Short-Time Variance Providing Evidential Reference Frequency for Lock-in Amplifier in Fault Diagnosis of Rolling Bearings

The purpose of this study is to propose a framework employing Lock-in amplifier for fault diagnosis of rolling bearings using vibration signals, addressing the challenges posed by noise interference and inaccurate estimation of Lock-in amplifier’s reference frequency.

By studying the properties of the pulse chains triggered by faults, the proposed framework utilizes the Short-time Variance of vibration signals to determine the bearing fault characteristic frequency, providing a reliable reference frequency for the Lock-in amplifier. This approach aims to overcome the limitations of previous methods reliant on geometric relationships for fault frequency estimation.

It has been proved that Short-time Variance can effectively identify sparse pulses in vibration signals. The Short-time Variance spectrum effectively characterizes bearing fault information and outperforms the benchmark method envelope spectrum in high-noise environments. Validation of the proposed framework is conducted using simulated signals and experimental data sourced from a public dataset. The results demonstrate the effectiveness of the framework in accurately diagnosing bearing faults through vibration signals.

This study confirms that directly applying theoretical fault characteristic frequencies as the reference frequency for a Lock-in amplifier can have a significant negative impact on diagnostic performance. It has been concluded that the proposed framework offers a robust approach to fault diagnosis of rolling bearings. By leveraging Lock-in amplifiers and the Short-time Variance, it provides accurate fault detection, thus ensuring the safe and reliable operation of mechanical equipment.