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Analytical design of multiloop PID controllers for desired closed‐loop responses
Author(s) -
Lee Moonyong,
Lee Kihong,
Kim Changgeun,
Lee Jietae
Publication year - 2004
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.10166
Subject(s) - engineering , library science , computer science
Most chemical processes are basically multiple input/multiple output (MIMO) systems. Despite considerablework on advanced multivariable controllers for MIMO sys-tems, multiloop proportional-integral-derivative (PID) con-trollers remain the standard for many industries because oftheir adequate performance with most simple, failure toler-ant, and easy to understand structure. In a multiloop system,once a control structure is xed, control performance is thendetermined mainly by tuning each multiple single-loop PIDcontroller. However, because the interactions that exist be-tween the control loops make the proper tuning of themultiloop PID controllers quite difcult, only a relativelyfew tuning methods are available to the multiloop PIDcontrollers and most of them require nonanalytical formswith complex iterative steps (Loh et al., 1993; Luyben,1986; Skogestad and Morari, 1989). The analytical tuningrule is very attractive, with respect to its practicality, but themathematical complexity attributed to the loop interactionshas mainly prevented the analytical approach to the mul-tiloop systems.In this article, we propose an analytical design method forthe multiloop PID controllers to give desired closed-loopresponses by extending the generalized IMC–PID methodfor single input/single output (SISO) systems (Lee et al.,1998) to MIMO systems. Simple but efcient tuning rulesare obtained for general process models by using the fre-quency-dependent property of the closed-loop interactions.