Flight Results from the SHEFEX2 Hybrid Navigation System Experiment

Abstract

The Hybrid Navigation System was flown on the second SHarp Edge Flight EXperiment sounding rocket mission on June 22, 2012 from Andya Rocket Range in Norway by the German Aerospace Center (Deutsches-Zentrum f�ur Luft- und Raumfahrt, DLR). The 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. 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, although it did not meet its performance requirements. The Hybrid Navigation System software is now at TRL 7.