Abstract: Aiming at the difficulty of identifying hydraulic pump faults, and the detected vibration signals containing noise and other irrelevant information, a method that combined variational mode extraction (VME) and detrended fluctuation analysis (DFA) to achieve identification and diagnosis of hydraulic pump faults was proposed. Firstly, the vibration signal collected by the hydraulic pump was decomposed by VME to obtain a series of intrinsic mode functions (IMFs), and the scale exponent of different mode components was obtained by DFA. The amplitude threshold of the scale exponent was used to distinguish useful signals and noise signals, and then the wavelet denoising was performed on the mode component with noise, so as to retain the effective information to the greatest extent. Finally, the denoised mode component and the non-noise mode component were reconstructed together. Through the Locality Preserving Projection (LPP), multiple statistical features of the reconstructed signal were calculated and the dimensionality was reduced. The results demonstrate that the root-mean-square-error (RMSE) between the decomposed signal and the original noise-free signal is only 0.325 1, which provides data support for the subsequent accurate clustering of different fault types of hydraulic pumps based on LPP. At the same time, the effectiveness of the proposed method is verified by analyzing the numerical simulation signal and the data collected by the axial plunger pump hydraulic experiment system.
Key words: hydraulic pump; fault diagnosis; variational mode extraction(VME); detrended fluctuation analysis(DFA); wavelet denoising

JIN Lin-cai, YE Jie-kai, TANG Xiao-ming,et al.Hydraulic pump fault diagnosis method based on VME and DFA[J].Journal of Mechanical & Electrical Engineering,2021,38(12):1628-1635.