CAD assembly model retrieval based on multi-source semantics information and weighted bipartite graph

Content-based CAD assembly model retrieval focusing on similarity measure of bottom-level geometry and topology information can hardly meet design demand of engineering designers in the product design reuse. To search quickly and effectively the CAD assembly models with specific functions by using requirements of mechanical product design, inspire designers' design thought and product design innovation, an assembly retrieval approach based on multi-source semantics information and weighted bipartite graph is proposed. The approach concerns the high-level semantics information rather than geometry and topology information of assembly model. First, the semantic ontology for mechanical assembly model is constructed considering multi-source semantics information including part semantics, assembly constraint semantics and functional semantics. Function region extraction algorithm is given for identifying functional structures in assembly model, and functional semantics of assembly model is annotated from the aspects of assembly structure granularity and part shape granularity. Subsequently, semantic similarity between concepts is evaluated comprehensively with WordNet and domain ontology, and a semantic matching model is built based on weighted bipartite graph (WBG) for solving the many-to-many semantics matching problem of semantic retrieval for CAD assembly models. Finally, a semantic-based assembly retrieval prototype system is developed and the experiment cases verify effectiveness and feasibility of the proposed assembly retrieval approach.