Performance Improvement of Adaptive Backstepping Output-Feedback Control for a Class of Nonlinear Plants with Unmatched Parametric Uncertainties

In the paper the problem of adaptive backstepping control of an uncertain nonlinear plant represented in the parametric output feedback canonical form is addressed. The state of the plant is not accessible for measurement and its parameters are not known. New modular backstepping state feedback design with high-order tuners recently proposed in [7], [8], [9] provides improvement of the transient performance of the closed-loop system by appropriate compensation of the deteriorating effect caused by the transients of the adjustable parameters. The main focus of the present paper is to extend the approach proposed in [7], [8], [9] to the case of output-feedback control. It is proved and demonstrated via simulation that the output-feedback adaptive controller designed accelerates the tuning of controller parameters.