SUMMARYThis paper investigates the problem of adaptive stabilization by output feedback for a class of uncertain nonlinear systems. The distinguishing feature of such a class of systems is the presence of uncertain control coefficient and unmeasured states dependent growth with growth rate of polynomial-of-output multiplying an unknown constant. First, new high-gain K-filters with two dynamic gains are introduced, and an appropriate state observer is constructed based on the K-filters. Then, motivated by the universal control idea, the backstepping scheme is successfully developed for the adaptive output feedback control design. By appropriate choice of the design parameters, the global stability of the closed-loop system can be guaranteed. Finally, numerical simulations are provided to illustrate the correctness of the theoretical results.

This paper is concerned with the problem of global adaptive stabilization by output feedback for a class of planar nonlinear systems with uncertain control coefficient and unknown growth rate. The control coefficient is not supposed to have known upper bound, and this relaxes the corresponding requirement in the existing literature (see e.g. 1, 2. First, by the universal control method, an observer is constructed based on the dynamic high‐gain K‐filters. Then, the control design procedure is developed to obtain the stabilizing controller and dynamic compensator for the uncertainties in the control coefficient. It is shown that the global stability of the closed‐loop system can be guaranteed by the appropriate choice of the design parameters. A simulation example is also provided to illustrate the correctness of the theoretical results. © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.

This paper investigates the problem of adaptive practical tracking control by output feedback for a class of nonlinear systems in which the nonlinearities are restricted to be upper bounded by a constant plus a polynomial function of the output multiplied by unmeasured states. To solve the problem, an observer with a dynamic high-gain is first introduced, and then an adaptive output feedback tracking controller is successfully designed using the universal control methodology. It is shown that all the states of the closed-loop system are bounded, and the tracking error can be made arbitrarily small by an appropriate choice of the design parameters after some large enough time. A simulation example is also provided to illustrate the correctness of the theoretical results.

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