Global practical tracking by output-feedback for nonlinear systems with unknown growth rate

Abstract

This paper is devoted to the global practical tracking by output-feedback for a class of uncertain nonlinear systems with only the tracking error measurable. Different from the closely related works, the systems have unmeasured states dependent growth with unknown constant rate, and the reference signal, as well as its first order derivative, has unknown bound. Mainly because of these, the tracking problem can hardly be solved by straightforwardly extending the existing results. In the paper, motivated by the related stabilization results, and flexibly using the ideas of universal control and dead zone, an adaptive output-feedback controller is designed to make the tracking error prescribed arbitrarily small after a finite time while keeping all the states of the closed-loop system bounded. A numerical example demonstrates the effectiveness of the theoretical results.

Global Practical Output Tracking of Inherently Nonlinear Systems Using Continuously Differentiable Controllers

“…Next, we will present several useful lemmas borrowed from [4,13,14,19], which will play an important role in our later controller design.…”

“…. , , system (1) reduces to the well-known feedback linearizable form, for which numerous design methodologies are developed; see [1][2][3][4][5] and the references therein. For the case that any one of the powers ( = 1, 2, .…”

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

“…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.…”

“…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.…”

“…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. On the other hand, control coefficients are precisely known in [2,4], and unknown in [1,5].…”