基于递归分割的机械零件三维形状结构检索方法

为实现设计重用，须对已有设计实例进行检索，实例检索中最为困难的是形状的相似性比较，为此提出基于递归分割的机械零件三维形状结构检索方法。生成模型凸包围盒获取机械零件的初始位置并对其进行归一化变换，再生成自适应有界分割面对实体进行分割，检测分割过程中实体的几何和拓扑参数变化，递归建立有序满二叉树，结合工程特征构建特征矢量，比较特征矢量的相似性获得非根结点实体的相似度，按广度优先变权遍历有序满二叉树，通过非根结点实体的相似度比较，获得各机械零件三维形状结构的相似度。将基于递归分割的机械零件三维形状结构检索方法在原型系统中对不同粒度的设计基元进行验证和应用，结果表明，该方法具有较高的计算效率和判断精度，能够快速准确地反映机械零件的总体轮廓形状和局部细节结构，对于实现设计重用提高设计效率具有重要意义。

3D Shape and Structure Retrieval Method of Mechanical Parts Based on Recursive Segmentation

To realize reusable design, the retrieval of existing engineering design cases is necessary in which the most difficult problem is shape similarity comparison. Therefore, a 3D shape and structure retrieval method of mechanical parts based on recursive segmentation is put forward. The initial position of mechanical parts is obtained by generating convex bounding box of the mechanical parts and the normalization transformation of mechanical parts is realized. The solid model is segmented by generating adaptive bounded segmentation plane. The ordered full binary tree is built through recursive algorithm with the change detection of both the geometry and topology of the model. The feature vectors combined with engineer features are constructed to obtain the similarity comparison of the solid model in non-root nodes by means of similarity comparison of the vectors. The breath-first and variable weight traversal of the ordered full binary tree is realized. The similarity of 3D shape and structure between the mechanical parts is obtained via the similarity comparison of the solid model in non-root nodes. The application and verification of 3D shape and structure retrieval method of mechanical parts based on recursive segmentation in prototype system indicates that the method has higher calculation efficiency and judgment precision and it can reflect not only the global sketchy shape but also the local detail structure of the mechanical parts. It has important significance to realizing design reuse and improving design efficiency.