Comment

This note presents some comments and further results concerning the descriptor system approach to H? control of linear time-delay systems. Upon the system model of the paper by Fridman and Shaked, we propose a new iterative state-feedback controller design procedure, which is based on a new bounded real lemma derived upon an inequality recently proposed by Moon. The proposed design solves both the instantaneous and delayed feedback problems in a unified framework, and is illustrated by a numerical example to be much less conservative than the above paper and other relevant references.