Feedback frameworks for active suspensions with electrohydraulic actuator dynamics

Since the initial conception in the late 1960's, the field of active suspensions for automotive applications has seen numerous research investigations. While there has been a wealth of information previously published, relatively few of these works have incorporated the dynamics of the actuator in their analysis. Including the electrohydraulic actuator dynamics with the plant model introduces the additional effects of the coupling between the actuator and the vehicle body motion. Controller designs using the linearized actuator dynamics typically use a tracking framework. Electrohydraulic systems are limited in their ability to do force or position tracking control when interacting with an environment possessing dynamics such as the 1/4 car model. This paper introduces a novel framework that includes electrohydraulic actuator dynamics in which the tracking problem is replaced by a properly posed regulation problem. Both force regulation and position regulation frameworks are considered and the relative merits/drawbacks of each presented.