ESA GNC Conference Papers Repository
Vision Based GNC For Autonomous RVD in Circular and Elliptical Orbit
Technologies for rendezvous and docking (RVD) in Europe have been studied and developed since the early 80s. Nowadays European space industry has reached full maturity in this field resulting in the successful Automated Transfer Vehicle (ATV) rendezvous and docking with the ISS. A more challenging perspective is represented by the complex RV operations envisaged for the future exploration missions as the case of Mars Sample Return. In particular, for this kind of mission, the requirement for an autonomous navigation system becomes mandatory due to the long communications delay with the Earth and the need for real time knowledge of the spacecraft state when carrying out RV operations. The work presented deals with the design and the performance assessment of an autonomous GNC system able to cover the whole Terminal RendezVous Phase (TRP) starting from 5 km range up to the attainment of the docking/capture conditions, using as the main navigation equipment a camera system. Two different scenarios, the circular orbit 500 km altitude and the elliptical orbit 300x2000 (pericenter-apocenter), have been investigated, yielding applicable RV profiles. The paper describes the guidance, navigation and control (GNC) algorithms developed and applicable for both type of scenarios and provides the results of the performance assessment activities carried-out to validate the complete GNC system in a realistic simulation environment. The paper is organised as follows. First, the circular and elliptical orbits scenarios are described. Afterwards, the GNC concept is presented, with a detailed description of the camera system and target pattern. Next three sections are dedicated to present in detail the different guidance, navigation and control algorithms developed, highlighting those specifically designed for elliptical orbits. Finally, last section presents the results of the performance assessment campaign carried-out. It is important to highlight that although the paper presents the vision-based GNC concept applicable for both circular and elliptical orbits, more relevance and details are provided for the elliptical case due to its novelty.