Design and Performance Tuning of Sliding-Mode Controller for High-Speed and High-Accuracy Positioning Systems in Disturbance Observer Framework

The tuning method of controllers can be used for effectively determining the overall performance of positioning systems. In particular, this method is highly effective in the case of high-speed and high-accuracy positioning systems. In this paper, a sliding-mode controller that uses one of the well-known approaches of robust control methodology is designed for high-speed positioning systems that require a high-accuracy performance. A performance-tuning method based on a disturbance observer (DOB) structure is also proposed. First, a generalized disturbance attenuation framework named robust internal-loop compensator (RIC) is introduced, and a sliding-mode controller based on a Lyapunov redesign is analyzed in the RIC framework. Then, the DOB properties of the sliding-mode controller are presented, and it is shown that the performance of the closed-loop system with a sliding-mode controller can be tuned up by using the structural characteristics of the DOB. These results make the design of an enhanced sliding-mode controller possible. Finally, the proposed algorithm is experimentally verified and discussed with two positioning systems. Experimental results show the effectiveness and the robustness of the proposed scheme.