Stability robustness analysis of linear time-variant systems with both time-varying structured and unstructured perturbations

The stability robustness of linear time-variant systems with both time-vary ing structured and unstructured perturbations is investigated by using the Lyapunov approach and some essential properties of matrix measures. Some ne w sufficient conditions are proposed for ensuring the linear time-variant s ystems with both time-varying structured and unstructured perturbations to be uniformly asymptotically stable. For the case that the linear time-varia nt system only subjects to time-varying structured perturbations, by mathem atical analysis, the presented sufficient conditions are proved to be less conservative than the existing ones reported in the literature. The result only for structured independent time-varying perturbations case is also ext ended to the stability analysis of time-variant interval systems.