Study On Virtual Assembly Technology Based On Pro/E & Virtools

Virtual assembly is an important application of virtual reality technology in the industrial field, and it is also a combination of design for assembly technology and virtual reality technology. During the assembly process simulation of parts in the virtual scene, we can verify whether the product can be assembled and make a plan of the assembly sequence. Virtual assembly can not only improve the assembly accuracy and efficiency of the product, but also reduce the manufacture cost of the physical prototype, and shorten the development period of the product as well. At present, virtual assembly has been widely used in industrial design, manufacturing, teaching and training, and many other fields.Combined with the secondary development of Pro/E, the disassembly/assembly demos and human-computer interactive assembly on the virtools development platform is realized, through the study of virtual assembly technology in this thesis. Meanwhile, there are several problems in the process of virtual assembly, such as the assembly sequence planning, model data transformation, script editing and interface design are discussed.In the development of virtual assembly based on Pro/E, through the traversal of model tree, the information of the feature and space pose of the parts is extracted and the interference table of parts is established after the interference checking during the process of automatic disassembly. The feasible disassembly sequence is generated with the disassembly direction of part which is chosen on the basis of the interference relationship among the parts. Based on the theory of what can be disassembled can be assembled, the disassembly sequence is reversed to assembly sequence. On that basis, the Bi-RRT algorithm is utilized for the path planning of the parts that can't be removed along a single direction because of their special positions. There are two searching trees at the same time, of which the first starts to search from the initial point of the part while the second starts to search from the target point. The search proceeding will end when the distance between the two nodes on different trees is less than the threshold or the sampled number is bigger than the maximum number. Then, reverse search the father node of target point to get the collision-free disassembly path. According to the path, the part in the complex environment is disassembled successfully.3ds Max is chosen as the software for conversion medium between Pro/E and Virtools, and the data conversion of Pro/E can be realized with help of the interface card called Virtools for Max. Then, the model exported from 3d Max and the scene pictures produced by Photoshop are imported into Virtools. The man-machine interface is generated to achieve the dynamic disassembly and assembly of the components and the interactive assembly of the assembly model with the BB modules and VSL program editing module. Finally, the virtual assembly instance is released as the.exe file that can be operated independently under Virtools environment.