Robust tracking control of AC servo system including a ball screw

This paper investigates the problem of position tracking for the servo system consisting of a permanent magnet synchronous motor and a ball screw. The objective is to design a suitable robust controller, guaranteeing the servo system can track object position smoothly without error. The method proposed in this paper is based on the vector control principle of a alternating current motor combined with mechanics laws of a ball screw and a new relative dynamic model is developed; then a robust position tracking control problem is formulated. By the Lyapunov approach, the existence conditions for a admissible controller are formulated employing convex optimization approach, and the controller design is cast into a asymptotically stable problem subject to several constraints. With the obtained controller, the position tracking problem can be completed with anticipant transient and stable performance. An illustrative example is provided to show the effectiveness of the proposed controller design method.