Wavelet-packet identification of dynamic systems in frequency subbands.

• Ano de defesa: 2005
• Autor(a) principal: Henrique Mohallem Paiva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Instituto Tecnológico de Aeronáutica
• Palavras-chave em Português: Identificação de sistemas; Sistemas dinâmicos; Análise de ondas localizadas; Processamento de sinais; Sistemas lineares; Códigos de detecção de erros; Filtragem; Algoritmos; Análise de falhas; Engenharia eletrônica
• Link de acesso: http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=217

This work presents a technique for linear system identification in frequency subbands by using wavelet packets. The wavelet-packet decomposition tree is used to establish frequency bands where subband models are created. An algorithm is proposed to adjust the tree structure, in order to achieve a compromise between accuracy and parsimony of the model. In a simulated example involving the identification of an aircraft model, the results of the proposed technique are favorably compared with those of a standard time-domain method.An application of the technique in the context of fault detection is also proposed. Once the identification is carried out, the difference between the outputs of the plant and of the model in the established frequency bands can be used as a residual signal for the purpose of fault detection. Two analytical redundancy approaches are exploited: input-output and output-output consistency check. Simulation studies involving a servomechanism and a Boeing 747 are provided to illustrate the proposed technique. The results show that the wavelet-packet method compares favorably with a standard observer-based scheme in terms of after-fault residue amplification, detection delay and number of successful fault detections.