Validation Of Mission Critical Vision-Based Navigation Systems For Planetary Landers, Rovers And In-Orbit Rendezvous

Vision-based navigation systems are being designed for a wide range of space applications including planetary landing, small-body rendezvous and landing, planetary rovers and in-orbit rendezvous and docking. Vision-based navigation is attractive because it can support safe, precise landing and has relatively low mass and power consumption, however, the testing and validation of a mission critical vision-based navigation systems is a difficult task. Vision systems are now able to perform absolute navigation, surface relative navigation and hazard detection tasks. While testing the flight system on a helicopter flying over a desert on Earth is possible, although very expensive, a terrestrial analogue for flying around a tumbling asteroid is not practical. This paper discusses the challenges in providing a simulation environment to test planetary landers, surface rovers and orbital rendezvous and describes the PANGU tool which can be used to test these mission-critical navigation systems. Given the position and orientation of a camera above the surface, PANGU generates the corresponding image and the position of the sun and other illumination conditions can be modelled. PANGU has been designed to give a high degree of realism while operating at real-time speeds to enable closed loop simulation of complete vision-based navigation systems.