Inner-loop design and analysis for hydraulic actuators, with an application to impedance control

Abstract The behaviour or manipulators equipped with hydraulic actuators is dominated by the dynamics of the hydraulics. The aim of an inner/outer loop control structure is to mask these hydraulic dynamics with an inner loop. Constructing the inner loop by using the inverse of the actuator dynamics, or by placing the poles of the actuator system, is fundamentally different. An analysis of these two options concludes that a pole placement is the best choice. First results of an actual implementation of a proposed method on an industrial hydraulic drive system, shows the practical relevance of this controller.