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Digital redesign of analog controllers based on minimizing integral of squared errors
Author(s) -
Hwang Chyi,
Chang FangPi,
Hwang JyhHaur
Publication year - 2003
Publication title -
optimal control applications and methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.458
H-Index - 44
eISSN - 1099-1514
pISSN - 0143-2087
DOI - 10.1002/oca.716
Subject(s) - discretization , controller (irrigation) , digital control , control theory (sociology) , parametric statistics , sampling (signal processing) , computer science , expression (computer science) , range (aeronautics) , discretization error , optimal control , mathematical optimization , mathematics , control (management) , engineering , electronic engineering , artificial intelligence , mathematical analysis , statistics , filter (signal processing) , aerospace engineering , agronomy , computer vision , biology , programming language
Digital redesign is to replace an existing well‐designed analog feedback controller by a digital one along with a sampler and a hold. In this paper, we present a digital redesign technique which takes into account both closed‐loop and intersample behaviour. More precisely, we give a numerical procedure to optimally discretize an analog controller such that the integral of the squared error between the closed‐loop step responses of the analog and digital controlled systems is minimized. A parametric expression is derived for evaluating the integral performance index. With this expression, the optimal digital redesign problem becomes an optimal parameter selection problem which can be solved using existing optimal parameter search algorithms. Moreover, it allows one to obtain optimal reduced‐order digital controllers for sampled‐data control systems over a range of sampling periods. Copyright © 2003 John Wiley & Sons, Ltd.