Asymptotic Tracking for Systems with Structured and Unstructured Uncertainties

The control of systems with uncertain nonlinear dynamics has been a decades long mainstream area of focus. The general trend for previous control strategies developed for uncertain nonlinear systems is that the more unstructured the system uncertainty, the more control effort (i.e., high gain or high frequency feedback) is required to reject the uncertainty, and the resulting stability and performance of the system is diminished (e.g., uniformly ultimately bounded stability). This paper is the first result that illustrates how the amalgamation of an adaptive model-based feedforward term with a high gain integral feedback term can be used to yield an asymptotic tracking result for systems that have mixed unstructured and structured uncertainties