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.

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.

Towards a Consistency Management in a Feature-Based Design

1993 ◽  
Author(s):  
Jivka Ovtcharova ◽  
Uwe Jasnoch
Keyword(s):  
User Requirements ◽  
Consistency Management ◽  
Current State ◽  
Starting Point ◽  
Information Set ◽  
Feature Based ◽  
Design Systems ◽  
Design Objects ◽  
Design Consistency ◽  
Feature Based Design

Abstract It is a common goal in the development of feature-based design systems to support users with extended facilities, such as comprehensive semantically correct feature-based models, conformability of tools to user requirements and to different applications, and communication via standardized interfaces. However, the current state of the art in feature-based design does not meet the most of these requirements, particularly the integration of design, reliability and maintainability of constraints. This paper presents recent research on design by features using the constraint satisfaction approach. We determine the basic requirements for defining and administering constraints in feature-based models and propose an architecture for consistency management in feature-based design systems. The two main modules of interest are Feature Frame and Consistency Manager. The Feature Frame intends to enclose different feature data into one information set, called Feature Resources and to create and manipulate such resources using Feature Mechanisms. The Consistency Manager provides functionality for definition, evaluation and satisfaction of constraints in feature-based models. Furthermore, in this paper the relation between feature-based design, consistency management and object-oriented paradigm is clarified. In contrast to previous publications where features and constraints are associated with objects in a programming language sense, our starting point is the ontological view to the object concept. We advocate that features and constraints are not objects themselves, but attributes and laws assigned by us to objects to describe properties of them. Thus, feature-based design can be characterized as the art of defining and manipulating properties of design objects.

Purely Declarative Feature-Based Design With Feature Type Property Maintenance

2004 ◽  
Author(s):  
Dhaval Lokagariwar ◽  
Bernhard Bettig
Keyword(s):  
Design Process ◽  
Research Work ◽  
Building Blocks ◽  
Feature Representation ◽  
Software Systems ◽  
Design Environment ◽  
Design Features ◽  
Planning Algorithm ◽  
Feature Based ◽  
Feature Based Design

Commercial feature-based design systems are based on describing the design model in some form of sequential representation of primitive shapes and operations called features. In these systems, the overall design process, the behavior of building blocks and the characteristics of the final model, are governed by the construction sequence. These systems do not check for the conformity of the final shape with the actual design intent of features, and allow their design and engineering intent to be altered during the design process. The research work presented here describes a new design methodology and feature representation for facilitating a design environment that is independent of any construction order or constraint-based dependencies and provides a mechanism for maintaining design and engineering intent of the design features. The methodology works by dynamically evaluating the features using a planning algorithm such that the validity of each feature is maintained. These are intended to serve as a generic template that can be used to design and develop specific design features and CAD software systems.

Methodology and Implementation of Dynamic Design Advisor (DDA) in a Feature-Based System

1999 ◽  
Author(s):  
Tridip K. Bardhan ◽  
Venkat N. Rajan ◽  
Abu S. M. Masud
Keyword(s):  
Design Stage ◽  
Design Environment ◽  
Regular Feature ◽  
Part Geometry ◽  
Advisory System ◽  
Systematic Methodology ◽  
Feature Based ◽  
Feature Based Design ◽  
Pipeline Design ◽  
First Time

Abstract Designing right the first time decreases cost significantly. If requirements of downstream activities could be considered during conceptual design, fewer changes would be required later. A design advisory system can provide enough information to the designer to achieve this goal of designing right at the conceptual stage. A systematic methodology for design advising in a feature-based design environment is developed to identify problems at the design stage, and provide the designer the opportunity to correct them. Five pre-conditions are also identified for this methodology. During the development of the part geometry, a multi-digit code is added to every feature. Based on the code, all applicable design rules are checked as constraints and in case of constraint violation, suggestions are generated and presented to the designer. During the design process, the designer can check a design rating, generated from the extent to which the constraints are satisfied. An example session is also presented to illustrate the ten steps of this method. To validate the developed methodology, a DDA system for pipeline design is developed in an actual industrial application. Effectiveness of the DDA methodology is analyzed by comparing the designers’ performance using the feature-based DDA system with performance using a regular feature based system. The performance measures used are: the number of errors in a design and the time taken to complete the design. Statistical results indicate that designers perform better with the DDA system in terms of fewer errors and less time to design.

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.

