Hardware-in-the-Loop Simulation of Rendezvous and Docking Maneuvers in On-Orbit Servicing Missions

On-orbit servicing (OOS) is of great significance with regard to spacecrafts’ lifetime extension and safe end-of-life de-orbiting. In an OOS mission a servicing satellite will approach a client/target satellite, will capture or dock on it and will take over its orbit and attitude control. This can be followed by additional maintenance tasks or by orbit maneuvers in a mated configuration. Rendezvous and docking (RvD) are considerably critical phases in such a mission and consequently RvD sensors and algorithms have to be verified and tested intensively. Therefore, DLR has established the second generation of a test facility called European Proximity Operations Simulator (EPOS 2.0) using robotic manipulators to generate the relative motion between two satellites. The last 25m of the rendezvous phase as well as the docking/capturing phase can be accurately simulated. This paper focuses on the rendezvous part to establish a hardware-in-the-loop (HIL) simulation of a close-range rendezvous process. As navigation sensor a monocular camera is used to track continuously the target satellite. The complex software functionality for relative guidance, navigation and control (GNC) and for the satellite dynamics is developed under Matlab/Simulink environment and auto-coded with Real-Time Workshop. The paper describes the realised HIL simulation and presents first results.