Adaptive output feedback tracking control for a class of uncertain switched nonlinear systems

Abstract

This paper deals with the global output feedback tracking control problem for a class of switched nonlinear systems involving unknown parameters and unmeasured states multiplied by output nonlinearities. The switching information is assumed to be unobservable. To approach this purpose, a modified high-gain observer is introduced, and then an adaptive output feedback controller is constructed by adopting the adaptive backstepping technique. It is shown that, under arbitrary switching the proposed controller can guarantee all signals of the closed-loop system are globally uniformly bounded and the tracking error converges to a residual set that can be made arbitrarily small by properly selecting the design parameters. Simulation results are presented to verify the effectiveness of the proposed approach.

Global output-feedback tracking for nonlinear cascade systems with unknown growth rate and control coefficients

“…Detailedly, compared with [3], Assumption 1 is apparently weaker, Assumption 2 shows that system (1) permits unknown relative degree and lower-order growing unmeasurable states, and Assumption 4 indicates that rather coarser information is required on the reference signal to be tracked. Unlike [1,4,5], Assumptions 2 and 4 imply that there is no known function or constant to dominate the nonlinearities of the η-subsystem and the reference signal and its derivative. Although [2] studied the case of unknown constant growth rate, it excludes zero-dynamics and unknown/time-varying control coefficients, and hence Assumptions 1-4 make the systems in [2] be a special case of this paper.…”

“…Quite differently, in [2], the system growth rate is an unknown constant, and the reference signal cannot be dominated by any known constant. On the other hand, control coefficients are precisely known in [2,4], and unknown in [1,5]. It is worth mentioning that in [1,2,4,5], the systems exclude zero-dynamics and time-varying control coefficients.…”

“…On the other hand, control coefficients are precisely known in [2,4], and unknown in [1,5]. It is worth mentioning that in [1,2,4,5], the systems exclude zero-dynamics and time-varying control coefficients. Although [3] considered the systems with zero-dynamics and the upper bound of the control coefficient is not necessarily known, more restrictions are needed on the system and the reference signal.…”

“…Particularly, [1][2][3][4][5] studied various nonlinear systems with unmeasured states dependent growth and proposed effective output-feedback tracking control design schemes. In [4,5] and [1], the system growth rate is a known constant and a known polynomial of output, respectively, and the reference signal to be tracked belongs to a known finite interval. Quite differently, in [2], the system growth rate is an unknown constant, and the reference signal cannot be dominated by any known constant.…”

“…Practical tracking control has received much attention over the last two decades for nonlinear systems, see, e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13]. Particularly, [1][2][3][4][5] studied various nonlinear systems with unmeasured states dependent growth and proposed effective output-feedback tracking control design schemes.…”