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 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.

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.

Geometric Reasoning Based on Graph Grammar Parsing

1994 ◽  
Vol 116 (3) ◽  
pp. 763-769 ◽  
Author(s):  
Z. Fu ◽  
A. de Pennington
Keyword(s):  
Intelligent Design ◽  
Feature Recognition ◽  
Geometric Reasoning ◽  
Geometric Constraints ◽  
Graph Grammar ◽  
Feature Interaction ◽  
Knowledge Based ◽  
Feature Based ◽  
Feature Information ◽  
And Performance

It has been recognized that future intelligent design support environments need to reason about the geometry of products and to evaluate product functionality and performance against given constraints. A first step towards this goal is to provide a more robust information model which directly relates to design functionality or manufacturing characteristics, on which reasoning can be carried out. This has motivated research on feature-based modelling and reasoning. In this paper, an approach is presented to geometric reasoning based on graph grammar parsing. Our approach is presented to geometric reasoning based on graph grammar parsing. Our work combines methodologies from both design by features and feature recognition. A graph grammar is used to represent and manipulate features and geometric constraints. Geometric constraints are used within symbolical definitions of features constraints. Geometric constraints are used within symbolical definitions of features and also to define relative position and orientation of features. The graph grammar parsing is incorporated with knowledge-based inference to derive feature information and propagate constraints. This approach can be used for the transformation of feature information and to deal with feature interaction.

Iterative Part Design With a Virtual Reality Interface

1996 ◽  
Author(s):  
S. N. Trika ◽  
P. Banerjee ◽  
R. L. Kashyap
Keyword(s):  
Virtual Reality ◽  
Computer Aided Design ◽  
Three Dimensions ◽  
Mechanical Parts ◽  
Cad System ◽  
Current State ◽  
Feature Based ◽  
New Feature ◽  
Feature Based Design ◽  
Aided Design

Abstract A virtual reality (VR) interface to a feature-based computer-aided design (CAD) system promises to provide a simple interface to a designer of mechanical parts, because it allows intuitive specification of design features such as holes, slots, and protrusions in three-dimensions. Given the current state of a part design, the designer is free to navigate around the part and in part cavities to specify the next feature. This method of feature specification also provides directives to the process-planner regarding the order in which the features may be manufactured. In iterative feature-based design, the existing part cavities represent constraints as to where the designer is allowed to navigate and place the new feature. The CAD system must be able to recognize the part cavities and enforce these constraints. Furthermore, the CAD system must be able to update its knowledge of part cavities when the new feature is added. In this paper, (i) we show how the CAD system can enforce the aforementioned constraints by exploiting the knowledge of part cavities and their adjacencies, and (ii) present efficient methods for updates of the set of part cavities when the designer adds a new feature.

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.

Representing Tolerance and Assembly Information in a Feature-Based Design Environment

1991 ◽  
Author(s):  
Rajneet Sodhi ◽  
Joshua U. Turner
Keyword(s):  
User Interface ◽  
Design Environment ◽  
Assembly Design ◽  
Assembly Features ◽  
Feature Based ◽  
The Creation ◽  
High Level ◽  
Feature Based Design

Abstract This paper describes a strategy for representing tolerance information and assembly information in a feature-based design environment. The concept of designing with features is extended to incorporate the specification of tolerance information. This allows appropriate tolerancing strategies to be provided within the feature definitions themselves. Thus a closer connection is formed between features and the functional intent implicit in their use. The concept of designing with features is also extended to incorporate the specification of assembly information, through the use of assembly features which provide a high-level user interface for the creation and modeling of assemblies, and which handle the identification and creation of mating relations between components. Several examples of component and assembly design using this extended feature-based approach are presented.

