Interactive Virtual Assembly Simulation System Based On STEP And OSG

The traditional CAD/CAM software play a key role in the product design environment, but it is relatively weak in the assembly operations and assembly analysis. The problem of product design is not found until the product has been put into production in extreme abundance, or the product has been sold for long time, it always causes irreparable damage to the enterprise. So we always hope that we can get the information of assembly at the design stage, we can guide the design of the products, but the target is difficult to achieve in traditional CAD/CAM software. Therefore we need to design a virtual assembly system, it can read CAD models into virtual assembly system, we can practice assembly and plan sequence in this system, we can immediately modify the design of CAD if we found that the part design problem. But the present virtual assembly system ofen adopt triangular facets model, not only lost the product engineering design information, so it is difficult to control and assembly model flexibly, but also it is difficult to two-way data transfer between virtual assembly results and the CAD system, which limits the application and development of the virtual assembly system.Focus on these problems, a virtual assembly system which is based on the STEP standard used in industrial CAD and refers to the technology character of the open source virtual-reality engine OSG (OpenSceneGraph) is designed. In addition the key technology problems are solved, the system can import STEP product model directly, Users can assemble these models freedomly and flexibily. It provides a convenient and effective support for the personnel training of assembly. It Also means that industral CAD and virtual reality system connected without any gap, the problems found in the virtual assembly process can be timely modify the CAD design, and the data can be two-way transfer.Finally, a primitive system is developed with OSG, STEP files are mapped to the OSG, and build an OSG scene tree, express the geometry morphology information of STEP model with the NURBS method, and rendering the geometry with OSG, the users can fulfills the assemble by selecting the model characteristic plane. The combination virtual reality engine OSG and industry standard STEP not only enhance the realism of the industrial model, but also expand the applications range of OSG, it can read the topology model for the first time, so that OSG go to the virtual assembly manufacturing from a simple rendering the triangle slice model.