Robustness of servo drive system under position control mode based on sliding mode controller

In various control strategies of servo drive system, PI controllers are still used due to their simplicity and ease of design. Unfortunately, PID controllers are not robust and their performance is deteriorated when the operating conditions change due to parameter variations of the motor. A position control method of servo motor based on sliding mode controller (SMC) is proposed in this paper, for improving the robustness, realizing precision positioning, and reducing the steady-state speed error of servo motor. Meanwhile, the SMC relieves low speed crawling phenomenon effectively for servo drive system. The experimental results indicate that robustness of the servo system has been improved significantly, and the dynamic and static performance is better under SMC when motor parameter mismatch. Moreover, low speed crawling phenomenon is also restrained, the method is feasible and effective.