Delay-dependent H∞ control of linear systems with input delay using composite state-derivative feedback

H_∞ control problem for input-delayed systems is considered in this paper. A composite state-derivative control law is used, in which, a composition of the state variables and their derivatives appear in the control law. Thus, the resulting closed-loop system turns into a specific time-delay system of neutral type. The significant specification of this neutral system is that its delayed term coefficients depend on the control law parameters. This condition provides new challenging issues which has its own merits in theoretical research as well as application aspects. New delay-dependent sufficient condition for the existence of H_∞ controller in terms of matrix inequalities is derived in the present paper. The resulting H_∞ controller guarantees asymptotic stability of the closed-loop system as well as a guaranteed limited H_∞ norm smaller than a prescribed level. Numerical examples are presented to illustrate the effectiveness of the proposed methods.