step protocol development and converter implementation processes at esa hans peter de koning -...
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STEP Protocol Development and Converter Implementation Processes
at ESA
Hans Peter de Koning - ESA/ESTEC - The [email protected]
Sandrine Fagot - Simulog - [email protected]
STEP for Aerospace Workshop, NASA-JPL, 16-19 January 2001
Sheet 216-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Topics
• What is Europe doing w.r.t. standardisation of product data exchange & archival for space applications?
• How did we develop STEP based solutions?• What successes?• What lessons learned?• Road ahead
Sheet 316-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
What is Europe doing?
• ECSS E-10-07 WG “Exchange of Product Data”– European Cooperation for Space Standardization– High level ‘meta-standard’ like NASA-STD-2817
• www.estec.esa.int/ecss
• ftp://ftp.estec.esa.nl/pub/ecss-e-10-07-wg/index.html
• Specific standards– STEP-TAS “Thermal Analysis for Space” (ESA)– STEP-NRF “Network-model Results Format” (ESA)– STEP-PRP “Propulsion” (CNES) (CNES = French Space Agency)– Active role AP232 “Technical Data Package” (CNES + Industry)– Active role AP233 “System Engineering” (Aerospace Industry)
w.r.t. standardisation of product data exchange & archival for space applicationsw.r.t. standardisation of product data exchange & archival for space applications
Sheet 416-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Focus of this presentation
• Development process of STEP-TAS and STEP-NRF• Achievements, some metrics and lessons learned• Objective:
To provide useful feedback for others contemplating to develop similar ‘niche’/specific purpose standards
Sheet 516-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Main characteristics NRF (1)Network-model Results Format
• Targets engineering-discipline independent exchange of bulk results data from analysis, test or operation– Representation of engineering objects by network models
consisting of discrete nodes and node-relationships– Hierarchical tree of network models / submodels– Definition of properties
• Quantitative, descriptive and functional properties
• Scalar, vector and tensor property values
• Property values only at discrete locations / discrete states
– Full annotation of analysis / test / operation context• Campaign, case, phase, run
• Facility/tool, environment, date and time, organisation, person, ...
Sheet 616-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Main characteristics NRF (2)NRF dataspace
abscissa_property
mod
el_c
ompo
nent
(mod
el,
node
, no
de_r
elat
ions
hip)
stat
e
prop
erty
_cla
ss
Each gridpoint in the 3D dataspace is a property value
Each can be scalar, vector, tensor
Data model and implementation designed to handle sparsely populated dataspace efficiently
Sheet 716-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Main characteristics NRF (3)Proposed NRF/HDF architecture
STEP-NRFprotocol
(discipline- independent)
NRFDictionaryStructural
NRFDictionaryThermal
NRFDictionaryElectrical
NRFDictionary
...
STEP-NRF SDAIprogramming library
HDF 5programming library
NRF – HDF mapping
HDF5binary
results file
User Application(Reading or Writing
Results Data)
AP203STEP file AP209
STEP file(future)
reference to product (-part),shape, location
reference to FEM / FE
COTS or PDData Analysis / Visualisation
Application with HDF i/f(also via WWW)
discipline-specific dictionaries
HDF5 = Hierachical Data Format v5- Public domain from NCSA- Efficient portable binary storage format- Full C, Fortran, Java libraries on >10 platforms- Standard for all NASA EOS missions and some ESA earth observation- Info/downloads at hdf.ncsa.uiuc.edu- Many COTS / PD tools with HDF interfaceHDF5 as an
efficient alternative for Part21for large amounts of similar data
Sheet 816-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Main characteristics TAS (1)Thermal Analysis for Space
• Self contained, complete Application Protocol– AAM, ARM, Mapping Table, AIM, Express-G– Conforms to TC184/SC4 methods and guidelines– Geometry defined conform AP203 CC4 surface model– Thermal-radiative model faces added as associated features
• Including possibility to support hierarchical submodel tree
• Associated notional thickness, surface material and bulk material
• Thermo-optical, thermo-physical properties for named material
• Concept of material property environment (Part 45)
– Kinematic model conform STEP Part 105• For articulated rigid bodies (e.g. rotating solar arrays, ...)
