Approach Algorithms for Smooth Tracking with Variable Structure Controller

A design procedure is developed for obtaining smooth continuous path tracking with variable structure controller. The planned trajectories are used to construct a continuous switching curve to eliminate the undesirable reaching phase. Algorithms are proposed to specify the rate of approach to the switching surfaces such that the frequency of switching of the controller can be reduced. Smooth sliding mode behaviour is obtained and the extent of chattering is reduced. This method is applied to the path tracking problem of a position servo system. Computer simulation results confirmed the existence of sliding mode behaviour throughout the entire response.