Algorithms to Detect Geometric Interactions in a Feature-Based Design System

1994 ◽  
Author(s):  
Rajeev Talwar ◽  
Souran Manoochehri
Keyword(s):  
Design System ◽  
Surface Information ◽  
Cad System ◽  
Knowledge Based ◽  
Feature Interactions ◽  
Different Types ◽  
Conditional Statements ◽  
Feature Based ◽  
Feature Based Design ◽  
Knowledge Based Design

Abstract This paper presents efficient and accurate algorithms for the analytical detection of geometric interactions between features in a CAD environment. The developed methodology is meant to be utilized in a knowledge-based design system using feature-based modeling. The algorithms take surface information from the CAD system and use geometric inferencing to evaluate these interactions. Features represented by both convex and concave polyhedra are considered. The methodology developed here is able to deal with concave features effectively and, therefore, eliminates the need for their decomposition into convex sub-features. Sets of conditional statements based on simple and elegant rules have been developed to distinguish different types of interactions. Feature interactions are classified as intersecting or non-intersecting. For the non-intersecting cases, the features can be contained or separate and, for both cases, they can touch each other through an edge, a vertex and/or a surface. For the intersecting cases, intersections through a surface, an edge, a common edge and a common surface are identified. For all the cases the vertices, edges and surfaces involved in the interactions are identified and the relevant distances are evaluated. A computer program has been successfully implemented for polyhedral features and examples have been given to demonstrate its effectiveness.

A Feature Extraction Interface for CAD Part Models

1991 ◽  
Author(s):  
David R. Nitschke ◽  
Yuh-Min Chen ◽  
R. Allen Miller
Keyword(s):  
Design System ◽  
Relative Positioning ◽  
Neutral Form ◽  
Cad System ◽  
Knowledge Based ◽  
Functional Specification ◽  
Design And Manufacturing ◽  
Feature Based ◽  
The Individual ◽  
Knowledge Based Design

Abstract The concept of “Features” has been recognized as a neutral form of communication between design and manufacturing. Since virtually all CAD systems define part models using B-Rep or CSG formats, a facility is needed to convert geometry based part models to ones which are feature based. This paper outlines the framework of a facility which would enable part models from any type of CAD system to be converted to a format which could be analyzed using a knowledge based design system. This facility relies on the user to recognize and isolate the individual features of the model and then extracts the dimensions, locations and relative positioning of the features within the model. These features are then organized into a feature graph for the construction of a feature based part representation. The procedures for the construction of this part representation include feature instantiation, feature placement and functional specification.

Design System Mfk—An Important Step towards an Engineering Workbench

1993 ◽  
Vol 207 (2) ◽  
pp. 105-116 ◽  
Author(s):  
H Meerkamm
Keyword(s):  
Computer Aided Design ◽  
Tolerance Analysis ◽  
Design System ◽  
Product Model ◽  
Cad System ◽  
Knowledge Based ◽  
Different Types ◽  
Analysis Design ◽  
Aided Design ◽  
Production Tolerance

The Design System mfk will support the designer by an object-orientated synthesis of parts and an integrated knowledge-based analysis. An own-product model which is completely independent from the data structure of the used computer aided design (CAD) system contains all necessary information on geometry, technology, function and organization. It allows different types of analysis: design for production, tolerance analysis, cost and stress calculation, repeated component search, etc. Usable for products of higher complexity the Design System can be seen as an approach to an engineering workbench.

Process and Tolerance Considerations in the Automated Design of Fixtures

1994 ◽  
Vol 116 (2) ◽  
pp. 480-486 ◽  
Author(s):  
D. A. King ◽  
A. de Sam Lazaro
Keyword(s):  
Data Structures ◽  
Lead Time ◽  
Design System ◽  
Fixture Design ◽  
Complex Data ◽  
Cad System ◽  
Knowledge Based ◽  
Modern Manufacturing ◽  
Interactive Session ◽  
Knowledge Based Design

The long lead time for jig and fixture design is a serious bottleneck in modern manufacturing. Efforts to automate the design process using intelligent CAD systems have not been taken beyond the prototype stage mainly because of several impediments. These include the requirement of complex data structures to represent the workpiece and its attributes. Two deficiencies in existing systems for fixture design are addressed. These are (a) design for a sequence of operations and (b) design with tolerance considerations. Tolerance and process specifications are obtained from the user during an interactive session. A knowledge-based design system, REFIX, then designs a fixture for the workpiece. The fixture is optimized for a particular datum specification and sequence of operations. It is then analyzed and presented via the CAD system. REFIX is automated to minimize user-induced errors.

