Feature Modeling Based on Topological and Geometrical Constraints for Realizing Designer's Intent

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Nowadays, CAD systems with parametric modeling functions are realized. However, efficient product development is not performed because designer's intent which was expressed as constraints and manufacturing information in the engineering drawings is not represented directly in a product model but as a history of commands and dimension values of shapes. Hence our object of this research is to develop functions such as symbolical representation of designer's intent using topological and geometrical constraints along with attribute information, efficient parametric design according to designer's direct indication, and representation and modeling of multiple views for design, manufacture and analysis. To achieve this objective, we have carried out the following research.1. We have developed algorithms which deduce topological constraints considering that geometrical elements with ambiguities caused by numerical calculation are degenerate, obtain consistent constraints according to transitio … More n rules among degenerate states, and make topology of the output solid from the constraints.2. We have introduced a method which describes topological constraints in a feature model from a type of feature and faces of a product where the feature is attached, and which represents geometrical constraints from designer's indication concerning allocation and sizes of the feature. When a parameter is changed, we modify the product shape detecting topological changes. Here, we obtain consistency between a feature model and a geometric model, modifying a feature type and over or under constraints of dimensions.3. We have represented a compound feature using a similar structure as a basic feature in a product model, and enabled users to access a library of compound features on the network by representing them in a XML file. We have also studied algorithms for retrieving resemblant features and protecting the library from registering the same feature type.4. We have developed a method which selects a design parameter and determines its value automatically to change of a product shape according to manufacturing requests (manufacturing constraint). We pick up dimensional parameters which affect the manufacturing constraint using the dependency graph in the geometrical constraint, and select the parameter which has the least influence on the designer's intent according to the attribute information. Then, we obtain the value solving an equation or equations generated from the face data table against the variable of the parameter. Less