An LMI approach to H∞ controller design for linear time-delay systems

We develop an output feedback H, control design method for linear time-delay systems based on the linear-matrix-inequality (LMI) approach. A sufficient condition for the existence of H, controllers of any order is given in terms of three LMIs. The condition is valid for both singular and regular problems. We also give a characterization of H, controllers in state space. The LMI existence condition can be easily determined whether or not, it is feasible and if it is then one can easily obtain H, controller gain matrices via convex optimization.