Study On The Intelligent Fault Diagnosis System Of Vacuum Unit Based On LabVIEW

With the development of technology and modern industry,artificial intelligence technology is continuously applied to machinery fault diagnosis.Petri Net is one of the most effective methods of artificial intelligence to describe,analyze and control discrete event system.But the research of fault diagnosis technology based on Petri Net still belongs to the starting stage.The complete theoretical system hasn't been established,and also with few application fruits.The large-scale vacuum brazing furnace often directly impacts the brazing quality of products,even results in the scrap of products and production downtime because of the failure of its vacuum system.That will cause great economical loss.The monitoring system of large-scale vacuum brazing furnace at home and abroad cann't realize condition monitoring and fault diagnosis of vacuum system now.The paper gives a deep research on vacuum system and Petri Net. Vacuum unit is regarded as a research object.We develop the intelligent fault diagnosis system of vacuum unit based on LabVIEW and Petri Net with the practical value.The research of this paper is to establish hierarchy fault diagnosis models based on Fuzzy Petri Net and hierarchy countermeasure models of fault for failures of large-scale vacuum system. Its operation and effectiveness is validated by the development of fuzzy fault diagnosis expert system of vacuum unit based on LabVIEW.Specific studies include:(l)Researeh on vacuum system.We determine major performance parameters for all types of vacuum pump based on the study of vacuum system and vacuum pump.In order to meet the need of fault diagnosis of vacuum unit,we add points of vacuum unit's fault monitoring.(2)Petri Net and modeling their hierarchy diagnosis theoretical models.The problem involves that the system is too complicated,the node is too much in Petri Net,and the analysis of model is too difficult. In order to solve it,we bring forward to establish hierarchy fault diagnosis models of Fuzzy Petri Net.Fault Tree Analysis and Production Rule have been adopted to model.We build the conversion model between Fault Tree and Petri Net,and also the conversion relation model between Fuzzy Production Rule and Petri Net.The fault diagnosis reasoning of Fuzzy Petri Net has been implemented.(3)Establish hierarchy fault diagnosis application models based on Fuzzy Petri Net and countermeasure models of fault for failures of large-scale vacuum system.We conclude and summarize vacuum unit's familiar failure of large-scale vacuum brazing furnace,The failure of vacuum equipments,the failure that vacuum value can not meet the requirement and the failure that the vacuumizing time is too long have been designed and classified in detail.Its hierarchy fault diagnosis application models of Fuzzy Petri Net and countermeasure models have been established based on Tree Analysis and Fuzzy Production Rule.(4)Develop the intelligent fault diagnosis system of vacuum unit based on LabVIEW.The overall design of intelligent fault diagnosis system of vacuum unit has been done using LabVIEW as the development platforrn.The intelligent fault diagnosis system of vacuum unit based on LabVIEW has been developed.Historical database management is desighed by relational database and LabSQL.We validate operation and effectiveness of fault diagnosis expert system of vacuum unit,using fault diagnosis of vacuum equipments as an application object. The result proves the feasibility and correctness of fault diagnosis method based on Petri Net.