Robust Higher Order Repetitive Controller for Disturbance Rejection and Multiplicative Uncertainty

Abstract

Conventional repetitive controller has a prominent capability for tracking any periodic reference signal or attenuating periodically distributed signal due to its infinite dimensional property and the condition for that is the period of the periodic signal should be equal to the amount of delay in RC loop. But due to this infinite dimensional property, the practical system remains unstable in higher frequency range. Small changes in the frequency and phase of input signals results in instability. This paper presents a multiloop approach to compute High-Order Repetitive Controllers (HORC) that results in delivering a robust performance in terms of stability and model uncertainty along with internal uncertainty and unstructured model uncertainty. Here, the LTI system deals with multiplicative parametric uncertainty. A novel multiple loop structure is proposed to make the system robust enough to reject disturbance signal and stable in the presence of internal uncertainty and model uncertainty. The ability of disturbance rejection of the proposed HORC is performed through MATLAB simulation. A comparative study has been carried out among RC, FDRC and HORC.