Automated Update Of A Feature Model Manipulated By Direct Modeling Operation

In recent years, as a highlight in the field of CAD, direct modeling technology develops rapidly and has been widely used. Different from traditional parametric feature modeling, direct modeling operations can edit the boundary representation model without the constraint of modeling history, which greatly enhancing the efficiency and flexibility of solid modeling. On the other hand, because the direct modeling only specializes in model editing, traditional parametric feature modeling is still the leading CAD modeling technique. Currently, although some commercial CAD systems have the ability to achieve direct modeling, they can’t integrate direct modeling and feature modeling, namely, they can’t effectively update feature model after editing the B-rep of the feature model, which seriously impacts the effect of direct modeling. To solve this problem, we study the method of the automated update of a feature model manipulated by direct modeling operation in order to achieve the integration of direct modeling and feature modeling, and improve the modeling capabilities and the efficiency of the CAD system.The main research work of this paper includes:1. Propose a conversion algorithm from the boundary changes generated by direct modeling operations to the boundary of the features. The algorithm can convert the impact of the direct modeling on the boundary representation to the feature model, thereby lays the foundation for the subsequent algorithms.2. Propose an algorithm to determine the candidate set of the feature model update operations that correspond to the direct modeling operation. The algorithm takes into account four feature modeling update operations:the feature parameter modification operation, the feature adding operation, the feature reordering operation and the feature deleting operation. And enumerates the potential candidate set of the feature modeling update operations that make the feature model consistent with the boundary representation edited by the direct modeling operation, achieves the conversion from the changes of boundary representation to the candidate feature modeling update operation.3. Propose a scoring-based algorithm to determine the optimal update operation. The algorithm establishes a quantitative evaluation for the maintenance of feature semantics and the satisfaction with user intent of every candidate feature modeling update operation, and determines an optimal operation from the candidate set of the feature modeling update operations.The experimental results show that our method can achieve the automated update of a feature model manipulated by direct modeling operation effectively.