Auto disturbance rejection motion control for direct-drive motors

A simple and high performance auto-disturbance rejection controller (ADRC) only based on the rotor position measurement is proposed for motion control of direct-drive motors. The motion controller is consisted of a nonlinear tracking differentiator in the feedforward path, an extended-state observer (ESO) and a nonlinear proportional derivative synthesizer in the feedback path. The ESO obtains the estimated state of the plant and the unknown disturbance action at the plant input with simple computation using only the measurement output of the plant. The proposed method is implemented to control an AC direct-drive servomotor system to verify its high-precise and robustness performance.