ROBUST STABILITY OF DISCRETE-TIME-SYSTEMS UNDER PARAMETRIC PERTURBATIONS

Stability robustness analysis of a system under parametric perturbatio ns is concerned with characterizing a region in the parameter space in which the system remains stable. In this paper, two methods are prese nted to estimate the stability robustness region of a linear, time-inv ariant, discrete-time system under multiparameter additive perturbatio ns. An inherent difficulty, which originates from the nonlinear appear ance of the perturbation parameters in the inequalities defining the r obustness region, is resolved by transforming the problem to stability of a higher order continuous-time system. This allows for application of the available results on stability robustness of continuous-time s ystems to discrete-time systems. The results are also applied to stabi lity analysis of discrete-time interconnected systems, where the inter connections are treated as perturbations on decoupled stable subsystem s.