Lock-in spectrum: a tool for representing long-term evolution of bearing fault in the time–frequency domain using vibration signal

Abstract

Purpose

This study aims to propose a method for monitoring bearing health in the time–frequency domain, termed the Lock-in spectrum, to track the evolution of bearing faults over time and frequency.

Design/methodology/approach

The Lock-in spectrum uses vibration signals captured by vibration sensors and uses a lock-in process to analyze specified frequency bands. It calculates the distribution of signal amplitudes around fault characteristic frequencies over short time intervals.

Findings

Experimental results demonstrate that the Lock-in spectrum effectively captures the degradation process of bearings from fault inception to complete failure. It provides time-varying information on fault frequencies and amplitudes, enabling early detection of fault growth, even in the initial stages when fault signals are weak. Compared to the benchmark short-time Fourier transform method, the Lock-in spectrum exhibits superior expressive ability, allowing for higher-resolution, long-term monitoring of bearing condition.

Originality/value

The proposed Lock-in spectrum offers a novel approach to bearing health monitoring by capturing the dynamic evolution of fault frequencies over time. It surpasses traditional methods by providing enhanced frequency resolution and early fault detection capabilities.

Citation

Zhang, M. (2024), "Lock-in spectrum: a tool for representing long-term evolution of bearing fault in the time–frequency domain using vibration signal", Sensor Review, Vol. 44 No. 5, pp. 598-610. https://doi.org/10.1108/SR-04-2024-0365