On Immediate, Delayed and Anticipatory Activation of Anti-Windup Mechanism: Static Anti-Windup Case

This technical note examines the immediate, delayed and anticipatory activation of anti-windup mechanism. Traditional anti-windup compensators are designed for immediate activation. A recent innovation is to delay the activation of the anti-windup mechanism until the degree of saturation reaches to a certain level. By allowing the nominal controller to function undisturbed in the face of modest actuator saturation, delayed activation of the anti-windup mechanism has been shown to lead to improvement in the closed-loop performance. In this technical note, we propose to activate the static anti-windup compensation in anticipation of actuator saturation and show that such a “precautionary” approach has the potential of leading to further improvement in the closed-loop performance, in terms of both the transient quality in reference tracking and the region of stability.