SINFONIA: An Open Feature-Based Design Module

1994 ◽  
Author(s):  
J. Ovtcharova ◽  
S. Haßinger ◽  
A. S. Vieira ◽  
U. Jasnoch ◽  
J. Rix
Keyword(s):  
Shape Representation ◽  
Design Feature ◽  
Modular Architecture ◽  
Design Environment ◽  
Design Features ◽  
Cad System ◽  
Feature Based ◽  
Definition Of ◽  
Feature Based Design ◽  
Solid Modeler

Abstract Sinfonia is a module for feature-based design which is configurable to users and applications within diverse CAD environments, particularly in the area of mechanical engineering. Sinfonia has an open and modular architecture that allows to modify and extend existing functionalities, and to integrate new modeling facilities and application tasks. This module enables the users to work with standard pre-defined design features delivered with the module, or to define dynamically their own specific design features during the design session. Furthermore, Sinfonia allows the interactive definition of constraints concerning the product semantics. Definition and administration of constraints in feature-based models provided by a consistency manager is supported to reach semantical correctness of the part models. The main modules of Sinfonia are the Feature Modeler and the Design Feature Manager. The Feature Modeler is responsible for the instantiation of features and the creation of the feature-based model. The Design Feature Manager allows feature data and design processes to be managed in a uniform way. The CAD system environment in which Sinfonia is integrated consists of the following modules: the User Interface System and the Application modules (offering tools for interaction of the user with application specific part models and for communication with external systems and applications, such as NC modules, etc.), the Solid Modeler (responsible for creating the shape representation of the feature-based model), the Consistency Manager (providing services to handle all kinds of different constraints within the design environment) and the Product Database which includes all services for storing and retrieving various product data.

Towards New Transitions Among Shape Representations

2003 ◽  
Author(s):  
Joris S. M. Vergeest ◽  
Chensheng Wang ◽  
Yu Song ◽  
Sander Spanjaard
Keyword(s):  
Feature Recognition ◽  
Shape Representation ◽  
Design Feature ◽  
Point Clouds ◽  
Shape Representations ◽  
New Methods ◽  
Feature Based ◽  
Representation Class ◽  
High Level ◽  
Feature Based Design

Four classes of shape representation are dominating nowadays in computer-supported design and modeling of products, (1) point clouds, (2) surface meshes, (3) solid/surface models and (4) design/styling models. To support applications such as high-level shape design, feature-based design, shape modeling, shape analysis, rapid prototyping, feature recognition and shape presentation, it is required that transitions among and within the four representation classes take place. Transitions from a “lower” representation class to “higher” class are far from trivial, and at the same time highly demanded for reverse design purposes. New methods and algorithms are needed to accomplish new transitions. A characterization of the four classes is presented, the most relevant transitions are reviewed and a relatively new transition, from point cloud directly to design/styling model is proposed and experimented. The importance of this transition for new methods of shape reuse and redesign is pointed out and demonstrated.

Conversions of Feature-Based Design Representations Using Graph Grammar Parsing

1994 ◽  
Vol 116 (3) ◽  
pp. 785-792 ◽  
Author(s):  
D. W. Rosen ◽  
J. R. Dixon ◽  
S. Finger
Keyword(s):  
Cost Evaluation ◽  
Graph Grammar ◽  
Manufacturing Cost ◽  
Graph Grammars ◽  
Design Features ◽  
Feature Based ◽  
Design Representations ◽  
Secondary Feature ◽  
Feature Based Design ◽  
Tool Cost

In order to trade off required functionality with manufacturing, cost, and other life-cycle considerations, it is necessary to evaluate designs in these secondary view-points. Representations of mechanical components designed with design features must be converted into representations containing relevant secondary viewpoint features. When describing a design verbally, designers often use languages of design features. In other viewpoints, different languages of viewpoint-specific features are used. Thus, translation capability between viewpoint languages is needed to convert from one representation to another. The approach taken here is to use formal graph grammars to define the feature-based design of thin-walled components and the secondary feature languages. Features are defined by graphs that explicitly represent the feature, its geometric entities, and their connectivity. Components are built up by combining feature graphs based on designer specified feature connectivity. To convert from the design to a secondary viewpoint, a three-step process is used where the last step is parsing by a grammar from the secondary viewpoint. To illustrate the conversion process, a converter for tool cost evaluation in injection molding and die casting is developed and applied to an example component.

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