A Framework for Feature Based Part Modeling

1991 ◽  
Author(s):  
Yuh-Min Chen ◽  
R. Allen Miller ◽  
K. Rao Vemuri
Keyword(s):  
Geometric Reasoning ◽  
Geometric Information ◽  
Cad System ◽  
Knowledge Based ◽  
Modeling Environment ◽  
Cad Cam ◽  
Feature Based ◽  
High Level ◽  
Feature Based Design ◽  
Part Modeling

Abstract To increase the capabilities and intelligence of CAD/CAM systems, a feature based modeling environment, integrated with a knowledge based environment, is under development utilizing a commercial CAD system. This environment allows designers to model parts with features, and provides high-level part models to support geometric reasoning in manufacturing assessment and related functions. Two fundamental issues have been considered: (1) What kind of information is required to specify a part and to support reasoning about the part in a wide variety of applications?, and (2) How can the results serve the geometric reasoning needs of the various engineering applications which need geometric information about the part? This paper will discuss the information required for defining net shaped parts (parts to be manufactured by net shape processes), a framework for a feature based modeling environment, the procedures for feature based design, and the construction of high-level (semantic) pan models suitable for geometric reasoning in a knowledge based environment.

Feature Interactions

2009 ◽  
pp. 109-125
Author(s):  
Xun Xu
Keyword(s):  
Feature Recognition ◽  
Basic Feature ◽  
Feature Model ◽  
Design System ◽  
Feature Interaction ◽  
Complete Suppression ◽  
Feature Interactions ◽  
Feature Based ◽  
The One ◽  
Feature Based Design

Feature interaction tends to have a wide range of consequences and effects on a feature model and its applications. While these may often be intended, it is also true that feature validity can be violated, one way or another, by feature interactions (Shah & Mäntylä, 1995, Gao & Shah, 1998, Lee & Kim, 1998). They may affect the semantics of a feature, ranging from slight changes in actual parameter values, to some substantial alterations to both geometry and topology or even complete suppression of its contribution to the model shape. To certain extent, successful applications of feature recognition and feature-based techniques have been hindered by interactions among the features. Feature interaction was first studied in relation to feature recognition systems. As an alternative to feature recognition, feature-based design methodology has also become prevalent in recent years. Although a number of successful and commercially available feature-based design systems have been reported, current CAD technology is still unable to provide an effective solution for fully handling the complexity of feature interactions. Very often in a feature-based design system, the interaction between two features gives rise to an unintended feature, nullifying the one-to-one mapping from design features to manufacturing features. The resulting manufacturing feature is usually of a form that the system cannot handle or represent. Thus feature interaction resolution is equally essential for a feature-based design system (Dereli & Baykasoglu, 2004). As discussed in Chapter IV, features can be represented either as a set of faces or as a volume. The interactions between surface features are different from those occurring between volumetric features. This chapter discusses different types of interactions that arise from these two feature representation schemes and uses the interacting entities to classify them. There are two types of surface feature interactions, basic feature interaction and complex feature interaction. Three types of basic feature interactions are discussed. They are nested, overlapping, and intersecting types. Interacting patches are used to classify volumetric feature interactions. These interacting patches can be of a containing, contained, or overlapping type. The significance of feature interactions lies in their effect on the machining sequence of the features involved. This is also discussed in this chapter. When features are close to each other but do not share any geometric entities, interactions may also happen for structural reasons. This type of feature interaction can be called interaction by vicinity. The main aim of this chapter is to take a holistic approach toward feature interaction solutions. The example parts used are from the “Catalogue of the NIST (National Institute of Standards and Technology) Design, Planning and Assembly Repository” (Regli & Gaines, 1996). A case study is provided in the end of the chapter.

