嫦娥三号着陆器动力下降的自主导航

Autonomous navigation for powered descent phase of Chang’E–3 lunar lander

中文关键词  嫦娥三号  动力下降  自主导航  组合导航

英文关键词  Chang’E–3 lunar lander  powered descent  autonomous navigation  integrated navigation

中文摘要

      嫦娥三号着陆器的月球动力下降过程是完全自主的, 导航系统需要向制导与控制系统实时提供着陆器的位置、速度和姿态信息. 考虑到月表起伏的不确定性, 嫦娥三号采用了惯导组合激光测距仪和微波测距测速仪的自主导航方案. 通过激光和微波测距的信息融合来修正惯导高度误差, 通过微波测速的多波束组合来修正惯导的速度误差. 在滤波方法设计上, 从工程实用出发, 采用了用函数近似的变系数滤波方法, 并设计了随高度变化的门限对测量数据进行有效性检验. 实际飞行数据表明该导航方法可靠、有效, 保证了任务的圆满完成.

英文摘要

      The powered descent phase of Chang’E–3 lunar lander is fully autonomous. The navigation system obtains the lander’s movement information such as position, velocity and attitude, and introduces them to the guidance and control system. To meet the requirement that landing on the lunar surface with terrain uncertain, an integrated navigation scheme is contrived, which combines a multiplicity of data types including a strap-down inertial measurement unit, a laser altimeter and a capable radar altimeter and velocimeter. The information from laser and radar altimeters are fused to correct the altitude output of INS, and the data from multi-beam doppler velocity radar are combined to decrease the velocity calculation error of INS. To simplify the algorithm, filters with variable gains which are calculated by predesigned functions are used to replace normal extend Kalman filters. And the validation of measurements from altimeters and radars are verified by some altitude-varing thresholds before they are introduced to these filters. The flight results demonstrate that this navigation method is reliable and effective to the Chang’E–3 lunar landing mission.