2004 Volume 40 Issue 5 Pages 493-501
This paper concerns a new design method of robust controllers which achieve robust stability as well as adequate disturbance rejection and tracking performance. In a previous paper, the robust PID controller has been designed for a plant which was commonly approximated by a first-order lag plus deadtime system. The PID parameters obtained by solving a two-disk type mixed sensitivity problem have been modified by contrast to those tuned by the traditional Ziegler-Nichols rule. The previous results showed that the proposed PID controller was effective enough for practical applications. In this paper we redesign a robust controller for the same plant with changes in characteristics of the plant through H∞ control theory. A practical and systematic design method for the H∞ compensator is proposed. This paper demonstrates a practical applicability of the H∞ compensator to a typical plant in process industries comparing with the control performance obtained by the robust PID controller.
