A REPRESENTATION SCHEME FOR PRISMATIC PARTS IN THE FEATURE-BASED ENVIRONMENT

• Main Authors: Sheu, Liang-Chyau, 許良僑
• Other Authors: Lin, James T.
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/79858223175376717433

博士 === 國立清華大學 === 工業工程研究所 === 83 === The functional requirements and methodologies being developed for feature creation, feature editing and the applications based on feature information are investigated first. A conclusion is reached that a feature representation scheme to support explicit form feature information and inter-feature relationships is essential for pro- viding a unified product database within the "feature-based environment." The FDG (Feature Dependency Graph) scheme is therefore developed to enable efficient feature manipulation by a high-level graph structure. It retains complete geometric information in the B- Rep level as well. Five basic constituents - B-Rep solid component, measure entities, size, location and constraints - are used to define a single form feature. The scheme also helps in extending the available fea- tures in the system by structurally combining feature constituents. Furthermore, the scheme uses dimensions to represent form features'' size and locations. Therefore, the manipulation of form features is consistent with the designer''s intent. On the basis of FDG scheme, an architecture of design system for prismatic parts, in which an expert system shell is used to acquire knowledge from experienced designers, is proposed. The co- operation of expert systems and feature-based design systems can provide significant advan- tages. A wide range of features'' behavior is available during the product design and sound design decisions can be made by the design sys- tem. The structure of knowledge base for product design and the interface between the expert sys- tem shell and feature database are explained in detail. Finally, a CAPP system called OBPLAN is included in this thesis to complete a basic link of CAD and CAM.