基于标准弹道的月球探测器再入制导方法

月球探测器返回具有再入速度大,动力学耦合剧烈以及误差作用明显的特点。利用标准弹道法研究了低升阻比月球探测器的再入制导问题。得到2 000 km和3 000 km航程的标准弹道;讨论了基于时间变量进行增益反馈的制导方法,给出2 000 km航程下的最大单项误差仿真结果,并针对两种航程进行了Monte-Carlo抽样。考虑到时间积分模式不能全面的采集关键点信息,引入能量作为标准弹道的离散量;针对有初始速度偏差时标准弹道与实际弹道初始能量不一致的情况,提出能量比例尺的概念,很好地解决了能量匹配的问题。Monte-Carlo仿真表明:基于能量的标准弹道法精度明显提高,2 000 km航程下纵程偏差在10 km以内,3 000 km航程基本控制在30 km以内。

Nominal-Trajectory Guidance for Lunar Return Vehicles

In order to advance nominal-trajectory guidance technology of low lift-to-drag ratio lunar return vehicles, two modes have been explored with the objective of increasing the landing accuracy and algorithm robustness. The reference trajectory of 2000km and 3000km range are obtained firstly, and the guidance approach divided by the flight time (Mode 1) is presented. The results of individual ultimate error are shown, and the Monte-Carlo simulation is also applied to the two range condition. Considering the shortcoming of collecting the information of "Key Node", another guidance mode based on energy axis (Mode 2) is delivered, and a new concept termed "Energy Scale Factor" is devised for the purpose of dealing with the energy matching problem when the initial velocity error is introduced. The Monte-Carlo simulation results have illustrated a conclusion that the energy parameter could improve the precision obviously, and the majority position dispersion at the end of the guidance phase (parachute deployment) is reduced below 10km for 2000 km range and 30km for 3000km range. This work and result could be available and feasible for the lunar sample return project and manned lunar missions