IJCAS

This paper presents a super twisting observer based repetitive control (STORC), which can not only track the periodic signals precisely, but also reject aperiodic disturbances. Firstly, a stable repetitive control (RC) is designed based on the small gain theorem to track the periodic references, and compensate the periodic disturbances. Secondly, a robust exact differentiator is employed to estimate the velocity required by the disturbance observer. Finally, the super twisting observer (STO) is constructed to reject aperiodic disturbances, and input unmatched periodic disturbances with reduced chattering. The stability analysis is conducted and the design conditions are derived for a stable system. The proposed algorithm is simulated in MATLAB Simulink, and verified on a brushless DC servo motor in real time to demonstrate the effectiveness. The comparison studies highlight the advantages of the proposed algorithm."

Keywords: Disturbance observer, periodic reference, repetitive control, super twisting observer.