Stereo vision-based navigation and guidance for pinpoint planetary landing in unknown environments

An autonomous navigation and guidance system based on stereo vision measurements is presented for pinpoint planetary landing in unknown environments. Firstly, a relative navigation coordinate system is established based on the stereo vision measurements of unknown landmarks and the positions of the unknown landmarks in the relative navigation coordinate system are calculated. Then the position, velocity and attitude of the spacecraft expressed in the relative navigation coordinate system are estimated. Finally, based on the estimated states of the spacecraft and the position of landing site calculated from its stereo vision measurements, the guidance command is computed by the Apollo guidance law. The numerical simulation results for Mars landing indicate that the proposed navigation and guidance method is effective and feasible.