Theory and application of robust stability analysis on state space using stability radii

The robust stability analysis problem of a linear time invariant feedback system is investigated. Based on the stability radii, a set of perturbed open-loop plants and/or controllers can be found such that the closed-loop system is still stable. Also, the derived robust stability conditions are used on a linear time invariant singularly perturbed system such that a stability bound /spl epsiv/~ is obtained and conditions are determined to ensure the stability property subjected to real or complex unstructured perturbations.