On the Perturbations of Regular Linear Systems and Linear Systems with State and Output Delays

This paper is concerned with perturbation problems of regularity linear systems. Two types of perturbation results are proved: (i) the perturbed system (A + P,B,C) generates a regular linear system provided both (A,B,C) and (A,B, P ) generate regular linear systems; and (ii) the perturbed system ((A−1 +ΔA)|X , B,C Λ ) generates a regular linear system if both (A,B,C) and (A,ΔA,C) generate regular linear systems. These allow us to establish a new variation of constants formula of the control system (A + P,B). Moreover, these results are applied to the linear systems with state and output delays. The regularity and the mild expressibility is deduced, and a necessary and sufficient condition for stabilizability of the delayed systems is proved. Mathematics Subject Classification (2010). Primary 47A55; Secondary 93C23.