时延自相关解调频原理及其在齿轮故障诊断中的应用  

Frequency demodulation based on delayed autocorrelation and its application in gear fault diagnosis

作　　者：何威[1] 江志农[1] 

机构地区：[1]北京化工大学故障诊断与自愈研究中心,北京100029

出　　处：《振动与冲击》2009年第9期195-199,共5页Journal of Vibration and Shock

基　　金：国家863高科技资助项目(2007AA04Z433)

摘　　要：当齿轮发生故障时,调幅和调频现象往往同时存在,但是传统方法通常只适用与解调幅,而不能解调频。同时振动信号中常含有大量的噪声,严重的影响了解调结果。由于高延迟的自相关函数具有受噪声影响比较小的特点,已有文献用时延自相关法解调幅,但是用做解调频还鲜有研究。为此,从理论上分析了调频信号和调幅调频信号的自相关函数,得出调频信号的自相关函数是调幅信号,调频调幅信号的自相关函数仍然是调幅调频信号,且其调制频率不变。这样就从理论上说明了时延自相关解调法是解调频和解调频的通用方法。最后通过仿真实验和实例分析,表明了时延自相关解调法不仅能有效的解调频,而且具有较好的抗噪性。When a gear has a local fault,the vibration signal of the gearbox usually is amplitude-modulated (AM) and frequency-modulated (FM). The demodulation analysis has been extensively used for gear diagnosis. However,traditional demodulation methods are mainly applicable to amplitude demodulation,while frequency modulation is usually ignored. Although Hilbert transformation can be used for frequency demodulation,it is affected by noise which often taints the gear vibration signal seriously. Due to the excellent anti-noise property of the delayed autocorrelation function,the delayed autocorrelation demodulation method was applied to amplitude demodulation with low SNR by some researchers,but was rarely used for frequency demodulation. By derivation,it was found that the autocorrelation function of the FM signal was amplitude-modulated and that of the AM-FM signal was amplitude-modulated and frequency-modulated. Moreover,the modulation frequencies of the latter were unchanged. Therefore,the delayed autocorrelation demodulation method was applicable not only to amplitude demodulation but also to frequency demodulation. The simulation experiments and gear vibration signal analysis verified this conclusion and showed that the delayed autocorrelation demodulation method is robust to noise.

关 键 词：故障诊断 时延自相关 解调分析 齿轮 调频 

分 类 号：TN911.72[电子电信—通信与信息系统] TP206[电子电信—信息与通信工程]