惯导/测距/测速相结合的安全软着陆自主导航方法

针对地外天体软着陆中惯导误差随时间增大，无法提供准确的高度和三维速度信息的问题，提出了一种惯导、测距和测速相结合的安全软着陆导航方法。该方法以惯导为基础，利用测距仪修正惯导的高度信息，利用测速敏感器修正惯导的速度信息。详细介绍了惯性导航的基本原理及测距、测速组合修正的策略，对软着陆过程的动力学模型、敏感器测量模型、滤波方程、地形对修正的影响,以及组合使用的策略和算法等问题进行了论述。数学仿真结果表明惯导、测距和测速相结合的方法能够满足安全软着陆的需要。

INS / Rangefinder / Velocimetry Based Autonomous Navigation Method for Safe Landing

Inertial navigation system (INS) is not sufficient to lead a probe to land on an extraterrestrial body safely, because its calculation error grows up with time. A practical navigation method which combines INS with rangefinder and doppler velocimetry is proposed to solve this problem. Altimeter and velocimetry can give direct measurements of altitude and three-dimensional surface-relative velocity respectively, and can be used to correct the outputs of INS. In this paper, the principle of INS and the strategy of altitude and velocity modification are introduced. And these key problems about the descent dynamics, sensor measurement models, filtering equations, influence of terrains are discussed in details. Numerical simulation results indicate that this method can satisfy the requirement of extraterrestrial bodies for safe landing.