iCAD Laboratory, KAIST
An XML-Based Macro Data Representation for a Parametric
CAD Model Exchange
Jeongsam Yang*, Soonhung Han, Byungchul Kim,Joonmyun Cho and Hyunyup Lee
International CAD Conference and Exhibition May 24-28, 2004Pattaya Beach, THAILAND
CAD04_039
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Contents
Introduction to our research Related work
Exchange of parametric information XML initiatives for product data
Macro-parametric methodology The macro-parametric approach A set of standard modeling commands
XML-based definition of modeling commands and experiments XML representation of standard modeling commands XML schema design A data exchange experiment
Conclusion
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Introduction
Components
1st Tier
Component supplierPart customerData supplier
Data customer
2st Tier
Part supplierData supplier
Data customer
Parts
Product data
Product data
Class-ASkin
L1 L2 L3 L4 Release
Conceptualdesign
Engineering design
OEM
Component customerData supplier
Data customer
NC
Manufa-cturing
Analysis
DMU
Downstream
Product data Product data
A closer, more collaborative work environment is essential in product development.
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CAD model sharing
Three major approaches Using a single CAD system in a company
No need for model exchange But, heavily dependent on a single commercial CAD
system. Introduction of direct translators between different
CAD systems Data loss and shape distortion occur during data
translation. N different CAD systems needs N(N-1)/2 translators.
Translating using a neutral format such as STEP and IGES A snapshot of the model, only B-Rep shape Two translations and has twice the data loss
Introduction
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B-Rep model deliveryIntroduction
Design knowledge is not portable !!
The sender CAD system The receiver system
The knowledge of design, the creative element of design is captured in the modeling process.
Lack of the design intent
Occurrence of poor design quality
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An overview for XML-based macro-parametric representation
XMLencoding
---------------------------A list of
macro commands
XML schema
An XML-based standard macro file
Macro-parametric translator
Pro/Engineer
Preprocessing
CAD Database
DB uploading
CATIACheck-out
Introduction
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Related works
Exchange of parametric information STEP ISO 10303 Part 42
No definitions for modeling functions based on design history, such as shelling, chamfering and drafting
Narrowly defines entities for constructive solid geometry ENGEN data model
A product data model with parameters, features, design history, and constraints based on Part 42 of STEP
The exchange experiments use the CAD systems of Pro/Engineer (PTC), I-DEAS (SDRC), and CADDS5 (CV)
It has insufficient entities for the design history, and it cannot be used to represent a history-based parametric model.
A solid model construction history schema of Varra and Anderson is for exchanging parameters, constraints, features and design history information
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Related works (cont.)
XML initiatives for product data Various XML initiatives
MatML, PDML, PDX, UCLP
Rezayat defined CAD models in terms of limited boundary representation using DTD of XML.
STEP ISO 10303-28 Implementation methods: XML representation of
EXPRESS schemas and data. enable XML to be used as a representation
mechanism for STEP-conformant schema and instance data.
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Comparison of EXPRESS schema with XML schema
SCHEMA example_part_schema;
ENTITY part;number : STRING;description : OPTIONAL STRING;release_date : date;UNIQUEunq : number;
END_ENTITY;
ENTITY date;day : INTEGER;month : INTEGER;year : INTEGER;WHEREdays_in_month : { 1 <= day <= 31 };
END_TYPE;
END_SCHEMA;
Related works
XML schema can express more powerful constraints in a context.
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Macro-parametric methodology
Motivation Take a hint from a database recovery when a
transaction log file is used for a crash recovery. Recording the modeling command sequence
issued in the originating system and replay them in the receiving system.
Scope Part modeling with parameters, constraints,
features and history information Out of scope
Assembly, Sheet metal, Context/appearance information
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Concept of the macro-parametric mapping
ModelingCommands
Macro File
Commercial CAD system Standard Macro-Parametric
MappingStructure
Standard ModelingCommands
Standard Macro FileData Translator
Schemalevel
Translatorlevel
Macro-parametric methodolog
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Standard modeling commands
Pro/E
CATIA
IDEAS SolidWorks
UG
A set ofmodeling commands
Macro-parametric methodolog
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Classification of standard modeling commands
No. of CC No. of NCC Sum
Sketch commands 30 27 57
Surface commands 17 6 23
Solid commands 22 18 40
Constraint commands
21 3 24
90 54 144
CC: Core commandsNCC: Non-core commands
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Classification of standard modeling commands
Chamfer
Create Protrusion
Extrude
Level 1 Level 2 Level 3 Level 4ROOT
SOLID
Revolve
Sweep
Helical
Loft
Operate
Cut …Delete
Copy
Filleting Fillet Constant
Variable
…
SKETCH
SURFACE
CONSTRAINT
…
Macro-parametric methodolog
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XML schema representation of Solid_Create_Protrusion_Extrude
profile_sketch
end_conditionend_depth
start_conditionstart_depth
Macro-parametric methodolog
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XML-based definition of modeling commands and experiments
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XML schema and instance of SOLID_ Create_Protrusion_Revolve
profile_sketch
start_angle
end_angle
flip = TRUEflip = FALSE
X
Y
< Schema document >
< Instance document >
XML-based definition
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CAD model exchange experiment using an XML based macro file
CATIA V5R9
TransCAD
XML-based definition
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Test models
3thGas Spring3thGas Spring
2nd Y-model2nd Y-model
1stL-block1stL-block
6th Pneumatics Cylinder6th Pneumatics Cylinder
7thBoat7thBoat
4thLinear Sensor4thLinear Sensor
5th Engine airfilter housing 5th Engine airfilter housing
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Enabler of the Web-based DEX service
Web DEXService
MPTranslators
XMLSchema
Web DEXService
MPTranslators
XMLSchema
Devices Browsers
Internet via HTTP
The 3rd Party TranslatorDevelopment Tools
The Macro-Parametric Organization
C3PE System
OperatingSystem and
Local Devices
Run Time
Call Web Service
Provide Application
Access Your Application
Provide Web Service
Provide Web Service
Conformance Testing
Release Translators Deploy MP Description
Notes: MP (Macro Parametric) DEX (Data Exchange)
XML-based definition
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Conclusion
In the product development complex products are sourced from hundreds of suppliers,
so a closer, more collaborative work environment is essential if the need is to exchange and modify design data.
Exchanging, design knowledge, as defined by features, history, constraints, has been a requirement.
The macro-parametric approach enables parametric information to be transferred as a
sequence of standard modeling commands.
XML representation of standard modeling commands is suitable for constructing a Web-based DEX service that
communicates with two loosely coupled systems through the HTTP standard protocol.
emphasizes the information representation and meaning, provides open data architecture for translator developers and standardization communities.
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Future works
Implementation of non-core commands,
The extension of standard modeling commands for complex models
Harmonization with the existing STEP Application Protocols of the ISO A group of sketch commands was submitted as a new
work item to ISO/TC/184/SC4/WG12
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