ADAPTIVE APPROXIMATE VARIABLE STRUCTURE CONTROL FOR A CLASS OF UNCERTAIN TIME DELAY SYSTEMS

The synthesis problem for a class of uncertain time-delay systems with unknown upper norms of uncertainties is studied in this paper. First, the proper switching function is chosen such that the obtained equivalent sliding-mode motion is stable. Then, the normal variable structure controller(VSC) and the adaptive variable structure controller with the estimation for the upper norms of uncertainties are presented. Furthermore, the modified controllers are proposed to avoid from the chatting phenomenon in VSC.