DARWIN PRECURSOR DEMONSTRATION MISSION : THE ICC2 STUDY, FROM GNC DESIGN TO REAL-TIME TEST BENCH VALIDATION

The implementation of a formation flying concept is being considered by ESA for the Darwin space interferometer mission, scheduled for 2015. In order to prepare this mission, some studies are led to demonstrate the feasibility of the global project. One of the critical points is the metrology chain and the GNC system that must be developed to answer to the constraining requirements imposed by the formation flying. The ICC2 project aims at elaborating a full GNC system for a DARWIN precursor mission composed of an interferometric arm (2 telescopes and a hub recombiner). By considering the GNC subsystem requirements, the first part of the study has consisted in analysing the environment, modelling the dynamics and proposing a set of metrology equipment. Using these inputs, an original GNC architecture has been developed, including avionics fault tolerant architecture. It is based on a sequential GNC logic and a mixed architecture decentralised-centralised. The design has then been refined and validated thanks to a fully representative, full degree of freedom Matlab simulation tool. The last step of the validation procedure was the implementation of the GNC design on a real-time testbench which involves three LEON processors and dSPACE facilities.