| With the development of lunar exploration mission, the spacecraft is expected to land more precisely and safely, it is important for the spacecraft to have the ability of obstacle detection and avoidance. Aimed at the specialty of lunar landing, this thesis deeply researches the obstacle detection and avoidance in lunar landing sequence.Firstly, advance a Lidar-based obstacle detection strategy. This strategy make use of the Lidar sampling data to calculate the plane of the landing area, this can distill the obstacles of landing area effectively. About the select of safe landing point, we advance a cockle stairs searching strategy to distill the nearest safe landing point to the prearranged landing point.Secondly, after a safe landing point is chosen, we design a avoidance guidance for variety and invariableness trust separately. For the variety trust, make use of the current states and object states to program the acceleration for spacecraft. For invariableness trust, we make use of SQP(Sequential Quadratic Programming) method to achieve a fuel consume least hazards avoidance orbit.Thirdly, to achieve the obstacle avoidance, based on the analysis of the attitude of spacecraft, we introduced a time-fuel optimal control.Finally, the obstacle detection and avoidance control simulation structure is designed and numerical simulation is performed. The simulation results suggest the obstacle detection and avoidance arithmetic proposed in this paper is feasible. |
