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Peaking free output‐feedback exact tracking of uncertain nonlinear systems via dwell‐time and norm observers
Author(s) -
Oliveira Tiago Roux,
Peixoto Alessandro Jacoud,
Hsu Liu
Publication year - 2011
Publication title -
international journal of robust and nonlinear control
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.361
H-Index - 106
eISSN - 1099-1239
pISSN - 1049-8923
DOI - 10.1002/rnc.1837
Subject(s) - control theory (sociology) , differentiator , dwell time , nonlinear system , robustness (evolution) , norm (philosophy) , high gain antenna , mathematics , lyapunov function , observer (physics) , exponential stability , output feedback , computer science , control (management) , engineering , bandwidth (computing) , law , physics , medicine , computer network , clinical psychology , biochemistry , chemistry , electrical engineering , quantum mechanics , artificial intelligence , political science , gene
SUMMARY The control of uncertain nonlinear systems by high‐gain observer based output feedback is addressed. Two tracking sliding mode controllers are designed for a broad class of uncertain nonlinear systems with arbitrary relative degree and unmatched polynomial nonlinearities in the unmeasured states. The proposed strategies are based either on dwell‐time for control activation or on simple norm state observers to remove the peaking phenomenon related with high‐gain observers, depending on the nonlinearity growth conditions. In contrast with previous works, exact tracking is also achieved by means of a switching strategy based on locally exact differentiators. Global or semi‐global stability is proved by using Lyapunov theory and on small‐gain analysis. Simulations show that the proposed methodologies provide better and uniform transient behavior, larger regions of attraction, performance recovery with significantly smaller observer gains and good robustness properties with respect to exogenous disturbances and measurement noise. Copyright © 2011 John Wiley & Sons, Ltd.