Adaptive Noise Reduction Method of Synchronous Hydraulic Motor Acoustic Signal Based on Improved Dislocation Superposition Method

Acoustic signal contains information on the state of mechanical motion, but the disadvantage of low signal-to-noise ratio (SNR) is that acoustic signal without noise reduction is difficult to apply to fault diagnosis directly. This study proposes an adaptive noise reduction method based on the dislocation superposition method (DSM), which can realize automatic noise reduction for acoustic signals of low SNR synchronous hydraulic motors. First, the theoretical rotation period of the synchronous hydraulic motor is obtained according to the flow meter. Then, the actual signal is subjected to DSM processing according to the measurement accuracy of the flow meter and the theoretical rotation period to adjust the exact superposition length and the initial position of the actual signal. Finally, when the stop condition is not satisfied, the number of superposition is increased and the above process is repeated. The superimposed signal satisfying the stop condition is taken as the noise reduction signal. According to experimental results, the proposed method has good noise reduction effect on the acoustic signals of the synchronous hydraulic motor health state, wear out state of gear and end cover, and rust state of the gear. The noise reduction signal has been verified to have higher accuracy than the actual signal. Therefore, the proposed automatic noise reduction method can be applied to the noise reduction processing of other kinds of rotating mechanical acoustic signals.