Research On Automatic Generation Method Of Assembly Dimension Chain Based On Ontology

As one of the key techniques of computer-aided tolerance design,automatic generation of dimension chain lays a foundation for tolerance synthesis and tolerance analysis.At present,the problems of dimensional chain technology mainly lie in two aspects: first,in the modeling level,with the development of tolerance mathematical model,the semantic complexity of dimensional chain model is increasing,so a semantic representation method with stronger expression ability is needed;Second,at the data level,there is a lack of an extensible and maintainable model or structure to realize intelligent information processing and semantic transmission.Aiming at the above problems,this paper introduces the ontology theory in the field of artificial intelligence into the research of dimensional chain technology,and proposes an ontology based automatic generation method of assembly dimensional chain.The main work includes:Established a hierarchical assembly accuracy information representation model and its ontology.The abstract description of the assembly accuracy information representation model is given in the form of adjacency matrix.The assembly accuracy information term set is defined in the form of description logic term formula,and the construction method of assembly accuracy information assertion set is given in the form of assertion formula set.The assembly accuracy information term set and assertion set constitute the assembly accuracy information ontology.A semantic representation method of assembly dimension chain based on Jena is proposed.The Jena general rule language is extended,and the extended Jena general rule language is used to express the relevant semantics of the assembly dimension chain.The method was verified by two sets of tests.A method of automatically generating assembly dimension chain based on ontology is proposed.Based on the assembly accuracy information representation model,an automatic generation method of assembly accuracy information ontology is designed.Based on the semantic representation method of assembly dimension chain based on Jena,the semantics of assembly constraints and assembly geometric relationship diagrams are expressed,so as to realize the automatic reasoning of assembly constraint information and assembly geometric relationship diagram information.Search the deviation transmission path on the assembly geometry diagram ontology to obtain the assembly dimension chain.Developed assembly dimension chain analysis system based on ontology.Based on the semantic representation model of assembly accuracy information,the semantic representation method of assembly dimension chain,the automatic generation method of assembly dimension chain,and the assembly tolerance modeling method based on auxiliary positioning joints,an ontology based assembly dimension chain analysis system was developed with Jena as the core framework of the application program.