ESA GNC Conference Papers Repository
Post-Mission Analysis of Flight Results from the SHEFEX-2 Hybrid Navigation System Experiment
On June 22, 2012 the SHEFEX2 mission (SHarp Edge Flight EXperiment) was launched from Andøya Rocket Range in Norway by the German Aerospace Center (Deutsches-Zentrum für Luft- und Raumfahrt, DLR). The purpose of the experimental vehicle was to test and verify re-entry technologies. One experiment onboard the SHEFEX2 vehicle was the Hybrid Navigation System. This on-board navigation algorithm fuses measurements from an IMU, GPS receiver and star tracker with a delayed extended Kalman filter to estimate a navigation solution over time. After the mission the in-flight navigation performance is calculated by comparing the navigation solution returned via telemetry to an accurate reconstruction of the trajectory. Trajectory reconstruction combines all available data sent via telemetry, more accurate state transition and measurement models and additional off-line information using the unscented Kalman filter and unscented Rauch-Tung-Striebel backward smoother. The reconstructed trajectory is computed off-line and is much more accurate than the in-flight navigation solution. Comparing the reconstructed trajectory to the telemetry data shows that the system behaved as expected. The Hybrid Navigation System software is now at TRL 7. The paper will give an introduction to the SHEFEX2 mission and the Hybrid Navigation System (HNS). It will present used navigation algorithms and the flight results including a comparison to the post-processed reconstructed trajectory.