D-stability analysis for discrete systems with a time delay

This paper first discusses the D-pole placement problem of discrete time-delay systems. Some criteria are proposed to ensure that all the closed-loop eigenvalues of discrete systems with a time delay are located inside a specific disk D(α, r) centered at (α, 0) with radius r. Then, several sufficient conditions for guaranteeing the D-stability of discrete time-delay systems subjected to parametric perturbations are presented. Both unstructured and highly structured parametric perturbations are considered. By these sufficient conditions, the tolerable parametric perturbation bounds that ensure all the closed-loop poles of discrete time-delay perturbed systems to remain inside the desired disk D(α, r) can be estimated. Finally, illustrative examples are given for demonstration.