Anti-Windup Control using Saturated State Observer

Abstract

Windup phenomena is usually observed in servo systems where the controller has integral term, when the control input is saturated due to the actuator's limited capacity. To avoid this problem, anti-windup (AW) controls have been proposed. However, they do not have enough AW performance due to the instability problem. In this paper, we clarify the stability condition. Most of the conventional methods are just to stop integration when the actuator is saturated. Such methods can not be applicable to higher order servo controllers, for example, those which are designed by H_∞ optimum control theory. To solve this problem, we propose a novel AW control strategy based on the saturated state observer, and show its effectiveness by simulation and experiment.