On the Design of Modified Variable Structure Repetitive Control with Fast Transient Response

A design strategy to combine modified repetitive control and variable-structure control for discrete-time linear systems with reference changes and plant uncertainties is presented in this paper. A modified repetitive control is adopted here to track/reject periodic signal and to be robust against high frequency unmodeled dynamics. Then, a variable-structure control is added to compensate the slow response of repetitive control and also to provide robustness against plant variations. Numerical simulation and comparison study are conducted to demonstrate the effectiveness of the proposed control design. Simulations results show that the proposed method is able to accurately track reference signal and to reject disturbance with fast transient response. The results also indicate that the closed-loop system remains stable in the presence of plant parameter variations.