Generalized-extended-state-observer-based Repetitive Control for DC Motor Servo System with Mismatched Disturbances

This paper presents a generalized-extended-state-observer (GESO)-based repetitive control (RC) method for a direct-current motor servo system (DCMSS) subject to parameter perturbation and load torque variation, which are mismatched. A GESO is constructed to estimate the lumped disturbance in real time fashion. Incorporating the estimate into a state-feedback RC law yields a composite controller with a dynamical compensation gain, which ensures that the suppression of the mismatched total disturbance and the tracking of periodic signal are achieved simultaneously. The stability criterion and design procedure of the system are developed. Finally, simulation results show that the GESO-RC based DCMSS effectively eliminates the influences on the output of the parameter variation and the load disturbance and has both satisfactory dynamical performance and robustness. Comparisons with conventional PID control, PID-RC, and standard extended-state-observer based RC demonstrate the superiority of this method.