H_∞-control of robust linear systems with interval state and input delays

In this paper, H_∞-control problem of uncertain linear systems with non-coincident time-varying state and input delays is considered. Both state and input delays are assumed to be in some given intervals. Contrary to the previous works, the lower bounds of these delays are not restricted to zero. By defining a suitable augmented Lyapunov-Krasovskii functional, a new delay-dependent sufficient condition is developed in terms of linear matrix inequalities to ensure H_∞-control of the system with minimum allowable disturbance attenuation level. The effectiveness and the advantages of the proposed method are illustrated on the various numerical examples.