Abstract: The online detection for roundness and cylindricity of heavy axle housings poses significant challenge to accuracy, smoothness and robustness of the rotational motion control for the servo motor. Aiming at improving the measurement accuracy, this paper develops a parallel PID control method on top of the electromechanical coupling dynamical modeling of the servo system, where three-loop controllers of position, velocity and current feedback are adopted. The controller parameters are further tuned according to the phase margin and the dominant pole configuration, such that the controller can effectively apply to practical industrial sites. The effectiveness of the proposed control architecture is further verified by real time experiments on a self -constructed axle housings online detection system, where accurate uniform motion with good smoothness and robustness are demonstrated. The proposed control method can significant improve the measurement accuracy of the axle housing detection device.