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Robust stability evaluation of sampled‐data control systems with a sector nonlinearity in a gain‐phase plane
Author(s) -
Okuyama Yoshifumi,
Takemori Fumiaki
Publication year - 1999
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/(sici)1099-1239(199901)9:1<15::aid-rnc389>3.0.co;2-m
Subject(s) - phase margin , nonlinear system , control theory (sociology) , nonlinear element , circle criterion , stability (learning theory) , frequency domain , automatic gain control , small gain theorem , computer science , robust control , mathematics , control (management) , exponential stability , telecommunications , artificial intelligence , amplifier , physics , operational amplifier , bandwidth (computing) , quantum mechanics , machine learning , computer vision
This paper describes a graphical evaluation of the robust stability in a frequency domain based on the results from our previous paper in which the extension of Popov's criterion to discrete‐time systems was expressed in an explicit form. The control system described herein is a sampled‐data control system with one time‐invariant nonlinear element (sector nonlinearity) in the forward path. For the purpose of application to a computer‐aided control system design (CACSD), we will present an evaluation method of the robust stability in connection with the size of sector nonlinearity and the gain margin on a gain‐phase diagram (i.e. a modified Nichols chart). We will show two results as numerical examples: one where Aizerman's conjecture was approved, and one where it was not. Copyright © 1999 John Wiley & Sons Ltd.