Research On Fault Diagnosis Method And Test Of Synchronous Hydraulic Motor Based On Acoustic Signal

Synchronous hydraulic motors often work under high load conditions,and online fault monitoring of them can avoid serious safety accidents and economic losses.In practical engineering applications,signal processing and diagnostic processes are an important part of online fault diagnosis.As a non-contact acquisition signal,acoustic signals are easier to acquire than vibration signals.Therefore,an automatic fault diagnosis method for synchronous hydraulic motors based on acoustic signals is proposed.The method includes an automatic noise signal reduction method(NRDSM)based on dislocation superimposition method(DSM),an automatic fault diagnosis method based on signal feature automatic extraction and failure mode recognition,and the construction of a synchronous hydraulic motor fault diagnosis software and hardware system.(1)NRDSM can realize the automatic noise reduction of the acoustic signal of the synchronous hydraulic motor with low signal-to-noise ratio.First,the theoretical rotation period of the synchronous hydraulic motor is obtained according to the flow meter.Then,DSM processing is performed on the actual acoustic signal according to the measurement accuracy of the flowmeter and the theoretical rotation period,and the optimal superposition length and the optimal initial position of the actual signal are determined using the Pearson correlation coefficient.Finally,use the set stop conditions to determine the optimal number of superpositios and superposition effects.(2)The automatic fault diagnosis method of synchronous hydraulic motor can realize the extraction and diagnosis of signal features.Among them,Pearson correlation coefficient is used to determine the optimal wavelet packet frequency scale range and the optimal decomposition level of the noise reduction signal,so as to realize the automatic extraction of signal features.Finally,the K-nearest neighbor(KNN)classifier is used to complete the fault diagnosis process.(3)A synchronous hydraulic motor test bench was designed and built with the geared synchronous hydraulic motor as the research object.Combined with data acquisition card,acoustic sensor,flow meter,and computer,these form the hardware part of synchronous hydraulic motor fault diagnosis system.Based on the joint programming of Lab VIEW and MATLAB,the design and construction of a real-time fault diagnosis platform for synchronous hydraulic motors were realized.According to the test results,NRDSM has a good noise reduction effect on the acoustic signals of the synchronous hydraulic motor during health,gear wear,gear rust,and end cover wear operation;the proposed automatic fault diagnosis method for signal characteristics can be used for different operating states of synchronous.hydraulic motor.The acoustic signals can be accurately identified and have certain anti-interference ability.