Robust discrete-time sliding mode control for uncertain systems with time-varying state delay

A robust discrete-time sliding mode control (DT-SMC) for uncertain linear systems with unknown time-varying state delay is analysed, in which uncertainties consist of mismatched uncertain parameters and unknown bounded nonlinear function. By using the linear matrix inequality approach, a sufficient condition for the existence of stable sliding surfaces depending on the lower and upper delay bounds is established. On the basis of this existence condition, the synthesised DT-SMC can guarantee the sliding mode reaching condition of the specified discrete-time sliding surface. Two examples verify the effectiveness of the proposed method.