Time domain design of PI-C controllers

Abstract PI-C (Proportional-Integral-Compensating) controllers are observer-based compensators with integral action containing an inverse model of the plant. Originally developed for windup prevention in case of sensor saturation they are also useful in the presence of actuator saturation. They allow to achieve a nearly perfect disturbance attenuation while the loop gain satisfies the Circle Criterion. It has also been demonstrated that PI-C controllers can solve the windup problem in case of joint input and output saturation. The design of PI-C controllers has only been formulated in the frequency domain so far which, in the MIMO case, requires the manipulation of polynomial matrices. Here, the state-space design of PI-C controllers is presented.