A fault feature extraction method of gearbox considering variable speed condition

Abstract In this paper, a fault feature extraction method based on the combination of COT and VMD is proposed to solve the problem of fault feature extraction of gearbox under variable speed conditions. Firstly, a speed estimation method based on forward backward greedy algorithm and Fourier fitting is proposed to solve the speed estimation problem under variable speed conditions. Then, a feature extraction method based on computational order tracking (COT), variational mode decomposition (VMD) and fast kurtogram is proposed. COT is used to calculate the order. After the signal is decomposed by VMD, fast kurtogram is used to filter the modal components with obvious fault features, so as to extract fault features. Finally, combined with the analysis of actual equipment examples, the experimental results show that the steady state filtering can effectively filter the background noise and improve the signal-to-noise ratio. The rotation speed estimated by forward backward greedy algorithm and Fourier fitting is very close to the actual speed, which verifies that the method proposed in this paper can effectively solve the problem of fault feature extraction of gearbox under variable speed conditions.