载人登月飞行器高速返回再入制导技术研究

A study on the reentry guidance for a manned lunar return vehicle

返回再入段是载人登月任务完成后,保证宇航员安全返回地球的关键阶段,其跳跃式再入制导方法的研究是我国载人登月任务需要突破的一项重要关键技术.由于探月返回飞行器速度极高,其弹道特性与神舟飞船一类的近地轨道返回的飞行器有较大差别,也给制导导航与控制(简称GNC,以下同)系统设计带来较大挑战.与无人再入飞行器相比,载人飞行器需要具备防过载超限能力、大范围再入航程适应能力、高精度落点控制能力.为了满足上述要求,本文提出了一套基于全系数自适应校正的预测制导方案.在再入前,通过对基本倾侧角进行校正,提高了规划弹道对再入初始条件散布的适应性;再入后利用外环的预测与全系数自适应校正实现对规划弹道的持续修正,保证规划弹道与飞行器状态的匹配性,内环则采用短周期的弹道跟踪制导;对于横向制导,本文给出和比较了采用实时漏斗制导律、独立预测–校正制导律方案以及横航向独立自校正和耦合自校正方案.

Returning the astronauts back the Earth soundly after the lunar mission is one of the most critical phases for the future human lunar exploration project, and the skip reentry guidance is one of the key technology that must be mastered. When returned from the moon, any object is speeded up by the earth gravity, and its velocity at entry point becomes very close to the second cosmic speed. Compared with Shenzhou, which is a typical reentry vehicle from the near earth orbit, the trajectory of a lunar return vehicle is quite different. To overcome this extreme velocity challenge, the guidance navigation and control （GNC） systems have a lot work to do. When a man is in the reentry vehicle, more requirements are raised, such as limited maximum over load, adaptation to range varying and guaranteed landing point distributions. To satisfy those requests, an all-coefficient adaptive prediction-correction scheme is presented in this paper. Before entering the atmosphere, an iterative corrector is called to modify the bank angle profile, which improving the robustness of the programmed trajectory to the entry Interface condition distribution. When the vehicle penetrates into the atmosphere, an outer-loop non-iterative corrector is called to modify the trajectory which is tracked by the inner-loop short-interval guidance. For the directional control, the classical bank angle reversal method is compared with two novel bank angle reversal time point programming methods, which are coupled down-range cross-range method and the decoupled one.