Modelling and evaluation of adaptive control techniques in satellite orientation during large actuator gain changes

Rossouw, Jacques Stefan (2004-04)

Thesis (MScEng)--University of Stellenbosch, 2004.


ENGLISH ABSTRACT: Improvements in the area of satellite orientation control in the presence of large actuator gain changes are investigated. Gain changes primarily originate from actuator failures, but may also result from intermittent sensor availability and geomagnetic field effects. The stability and performance of a classic LQR control solution under these conditions is analyzed through simulation, and two adaptive schemes are developed to improve the response. The adaptive schemes mix elements from bang-bang control to increase performance, and banded control to increase robustness. These control schemes are thoroughly tested through simulation and the results are compared with those obtained for the classic solution. Extensive modelling of the system in the MATLAB™ environment is done to support the analysis of the controllers, and hardware sensors are built to provide realistic orientation measurements to the controllers.

AFRIKAANSE OPSOMMING: Verbeterings in die veld van satelliet oriëntasie beheer in die gevalle waar die aktueerders groot veranderinge in aanwins toon, word ondersoek. Aanwins veranderinge word primêr veroorsaak deur aktueerder falings, maar kan ook deur diskontinue sensor metings en magneetveld effekte van die aarde veroorsaak word. Die stabiliteit en gehalte van 'n klassieke LQR beheer strategie onder hierdie omstandighede word ondersoek deur simulasie, en twee aanpasbare beheer strategieë word ontwikkelom die oordrag te verbeter. Die aanpasbare beheer strategieë meng elemente van "bang-bang" beheer om die gehalte te verbeter, en gebande beheer tegnieke om die robuustheid van die stelsel te verbeter. Hierdie beheer strategieë is deeglik in simulasies getoets en die resultate is vergelyk met dié van die klassieke beheerder. Ekstensiewe modelleering van die stelsel is in die MATLAB™ omgewing gedoen om die beheerders te analiseer, en hardeware sensore is gebou om realistiese orientasie metings aan die beheerders te verskaf.

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