{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,18]],"date-time":"2025-11-18T09:30:09Z","timestamp":1763458209597,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2023,1,31]],"date-time":"2023-01-31T00:00:00Z","timestamp":1675123200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Slovenian Research Agency","award":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"],"award-info":[{"award-number":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"]}]},{"name":"Clean Hydrogen Partnership (EU Horizon 2020)","award":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"],"award-info":[{"award-number":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"]}]},{"name":"Operational Programme Integrated Infrastructure","award":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"],"award-info":[{"award-number":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"]}]},{"name":"European Regional Development Fund","award":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"],"award-info":[{"award-number":["P2-0001","101007175","313021X329","LA\/P\/0063\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Mathematics"],"abstract":"<jats:p>The main objective of this work was to develop a tuning method for PID controllers suitable for use in an industrial environment. Therefore, a computationally simple tuning method is presented based on a simple experiment on the process without requiring any input from the user. Essentially, the method matches the closed-loop response to the response obtained in the steady-state change experiment. The proposed method requires no prior knowledge of the process and, in its basic form, only the measurement of the change in the steady state of the process in the manually or automatically performed experiment is needed, which is not limited to step-like process input signals. The user does not need to provide any prior information about the process or any information about the closed-loop behavior. Although the control loop dynamics is not defined by the user, it is still known in advance because it is implicitly defined by the process open-loop response. Therefore, no exaggerated control signal swings are expected when the reference signal changes, which is an advantage in many industrial plants. The presented method was designed to be computationally undemanding and can be easily implemented on less powerful hardware, such as lower-end PLC controllers. The work has shown that the proposed model-free method is relatively insensitive to process output noise. Another advantage of the proposed tuning method is that it automatically handles the tuning of highly delayed processes, since the method discards the initial process response. The simplicity and efficiency of the tuning method is demonstrated on several process models and on a laboratory thermal system. The method was also compared to a tuning method based on a similar closed-loop criterion. In addition, all necessary Matlab\/Octave files for the calculation of the controller parameters are provided online.<\/jats:p>","DOI":"10.3390\/math11030715","type":"journal-article","created":{"date-parts":[[2023,2,1]],"date-time":"2023-02-01T05:04:48Z","timestamp":1675227888000},"page":"715","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Model-Free VRFT-Based Tuning Method for PID Controllers"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8110-8985","authenticated-orcid":false,"given":"Damir","family":"Vran\u010di\u0107","sequence":"first","affiliation":[{"name":"Jo\u017eef Stefan Institute, SI-1000 Ljubljana, Slovenia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4283-1243","authenticated-orcid":false,"given":"Paulo","family":"Moura Oliveira","sequence":"additional","affiliation":[{"name":"INESC-TEC, Department of Engineering, School of Sciences and Technology, University of Tr\u00e1s-os-Montes and Alto Douro, 5001-911 Vila Real, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1167-1681","authenticated-orcid":false,"given":"Pavol","family":"Bist\u00e1k","sequence":"additional","affiliation":[{"name":"Institute of Automotive Mechatronics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava, SK-812 19 Bratislava, Slovakia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4957-1894","authenticated-orcid":false,"given":"Mikul\u00e1\u0161","family":"Huba","sequence":"additional","affiliation":[{"name":"Institute of Automotive Mechatronics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava, SK-812 19 Bratislava, Slovakia"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1337","DOI":"10.1016\/S0005-1098(02)00032-8","article-title":"Virtual reference feedback tuning: A direct method for the design of feedback controllers","volume":"38","author":"Campi","year":"2002","journal-title":"Automatica"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.jprocont.2015.12.010","article-title":"Unbiased MIMO VRFT with application to process control","volume":"39","author":"Campestrini","year":"2016","journal-title":"J. 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