Adaptive output feedback high gain controller for a class of nonlinear systems

In this paper, an adaptive output feedback controller of MIMO nonlinear systems with unknown constant parameters is considered. This controller obtained by simply combining an appropriate high gain state feedback control with a high gain adaptive observer. The convergence of the later is guaranteed under certain persistent excitation condition. Furthermore, it is shown that a filtered integral action can be simply incorporated into the control design to carry out a robust compensation of step like disturbances while reducing appropriately the noise control system sensitivity. An academic adaptive tracking problem, involving a nonlinear double integrator, is addressed to show the effectiveness of the proposed control design method.