Autonomous Satellite Orbit Determination Based on Magnetometer and Sun Sensor Measurements : Design, Test and Verication

In preparation for the fourth satellite in the CubeSat program at the Julius-Maximilians-Universität in Würzburg, a real-time orbit determination algorithm was developed. Due to strict power and volumetric constraints, the goal was to make use of sensors already existing onboard the third satellite in the program, called UWE-3.The algorithm implemented is an Extended Kalman Filter (EKF) that makes use of magnetometer and sun sensor measurements in its update step. It is attitude independent as it uses only the norm of the magnetic field, and the cosine of the angle between the magnetic field and the sun vector. The propagation step models the satellite dynamics as a two-body problem with J2 perturbations. The update step uses the International Geomagnetic Reference Field (IGRF) and a model of the earth's movement around the sun as references.The filter was first tested with simulated measurements based on the orbit of UWE-3, followed by tests with real flight data from the satellite. Using the simulated measurements, the average root sum square (RSS) error of the absolute position was found to be 11.56 km. When using real flight data, this value increased to 22.24 km.Validerat; 20150901 (global_studentproject_submitter