Robust Adaptive Stabilization of Switched Higher-Order Planar Nonlinear Systems with Unknown Time-Varying Delays

Abstract

This paper addresses robust adaptive stabilization of uncertain switched time-delay systems with unknown disturbances in a high-order form. In addition to parametric uncertainty, an extra source of uncertainty arises from having time-varying delays. In particular, the upper bound of the changing rate of the delay is assumed to be unknown. To this purpose, a new reparametrization method is proposed, which incorporates both sources of uncertainty in a single scalar parameter. Therefore, a single scalar adaptive law is designed for parametric uncertainties and time-varying delays, which is combined with a new dynamic gain embedded in the control action. The new dynamic gain is designed to dominate the nonlinear effects caused by both the parametric uncertainty and the unknown variation of the time delay. The proposed design guarantees global asymptotic stability for arbitrary switching. A numerical example illustrates the effectiveness of the method.