A variable structure controller with adaptive switching surfaces [brushless DC motor]

A servo system with a variable structure controller (VSC) operating in the sliding mode is robust to disturbances. This advantage may not be obtained during the reaching phase. The authors propose to reduce the reaching phase duration by adapting the components of the gradient vector of the switching hypersurface to the inverse of the tracking error. The effectiveness of this method is illustrated by simulation results from a brushless DC motor velocity tracking system.