Research And Development Of General Layout System Of Tourist Bus Body Based On Knowledge

The overall layout of the bus body is an important part of the passenger bus production design,but the total number of parts involved in the bus body layout is very large,and the relationship between the key parameters of the arrangement is complex.The overall layout of the bus body has a strong dependence on experience of the developers,due to the numerous national standards and industry standards.Therefore,the overall layout design system of the tourist bus body was developed.The main work was as follows:The key technology of bus body layout design system was studied.In this paper the knowledge-based design theory and method were summarized firstly,and the research content of knowledge reuse was discussed.Through the comparison of eight different reuse research methods,the mixed reasoning of the rule-based reasoning and case-based reasoning was selected to reason reuse of knowledge.Then,two programming API of CATIA were compared.Automation API technology was selected to realize the secondary development of CATIA.And the macro recording function that comes with CATIA was introduced.Finally,VB access technology to CATIA was introduced,and VB call to CATIA was realized.The dimension correlation of each module of bus body layout was analyzed and the parametric modeling was completed.In this paper,the principle and method of parametric modeling was firstly discussed and the definition of parameters in CATIA modeling was illustrated by combining an example.Then the key dimensions of each module in the bus body layout were analyzed.And dimension association between each layout module and each inside module was proposed.Finally,the parametric modeling of the external layout,floor layout,cab layout and passenger area layout of passenger cars was completed,and the parametric design of the bus body layout was realized.The knowledge system of bus body layout design system was established and the reuse of bus body layout model design was studied and realized.In this chapter the requirements of the system was firstly analyzed and the system was divided into four functional modules according to the requirements:system management module,bus body overall layout design module,knowledge system module and knowledge system management module.Then the bus overall size parameter database,bus body overall layout rule database and bus body overall layout example database were established.The evaluation index of parameterized case of bus body layout was analyzed by using AHP analysis method.The evaluation system of case of knowledge system was put forward,which facilitated the management of knowledge system.Through the research on the system reasoning mechanism,a hybrid reasoning mode combining rule-based reasoning and case-based reasoning was applied,and the nearest neighbor method was combined to set the feature weight of retrieving the parameterized 3d model of the bus body exterior and the overall similarity threshold of the instance,which realizes the modification and reuse of the instance.Finally,the development of VB interface was discussed,and an example was given.The system has complete functions,which can effectively realize the query,add and delete of knowledge base.The system is also convenient for the accumulation and inheritance of enterprise knowledge.The system included four modules:system management,bus body layout module,knowledge system,knowledge management,can input design parameters through the interface of on the instance model of knowledge base retrieval and reuse retrieval examples according to the design demand,and by providing design principles to guide and help developers to quickly complete the bus body layout.