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

1. International CAD Conference and Exhibition May 24-28, 2004Pattaya Beach, THAILAND CAD04_039 An XML-Based Macro Data Representation for a Parametric CAD Model Exchange Jeongsam Yang*, Soonhung Han, Byungchul Kim, Joonmyun Cho and Hyunyup Lee

2. 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

3. Downstream DMU 1st Tier 2st Tier Component supplier Part customer Data supplier Data customer Parts Part supplier Data supplier Data customer Analysis NC Manufa- cturing OEM Component customer Data supplier Data customer Introduction Conceptualdesign Engineering design Release L1 L2 L3 L4 Class-A Skin Product data Product data Components Product data Product data A closer, more collaborative work environment is essential in product development.

4. Introduction 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

5. Introduction B-Rep model delivery Design knowledge is not portable !! The sender CAD system The receiver system Lack of the design intent Occurrence of poor design quality The knowledge of design, the creative element of design is captured in the modeling process.

6. --------------------------- A list of macro commands XMLencoding DB uploading Preprocessing An XML-based standard macro file CAD Database XML schema Check-out Pro/Engineer CATIA Introduction An overview for XML-based macro-parametric representation Macro-parametric translator

7. 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

8. Related works (cont.) • XML initiatives for product data • Various XML initiatives • MatML, PDML, PDX, UCLP • Rezayat definedCAD 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.

9. Related works Comparison of EXPRESS schema with XML schema SCHEMA example_part_schema; ENTITY part; number : STRING; description : OPTIONAL STRING; release_date : date; UNIQUE unq : number; END_ENTITY; ENTITY date; day : INTEGER; month : INTEGER; year : INTEGER; WHERE days_in_month : { 1 <= day <= 31 }; END_TYPE; END_SCHEMA; XML schema can express more powerful constraints in a context.

10. 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

11. Commercial CAD system Standard Macro-Parametric Modeling Commands MappingStructure Standard Modeling Commands Schemalevel Translatorlevel Macro File Data Translator Standard Macro File Macro-parametric methodolog Concept of the macro-parametric mapping

12. Macro-parametric methodolog Standard modeling commands Pro/E CATIA UG A set ofmodeling commands IDEAS SolidWorks

13. Classification of standard modeling commands CC: Core commands NCC: Non-core commands

14. ROOT Level 1 Level 2 Level 3 Level 4 SKETCH Extrude Revolve SURFACE Sweep Protrusion Create Helical SOLID Loft Cut … Delete … Copy Operate Filleting Fillet Constant Chamfer Variable CONSTRAINT … Macro-parametric methodolog Classification of standard modeling commands

15. Macro-parametric methodolog XML schema representation of Solid_Create_Protrusion_Extrude profile_sketch start_condition start_depth end_condition end_depth

16. XML-based definition of modeling commands and experiments

17. flip = TRUE flip = FALSE profile_sketch end_angle Y start_angle X XML-based definition XML schema and instance of SOLID_ Create_Protrusion_Revolve < Schema document > < Instance document >

18. XML-based definition CAD model exchange experiment using an XML based macro file CATIA V5R9 TransCAD

19. Test models 1st L-block 2nd Y-model 3th Gas Spring 4th Linear Sensor 7th Boat 6th Pneumatics Cylinder 5th Engine airfilter housing

20. C3PE System Internet via HTTP Web DEXService Web DEXService Run Time OperatingSystem and Local Devices MPTranslators MPTranslators XMLSchema XMLSchema XML-based definition Enabler of the Web-based DEX service Devices Browsers Access Your Application Provide Web Service Call Web Service Provide Application Provide Web Service Release Translators Deploy MP Description The Macro-Parametric Organization The 3rd Party TranslatorDevelopment Tools Notes: MP (Macro Parametric) DEX (Data Exchange) Conformance Testing

21. 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.

22. 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