Date: 29th April 2009
CAD unification helps Nimrod project
BAE Systems has used Theorem's Process Manager (TPM) CAD translation solution to migrate CADDS data into CATIA for the Nimrod MRA4 project. CADDS had originally been selected for wing design and CATIA was being used elsewhere on the airframe, and there were clear benefits to unifying the project onto a single CAD system if it could be done effectively and economically.
There were, however, significant challenges involved. BAE had built up a large CADDS database of designs comprising more than 120,000 models and drawings including standalone 2D drawings and model data, and 3D wire frame, surface data and solids - and all the various combinations. Standards based methods such as IGES or STEP would only assist in the migration of some elements of this data. Even a direct database CADDS to CATIA translator supplied by Theorem was unable to offer a full solution.
BAE was aware that while fully defined procedures existed for checking and validation of translations, these would need to be applied to migrated data to ensure that model and drawing integrity had not been compromised by the process. The project also demanded a detailed audit trail and traceability of every action taken throughout the migration.
For everything to be checked manually and the project completed within an acceptable time frame, significant additional manpower would be required, negating any perceived benefits. Prone to error, this would fail to satisfy one of the key project criteria of proving that the data was correct and consistent.
So, Theorem was asked to help identify and propose acceptable ways of overcoming these issues. Its standard CADDS to CATIA CADverter, already in use on this project, would translate 3D models and 2D geometry but not drawings. However, the enhancement of this module to meet BAE's specific needs solved the problem. It was decided to compare the two data sets immediately after translation when the target CATIA file had been written to disc.
A process was developed using Theorem's CADverter to translate all forms of CADDS geometry into CATIA format and carry out three comparisons on the source data and resulting destination data. Each entity in the source CAD file would be compared with its equivalent in the destination CATIA file. The data created by the checking process automatically created detailed reports.
The prospect of manually trying to interpret such documents was unacceptable. However, TPM provides the ability to 'read' all the detailed comparison logs and build summary and exception reports including detail from other system messages during the process. Data in the summarised results was compared with user defined 'range tables', and any translations that included values outside acceptable ranges were pinpointed and specific exception reports created, directing manual checking to the translations that showed potential problems - avoiding the need to check 'just in case'. TPM has therefore automated the checking process and removed one of the most labour intensive and significant cost overheads for BAE.
A by-product of applying TPM to the checking process has been that detailed audit trails are also automatically produced. This removes the need to create and validate an audit trail manually and further reinforces the effectiveness of the migration process to a point where the effort is readily justifiable and the anticipated benefits can be achieved.
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