Browsing by Keyword "Space vehicle"
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Item Correlation of thermal mathematical models for thermal control of space vehicles by means of genetic algorithms(2015-03) Anglada, Eva; Garmendia, Iñaki; CIRMETALThe design of the thermal control system of space vehicles, needed to maintain the equipment components into their admissible range of temperatures, is usually developed by means of thermal mathematical models. These thermal mathematical models need to be correlated with the equipment real behavior registered during the thermal test campaign, in order to adapt them to the real state of the vehicle "as built". The correlation of this type of mathematical models is a very complex task, usually based on manual procedures, which requires a big effort in time and cost. For this reason, the development of methodologies able to perform this correlation automatically, would be a key aspect in the improvement of the space vehicles thermal control design and validation. The implementation, study and validation of a genetic algorithm able to perform this type of correlation in an automatized way are presented in this paper. The study and validation of the algorithm have been performed based on a simplified model of a real space instrument. The algorithm is able to correlate thermal mathematical models in steady state and transient analyses, and it is also able to perform the simultaneous correlation of several cases, as for example hot and cold cases.Item Thermal mathematical model correlation through genetic algorithms of an experiment conducted on board the International Space Station(2016-05-01) Garmendia, Iñaki; Anglada, Eva; CIRMETALGenetic algorithms have been used for matching temperature values generated using thermal mathematical models against actual temperatures measured in thermal testing of spacecrafts and space instruments. Up to now, results for small models have been very encouraging. This work will examine the correlation of a small-medium size model, whose thermal test results were available, by means of genetic algorithms. The thermal mathematical model reviewed herein corresponds to Tribolab, a materials experiment deployed on board the International Space Station and subjected to preflight thermal testing. This paper will also discuss in great detail the influence of both the number of reference temperatures available and the number of thermal parameters included in the correlation, taking into account the presence of heat sources and the maximum range of temperature mismatch. Conclusions and recommendations for the thermal test design will be provided, as well as some indications for future improvements.Item Thermal parameters identification in the correlation of spacecraft thermal models against thermal test results(2022-02) Garmendia, Iñaki; Anglada, Eva; CIRMETALTemperatures predicted by the Thermal Mathematical Models (TMMs) used in the thermal control design of spacecraft, usually present differences with the values measured during the thermal test campaign. Therefore, the TMMs must be correlated with the thermal tests to reduce these differences to admissible values. This task can be addressed in an automatized way considering the correlation as an optimization problem, where the differences between predicted and measured temperatures are minimized. This is achieved modifying the values assigned to some parameters used in the TMMs. The main drawback of this approximation is the risk of loosing the physical sense of some model parameters. The reason is that the thermal inverse problem, that is, calculate the thermal parameters that produce a specific temperature distribution, often has not a unique solution. A methodology of automatized correlation to calculate the correct values of the model parameters, in the sense that they maintain its physical interpretation, is presented in this article. The key point relies in setting up an overdetermined system of equations. The expression to calculate the minimum number of load cases required, is developed, and several case studies are presented to validate the proposed methodology. A gradient based public available set of subroutines (TOLMIN) has been used as optimization algorithm.