A flat-zone modification for robust adaptive control of nonlinear output feedback systems with unknown high-frequency gains

Author

Ding, Zhengtao ; Ye, Xudong

Author_Institution

Dept. of Mech. Eng., Ngee Ann Polytech., Singapore, Singapore

Volume

47

Issue

2

fYear

2002

fDate

2/1/2002 12:00:00 AM

Firstpage

358

Lastpage

363

Abstract

This note deals with adaptive control of perturbed nonlinear output feedback systems with unknown high-frequency gains. The disturbances in the systems are assumed to be bounded, but the bounds are unknown. A flat-zone modification is proposed to incorporate both the bound estimation and Nussbaum gain design in the nonlinear adaptive control. To ensure the differentiability of stabilizing functions needed for backstepping design, high order terms are introduced in the Lyapunov function candidate with a flat zone around the neighborhood of the origin. The output tracking error converges to an arbitrarily small interval around zero

Keywords

Lyapunov methods; adaptive control; convergence; feedback; nonlinear control systems; robust control; uncertain systems; Lyapunov function; Nussbaum gain design; backstepping design; bound estimation; flat-zone modification; high-order terms; nonlinear adaptive control; output tracking error convergence; perturbed nonlinear output feedback systems; robust adaptive control; stabilizing function differentiability; unknown high-frequency gains; Adaptive control; Automatic control; Backstepping; Control system synthesis; Control systems; Design optimization; Linear systems; Output feedback; Robust control; Transfer functions;

fLanguage

English

Journal_Title

Automatic Control, IEEE Transactions on

Publisher

ieee

ISSN

0018-9286

Type

jour

DOI

10.1109/9.983380

Filename

983380