| Summary: | 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.
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