Auto-Coded Flight Software for the GNC VTVL Demonstrator EAGLE

The paper will present the simulation and on-board software design for the Vertical Take-Off, Vertical Landing (VTVL) demonstrator EAGLE (Environment for Autonomous GNC Landing Experiments) developed by the Department of Guidance, Navigation and Control Systems at the DLR Institute of Space Systems. The simulation and on-board software primarily relies on auto-coding, easing the effort of the iteration between simulation, preliminary hardware tests, and real flight software. EAGLE demonstrates Guidance, Navigation, and Control (GNC) functionality for planetary landers and reusable launch vehicles. The implemented design approach allows to successively implement or enhance algorithms through simulation (SiL, PiL, and HiL), quickly reaching a level of confidence for a real test flight. After the first tethered flight tests, this development cycle was tested to the full extend to implement a Mission and Vehicle Management system, that was required for automated lift-off and landing. The next feature to be added to the demonstrator is the capability to rely on a GNSS receiver to fly safely in a larger envelope. The satellite-based navigation is typically aided with correction data for precise positioning, but shall also work in absence of aiding information and under sub-optimal conditions. The full Hardwarein-the-Loop setup comprises the on-board computer, a dSPACE real-time system, as well as the Ground Station as part of the Electronic Ground Support Equipment (EGSE). This provides the opportunity to safely train the operations of EAGLE for developing and testing procedures for ultimately demonstrating free (untethered) flight.