关键词: 提升小波包变换, 振动信号, 阈值, 降噪, 特征提取, 故障诊断

Abstract:

In order to on-line process engine cylinder head vibration signals of mobile equipment, a de-noising method with gradual changing threshold based on lifting wavelet package transform was proposed. The lifting wavelet package transform based on interpolating subdivision was introduced. The engine cylinder head vibration signal’s time-frequency characteristics were analyzed. To fit in with the features of signal and noise, a strategy of gradual changing threshold selection and quantization was presented. The evaluation criterion of de-noising effect based on separability measurement of feature classes was introduced, and the quantitative evaluation of de-noising effect for the real vibration signals was realized.From the application example,using the strategy of gradual changing threshold selection and quantization,the noise is deleted and the useful information is reserved well in the whole frequency band.Compared with other methods,it owns better de-noising effect and universality.

Key words: lifting wavelet package transform, vibration signal, threshold, de-noising, feature extraction, fault diagnosis