Design and Implementation of a Navigation Postprocessing Framework for the Reusability Flight Experiment (ReFEx)

Abstract

Reusable Launch Vehicles (RLVs) have been growing in popularity for space exploration over the past years due to their promising improvement in safety and cost reduction when compared to disposable rockets. These vehicles need high-performance navigation systems to control and guide themselves autonomously throughout the desired trajectory. This thesis addresses possible improvements for the navigation system of the ReFEX mission conducted by the German Aerospace Center (DLR), in par�ticular, the implementation of a post-processing framework and the enhancement of the existing online navigation filter. The post-processing framework consists of two Raunch-Tung-Striebel (RTS) smoothers that complement both a 6 degrees of freedom (6DoF) extended Kalman filter and an aerodynamic vari�ables extended Kalman filter. The results obtained with a high-fidelity simulator validate the efficiency of the smoothing algorithm, where undesired drift error, error peaks, and noise are attenuated, especially for the 6DoF filter. The online navigation filter was enhanced by introducing new measurements to the aerodynamic filter and correcting existing ones, showing significant developments in the estimation of the angle of attack.