基于STFT的振动信号解调方法及其在轴承故障检测中的应用

从信号滤波角度,对基于STFT的振动信号解调方法的原理和影响其解调性能的各种因素进行了严格的理论分析,指出该解调方法实质是基于复解析带通滤波的Hilbert变换解调法.严格证明了在利用Hilbert变换进行包络解调分析时,只要带通滤波器通带范围包括调制信号的部分频率成分,就可解调出被调制信号的周期成分.为了避免对所有的解调信号序列进行包络谱分析,提出按峭度值最大化准则选择一组含有丰富故障信息的解调信号序列进行包络幅值谱分析.基于以上讨论,给出了实用的基于STFT的振动信号解调算法.为了验证提出的解调算法的有效性,用该算法对仿真和实际轴承故障信号进行了解调分析,分析结果表明,利用该算法能有效地检测轴承故障.

Vibration Signal Demodulation Method Based on STFT and Its Application in Rolling Bearing Fault Detections

From the view point of signal filtering,the principle of vibration signal demodulation method based on STFT is described and some factors affecting the demodulating performance are discussed.Through theoretical analysis,it is pointed out that the vibration signal demodulation method based on STFT is a special demodulation method based on complex-analytic band-pass filtering and Hilbert transformation.It is theoretically proven that the signal which has the same period as that of the modulated signal can be restored by demodulation analysis if some frequency components of the modulated signal are included in pass range of a complex-analytic band-pass filter.In order to avoid envelop spectrum analyses for all groups of demodulated signal series,a criteria in terms of the maximum of kurtosis factor is proposed to choose a group of demodulated signal series,which contains abundant fault information,for envelop spectrum analysis.On the discussion above,a demodulation algorithm based on STFT is proposed.The algorithm is applied to detect rolling bearing faults,and the results show that it performs effectively to extract the fault characteristic.