A charge coupled device star sensor system for a low earth orbit microsatellite

Greyling, B. C.(Barend Christiaan) (1995)

Thesis (M. Ing.) -- University of Stellenbosch, 1995.

Thesis

ENGLISH ABSTRACT: Star sensor systems provide extra accuracy to the attitude determination and control systems of spacecraft These systems are generally complex and costly. This text describes the development of a low cost CCD star sensor system to meet the needs of a low earth orbit micro satellite. The attitude accuracy of this satellite is low (3 arc minutes) compared to other systems. This makes the use of cheaper and less sophisticated equipment possible. An investigation was done into the system as a whole with more detailed study of the camera electronics, processing of the stellar image and pattern recognition techniques for finding the attitude. In all sub-sections of the system an attempt has been made to optimise the space of electronics and processing time of algorithms in keeping with the requirements of a micro satellite. Algorithms for image segmentation, centroid determination, pattern recognition and attitude calculation were implemented and developed. A prototype star camera was developed using the TC211 CCD and a Cosmicar lens in order to gain experience in CCD camera design and show that such a low cost system is feasible. It was found that such a project for the development and implementation of a star sensor system for a micro satellite is within reach of a small project group with limited resources and that this paper could serve as basis for such a venture .

AFRIKAANSE OPSOMMING: Stersensorstelsels verskaf ekstra akkuraatheid aan die standbepaling- en beheerstelsels van ruimtetuie. Sulke stelsels is gewoonlik ingewikkeld en duur. Die ontwikkeling van 'n lae koste CCD-stersensorstelsel om die behoeftes van 'n lae-aardwentelbaan mikrosatelliet te bevredig, word hi er beskryf Die standakkuraatheid van hierdie satelliet is laag (3 minute) in vergelyking met ander soortgelyke stelsels. Dit maak die gebruik van goedkoper en minder gesofistikeerde apparaat moontlik. 'n Ondersoek is gedoen na die algehele stelsel met meer noukeurige studie van die kameraelektronika, verwerking van die sterrebeelde en patroonherkenningstegnieke vir standbepaling. Daar is in die analise van alle substelsels gepoog om die ruimte wat die elektronika beslaan en die uitvoertyd van algoritmes te optimiseer in tred met die vereistes van 'n mikrosatelliet. Algoritmes vir beeldsegmentering, beeldswaartepuntbepaling, patroonherkenning en standberekening is ontwikkel en gei:mplimenteer. 'n Prototipe sterkamera is ontwikkel met die gebruik van die TC211 CCD en 'n Cosmicar lens om ondervinding in CCD-kameraontwerp in te win en te wys dat 'n lae koste stelsel lewensvatbaar is. Daar is bevind dat 'n projek vir die ontwikkeling en implimentering van 'n stersensorstelsel vir 'n mikrosatelliet binne die bereik is van 'n klein projekspan met beperkte hulpbronne en dat hierdie tesis as basis kan dien vir so 'n ondememing.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/54625
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