Abstracts Category : Other

Combined Attitude and Orbital MPC for Thruster Based Spacecrafts

by Joakim Lilja

A spacecraft needs to simultaneously provide orbital and attitude controlbut these are in general treated as separate systems. Normally the attitudecontrol is conducted via reaction wheels but can in scenarios with high manoeuvrabilitydemands be handed over to pure thruster control. In specificcases the reaction wheels are removed from the spacecraft to save mass. Ifboth the orbital and attitude control is regulated with thrusters, there is apotential to save fuel in a combined control strategy. Model predictive controlhas been shown to be a viable method for orbital control with a fuel minimisingobjective. This thesis investigates a combined orbital and attitude model predictivecontrol strategy. Three test cases are simulated with a specific thrusterconfiguration; maintaining a passive orbit relative to a target, large-angle reorientationand repositioning, and rendezvous. Preliminary results show thatincluding the coupled dynamics lowers the overall fuel consumption while satisfyingrequirements on position and attitude in scenarios where the timescaleof the orbital and attitude control is similar. En rymdfarkost behver simultant reglera bde omloppsbana och attityd,men vanligtvis hanteras detta av tv separata system. Normalt styrs attitydregleringenav reaktionshjul men kan i scenarion med hga krav p manvrerbarhetistllet sktas av styrraketer. I speciella fall tas reaktionshjulen bort fr attspara p massa. Om bde omloppsbana samt attityd regleras via styrraketerkan det finnas en potential att spara brnsle genom en kombinerad reglerstrategi.Modellprediktiv reglering (MPC) har visats vara en kapabel metodfr reglering av omloppsbana med ett brnsleminimerande ml. Denna uppsatsundersker en kombinerad MPC fr attityd och omloppsbana. Tre testfallr simulerade med en specifik konfiguration av styrraketer; bibehlla en passivbana relativt ett ml, stor omorientering och ompositionering samt rendezvous.Preliminra resultat visar att om hnsyn tas till den kopplade dynamiken, kanbrnslefrbrukningen minskas i scenarion dr tidsskalan fr regleringen av attitydoch omloppsbana r liknande.