Wavelet-packet identification of dynamic systems in frequency subbands.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

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.

ASSUNTO(S)

sistemas dinÃmicos anÃlise de falhas processamento de sinais identificaÃÃo de sistemas algoritmos filtragem cÃdigos de detecÃÃo de erros anÃlise de ondas localizadas sistemas lineares

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