THE EQUIVALENCE OF 2ND-ORDER IMPEDANCE CONTROL AND PROPORTIONAL GAIN EXPLICIT FORCE CONTROL

This article discusses the essential equivalence of second-order imped ance control with force feedback and proportional gain explicit force control with force feedforward. This is first done analytically by rev iewing each control method and showing how they mathematically corresp ond for constrained manipulator control. For stiff environments the co rrespondence is exact. However even for softer environments, a similar response of the system is indicated. Next, the results of an implemen tation of these control schemes on the CMU DD Am II are presented, con firming the predictions of the analysis. These results experimentally demonstrate that proportional gain force control and impedance control , with and without dynamics compensation, have equivalent response to commanded force trajectories.