A new approach to delay-dependent state-feedback H∞ control of time-delay systems

New delay-dependent bounded real criteria are derived for linear continuous-time retarded and neutral type systems. A sufficient condition for the system to possess a H_∞-norm that is less than a prescribed level, is given in terms of a linear matrix inequality (LMI). A delay-dependent solution is obtained by using a descriptor model transformation of the system and by applying Park´s inequality for bounding cross terms. The proposed criteria are less conservative than other existing criteria since they are based on a new model tranformation that is equivalent to the original system and since they require bounds for fewer terms. We apply the new bounded real criteria to state-feedback H_∞ control problem.