时延自相关解调频原理及其在齿轮故障诊断中的应用

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振动与冲击 ›› 2009, Vol. 28 ›› Issue (9) : 195-199.

论文

时延自相关解调频原理及其在齿轮故障诊断中的应用

何威江志农

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Frequency Demodulation Based on Delayed Autocorrelation and Its Application to Gear Fault Diagnosis

He Wei Jiang Zhinong

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文章历史 +

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。

Abstract

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 transform can be used for frequency demodulation, it is liable to be 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 has been applied to amplitude demodulation in low SNR by some researchers, but is rarely used for frequency demodulation. By derivation, it is found that the autocorrelation function of the FM signal is amplitude-modulated and that of the AM-FM signal is amplitude-modulated and frequency-modulated. Moreover, the modulation frequencies of both are unchanged. Therefore, the delayed autocorrelation demodulation method is applicable not only to amplitude demodulation but also to frequency demodulation. The simulation experiments and gear vibration signal analysis verify this conclusion and show that the delayed autocorrelation demodulation method is robust to noise.

导出引用

何威江志农. 时延自相关解调频原理及其在齿轮故障诊断中的应用 [J]. 振动与冲击, 2009, 28(9): 195-199

He Wei Jiang Zhinong. Frequency Demodulation Based on Delayed Autocorrelation and Its Application to Gear Fault Diagnosis[J]. Journal of Vibration and Shock, 2009, 28(9): 195-199