Output feedback variable structure control for discrete-time linear systems with unmatched uncertainties

The problem of output feedback variable control of discrete-time linear systems with unmatched uncertainties is studied in this paper. The output feedback control doesnpsilat need state available and estimated state. First, the sliding surface is designed by using linear matrix inequality (LMI) technique when there exists the unmatched uncertainties. The sufficient condition for the existence of stable sliding surface is derived in terms of LMIS. Then the design of sliding mode control is presented according to the reachability condition. Finally, an illustrative example is presented to show the feasibility and effectiveness of the proposed method.