Pole-placement design for perturbed discrete systems with time-delay

The sufficient condition to guarantee robust pole location within a prescribed circular region for perturbed discrete time-delay systems via the dynamic output feedback controller is introduced. By the sufficient condition, the tolerable parametric perturbation bounds that ensure all the poles of perturbed discrete time-delay systems remain inside the desired disk D(e,f), centered at (e,0) with radius f<1 and |e|+ f<1, can be estimated. The stability radius of a matrix is employed to investigate the problem, and the result obtained by the presented sufficient condition is a significant improvement over the method reported by Lee et al.(1992). Finally, the authors´ result is demonstrated by an example