Predictive extended state observer-based repetitive controller for uncertain systems with input delay

This article presents a predictive extended state observer-based repetitive controller (PESO-RC) to simultaneously track and reject periodic signals on systems with long input delay and parameter uncertainties. First, a novel extended state observer (ESO) is proposed to tackle periodic signals on processes with input delay. Then a simple low pass filter is incorporated and tuned to improve robustness against modelling errors. Moreover, the modified repetitive controller (MRC) is integrated to enhance the performance when compensating periodic signals without affecting the overall system’s stability. Stability criteria and robust stability analysis under modelling errors are studied to develop tuning guidelines. Furthermore, validation of the proposed controller and comparison studies are simulated in MATLAB and tested on a brushless DC servo motor which highlight the superior performance of PESO-RC

Sliding mode based repetitive control for improved reference tracking

A sliding mode based repetitive control system is proposed, to improve reference tracking performance, as well as compensate output disturbances. The design algorithm is based on the concept of sliding mode controller (SMC), feedback controller, and modified repetitive controller (MRC). With two tuning parameters, the sliding mode based RC provides a simple and convenient method to solve the complex engineering problems. The comparison study was conducted to demonstrate the effectiveness of sliding mode based RC over state feedback based RC