Compound Controller for DC Motor Servo System Based on Inner-Loop Extended State Observer

As DC motor servo systems are more and more widely applied in the manufacturing industry and aerospace domain, the requirements on control performance are increased by the complicated various working environments. With regard to the uncertainties including modeling error, parameter variations and external disturbances in DC motor servo system, one Nonlinear Extended Disturbance Observer (NESO) is constructed, and its output will be used as the design reference of disturbance compensation term in control system. Based on the as-built NESO in inner loop, one outer-loop compound controller by means of state-space design method is proposed in order to realize the high-precision position tracking ability of the servo system. Computer simulation results show that compared with conventional control schemes, the proposed control scheme can guarantee fewer tracking errors of DC motor servo system. Moreover, it possesses stronger robustness against system uncertainties including modeling error, parameter variations and friction moment disturbance.