Feature Recognition

2009 ◽  
pp. 90-108
Author(s):  
Xun Xu
Keyword(s):  
Feature Recognition ◽  
Geometric Model ◽  
Feature Model ◽  
Design System ◽  
Cad System ◽  
Domain Specific ◽  
Cad Models ◽  
Feature Based ◽  
High Level ◽  
Feature Based Design

Conventional CAD models only provide pure geometry and topology for mechanical designs such as vertices, edges, faces, simple primitives, and the relationship among them. Feature recognition is then required to interpret this low-level part information into high-level and domain-specific features such as machining features. Over the years, CAD has been undergoing fundamental changes toward the direction of feature-based design or design by features. Commercial implementations of FBD technique became available in the late 1980’s. One of the main benefits of adopting feature- based approach is the fact that features can convey and encapsulate designers’ intents in a natural way. In other words, the initial design can be synthesized quickly from the high-level entities and their relations, which a conventional CAD modeller is incapable of doing. However, such a feature-based design system, though capable of generating feature models as its end result, lacks the necessary link to a CAPP system, simply because the design features do not always carry the manufacturing information which is essential for process planning activities. This type of domain-dependent nature has been elaborated on in the previous chapter. In essence, feature recognition has become the first task of a CAPP system. It serves as an automatic and intelligent interpreter to link CAD with CAM, regardless of the CAD output being a pure geometric model or a feature model from a FBD system. To be specific, the goal of feature recognition systems is to bridge the gap between a CAD database and a CAPP system by automatically recognizing features of a part from the data stored in the CAD system, and based on the recognized features, to drive the CAPP system which produces process plans for manufacturing the part. Human interpretation of translating CAD data into technological information required by a CAPP system is thus minimized if not eliminated.

Linking a CAD System to an Expert System: A Step Towards a Knowledge-Based Design System for Mechanisms

1994 ◽  
Author(s):  
Wolfram Funk ◽  
Rudolf Kinzinger
Keyword(s):  
Expert System ◽  
Design Process ◽  
Computer Support ◽  
Design System ◽  
Knowledge Based Systems ◽  
Cad System ◽  
Knowledge Based ◽  
System A ◽  
Knowledge Based Design ◽  
Conventional Computer

Abstract The design process can be divided into different phases. The best order in which the designer should execute these steps remains difficult to predict. In principle, conventional computer programs can only be applied to problems for which algorithms are available. Therefore, in many fields the design process did not allow computer support. The technology of knowledge-based systems has led to new perspectives. However, knowledge-based systems can only be utilized if the well-established design aid, CAD system, is integrated into the concept of knowledge-based computer support. Conceptual considerations and new approaches to linking a CAD system to an expert system, which assists the designer in solving kinematic problems, especially in the conceptual phase, are presented.

DEVELOPMENT OF A KNOWLEDGE-BASED INTELLIGENT CAD SYSTEM FOR AUTOMOTIVE PANEL DIE

2008 ◽  
Vol 07 (01) ◽  
pp. 51-54 ◽  
Author(s):  
HUI-XIA LIU ◽  
WEI WEI ◽  
XIAO WANG ◽  
LAN CAI
Keyword(s):  
Die Design ◽  
Design System ◽  
Working Process ◽  
Cad System ◽  
Knowledge Based ◽  
Working Principle ◽  
Panel Die ◽  
Automotive Panels ◽  
Automotive Panel

A knowledge-based intelligent die design system for automotive panels is developed by UG software platform. This system can accomplish design intelligently and automatically through engineering rules in the knowledge base. The framework and implementation of the system are discussed. Finally, a case study of the panel die design of car trunk in the system is implemented, which illustrates working process, working principle, implement method and practicability of the system, and validates the advanced design conception proposed in this paper.

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