A Degradation Feature Extraction Method for Hydraulic Pumps Based Upon MUWDF and MF-DFA

Hydraulic pump degradation feature extraction is a key step of condition-based maintenance. Since vibration signals of hydraulic pumps during degradation are strongly nonlinear and the feature information is too weak to be effectively extracted, a method based upon MUWDF and MF-DFA is proposed. Initially, the MUWDF is presented to reduce disturbances and improve feature information. Approximate signals of various decomposition layers are selected by feature energy factor and fused according to the presented fusion rules. On this basis, the fused signal is further processed by MF-DFA with a sliding window. Multi-fractal spectrum sensitive factors are selected to be the degradation feature vector of the hydraulic pump. The proposed method is verified by vibration signals sampled in a hydraulic pump degradation experiment.