Research On Automatic Adjustment Of Invalid Feature Models And Constraint-Solving In Feature-Based Modeling

Feature modeling is one of important techniques in integrated system of CAD or CAM, which is a key to product modeling. The integral model of product information based on feature should be built, which can solve data exchanging and data sharing in the process of designing, production, quality-controlling, and organization-management. At the same time, the parametric design technique is applied to feature-based design system, where the feature can be adjusted, which improves the efficiency of designing process. So, the parametric design technique based on feature has become very important in most CAID systems.HUST-CAID (Computer Aided Industry Design System developed by Harbin University of Science and Technology) is a parametric modeling design system based on feature. This system describes entities based on mixed model of boundary representation,CSG tree and feature description tree (FDT), in which the design of solid model and feature-editing can be completed with rebuilding CSG tree and feature description tree. But, in the feature modeling, with the number of features increasing, the design model becomes more and more complex. The efficiency of designing is decreased.In order to maintain the intent of designers and satisfy them, a new management system of feature model definition and validation is put forward based on old design system. Methods of automatic adjustment of invalid feature models are illustrated in this system. After the research of methods of constraint-solving and feature-editing in old system, a new way of constraint-solving is presented.