Design of a robust discrete time sliding mode repetitive controller

This paper presents the design of a robust discrete-time sliding mode repetitive controller (DSMRC) which combines the features of repetitive control (RC) and sliding mode control (SMC) to achieve fast transient response, improved robustness to various matched uncertainties, and improved steady state performance. The new control structure consists of a repetitive control component and a sliding mode control part. The task of the sliding mode component is to provide a fast dynamic response and improve the robustness of the system against various uncertainties. The repetitive control part is added to the system to reduce the periodic error and improve the steady state performance of the system. A small pure phase lead component is added to the RC structure to ensure system stability and achieve high bandwidth tracking performance in the presence of bounded uncertainties. The proposed control structure is applied to a linear actuator (LA) system subjected to payload variations. A detailed analysis of the new control structure is presented in this paper to show the significance of the proposed scheme. Simulation results verify the effectiveness of the proposed method.