基于虚拟落点策略的月球返回飞船再入制导方法

针对长航程大偏差状况下阿波罗再入制导算法的精度退化问题提出改进，采用数值预测-校正方法规划和调制线性参数化的倾侧角剖面，给出了一种在全航程包络内适用的月球返回飞船再入制导方法。引入虚拟落点策略，在一次再入段利用算法预测能力预测二次再入段初始侧向偏差并进行前馈补偿，给出了简便有效的虚拟落点瞄准程序。大偏差任务想定下的蒙特卡洛仿真分析表明，该算法在3000km到10000km的再入航程范围内，能够确保偏差小于3km的落点精度。

Lunar Return Entry Guidance Based on Virtual Landing Point Strategy

An adaptive skip entry guidance algorithm for vehicles with low lift to drag ratios is presented. The algorithm is based on the Apollo entry guidance algorithm and upgraded by using numeric predictor corrector in planning and modulating the linear parameterized bank angle profile. Based on the virtual landing point strategy, a simple and effective bias targeting feed forward procedure is developed for precision landing in large entry range case. The upgraded algorithm is tested against various entry scenarios including perturbations in initial entry conditions as well as extensive dispersion in vehicle mass, aerodynamic properties, and atmospheric density. The algorithm is shown to be sufficiently robust and general enough to allow precision landing with a delivery error of less than 3km in the entire range between 3000km and 10000km.