Fuzzy adaptive observer and filter backsteppping control for nonlinear systems

In this paper, a new fuzzy adaptive control approach is developed for a class of SISO nonlinear systems with unmeasured states. Using fuzzy logic systems to approximate the unknown nonlinear functions, a fuzzy adaptive observer based on filters is introduced for state estimation as well as system identification. Under the framework of the backstepping design, fuzzy adaptive output feedback control is constructed recursively. By theoretical analysis, all the closed-loop signals are semi-globally uniformly ultimately bounded, and the tracking errors are proved to converge to a small residual set around the origin.