1. 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, 2004 Pattaya Beach, THAILAND CAD04_039

2. 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

3. 3 iCAD Laboratory, KAIST Introduction Components 1 st Tier Component supplier Part customer Data supplier Data customer 2 st Tier Part supplier Data supplier Data customer Parts Product data Class-A Skin L1L2L3L4 Release Conceptual design Engineering design OEM Component customer Data supplier Data customer NC Manufa- cturing Analysis DMU Downstream Product data A closer, more collaborative work environment is essential in product development.

4. 4 iCAD Laboratory, KAIST 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

5. 5 iCAD Laboratory, KAIST B-Rep model delivery Introduction 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

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

7. 7 iCAD Laboratory, KAIST 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. 8 iCAD Laboratory, KAIST 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.

9. 9 iCAD Laboratory, KAIST 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; Related works XML schema can express more powerful constraints in a context.

10. 10 iCAD Laboratory, KAIST 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. 11 iCAD Laboratory, KAIST Concept of the macro-parametric mapping Modeling Commands Macro File Commercial CAD systemStandard Macro-Parametric Mapping Structure Standard Modeling Commands Standard Macro FileData Translator Schema level Translator level Macro-parametric methodolog

12. 12 iCAD Laboratory, KAIST Standard modeling commands Pro/E CATIA IDEAS SolidWorks UG A set of modeling commands Macro-parametric methodolog

13. 13 iCAD Laboratory, KAIST Classification of standard modeling commands No. of CCNo. of NCCSum Sketch commands302757 Surface commands17623 Solid commands221840 Constraint commands21324 9054144 CC: Core commands NCC: Non-core commands

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

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

16. 16 iCAD Laboratory, KAIST XML-based definition of modeling commands and experiments

17. 17 iCAD Laboratory, KAIST XML schema and instance of SOLID_ Create_Protrusion_Revolve profile_sketch start_angle end_angle flip = TRUE flip = FALSE X Y XML-based definition

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

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

20. 20 iCAD Laboratory, KAIST Enabler of the Web-based DEX service  Web DEX Service MP Translators XML Schema  Web DEX Service MP Translators XML Schema DevicesBrowsers Internet via HTTP The 3 rd Party Translator Development Tools The Macro-Parametric Organization  C3PE System Operating System and Local Devices Run Time Call Web Service Provide Application Access Your Application Provide Web Service Conformance Testing Release TranslatorsDeploy MP Description Notes: MP (Macro Parametric) DEX (Data Exchange) XML-based definition

21. 21 iCAD Laboratory, KAIST 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. 22 iCAD Laboratory, KAIST 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