定时定点月面着陆全程轨道控制设计

针对定时定点月面着陆的目标要求，提出了全程轨道控制设计方法。进行了包括地月转移、近月制动、环月降轨和动力下降的全程轨道控制的分段设计和联合规划，实现在入轨轨道偏差条件下的定时定点月面着陆。分别构建了中途修正、近月制动、环月降轨三段轨道控制的规划变量和目标参数；根据轨道倾角建立了动力下降点与着陆点的匹配转换关系。设计了中途修正、近月制动、环月降轨、动力下降的全程轨道控制策略的联合规划。建立了着陆位置偏差与轨道倾角偏差、着陆时间偏差与轨道半长轴偏差的修正关系，修正设计了中途修正目标倾角和近月制动目标半长轴。仿真算例表明，在入轨偏差轨道条件下，保证了中途修正后的飞行轨道与标称轨道基本一致，实现了与标称状态基本一致的定时定点月面着陆。可应用于月球着陆、月球采样返回以及载人登月等实施月面定时定点着陆任务的轨道设计和控制实施。

Design of Orbit Maneuvers of Whole Course for Pinpoint Lunar Landing at Fixed Time

In order to meet the objective requirements of landing on lunar surface at the fixed point and at the fixed time, a design method of orbit maneuvers of whole course is proposed. The phased design and joint planning of the whole-course orbit maneuvers including Earth-Moon transfer, lunar orbit insertion, lunar orbit height descent and powered descent are carried out to realize the time-fixed pinpoint lunar landing under the condition of the orbit injection deviation. The planning variables and target parameters of the three-phase orbit maneuvers with mid-course correction, lunar orbit insertion, and lunar orbit height descent are respectively constructed. According to the orbital inclination, the matching transformation relationship between the powered descent point and the landing point is established. The joint planning of the whole-course orbit maneuver strategy including mid-course correction, lunar orbit insertion, lunar orbit height descent and powered descent is designed. The time and position’s deviation of the landing point are converted into the inclination deviation and the semi-major axis deviation, and the corrections are made to the inclination of the mid-course correction’s aiming target and the semi-major axis of the lunar orbit insertion’s aiming target. The simulation examples show that with the deviation of the injection orbit, the flight orbit after mid-course correction is basically consistent with the nominal orbit and the flight orbits of the orbit height descent and powered descent are basically unchanged. The design method of the whole-course orbit maneuvers can be applied to the orbit design and control implementation of the lunar landing, lunar sampling return, and manned lunar landing missions.