REAL-TIME CONDITION MONITORING BY SIGNIFICANT AND NATURAL FREQUENCIES ANALYSIS OF VIBRATION SIGNAL WITH WAVELET FILTER AND AUTOCORRELATION ENHANCEMENT

摘要

Vibration signals from machining processes contain very useful information and offer excellent possibilities for in-process condition monitoring. Significant and natural frequencies in vibration signals reflect the inherent property of the system. Any change in the condition will result in the change in these frequencies. The time-frequency localization of the wavelet transform makes it very useful in signal processing, so that it can be used in filter design. In this paper, the wavelet filter with very narrow frequency-band and autocorrelation enhancement is proposed as a means of monitoring the natural frequencies in real-time. With the efficient, reliable and flexible wavelet filters, any number of natural frequencies in either the time or the frequency domain can be observed at the same time. After filtering, the signal with a single central frequency is enhanced by an autocorrelation algorithm in the time domain. This can provide real-time monitoring based on the changes of significant and natural frequencies, corresponding to the change in conditions.