Adaptive output feedback control for a class of uncertain nonlinear systems using fuzzy logic systems

A nonlinear adaptive observer is designer based on function approximation for a class of uncertain nonlinear systems with unmeasured states. The nonlinearities are not restricted to output nonlinearities. To guarantee the boundedness of the parameter estimate error, we use the projection algorithm in the adaptive law. Based on this observer, observer backstepping method is used to design controller. Nonlinear damping terms are used to counteract the destabilizing effect of the parameter estimation errors and observation estimation errors. The overall adaptive scheme is shown to be guaranteed semiglobal uniform ultimate boundedness.