一种利用磁强计和星敏感器的自主导航方法

A Method of Autonomous Navigation Using the Magnetometer and Star Sensor

基于地磁矢量高度方向梯度大的特点能够获得高精度的地心距信息,结合利用星敏感器精密测角信息可以得到航天器地心距矢量的高精度方位信息的特性,提出一种基于磁强计与星敏感器的自主导航方法。同时为降低星上计算量、提高自主导航收敛速度和导航精度,以地球固联坐标系下的轨道动力学方程作为系统状态方程,并在此基础上设计了组合导航扩展卡尔曼滤波器(EKF),利用Swarm卫星高精度磁测数据进行数值仿真校验。结果表明,自主导航滤波器收敛速度快,导航精度明显提高,位置精度和速度精度分别为0.52 km、0.89 m/s(1σ)。

High precision magnitude information of the geocentric vector can be obtained using a magnetometer, as the gradient of the magnetic field along the altitude direction is large. High accuracy orientation information of the geocentric vector can be obtained using a star sensor. Combining the advantages of the magnetometer and the star sensor, an integrated autonomous navigation method is proposed. To reduce the computation and improve the navigation accuracy and convergence rate, the orbit dynamics equation in the Earth-centered Earth-fixed （ECEF） reference frame is established as the navigation system state equation. The extended Kalman filter （EKF） algorithm is designed for the integrated autonomous navigation system. Numerical simulation is implemented under the real magnetic measurement data of the Alpha satellite of the Swarm constellation. Simulation resuhs show that the proposed method can improve both the convergence rate and the navigation precision, and the position accuracy and speed accuracy are on the order of 0. 52 km （ 1σ） and 0.89 m/s （1σ） respectively.