Modelagem de sistemas dinamicos não lineares utilizando sistemas fuzzy, algoritmos geneticos e funções de base ortonormal / Modeling of nonlinear dynamics systems using fuzzy systems, genetic algorithms and orthonormal basis functions

AUTOR(ES)

Anderson Vinicius de Medeiros

DATA DE PUBLICAÇÃO

2006

RESUMO

This work introduces a methodology for the generation and optimization of Takagi-Sugeno (TS) fuzzy models with Orthonormal Basis Functions (OBF) for nonlinear dynamic systems based on a genetic algorithm. Orthonormal basis functions have been used because they provide models with properties like absence of output feedback and the possibility to reach a reasonable approximation capability with just a few parameters. TS fuzzy models aggregate to these properties the characteristics of interpretability and easiness to knowledge representation in a linguistic manner. Genetic algorithms appear as a well-established method for tuning parameters of TS fuzzy models. In this context, it was developed a genetic algorithm for the optimization of two architectures, the OBF TS fuzzy model and its extension, the Generalized OBF TS fuzzy model. Local linear and nonlinear models in the consequent of the fuzzy rules were analyzed, as well as the difference between local and global estimation (using least squares estimation) of the parameters of these local models. Each architecture had a specific chromosome representation in the genetic algorithm. It was developed a fitness function based on the Akaike information criterion. With respect to the genetic operators, the arithmetic crossover was modified in order to maintain the population diversity and the Gaussian mutation had its distribution varied along the generations and differentiated for each gene. Besides, it was used, in the first architecture presented, a method for simplifying the solutions by using similarity measures. The whole methodology was evaluated in modeling two nonlinear dynamic systems, a polymerization process and a magnetic levitator

ASSUNTO(S)

dynamic systems modeling takagi-sugeno fuzzy model similarity measures teoria dos sitemas dinamicos algoritmos geneticos identificação de sistemas optimization of models otimização matematica sistemas não-lineares orthonormal basis functions genetic algorithms akaike information criterion sistemas difusos

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