Abstract
In this paper, a robust adaptive control scheme is proposed to reduce the effect of harmonic disturbances in feed drive systems. Harmonic forces are one of the most common disturbances in machine tools. They are generated, for instance, due the external cutting forces in milling or internally by the servo structure itself such as torque ripples of the motor and gear mechanism. If these sinusoidal disturbances could not be rejected by the feedback control, tracking performance of the drive system would be degraded. Hence, an adaptive torque ripple compensation technique is developed in this research, which can track the amplitude and phase of the sinusoidal disturbance forces synchronized with the servo position. A suppression signal is then generated to reject the specific frequency of the disturbances. In conjunction with the ripple compensator, a robust feedback controller is designed employing the variable structure control framework. Both, controller stability and the adaptation convergence are proven using the Lyapunov theory. The proposed controller is applied to various servo systems and its performance is verified.
