Fast guidance method of lunar landing based on dynamic programming

基于动态规划的月面定点着陆快速制导方法

¹ School of Astronautics, Northwestern Polytechnical University, Xi'an 710072, China
² National Key Laboratory of Aerospace Flight Dynamic, Xi'an 710072, China

Received: 8 May 2020

Abstract

In this paper, a novel multi-stage trajectory transfer and fixed-point landing time optimal guidance method for the lunar surface emergency rescue mission is proposed. Firstly, the whole process motion and dynamics model for the lunar surface emergency rescue with four stages are established. Then, in the initial orbit transfer phase, the Lambert algorithm based on "prediction + correction" is designed for the non spherical gravitational perturbation of the moon. In the powered descent phase, the Hamiltonian function is used to design a time suboptimal explicit guidance law that can be applied in orbit in real time. Finally, aiming at the multi-stage global time optimal guidance, the whole time process guidance law is obtained by establishing the allowable control set for each stage in the whole process. The simulation results show that compared with the piecewise optimal control method, the present method has better optimization effect and shorter whole process time. It is of great significance to the possible emergency rescue mission of manned lunar exploration in the future.

摘要

提出了一种面向月面紧急救援任务的多阶段轨道转移与定点着陆全程时间最优制导新方法。建立了包含4个阶段的月面紧急救援全程运动及动力学模型。在初轨转移段，设计了在月球非球形引力摄动下基于"预测+校正"的Lambert算法。在动力下降段，利用哈密尔顿函数设计了一种可在轨实时应用的时间次优显式制导律。针对多阶段全局时间最优制导问题，通过对全程各段建立允许控制集，采用动态规划法得到了全程时间最优的制导律。仿真结果表明该方法相比于分段最优控制方法优化效果更好，全过程用时更短，对未来载人月球探测过程可能出现的月面紧急救援任务具有重要意义。