DocumentCode :
1103819
Title :
Fragility problem revisited: overview and reformulation
Author :
Moreira, M.V. ; Basilio, J.C.
Author_Institution :
Univ. Fed. do Rio de Janeiro, Rio de Janeiro
Volume :
1
Issue :
5
fYear :
2007
Firstpage :
1496
Lastpage :
1503
Abstract :
In a debate paper, Keel and Bhattacharyya have suggested, by means of simple examples taken from the open literature, that optimal and robust controllers can be fragile in the sense that a minute perturbation in the controller parameters can make the closed-loop system unstable. However, is it true that the optimal and robust controllers presented by Keel and Bhattacharyya are actually fragile? It is demonstrated that the particular parametric stability margin used by Keel and Bhattacharyya can be very conservative and to overcome this problem, two non-conservative measures of controller fragility are proposed. In addition, it will be shown that the examples in Keel and Bhattacharyya´s paper are very special and the resulting fragility cannot be linked to the Hinfin optimisation but to non-appropriate Hinfin optimisation criterions and to bad choice of weights.
Keywords :
closed loop systems; optimal control; optimisation; perturbation techniques; robust control; closed-loop system; controller fragility; controller parameter; fragile optimal controller; fragile robust controller; fragility problem; minute perturbation; optimisation criterion; parametric stability;
fLanguage :
English
Journal_Title :
Control Theory & Applications, IET
Publisher :
iet
ISSN :
1751-8644
Type :
jour
DOI :
10.1049/iet-cta:20060473
Filename :
4293157
Link To Document :
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