Perfect Tracking Control Method Based on Multirate Feedforward Control

Abstract

In this paper, a novel perfect tracking control method based on the multirate sampling control is proposed, in which the concept of the two-degree-of-freedom preview control is employed. In the proposed method, it is assumed that the usual single-rate robust feedback controller such as the disturbance observer or the H∞ controller already exists, and only the feedforward controller is designed by using the multirate sampling control. The advantages of the proposed method are that 1) the controller can be designed without considering the unstable zeros of the discrete-time plant, 2) the states of the plant match the desired trajectories at every sampling point, 3) high robust performance is assured by the robust feedback controller. An illustrative example of position control using a servo motor is presented, and the advantages of this approach are demonstrated.