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A relaxed solution to unknown input observers for state and fault estimation

Tan, Daoliang; Patton, Ron J.; Wang, Xi


Daoliang Tan

Xi Wang


A lot of effort has been devoted to the unknown input observer (UIO) research over the past years. However, the strong disturbance decoupling assumption (manifested as some rank constraint) is often implicitly embedded in much of the existing UIO work. With the purpose of state and fault estimation, this fact motivates us to investigate the viability of the UIO research when the strong disturbance decoupling is not possible, i.e., a “degenerate” problem of UIO decoupling exists. Inspired by the scheme of reducing the effect of external disturbance on estimation error, this paper incorporates the relaxed UIO (RxUIO) concept by means of the H∞H2, and mixed H2¡H∞ techniques. Necessary and sufficient conditions for the existence of different RxUIOs are presented in the tractable linear matrix inequality (LMI) form. Numerical experiments are presented to illustrate the effectiveness of the suggested method.


Tan, D., Patton, R. J., & Wang, X. (2015). A relaxed solution to unknown input observers for state and fault estimation. IFAC Proceedings Volumes/ International Federation of Automatic Control, 28(21), 1048-1053.

Journal Article Type Article
Conference Name IFAC-PapersOnLine
Acceptance Date Jul 10, 2015
Online Publication Date Oct 15, 2015
Publication Date Sep 1, 2015
Deposit Date Feb 12, 2016
Publicly Available Date Feb 12, 2016
Journal IFAC-PapersOnLine
Print ISSN 1474-6670
Electronic ISSN 2405-8963
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 28
Issue 21
Pages 1048-1053
Keywords Fault diagnosis, Fault estimation, Unknown input observer, Linear matrix inequality
Public URL
Publisher URL
Additional Information This is an authors accepted manuscript version of a paper published in IFAC-PapersOnLine, 2015, v.48 issue 21.


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Copyright Statement
© 2016 IFAC. Originally published in IFAC-PapersOnline, vol. 48, no. 21 by Elsevier Ltd. (DOI 10.1016/j.ifacol.2015.09.665)

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