ROBUST EXPONENTIAL STABILITY OF TIME-VARYING LINEAR-SYSTEMS

This paper investigates the robustness of time-varying linear systems under a large class of complex time-varying perturbations. Previous results8 which were restricted to bounded linear perturbations of output feedback type are generalized to unbounded and nonlinear perturbations of multi-output feedback type. We establish a lower bound for the stability radius of these systems and show how it may be possible to improve the bound using time-varying scalar transformations of the state, input and output variables. The results are applied to derive Gershgorin type stability criteria for time-varying linear systems.