Sheet 916-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Main characteristics TAS (2)
– Space mission aspects• orbit arc (Keplerian and discrete ephemeris)
• space co-ordinate system, celestial bodies
• orientation, general and named pointing, spinning, linear rotation rates
• space thermal environment, including constant or lat/long dependent albedo / planetshine tables
– Boolean construction surfaces available for advanced tools– STEP-TAS CC1 Abstract Test Suite
• conform STEP Part 3xx series
• test suite used in validation of TAS processors
Sheet 1016-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Main characteristics TAS (3)STEP-TAS Conformance Classes
thermal-radiative model with basic geometry
kinematic model
constructivegeometry
space missionaspects
CC-1
CC-2
CC-3
CC-4
CC-5
CC-6
Sheet 1116-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Brief history TAS and NRF developments
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
SET-ATS precursor (French standard, CNES)
ESA R&D project “Thermal neutral formats”
TAS protocol (pure extension of NRF)
Space IR and NRF protocol
Programming libraries v1 with C & F77 API / porting 5 platforms
Abstract test suite TAS-CC1 / roundtrip ESARAD/STEP-TAS
Prototype NASA-JPL, import in TSS, export from TRASYS
Editorial update protocol to TC184/SC4 MS-Word format
Production release ESARAD/STEP-TAS-CC1 converter
Porting F77 API 5 platforms; Thermica/STEP-TAS-CC1 converter (Astrium)
US STEP-TAS pilot (JPL, 5 thermal tool vendors)
Thermal Desktop/STEP-TAS-CC1 converter (C&R, NASA-LaRC)
Large model cross validation ESARAD & Thermica; update architecture and libraries
Sheet 1216-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Challenge
• Find an effective development process– Within modest budget constraints– TAS for a ‘niche’ market
• Between 20 to ~300 real users per space thermal analysis tool
– Make sure that user requirements are well captured– Ensure implementations can be, and are, validated– Facilitate efficient and maintainable converters– Attempt to obtain global consensus
• Ensure robustness and ease of use for end-users
Sheet 1316-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Incremental development scheme
Define / Refine / Extend Protocol
(ARM, AIM, Express)
Develop / UpgradeLibraries
Develop / UpgradeConverters
& Test Suites
ValidateConverters
with Test Suites
Sheet 1416-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Stable Team with Clear Roles
• Simulog (F, software engineering services)– lead since 1998, implementation libraries and some converters
• Fokker Space (NL, space subsystems contractor)– initial lead, user requirements, ARM, ATS
• GOSET (F, STEP standardisation experts)– mapping table, AIM, EXPRESS/p21 verification
• Epsilon Ingénierie (F, thermal analysis services)– check user requirements, converter implementation
• ALSTOM Power (UK, thermal tool vendor)– converter implementation, distribution to end-user
• CNES (F, French Space Agency)– Review requirements and model, generation of test suites
Sheet 1516-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Approach to Developing with STEP
• Be as precise as possible on semantics– Regular feedback between protocol editor and implementors
• Minimise ARM - AIM mapping need as much as possible– Use IR contructs where possible direct in ARM
• Automate generation of library APIs as much as possible– Directly from EXPRESS model
• Design for simplicity, implementability and testability– E.g. do not use EXPRESS ANDOR
• Use a high level programming interface to build converters• Use an SDAI toolkit for low level interface
Sheet 1616-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
STEP-TAS High Level Libraries Toolkit
• High-level API to support efficient converter development– Use ARM constructs - close to thermal developer’s data model– Hide STEP complexity– Full set of reading / writing functions in ANSI-C and F77– Associated documentation, examples and test suite
• BagheraView (CNES) included to perform independent visual inspection and model reporting on PC/Windows
• Distribute toolkit at nominal cost to attract tool vendors
API = Application Programming Interface
Sheet 1716-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
BagheraView Screenshot
Sheet 1816-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Benefits of High Level Libraries Approach
• Already ported and tested with target compilers– PC/Windows, Sun/Solaris, HP/HP-UX, Compaq/Tru64, SGI/Irix
• Enables to jumpstart converter implementation• Reduces converter validation / verification effort• All converters share reading/writing interface
– implementation mismatch is minimised– increased reliability
• Extensibility at affordable cost– e.g. to add HDF or XML encoding
Sheet 1916-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
STEP-TAS
EXPRESS
data model
STEP-TAS
EXPRESS
data model STEP-TAS
physical
file
(ISO 10303-21)
STEP-TAS
physical
file
(ISO 10303-21)
Thermal Analysis Tool(ESARAD, THERMICA, TRASYS, …)
Thermal Analysis Tool(ESARAD, THERMICA, TRASYS, …)
STEP-TAS High Level LibrariesC and Fortran API(Simulog, France)
