LOD Technology Research On Virtual Assembly System Used In Overhaul And Maintenance Of EMU

With the introduction of high speed EMUs into China, industries relating the field of EMU are facing enormous challenges and opportunities, and the assembly and maintenance of EMU are no exceptions. Bogie is one of the key component parts that makes sure the safe operation of high-speed EMU. Its structure and assembly relationships are very complex, so using the actual equipment for training have brought a great deal on restrictions in time, space and security, such as high training costs and prototype that is easy to damage and so on. In order to overcome these drawbacks, we must vigorously develop the virtual assembly technique.First, the research background and virtual assembly, virtual reality and virtual maintenance of relationships are introduced. Virtual Maintenance is the application or implementation of virtual reality technology in the field of maintenance, the virtual assembly is an important application of virtual maintenance process in practice, whether it is virtual assembly and virtual maintenance of large-scale simulation environment, the primary problems is the loaded model problem which is usually caused the program crashes and slow loading conditions. The major work of this paper is how to solve this problem. Secondly,through the OSG platform library research, the model the main scene graph structure and the composition of the scene graph structure of nodes which is categorized is analyzed. At the same time, rendering methods and traversal methods of the scene graph and the internal structure of the model analyses in-depth. Then LOD basic framework is studied, and these help to understand the basic framework for the classification of the LOD model and switching factors, and right at this stage the model commonly used in low-level simplification algorithm are described and compared. And then learning from the advantages of the discrete LOD and continuous LOD, the model for the dynamic Bogie discrete distribution of the more obvious characteristics of the state, proposed a model based on the AABB bounding box simplification algorithm, and analysis of the algorithm advantages and limitations. On this basis, for the point of view of the scene model was further optimized. This paper uses the characteristics for the bogie model in the high-level to simplify the model, and apply the hybrid algorithm to simplify the model. And LOD technology is new applied in the field of complex industrial products.