Contact stability issues in position based impedance control: theory and experiments

The contact stability has been considered based on simplified linearized models of robot and environment. It is shown that the most crucial parameter for contact stability is the target damping ratio. When a high compliance is required the stability boundary conditions require significantly overdamped impedance behavior to ensure a stable contact with a stiff environment. These conditions for a SISO system are defined in the analytic form. Obtained minimal damping ratio values are significantly lower than those previously proposed in the literature.