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An executive master's programme thesis from Aalborg University
Book cover


Control of Satellite Swarms

Author

Term

4. semester

Publication year

2025

Submitted on

Pages

41

Abstract

Dette projekt undersøger, om to små CubeSats kan bruge magnetorquere til at danne en enkel sværm-formation. Magnetorquere er elektromagnetiske spoler, der skaber magnetfelter. Målet er, at satellitterne med magnetisk påvirkning kan tiltrække hinanden og stabilisere sig i en ønsket, fast indbyrdes afstand. Bevægelsen og den magnetiske kobling er stærkt ikke-lineær, så vi opstiller først en forenklet model og lineariserer den omkring det ønskede arbejdspunkt og flere nærliggende punkter. Det gør det muligt at anvende lineær tilstandsrum-kontrol med gain scheduling. Den ikke-lineære model analyseres og tilnærmes, bl.a. ved translation (forskydning af arbejdspunkt) og planlagte forstærkninger. Vi beregner desuden en fiktiv kraft, der repræsenterer den krævede magnetiske påvirkning for satellitter i forskellige baner omkring Jorden, som et minimumskrav for projektets gennemførlighed. På denne baggrund designer vi en observatørbaseret kontrolstrategi med fuld tilstands-feedback. Controlleren implementeres og afprøves i MATLAB/Simulink i forhold til de afledte krav.

This project investigates whether two small CubeSats can use magnetorquers to form a simple swarm. Magnetorquers are electromagnetic coils that generate magnetic fields. The goal is for the satellites to magnetically attract each other and settle at a chosen separation distance. Because the motion and magnetic coupling are highly nonlinear, we first develop an approximate model and then linearize it around the desired operating point and several nearby points. This enables a linear state-space controller with gain scheduling. The nonlinear system is analyzed and simplified using translation (shifting the operating point) and scheduled gains. We also compute a fictitious force that represents the required magnetic interaction for satellites in different Earth orbits, used as a minimum feasibility requirement. Based on this, we design an observer-based control strategy with full state feedback. The controller is implemented and tested in MATLAB/Simulink against the derived requirements.

[This summary has been rewritten with the help of AI based on the project's original abstract]