Robust Adaptive Control Revisited: Semi-global Boundedness and Margins

Abstract

While stability of adaptive control systems and their robustness to disturbances, unmodeled dynamics, and time-delays have been extensively analyzed in the literature, what is missing is the development of quantifiable margins that explicitly define the extent of these perturbations that the adaptive controller can withstand. In this paper, a first attempt is made to quantify robustness of adaptive controllers to time-delays, unmodeled dynamics, and state-dependent nonlinearities. Formal stability margin analysis is conducted and the theoretical predictions are validated using high performance aircraft flight simulation environment.