|M.Sc Student||Linn Barnett Danna|
|Subject||Formation flying Control Using Line-of-Sight Measurements|
|Department||Department of Aerospace Engineering||Supervisor||Professor Emeritus Mauricio Guelman|
|Full Thesis text|
There are several concepts of space applications which require operating a satellite cluster in close formation, and one of the most useful formations is a “leader - follower” formation. The problem of reconfiguration of such a formation is addressed.
A controller was developed to enable a follower satellite to transfer from one relative elliptical orbit around the leader satellite to another, using a continuous low thrust engine. It is assumed that both satellites are in a formation around a planet. For simulation purposes a low Earth orbit was assumed. The maneuver has to be performed autonomously by the follower satellite, since the leader satellite is passive. The follower needs to get to the required relative orbit using only sensors that provide line-of-sight (LOS) relative range and angular rate to the leader satellite.
A model for relative motion using polar coordinates was developed and compared to the Clohessy-Wiltshire analytical solutions. Polar coordinate system was chosen to simplify the usage of the LOS measurements as well as allowing separation in the thrust activation directions. Control using continuous constant low thrust normal to the LOS direction, as well as a feedback controller, were developed. The performance of the controller was studied in the nominal and in the perturbed case with J2 perturbations effects. Simulations show that the achieved maneuver can be performed in a few orbits and with a small amount of fuel.