On the Design and Analysis of Discrete-Time Plug- in Repetitive Controller with Three Different Internal Models

This paper presents a design strategy for a discrete-time plug-in repetitive control (RC) method using three different internal models for a class of linear minimum phase systems. The internal models are the modified internal model, the odd-harmonics internal model, and the multi-periods internal model. The RC design includes an RC internal model, which generates periodic signals, and an RC compensator, which serves as a stabilizing controller. Simulations on a servo motor plant model are conducted to evaluate the performance of the designed RCs. The results demonstrate that the modified internal model offers an excellent tracking accuracy, the odd-harmonics internal model achieves the fastest convergence, and the multi-periods internal model excels in handling complex multi-frequency references. Overall, the results show that the plug-in RC method with the three different internal models demonstrates an optimal response, each with its own advantages and disadvantages.