Abstract
A focus of decades of research has been to develop nonlinear control strategies to compensate for unstructured terms in a dynamic model that can be bounded by constants. Both continuous and discontinuous controllers have been developed; however, these controllers are limited to certain classes of smooth nonlinear systems, contain unsaturated functions of the system’s states, and/or are prone to chattering. An open problem is the development of chatter-mitigating and saturated controllers for a wide class of dynamic models, that compensate for uncertain terms in the dynamic model. In this paper, a continuous controller, that can be used for a wide range of nonsmooth and switched systems, is developed. To enable uncertainty rejection, a sliding mode (SM) term is included in a filtered tracking error but not in the controller itself. In addition to the filtered tracking error, an adaptive estimate is developed to compensate for the unknown control effectiveness matrix in the dynamics. Furthermore, the controller is designed to be saturated to increase the feasibility of the control system. A Lyapunov-like stability analysis is performed to prove that the proposed controller yields uniform trajectory tracking to an ultimate bound.
