Bearing Fault Diagnosis Method Based on Local Mean Decomposition and Wigner Higher Moment Spectrum

Abstract

Combining local mean decomposition (LMD) and Wigner higher moment spectrum (WHOS), a bearing fault diagnosis method was proposed, called LMD-WHOS method. Firstly, LMD decomposed fault diagnosis signal into a series of production function (PF), and then the “real” components were found out from the decomposed components by calculating correlation coefficient between the component and the original signal. Secondly, the WHOS of the selected components was estimated. These estimated spectrums were added up to obtain the WHOS of original signal. Finally diagnosis conclusion can be drawn from the WHOS and its corresponding marginal spectrum. The algorithms of LMD and WHOS were described, and the major steps of proposed method were provided. Simulated signal and some measured rolling bearing fault signal were analyzed based on the presented method, and the results were compared with that of Wigner-Ville distribution (WVD) method. Results show that the proposed method reserves the advantages of LMD and WHOS, and can effectively inhibit the cross-term effect, which arises in Wigner-Ville spectrum. With the new method, the nature of the bearing fault signal is kept exactly and its dynamic changing characteristics of energy distribution with time and frequency can be clearly exhibited in the WHOS spectrum. LMD-WHOS method provides a new way for the accurate judgment of bearing fault state.