An XML-Based Macro Data Representation for a Parametric CAD Model Exchange

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

2 iCAD Laboratory, KAIST

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


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.


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


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


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


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


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.


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.


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


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


Standard modeling commands

Pro/E

CATIA

IDEAS SolidWorks

UG

A set ofmodeling commands



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


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

…



XML schema representation of Solid_Create_Protrusion_Extrude

profile_sketch

end_conditionend_depth

start_conditionstart_depth



XML-based definition of modeling commands and experiments


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


CAD model exchange experiment using an XML based macro file

CATIA V5R9

TransCAD



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


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)



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.


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

Documents

An XML-Based Macro Data Representation for a Parametric CAD Model Exchange