关键词: 振动信号, 去噪, 小波分析, 探测插值, 多阈值, 类间距判据

Abstract: Aiming at the problems of denoising in mechine vibration signal extrations, based on the wavelet packet multi-threshold criterion denoising method, an improved wavelet packet denoising method to multi threshold standards was proposed herein, referred to improved FMC denoising method. This method was applied to pre-process original vibration signals of machine tools by pseudo point elimination technique to eliminate interferences of external noise signals to vibration signal extractions. Then the method of determining decomposition level was optimized by the method of determining maximum decomposition level with minimum frequency components of useful signals, and optimal wavelet packet basis was determined by minimum cost principle. Finally, vibration signals were reconstructed by wavelet packet multi threshold denoising criterion. Simulation experiments were implemented, and the results show that the method has good noise reduction effect, especially in strong noise background with a mutation of noise signal recovery. Experimental results show that the improved FMC denoising method may effectively eliminate band noises and improve separability of signal characteristics. Experiments were carried out to analyze the vibration signals of air bag dressing machine using this method, and experimental results show that the improved FMC denoising method may effectively eliminate the band noise and improve signal feature separability.

Key words: vibration signal, denoising, wavelet analysis, probe interpolation, multi threshold, class distance criterion