Strategies for the curation of CAD Engineering Models

Strategies for the Curation of CAD Engineering Models 4th International Digital Curation Conference "Radical Sharing: Transforming Science?“ 1 st -3 rd December 2008 Edinburgh, UK Manjula Patel, Alexander Ball, Lian Ding UKOLN, DCC, IdMRC University of Bath, UK

Overview
Need for long-term data retention and curation in engineering
Product-Service Paradigm
Product Lifecycle Management (PLM)
Switch to creating engineering data digitally
Importance of Computer Aided Design (CAD) models
Specific curation challenges
Prototypes
LiMMA: Lightweight Models with Multilayered Annotation
RRoRIfE: Registry/Repository of Representation Information of Engineering

Product-Service Paradigm
Products are being purchased and sold as services rather than artefacts
Commitment to provide support for lifetime of product –could be 50 years or even longer!

Product Lifecycle Management
Management of product data across an (extended) enterprise over the entire lifecycle of a product
Gained prominence over the last decade or so
Globalisation has led to collaborative practices
Product development, manufacture and maintenance occur in a geographically distributed and networked environment
Product data dispersed over many organisations and locations

PLM Information Flows Conceptualisation; Design Organisation; Design; Evaluation; Manufacture & Delivery; Sales & Distribution; Service & Support; Decommission & Disposal Pre-existing information & experience Design team Design team In service In service Upgrade Production In service In service Upgrade Production Design Product 1 Product 2 Partners Regulators Customers

Product Lifecycle Management (1)
Efficient capture, representation, organisation, retrieval and reuse of product data over its entire life
Sharing of product information between many distributed organisations
Issues relating to security of information and Intellectual Property
Large variety of data, information and knowledge
Structured e.g. Geometric models and databases; test data (photographs, images, load diagrams, finite element analyses); manufacturing process plans; assembly plans; production and manufacturing logs; maintenance and service data;
Unstructured e.g. email; minutes of meetings; design reviews; contracts
Tacit knowledge e.g. design rationale; lessons learnt; procedures and processes
Exchange of information between heterogeneous computer systems
CAD/CAE/CAM (Computer Aided Design/Engineering/Manufacture)
ERP/CRM/SCM ( Enterprise Resource Planning/ Customer Relationship Management/ Supply Chain Management)

Product Lifecycle Management (2)
Different stages of PLM require different subsets and interpretations of the same data i.e. different viewpoints
e.g. Manufacturing engineers need machining features and tolerances Marketing staff need a final visualisation of the product
Data needs to be trustworthy, reliable and accurate for use in downstream processes
Vital to actively manage all information and data related to a product
Legal issues e.g. accident investigation; failure analysis; mergers and acquisitions; patent infringement
Operational support e.g. maintenance; replenishment of spare parts; recycling; disposal
Product development and management e.g. tracing design rationale; design reuse; customisation and upgrade; reverse engineering; test and validation
Various PLM systems under development (e.g. Arena, EDS, Dassault, MatrixOne, PTC etc.)
At present, no one single system capable of managing the entire product lifecycle

Curating CAD Model Data (1)
Computer Aided Design (CAD) models
Important in engineering practice
Definitive record of product data
Gradually superseding paper-based workflow
Communication of design to manufacturers, builders, maintenance crews and regulatory authorities
CAD software and file formats
An array of commercial CAD systems e.g. AutoCAD; CATIA; ProENGINEER; SolidWorks
Proliferation of CAD formats; proprietary, closed and subject to frequent change (unsuitable for data exchange as well as long-term preservation)
Complex dependencies and relationships between file formats, hardware and software (processing is often tied to hardware features to improve performance)
Interoperability between CAD software is virtually non-existent
Economically unviable to install and run multiple CAD systems
Product is likely to outlive several generations of the software used to design and create it!

CAD File Formats

Curating CAD Model Data (2)
CAD models comprise large volumes of data
A single, simple component can be several Megabytes
Complex products (e.g. cars, aircraft) can amount to several Gigabytes or even Terabytes
Reducing 3D model to 2D hard-copy documentation
Entails considerable information loss; also constrains reuse of data
Emulating old software and hardware
Heavy investment in IT support
Difficulties with integration into complex and more modern workflows and systems
Migration to successive proprietary formats
Risk of data loss and subtle design corruption
Rechecking and revalidating costs are substantial
Use of open standards e.g. IGES, STEP
Long timescales make it difficult to keep up with latest capabilities of CAD tools
Level of support for standards is variable between tools
[Extension of STEP for various stages of PLM underway]
Complex and dynamic environment
Difficult to reliably retrieve and trace provenance information to check reliability and quality of data
Mergers, acquisitions etc.

CAD Model Representations
Used in Design, Manufacture and Evaluation phases of PLM
Product information stored is still largely based on conventional product representations (geometry, topology)
Procedural definitions e.g. CSG
Explicit representation based on underlying mathematical forms e.g. B-rep
Free form surface modelling e.g. NURBS or Bézier
Feature-based (pre-defined parts) or parametric modelling
Typical components of a CAD Model
Geometry
Dimensions
Tolerances
Materials
Feature semantics
Model history

Challenges for CAD Models
For CAD models to support information flows in PLM, they need to address:
Protection of commercially sensitive information ( Intellectual Property )
Generation of viewpoint specific representations to support differing processes and users
Rapid sharing of information between geographically distributed applications and users (interoperability, platform and application independence, use of standards, reduced file sizes etc.)
Support for recording feedback from downstream processes
Curation (recording of metadata, design rationale, open formats, Representation Information, use of standards etc.)

