Processing of onboard images to assist automatic forward motion compensation for micro-satellites

Mouton, Christiaan J. (2003-03)

Thesis (MScEng)--Stellenbosch University, 2003.

Thesis

ENGLISH ABSTRACT: South Africa's first micro satellite, SUNSAT, was operational in orbit for 23 months since its NASA-sponsored launch on February 23, 1999. SUNSAT is a graduate studentdeveloped satellite from the University of Stellenbosch in South Africa. Research work is in progress on improving SUNSAT's 15m multi-spectral imager to a 2.5m-resolution multi-sensor imager. This will require the use of Forward Motion Compensation for exposure control. This thesis presents Automatic Forward Motion Compensation for Micro Satellites using a new earth sensor that measures the bore-sight projection's speed on the earth directly. This sensor will have no drift and will make use of a series of images and crosscorrelation of them. The high-resolution imager's bore-sight motion can be controlled by this technique to ensure high quality stereo images. A control system based on the DLR-TUBSAT was designed and is simulated in MATLAB. This technique of measuring the bore-sight projection's speed on the earth directly was tested on a 2-axis telescope and used to measure random movement of a satellite.

AFRIKAANSE OPSOMMING: SUNSAT, Suid Afrika se eerste satelliet was vir 23 maande in werking in 'n wentelbaan na sy NASA-geborgde lasering op 23 Februarie 1999. SUNSAT is 'n satelliet wat ontwikkel is deur nagraadse studente aan die Universiteit van Stellenbosch. Navorsingswerk is aan die gang om SUNSAT se 15m resolusie multi-spektrale kamera te verbeter tot 'n 2.5m resolusie multi-sensor kamera. Die navorsing sal die gebruik van Voorwaartse Bewegingskompensasie benodig. Die tesis handeloor automatiese voorwaartse bewegingskompensasie vir mikrosatelliete deur gebruik te maak van 'n nuwe aardgerigte sensor, wat die siglyn projeksie se snelheid op die aarde direk sal meet. Die sensor sal gebruik maak van 'n reeks foto's wat gekruiskorreleer word en sal geen tempo-wegdrywing hê nie. Hoë resolusie kameras se siglyn kan deur middel van hierdie tegniek beheer word om hoë kwaliteit stereo foto's te verseker. 'n Beheerstelsel wat gebaseer is op dié van DLR-TUBSAT, is ontwerp en is gesimuleer in MATLAB. Die tegniek om die siglyn projeksie se snelheid op die aarde direk te meet, is getoets op 'n 2-as teleskoop en is gebruik om onverwille keurige beweging van 'n satelliet te meet.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/53559
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