The Output Feedback Variable Structure Control for Discrete-Time Systems with Uncertainties and Time Delay

In this paper, we propose an output feedback variable structure control for discrete-time systems with uncertainties and time-delay. The output feedback control doesnpsilat need full observability. An asymptotically stable sliding surface is designed by means of linear matrix inequality (LMI). The sliding surface can compensate for the effect of mismatched parameter uncertainties in system state. A robust sliding mode controller is designed to ensure the existence of a sliding mode and to overcome the effect of the time delay and the uncertainties of the system. For a class slowly varying system, the proposed controller regards the influence of parameter uncertainties as an equivalent disturbance and generates an on-line estimation to cancel the uncertainties by the mechanism of time delay. The controller is designed by using discrete approach law. The simulation results are offered to illustrate the effectiveness of the proposed approach.