Fault Feature Extraction of Hydraulic Pump Based on CNC De-noising and HHT

Abstract

The noise in the vibration signal of hydraulic pump seriously affects the extraction of its fault feature. In order to solve this problem, the discrete cosine transform (DCT) de-noising method is studied and the cosine neighboring coefficients (CNC) de-noising method is put forward aiming at the existing problems of DCT de-noising method. Then a novel method for the fault feature extraction of hydraulic pump is proposed based on the combination of CNC de-noising method and Hilbert–Huang transform (HHT). The vibration signal of pump is de-noised with CNC de-noising method and the fault feature is extracted by performing HHT to the output signal. The analysis results of the simulation signal and the actual one demonstrate that the amount of noise exist in signal affects the complexity and the result of HHT operation, and also testify that the proposed CNC de-noising method and the fault feature extraction method have more superior ability than the traditional ones.