Journal ArticleDOI
Automatic tuning of systems with one or two unstable poles
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TLDR
In this paper, two limit points of conditional stability are characterized using closed-loop dynamics with a relay and a novel nonlinear element, and an easily tuned cascade PID control structure is then proposed to stabilize the system and achieve desirable performance.Abstract:
Stabilizability and identification of systems with one or two unstable poles is addressed. Two limit points of conditional stability are characterized using closed-loop dynamics with a relay and a novel nonlinear element. An algorithm is developed to analyze information from the resultant stable limit cycles in the process input and output. An easily tuned cascade PID control structure is then proposed to stabilize the system and achieve desirable performance. The proposed autotuning technique is tested with good results on a wide variety of unstable systems.read more
Citations
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Journal ArticleDOI
Brief Identification and control of open-loop unstable processes by relay methods
TL;DR: An overview of the automatic PID tuning method, states conditions that need to be satisfied for its successful implementation, and demonstrates its application on a number of examples are provided.
Journal ArticleDOI
Identification of integrating and unstable processes from relay feedback
Tao Liu,Furong Gao +1 more
TL;DR: In this paper, the exact relay response expressions are derived for integrating and unstable 1st or 2nd order processes and identification algorithms are developed in terms of the measurable parameters under relay feedback and fitting conditions of the limit cycle.
Journal ArticleDOI
Closed-loop step response identification of integrating and unstable processes
Tao Liu,Furong Gao +1 more
TL;DR: In this article, a closed-loop identification method based on step response test is proposed to facilitate closedloop system operation and on-line optimization, and three model identification algorithms are derived analytically in frequency domain to obtain the widely used low-order process models of first-order plus dead time (FOPDT) and second-order-plus-dead-time (SOPDT).
Journal ArticleDOI
Identification and Control for Unstable Processes of Three Dynamic Types
Lih Wei Wang,Shyh Hong Hwang +1 more
TL;DR: In this paper, the authors classify the process dynamics involving one or two unstable poles into three types, which are of paramount importance in controller design: gain and relay stabilizability of such dynamics.
Journal ArticleDOI
Improved Relay Auto-Tuning of PID Controllers for Unstable SOPTD Systems
Saxena Nikita,M. Chidambaram +1 more
TL;DR: In this article, an improved analysis of the relay auto-tuning method is proposed to calculate the maximum value of the controller gain by considering the higher-order harmonics, which gives enhanced closed-loop performances in all the cases.
References
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Book
Applied Nonlinear Control
TL;DR: Covers in a progressive fashion a number of analysis tools and design techniques directly applicable to nonlinear control problems in high performance systems (in aerospace, robotics and automotive areas).
Journal ArticleDOI
Paper: Automatic tuning of simple regulators with specifications on phase and amplitude margins
Karl Johan Åström,Tore Hägglund +1 more
TL;DR: A simple method for estimating the critical gain and the critical frequency is described, which may be used for automatic tuning of simple regulators as well as initialization of more complicated adaptive regulators.
Journal ArticleDOI
Automatic Tuning of Simple Regulators
Karl Johan Åström,Tore Hägglund +1 more
TL;DR: This paper proposes methods for automatic tuning of slmple regulators that will give a solution to the longstanding problem of safe Initialization of more sophisticated adaptive controllers.
Journal ArticleDOI
Controllers of Ziegler-Nichols type for unstable process with time delay
Annraoi M. de Paor,Mark O'Malley +1 more
TL;DR: In this paper, a time-delayed process with a single right half-plane pole at s = ε is designed for proportional (P), proportional plus integral (PI), and proportional plus plus integral plus derivative (PID) controllers, and an optimum stability approach for PI controllers is based on a parameter plane study.
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