Proxy-based sliding mode control for accurate and safe position control

High-gain PID position control, which is widely used with industrial robots, involves some risks in cases of abnormal events, such as unexpected environment contacts and temporal power failures. This paper proposes a new position control method to achieve both accurate, responsive tracking during normal operation and smooth, overdamped recovery from a large positional error after abnormal events. The proposed method, which we call proxy-based sliding mode control, is a modified version of sliding mode control adapted to discrete-time systems, and also is an extension of PID control. The validity of the proposed method is demonstrated through experiments.