Abstract: To reduce the contour error of the part machine, for the linear servo drive system, a robust tracking control strategy based on combining zero phase error tracking control (ZPETC) with the disturbance observer (DOB) is proposed. The zero phase error tracking controller is designed to ensure that the system has fast tracking performance and implements exactly tracking; while the DOB can overcome the influences of the uncertainties of the parameters perturbation, the external load disturbances, unmod-elled dynamic and mechanical nonlinearity etc. DOB can com-pensate for each axis according to predicted disturbance information to eliminate the influences of the disturbance to the system, thus the stability and robustness of the system are obtained. The simulation results show that the control scheme not only can enhance the fast tracking performance in the linear servo system, but also has a strong robustness to parametric variations and resistance disturbances. Therefore the contour error is reduced effectively, and the precision of the contour machining is improved greatly.

Key words: Contouring control, Disturbance observer, Linear servo Zero phase error tracking control Tracking control