The hardware order tracking needs professional Keyphasor device, which has high cost, complex installation and large application scope; the order tracking technology without tachometer can track the order by analyzing the instantaneous frequency without hardware equipment, but when there are multiple interference sources, the analysis effect is poor; Calculation order tracking technology does not need professional Keyphasor device, only need to install tachometer to collect speed signal, and there are no other constraints on signal analysis, so it is suitable for the fault diagnosis research of gear box in this paper.
Order tracking technology can eliminate the influence of speed change, but in thegear fault analysis, it is easy to be interfered by other order signals, and can not accurately extract the fault feature order of the fault gear. VMD technology is proposed by Konstantin dragomiretskiy et al
The signal is decomposed into a specified number of components according to different center frequencies. Compared with EMD, it can effectively avoid modal aliasing and has higher decomposition accuracy, which is widely used in the field of signal processing. In order to solve the problem of difficulty in feature order extraction of gearbox fault, this paper adopts the method of combining VMD with calculation order tracking for feature extraction. Firstly, the original signal is resampled into angle domain signal by computational order tracking, and the resampled signal is denoised by VMD filtering, and several IMF components are obtained. The IMF components sensitive to fault information are selected as fault signals by kurtosis criterion, and the fault features are extracted by fast spectral kurtosis method. The experimental results show that this method can effectively extract the order spectrum information of gear fault features, and compare with EMD and itd (intrinsic time scale decomposition) methods. The results show that this method is effective and superior.
The fault feature extraction of gear box under variable speed condition is studied, and a feature extraction method based on VMD order tracking is proposed. Through the experimental verification, the method successfully extracts the gear fault features, which proves the effectiveness of the method. Compared with EMD method and itd method, the results show that the fault feature extracted by VMD method is more obvious, the noise reduction effect is better, and it has certain advantages, which can be used for feature extraction and fault diagnosis of gearbox gear fault. There are also some shortcomings. This method only analyzes the situation of uniform change of speed, and lacks the research of fault feature extraction under drastic change of speed, which needs to be further strengthened.