Perturbation bounds for root-clustering of linear systems in aspecified second order subregion

Sufficient bounds for structured and unstructured uncertainties for root-clustering in a specified second order subregion of the complex plane, for both continuous-time and discrete-time systems, are given using the generalized Lyapunov theory. Furthermore, for unstructured uncertainties, a still less conservative result is obtained by shifting the center or focus of the subregion along the real axis to the origin and by applying root-clustering to the “shifted eigenvalue” system matrix, which is obtained by shifting the eigenvalues of the system matrix correspondingly