Output feedback controller for a class of nonlinear systems

This paper deals with an observer based output feedback controller for a class of controllable and observable nonlinear systems with an admissible tracking capability. Two fundamental features are worth to be mentioned. The first one consists in the high gain nature of the underlying state feedback control and observer designs. More specifically, a unified high gain control design framework is proposed thanks to the duality between control and observation. The second feature consists in incorporating a filtered integral action into the control design. The filtering is mainly motivated by measurement noise sensitivity reduction while the integral action allows to achieve a robust offset free performance in the presence of step like disturbances. An academic servo problem, involving a nonlinear double integrator, is addressed to show the effectiveness of the proposed control design method.