Relations Between Features: Prototyping Object-Oriented Language Extensions on an Industrial Example

1996 ◽  
Author(s):  
Brendan D. Brett ◽  
Thomas J. Peters ◽  
Steven A. Demurjian ◽  
Donald M. Needham
Keyword(s):  
Object Oriented ◽  
Critical Feature ◽  
Cad Cam ◽  
Change Notification ◽  
Feature Based ◽  
Software Object ◽  
Feature Based Design ◽  
Parent Child Relationships ◽  
Cam Software ◽  
Object Oriented Languages

Abstract Feature-based design techniques are being broadly incorporated into supporting CAD/CAM software. Object-oriented methodologies effectively capture parent-child relationships between features. However, realistic design, manufacturing and assembly domains often require more subtle inter-relationships between features, where contemporary object-oriented languages lack capabilities to facilitate such modeling. This research focuses upon prototyping object-oriented techniques to express non-ancestral relationships between features. This research was undertaken to support an industrial design team and our research goals were to: • determine critical feature inter-relationships, • prototype object-oriented software mechanisms for expressing these non-ancestral inter-relationships, and • equip those mechanisms with methods for change notification.

Representing and Recognizing Features in Mechanical Designs

1990 ◽  
Author(s):  
Susan Finger ◽  
Scott A. Safier
Keyword(s):  
Graph Grammars ◽  
Design Environment ◽  
Geometric Models ◽  
Feature Based ◽  
Geometric Representations ◽  
Design Systems ◽  
High Level ◽  
Feature Based Design ◽  
Structural Engineers ◽  
Rough Surface Finish

Abstract When experts view an object, they perceive it in terms of their own expertise. For example, manufacturers see features that affect the processes used to fabricate a part, while structural engineers see sources of stresses and other features that tend to reduce the life of a part. Features can be geometric, such as slots or chamfers; they can be quantitative, such as distances between holes; they can be functional, such as alignment; or they can be qualitative, such as a rough surface finish. Research in feature-based design systems for mechanical designers has been motivated by the realization that geometric models represent the design in greater detail than can be utilized by designers, process planners, assembly planners, or by systems that emulate these activities. Features provide abstractions to facilitate the creation, representation, and analysis of designs. Our goal is to enable designers to compose mechanical designs from high-level features that embody functional and geometric properties. In addition, we want to provide designers with feedback on the manufacturability, assemblability, functionality, cost, etc. of the design as it evolves. To support this process in an intelligent CAD environment requires the integration of geometric models, analysis tools, and synthesis tools so that all aspects of the design can be considered while it is in progress. We are developing a design environment based on a shared representation of the design in which we can extract and reason about features of the design from different perspectives. Our approach is to represent both the design and the features using graph grammars. By representing the features using the same grammar as the design, we can recognize features by parsing a feature against the graph that represents the design. We are exploring grammars for behavior as well as geometry in order to provide a link between behavioral and geometric representations. In this paper, we focus on the representation and recognition of features.

Integrated Environment for PDM, RE and CAD/ CAM System

2011 ◽  
Vol 130-134 ◽  
pp. 491-494 ◽  
Author(s):  
Yi Fei Tong ◽  
Yi Chun Yang ◽  
Hao Tian ◽  
Dong Bo Li
Keyword(s):  
Functional Model ◽  
Coordinate Measuring Machine ◽  
Original Data ◽  
Geometric Information ◽  
Engineering Software ◽  
Cad System ◽  
Integrated Environment ◽  
Reconstructed Surfaces ◽  
Cad Cam ◽  
Measuring Machine

Functional model for realizing the data integration of product data management, reverse engineering software and CAD/CAM system is proposed to support digitized prototyping and shorten the time market of new product. Measured data from CMM (Coordinate Measuring Machine), describing the geometric information of product would be sent directly to RE software. After refining and smoothing the “data cloud”, meshes of curves would be generated and sent to CAD/CAM system. The original data will be overlaid onto NURBS model obtained from CAD system to verify the reconstructed surfaces. The CAD model may be further faired, analyzed or NC machined within the context of current CAD/CAM system. Feasibility of such an approach has been testified on a sample part.

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