Adaptive output-feedback tracking control for uncertain nonlinear systems

The robust adaptive output-feedback control is considered in this paper for uncertain nonlinear systems with unknown parameters. At first, a filter of steady state is constructed and the real-time state is estimated, and then the adaptive output-feedback tracker is constructively designed. It is proved that the designed tracker is robust to the uncertainties of both the unknown parameter and the system state. Those results have guaranteed the global stability of resulting closed loop systems and have solved the ε-tracking problem. Meanwhile, it is also proved that the tracking error tends to "steady-state" at the negative exponential attenuating rate. Simulation show that the tracking effects of designed robust adaptive tracker are good, and the control quantities used on the spot are within the range of the admissible control.