Relay autotuning: an overview and alternative approach

Atherton, Derek P (2006) Relay autotuning: an overview and alternative approach. Industrial and Engineering Chemistry Research, 45 (12). pp. 4075-4080. ISSN 0888-5885

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This paper discusses the use of relay-produced limit cycles for selecting the parameters of fixed controllers, with particular reference to the proportional−integral−derivative (PID) controller. This work shows how the current ideas relate to the early work of Ziegler and Nichols, particularly their loop cycling test. The evaluation of limit cycles in relay feedback systems is discussed, and details of their possibilities for determining parameters of an assumed plant transfer function or the value of the plant critical point are given. To conclude, it is shown how the approximate value of points on the plant frequency response locus can be determined from using the relay in parallel with the controller, which can be done without opening the control loop.

Item Type: Article
Additional Information: The paper was invited for a special edition on relay autotuning of PID controllers. The paper first reviews the loop cycling method and exact methods for finding limit cycles in relay feedback systems, on which the author is an acknowledge world leader (see his 1975 book). One disadvantage of the autotuning method, suggested by Astrom, is that the loop must be opened to convert the controller to a relay. The paper then presents a new contribution showing how this can be avoided by obtaining results for a limit cycle when the relay is placed in parallel with the controller.
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Depositing User: Derek Atherton
Date Deposited: 06 Feb 2012 21:08
Last Modified: 17 Jul 2012 09:02
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