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EPOSx Test and Verification Facility


ATV docking The Automated Transfer Vehicle (ATV) is the first European spacecraft to dock fully automated to the International Space Station. To ensure the safety of the ISS crew, the system must be thoroughly validated before launch. The Extra large European Proximity Operations Simulator Integrate and Verification Facility (EPOSx-IVF) combines and integrates a number of earlier ESA developments to create a complete facility for rendezvous and docking tests at the EPOSx facilities at DGA, Val de Reuill, France. The EPOSx-IVF components are:
  • Extra large European Proximity Operations Simulator (EPOSx),
  • Onboard Computer Simulator (OCS),
  • ATV optical RVD sensors and ISS target reflectors,
  • Model Software (MSW),
  • EuroSim.


EPOSx is a real-time simulation facility for performing Rendezvous and Docking (RVD) simulations in real-size (i.e. 350m range), real-motion (i.e. moving masses of several tonnes), real-time, and with real sensors. The EPOSx facility allows rendez-vous and docking sensors to be tested in the loop under various realistic lighting conditions and with a an accuracy of a few millimeters. It is a distributed, PC-based real-time control system that operates all robot systems. The EPOSx facility has been used extensively to validate the ATV equipment and its docking procedures to ISS. After these successful test campaigns, the first ATV -Jules Verne- docked flawlessly with a 1 cm precision to the ISS in April 2008.

EPOSx docking test

Role of EuroSim

In the EPOSx-IVF setup, a EuroSim based simulator is at the hart of a Hardware in the Loop simulation that contains the real ATV Onboard Computer (OBC) ,RVD sensors and ISS target reflectors in the loop. The Model Software simulates the environment (like orbital movement) and sensor that are not present in real hardware (like GPS). The aim is to validate all components at system level to see if they will perform an autonomous docking from approximately 300m. The Eurosim machine communicates with the RVD sensors via MIL-1553b busses and via a dedicated Ethernet link to EPOSx facility which is responsible for positioning the real devices at the appropriate relative positions in real-time.

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