Abstract:

For the fact that the mechanical components and parts have the tolerance information, an assembly method based on tolerance constraint in virtual assembly was proposed in this paper. Firstly, the hierarchical information models of the components and parts were constructed. Secondly, the compressed method of space Bounding Volume (BV) based on volume decomposition was proposed to segment and compress the original BV, the Balanced Binary Tree (BBT) was constructed according to the result of the segmenting and compressing the BV, the collision model of the components and parts was constructed corresponding to the leaves of the constructed BBT, and the method of indexing redundant triangle patches was given to solve the problem of the redundant patches created in the process of the BV segmentation. Thirdly, the space environment segmenting method nearby the static components and parts in virtual environment was illustrated and separating axis was used in the segmented virtual environment cube to judge whether the collision occurs between the collision models of the components and parts. Fourthly, the method of calculating the collision penetration depth of triangle patches was mentioned and by contrasting the depth value calculated with the part tolerance range, it was confirmed whether the collision is in the tolerance range. Fifthly, as the holeaxis assembly an example, the method of judging assembly intention and the assembly constraint formulas were indicated. Finally, the assembly process of components and parts was shown by assembly simulation. The simulation result indicates that this method can increase the assembly efficiency and enhance assembly simulation performance.

Key words: virtual assembly;collision detection;bounding volume;redundant patch;tolerance;constraint