一种跳跃式返回再入的预测—校正制导方法

A Predictor-Corrector Guidance Method for Skip Reentry Missions

再入地球大气是探月飞船返回的关键阶段,再入制导是返回再入中的难点问题。飞船跳跃式再入过程复杂,标准轨道制导方法难以满足任务要求,因此具有高精度和强鲁棒性的预测—校正制导方法成为解决问题的首选。以探月飞船跳跃式再入为背景,设计了数值预测—校正制导律,研究了基于嵌套式积分算法的航程快速预报方法和基于有界试位法的倾侧角剖面快速更新算法,提出了一种气动系数误差和大气密度误差的在线参数辨识方法,并基于最大偏差法和蒙特卡洛打靶法进行了仿真分析。结果表明,预测—校正再入制导方法在跳跃式再入问题上具有较高的精度和较好的鲁棒性。5 000km再入航程时,开伞点误差在2.5km以内。

Reentry into earth atmosphere is a key phase for a lunar exploration spaceship and one challenge is guidance for the reentry.For the skip reentry of a spaceship,the procedure is very complicated and conventional nominal trajectory tracking guidance methods don＇t meet mission requirements.Predictor-corrector guidance method,which features high accuracy and strong robustness,becomes the first choice for such missions.Focusing on the skip reentry of a lunar exploration spaceship,a predictor-corrector guidance law is presented.A fast reentry trajectory prediction algorithm based on embedded integration method and a bank angle profile updating algorithm based on bounded false position method are explored.An online parameter identification algorithm to estimate the errors of aerodynamic coefficients and atmospheric density is introduced to enhance the accuracy of the guidance scheme.Methods of maximum deviation and Monte Carlo shooting are employed to evaluate performance of the guidance law.Numerical simulation results show that the proposed predictor-corrector guidance law is qualified for the skip reentry mission with high accuracy and robustness.For a 5000 km downrange entry scenario,the terminal position error is less than 2.5 km.