Autonomous navigation and hazard-avoidance method based on sequential images for Mars soft landing

Abstract

An autonomous navigation and hazard-avoidance method based on sequential images for Mars soft landing is presented in this paper. In this method, the lander is assumed to be equipped with only a monocular camera and an inertial measurement unit, and the up-south-east frame of the subsatellite point at initial time is built as the landing reference frame. Then, an implicit measurement model is derived from observations of features with unknown three-dimensional positions tracked in sequential images. To estimate the position and velocity relative to the target landing site, the derived measurement model is used in combination with measurements from the inertial measurement unit using an extended Kalman filter. Finally, a modified polynomial guidance is adopted to implement large hazard avoidance. Simulation results indicate that the proposed method can effectively estimate the position and velocity relative to the target landing site and that the precision of the horizontal hazard avoidance is better than 0.5 m, ensuring the safety and reliability of Mars soft landing.