model-correlation

Thermal Model Correlation Using Genetic Algorithms

Contacts

Frédéric Jouffroy, EADS Astrium

James Etchells, ESA/ESTEC

Background

The correlation of Thermal Mathematical Models (TMMs) with test data is a particularly challenging activity because it happens just before the final flight predictions when the project is on the critical path. Current methods for correlation of TMMs typically rely on a heuristic approach which requires a great deal of manual work. This often yields results which are barely satisfactory, in terms of accuracy, but extremely costly, in terms of engineering time.

Although current methods for TMM correlation are predominantly manual, there are, in principle, a variety of different optimisation algorithms that could be used to automate or semi-automate the process. Among these stochastic techniques, Genetic Algorithms (GA) seem well suited to the problem in question and, furthermore, they have already been used by Astrium (and others) for post-test mechanical model correlation.

In 2005-2006 a joint CNES-Astrium R&D activity was initiated with the objective of verifying the feasibility of correlating thermal models to test results using GA. The conclusions of this study were that, although promising results were obtained, more work was required to obtain a well established and generic methodology suitable for use on space projects.

Using the 2005-2006 CNES activity as a starting point, two further activities were intiated in 2006-2007, the current activity (ESA/ESTEC contract No. 19840/06/NL/PA) sought to:

1. continue to assess the applicability of genetic algorithms for TMM correlation
2. evaluate the possibility of using alternative optimisation techniques (either stochastic or deterministic)

Additionally, a second CNES-Astrium R&D activity was started to investigate further the localisation of errors in TMMs

In order to draw on more experience in the field of optimisation, a cooperation was established between Astrium and the Laboratoire d’Optimisation Globale (DSNA/SDER/LOG), located at the École Nationale de l’Aviation Civile (ENAC) in Toulouse.

Material Available for Download

The following material is available for download on this website:

Document Summary for ESA Study

File Name	Document Title
thcor-asf-005-rpt.pdf	Bibliography study of optimisation methods with focus on genetic algorithm techniques w.r.t. post-test thermal model correlation problem
thcor-asf-006-tn.pdf	Test plan & test models for verification of post-test thermal model correlation by using a stochastic global optimisation method
thcor-asf-013-tn-1.pdf	Verification of feasibility of post-test thermal model correlation by using genetic algorithms: analysis of test plan results
GeneticAlgorithms.pdf	Presentation given at the 2007 European Workshop on Thermal and ECLS Software

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