绕月自由返回飞行任务的轨道设计方法

Method of Mission Trajectory Design for Circumlunar Free Return Flight

针对绕月自由返回飞行提出一种任务轨道设计方法。在双二体模型下基于圆锥曲线拼接和能量匹配原则迭代计算初值,采用Broyden法构造新的微分修正格式,在精确模型下分别针对三组不同的目标变量和目标值对初值进行逐级修正使之满足再入参数。采用简单迭代调整近地点时刻、飞行时间完成发射弹道拼接和落点位置匹配,迭代初值根据落点纬度插值确定,插值表通过对若干飞行时间进行初值计算和发射弹道拼接构造。算例表明,该流程能够扩展初值计算的适用范围,具有良好的收敛性和计算效率。

A method of mission trajectory design is proposed in this paper for the circumlunar free return flight. The initial values are obtained by using the iterative calculation based on the patched-conic approach and the energy match principle under the double two-body model. Then a three-stage initial value correction strategy based on Broyden quasi- Newton formula is applied to satisfy the atmosphere entry constrains under the accurate model. The Launch trajectory connection and the landing point location match are achieved by rectifying the time past perigee and the time of flight by use of the simple iteration algorithm. And the initial iterative values are acquired by using interpolation or extrapolation of the data table constructed by use of the initial value calculation and the launch trajectory connection according to the landing point latitude. The design example demonstrates the effectiveness of the approach proposed in extension of scope of application of the initial value calculation and reduction of the computational effort.