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Area method for a biased relay feedback system / Jietae Lee in Industrial & engineering chemistry research, Vol. 49 N° 17 (Septembre 1, 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 8016–8020 Titre : Area method for a biased relay feedback system Type de document : texte imprimé Auteurs : Jietae Lee, Auteur ; Su Whan Sung, Auteur Année de publication : 2010 Article en page(s) : pp 8016–8020 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Biased  relay  Feedback  system. Résumé : The relay feedback system often shows an asymmetric response because of initial transient states, disturbances, and process nonlinearity. To restore a symmetric response of the relay feedback system, an iterative adjustment of input or output bias is required. Instead of trying to obtain a symmetric response, the asymmetric response can be analyzed to estimate the ultimate data or a parametric model of process. However, the asymmetric response causes additional errors in estimating the ultimate properties of the process. An area method is proposed to reduce these errors. Because integrals (areas) of the relay responses reduce the effects of the high-order harmonic terms significantly, the proposed method shows better accuracy in obtaining frequency response data and parametric models compared with previous approaches. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1003027 [article] Area method for a biased relay feedback system [texte imprimé] / Jietae Lee, Auteur ; Su Whan Sung, Auteur . - 2010 . - pp 8016–8020. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 8016–8020 Mots-clés : Biased  relay  Feedback  system. Résumé : The relay feedback system often shows an asymmetric response because of initial transient states, disturbances, and process nonlinearity. To restore a symmetric response of the relay feedback system, an iterative adjustment of input or output bias is required. Instead of trying to obtain a symmetric response, the asymmetric response can be analyzed to estimate the ultimate data or a parametric model of process. However, the asymmetric response causes additional errors in estimating the ultimate properties of the process. An area method is proposed to reduce these errors. Because integrals (areas) of the relay responses reduce the effects of the high-order harmonic terms significantly, the proposed method shows better accuracy in obtaining frequency response data and parametric models compared with previous approaches. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1003027

Area methods for relay feedback tests / Jietae Lee in Industrial & engineering chemistry research, Vol. 49 N° 17 (Septembre 1, 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 7807–7813 Titre : Area methods for relay feedback tests Type de document : texte imprimé Auteurs : Jietae Lee, Auteur ; Su Whan Sung, Auteur Année de publication : 2010 Article en page(s) : pp 7807–7813 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Area  methods  Feedback. Résumé : The amplitude and period of the relay feedback oscillation are used to obtain the ultimate parameter of a dynamic process and to tune a proportional−integral−derivative (PID) controller automatically. Equations for the ultimate gain and period are based on ignoring higher harmonic terms in the relay feedback response. The integral of the relay feedback response can suppress the higher harmonic terms, and the amplitude of this integral has been found to be better for estimating the ultimate gain of a process. As extensions, simpler methods that use several area calculations of the relay feedback response are proposed and shown to provide more accurate frequency responses, ultimate gain and period, and parametric models. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901546j [article] Area methods for relay feedback tests [texte imprimé] / Jietae Lee, Auteur ; Su Whan Sung, Auteur . - 2010 . - pp 7807–7813. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 7807–7813 Mots-clés : Area  methods  Feedback. Résumé : The amplitude and period of the relay feedback oscillation are used to obtain the ultimate parameter of a dynamic process and to tune a proportional−integral−derivative (PID) controller automatically. Equations for the ultimate gain and period are based on ignoring higher harmonic terms in the relay feedback response. The integral of the relay feedback response can suppress the higher harmonic terms, and the amplitude of this integral has been found to be better for estimating the ultimate gain of a process. As extensions, simpler methods that use several area calculations of the relay feedback response are proposed and shown to provide more accurate frequency responses, ultimate gain and period, and parametric models. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901546j