基于装配结构相似的零件三维模型检索方法

Part 3D Model Retrieval Method Based on Assembly Structure Similarity

提出一种基于装配结构相似的零件三维模型检索方法。将零件功能表面类型、相对位置、朝向以及面与面之间拓扑关系抽象成定性符号集合,并分别用功能面邻接图和定性几何约束图来定义零件功能表面间的拓扑关系和定性空间关系,建立零件装配结构定性模型。功能面邻接图中的环结构和分支结构分别通过断环和圆括弧描述,这样,零件装配结构就可以用字母和数字的线性序列来表示。借鉴化学数据库中化合物的线性符号表示法,对装配结构进行编码,通过装配结构码,建立零件装配结构的检索机制。并以轴承端盖为例验证方法的有效性。

A part 3D model retrieval method based on assembly structure similarity is presented. By abstracting the type, relative position, orientation and topology relation among part function surfaces as a qualitative symbol set, the topological relations and qualitative spatial relations among function surfaces are defined by function surface adjacent graph and qualitative geometrical constraint graph respectively and the part assembly structure qualitative models are presented. Cyclic structures and branches in a function surface adjacency graph are specified by breaking one link relation in each ring and enclosing them in parentheses respectively. In this way, part assembly structures can be expressed by a line notation of letters and digits. On the basis of referring to the line notation for compounds in chemical database, a structure coding method is presented. The retrieval mechanisms of part assembly structures based on assembly structure notations are presented. The method is validated by taking a bearing end cover as example.