Fuzzy multi‐model based adaptive predictive control and its application to thermoplastic injection molding

Many chemical processes are inherently nonlinear. A single linear model is ineffective for these processes. Several local linear models may be developed for different operating conditions. A combination of these local models, through a fuzzy logic representation, results in an overall model for a wider operation range. In this paper, on-line improvements and a fuzzy multi-model have been proposed for predictive control implementation. Firstly, assuming that the premises of the fuzzy rules keep their original structures, the linear parameters in the rule consequents are on-line updated by a weighted recursive least squares algorithm at each sample interval. Secondly, a batch learning algorithm is proposed to tune the fuzzy rule premises using a competitive learning algorithm. The effectiveness of the proposed improvements is demonstrated with experimental applications to the filling velocity control of thermoplastic injection molding De nombreux procedes chimiques sont par nature non lineaires. Un modele lineaire simple est donc inefficace pour ces procedes. Plusieurs modeles lineaires locaux peuvent ětre mis au point pour differentes conditions de fonetionnement. Une combinaison de ces modeles locaux, par une representation en logique floue, peut donner un modele global pour une gamme plus large de fonctionnement. Dans cet article, des ameliorations en ligne et un multi-modele flou sont proposes pour la mise en place d'un contrǒle predictif. Premierement, en supposant que les premissses des regles floues gardent leurs structures originales, les parametres lineaires dans les consequences des regles sont mises a jour en ligne par un algorithme de moindres carres recurrents pondere a chaque intervalle d'echantillon. Deuxiemement, on propose un algorithme d'apprentissage discontinu pour ajuster les premisses des regles floues a l'aide d'un algorithme d'apprentissage competitif. L'efficacite des ameliorations proposees est demontree par des applications experimentales du contrǒle de la Vitesse de remplissage en moulage par injection de thermoplastique

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