Based on the quadratic stability theory, the robust
H∞ control problem for uncertain discrete-time systems with timedelay was deal with. The problem of robust
H∞ control with memory state feedback was discussed by linear matrix inequality approach. The sufficient condition for a robust
H∞ controller was derived. An
H∞ state feedback controller was designed and the controller could be solved by one LMI. An illustrative example was presented to prove the correctness of this method.