STEP-TAS High Level LibrariesC and Fortran API(Simulog, France)
SDAI C Library (ISO 10303-24)ST-Developer
(STEP Tools Inc., USA)
SDAI C Library (ISO 10303-24)ST-Developer
(STEP Tools Inc., USA)
STEP-TAS Converter Architecture
Native
Tool
Format
Native
Tool
Format
Sheet 2016-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Successes …
• Full implementation of converters at reasonable cost– ESARAD/STEP-TAS-CC1 since mid 1999– Thermica/STEP-TAS-CC1 since Dec 2000
• Broad awareness and (prototype) implementation in US– JPL STEP-TAS demonstrator in 5 US thermal tools– Full bi-directional implementation STEP-TAS-CC1 in Thermal
Desktop 3.3Beta (Cullimore & Ring sponsored by NASA-LaRC)
• Reached almost 100% of space thermal tool vendors• Very close to robust and reliable quality exchange for
STEP-TAS-CC1 in production tools
Sheet 2116-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
… Problems with STEP
• Bulkiness and incomprehensibility for humans of AIM• Makes validation cumbersome and costly
• Causes large overheads
• Additional in-core storage
• Addition interface layer in library
• Part21 files much larger than really really necessary
• ARM to AIM mapping is not computer interpretable• EXPRESS-X was not available for TAS: a lot of handwork for high
level library interface mapping
• Conformance checking / Abstract Test Suite (Parts 3x)• Very cumbersome and costly to develop and maintain
• Not well designed for automation of regression testing
Sheet 2216-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Lessons Learned
• Iterative, incremental development necessary– Can not get things right in one go …
• High level programming library very useful– Greatly reduces converter development effort– Speeds up standard penetration & increases exchange reliability– Chosen API close to old SET-ATS interface needs reconsideration
• Continuous resource / funding level is needed– To meet vendor expectations by providing timely support
and library updates resolving SPRs
• Communication must be improved– Start a ‘STEP-TAS implementors forum’ ?
Sheet 2316-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Metrics
• STEP-TAS took ~5 years from conception to CC1 industrial converter release
• Up to now funded with roughly 1 million Euro / USD– Excluding US converter developments– Appears to be a quite good price/performance ratio
• Approximately 20 different people have worked on different parts of STEP-TAS and STEP-NRF
Sheet 2416-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Why was STEP-TAS not yet submitted as an ISO TC184/SC4 work item?
• Valid question• Started as a European effort to follow up SET-ATS• Limited resources prevented us to bear the additional
effort of formal ISO standardisation - no added value yet• With the good co-operation with NASA in place,
nearly 100% of the space thermal tool vendors in the world were reached
• However it is agreed that a formal way of publishing and maintaining the standard is now needed imminently
Sheet 2516-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Road Ahead (1)
• Web-based collaboration on further development– ftp://ftp.estec.esa.nl/step-tas/index.html as a start– Publication of protocol, SPR list, test suite– FTP distribution of STEP-TAS toolkit releases– E-mail tech support
• Take European / US collaboration to a next stage– Action ESA and NASA together with Simulog– Clarify/establish intellectual property rights and support
Sheet 2616-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Road Ahead (2)
• Currently trade-off for ‘Return on Investment’ next 5 years– Appropriate level of formal publishing (ISO?, ECSS?, NASA?)– Select AIM or ARM based exchange?– Upgrade high level API to support all STEP-TAS constructs
• e.g. submodelling, non-uniform meshing and node numbering
• Upgrade libraries to resolve all reported issues (SPRs)• Upgrade converter options
– Consistently support length unit selection / conversion– Meta data entry
Sheet 2716-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Road Ahead (3)
• TRASYS/STEP-TAS-CC1 bi-directional converter– Stand-alone tool by Simulog on ESA funding
– Will be made available at nominal cost or preferrably free
• Upgrade BagheraView capabilities– By Simulog sponsored by CNES
• PATRAN/STEP-TAS-CC1 interface– By MSC sponsored by NASA-LaRC
• Continue NRF developments– HDF5 binding (co-operation with EDF, NCSA and others)
– Assess links with Engineering Analysis modules, ISO 10303-50
– Pilot web-based remote consultation of structural test results
Sheet 2816-19 Jan 2001 STEP for Aerospace Workshop - NASA-JPL
Acknowledgements
• STEP-TAS and STEP-NRF were developed under ESA contract by an industrial consortium, consisting of:– Simulog (F, prime)– Fokker Space (NL)– Association GOSET (F)– Epsilon Ingénierie (F)– Alstom Power (UK)
and supported by CNES (F)
• Special thanks to Georg Siebes (NASA-JPL) who is and has been the driving force for the development and acceptance of STEP-TAS in the US
• Also acknowledgements to Ruth Amundsen (NASA-LaRC)for actively promoting STEP-TAS implementations