Popov criterion.