Proposed Strategy
To extend a CAD model from the design stage into all the phases of a product’s lifecycle, we propose the use of:
LiMMA: Lightweight Models with Multilayered Annotations
Combines open, lightweight CAD models with annotations to augment geometric data with supplementary information from PLM phases
RRoRIfE: A registry/repository of Representation Information for Engineering Information
Supports decisions relating to migration of file formats for continuous and long-term access and reuse

Lightweight CAD Formats (LWFs)
Simpler formats : do not retain all the richness of a native CAD model
Analogous to the notion of desiccated formats
Reduced file sizes via compression techniques
Platform and application independent
Easier to curate and preserve
Simpler and more open specifications
Wider and more affordable software support
Smaller files sizes support distributed exchange
Only contain as much information as a particular recipient needs
Variety of LWFs in current use:
Universal 3D, 3D XML, JT Format, PLM XML, PRC, X3D, XGL/ZGL
Each with properties better suited to some purposes than others
Suitable for access, collaboration and dissemination as well as preservation
Alleviate collaborative exchange, offer customised views, security of IP, application independence, reduced file sizes etc.

Multilayered Annotation
Need feedback from downstream processes
Augment geometric model with information from different phases of PLM
Annotation allows incorporation of varied information:
Design rationale, in-service data and other information useful in an iterative design process e.g. context, provenance etc.
Extra information needed for a certain viewpoint
Embedding of security levels to restrict access to certain partners or users
“ stand-off” (vs. “in-line”) annotation
Stored separately to CAD model; actual model unchanged
Can be selective about which annotations are shared
Same annotation can be applied to derivatives of full CAD model
Use of XML for machine-processing

LiMMA LiMMA (Lightweight Models with Multilayered Annotations)
A framework for representing CAD models using LWFs with additional layers of XML-encoded Annotations
Annotation layers for
different viewpoints e.g. design, manufacture, service, marketing
different security and access levels

LiMMA LiMMA (Lightweight Models with Multilayered Annotations) 1. Designers create several annotation documents, at the same time as the CAD model.

LiMMA LiMMA (Lightweight Models with Multilayered Annotations) 2. CAD model can be derived to different LWFs for different users requiring different viewpoints: e.g. PRC for manufacturing engineers; JT for assembly engineers

LiMMA LiMMA (Lightweight Models with Multilayered Annotations) 3. All users throughout the product lifecycle are able to feedback their knowledge and experiences through annotations rather than modifying the CAD model itself. e.g. service staff can provide information regarding wear and tear.

Annotation Environments Annotation interfaces in UGS NX CAD package and 3D PDF viewer Adobe Acrobat

OAIS Representation Information
A wide range of LWFs with differing characteristics are available
Need format appropriate not only for a particular use and view of the product, but also for long-term retention
Open Archival Information System (OAIS) Reference Model
Preservation and curation environment for all types of data
Developed by CCSDS, published as ISO 14721:2003
Defines a functional model and an information model
Representation Information is any information required to render, interpret, process and understand data
e.g. Software tools for rendering and interpretation; file format specifications and references; conventions and semantics used
Essential for both curation and contemporary use
A planning tool - Registry/Repository of Representation Information for Engineering (RRoRIfE)

RRoRIfE (1)
Holds two XML schemata (derived from engineering use cases) relating to:
significant properties of CAD file formats e.g. 2D and 3D geometric entities; modelling history; size; compression; geometry-related metadata (e.g. tolerances, finishes)
characteristics of processing software ; record of how well each property is preserved for each format conversion –None; Good; Fair; Poor
Ball, Patel & Ding paper –iPRES 2008
Registry/Repository of Representation Information for Engineering

RRoRIfE (2)
Characteristics of file formats and conversion tools
Select a characteristic and see which format supports it
Generate possible migration pathways between two formats
Given a start format and significant characteristics, generate a list of suitable destination formats and conversion pathways
Facilitates simple preservation planning queries:

Further Work & Conclusions
Further Work
Develop a more integrated framework
Persistent identification of geometry between native CAD formats and the LWFs derived from them
RRoRIfE: accumulate a corpus of information on significant properties of file formats and characteristics of conversion tools
Non-intrusive and automated capture of information in PLM
Selection and appraisal of product lifecycle data
Conclusions
Digital curation challenges posed by PLM are significant
Several tools and techniques specific to improving the robustness and sustainability of CAD file formats
LiMMA: Lightweight Models with Multilayered Annotations
RRoRIfE: Registry/Repository of Representation Information for Engineering information

Questions?
Thank you
Manjula Patel
UKOLN, University of Bath, UK
[email_address]
www.ukoln.ac.uk
Digital Curation Centre UKOLN, University of Bath Innovative Design & Manufacturing Research Centre Knowledge and Information Management Through Life (Grand-Challenge) Project

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Strategies for the curation of CAD Engineering Models

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Strategies for the curation of CAD Engineering Models — Presentation Transcript