Research On Fault Diagnosis Of Hydraulic Motor For Driving The Cutterhead Of Shield Machine

With the development of artificial intelligence and information tec hnology in mechanical industry,the technology of mechanical fault diagnosis is developing in the direction of intelligence.The diameter of the cutter head of the shield machine is large,the working environment is bad and the force is complex,and there are 8 hydraulic motors which drive the cutter head of shield machine,and the distribution range is large.The failure of the hydraulic motors will cause the shield machine to work abnormally,even cause accident.Using the traditional manual or semi automatic fault diagnosis methods which based on the personal experience of the maintenance to diagnose the fault of the hydraulic motors,the work efficiency is low and the accuracy is not high.In this paper,the research of the shield driving hydraulic motors diagnosis system is to develop a more efficient and intelligent fault diagnosis methods,therefore,it is of great significance for the maintenance of large machine.Based on BP neural network a nd expert system diagnosis method,the fault diagnosis system of hydraulic motors was researched by this paper.Firstly,the failure mechanism and failure rule of the shield driv ing hydraulic motors are studied,and the expert knowledge is accumulated for the fault diagnosis system of the hydraulic motors.Secondly,the pattern of hydraulic motors fault was recongnized,the fault characteristic signal and fault characteristic monitoring parameters were selected.Fault location,signal acquisition and signal scaling process were determined.And then the application of the filtering method in the preprocessing of the fault signal was analyzed.The time domain analysis and frequency domain analysis methods for fault feature extraction are studied.Thirdly,the fault diagnosis method based on BP neural network and expert system is studied.The topological structure of artificial neural network,the structure of expert system and the algorithm of BP neural network were analyzed.The knowledge representation of expert system knowledge base,the knowledge acquisition model of expert system and the knowledge base structure of the fault of hydraulic motor were studied.On this basis,the structure of the neural network expert system and the fault diagnosis model of the shield driving hydraulic motors were studied.The inference mechanism and explanation mechanism of neural network expert system were deeply studied.Finally,the development process of the fault diagnosis system of shield driv ing hydraulic motors were studied.At the same time,the hardware system of fault diagnosis system is constructed and The hardware platform of data acquisition,data processing and data communication were selected.On this basis,the overall structure of the software for the fault diagnosis system of the shield driving hydraulic motors were designed by using modularization,then using the C++ language to write the source code of each module.The interface of each module in the software of the fault diagnosis system of the shield driving hydraulic motors was established in the Visual Studio 2005 software,including hydraulic motors fault diagnosis system login interface,Condition monitoring and fault diagnosis function of hydraulic motor for driving the cutterhead of shield,fault alarm and diagnosis function of hydraulic motor for driving the cutterhead of shield,BP neural network training designning,knowledge management,etc.Through the research of this paper,the research results could guide the fault diagnosis and maintenance of hydraulic motors of large equipment,At the same time,it can be used as reference for fault monitoring and diagnosis of key components of hydraulic system.