GPS移动基准站差分定位算法

相对导航定位技术在空中加油任务中起着至关重要的引导作用。针对传统差分定位模式受限于基准站位置固定、覆盖范围有限等问题，研究了一种无固定基准站差分定位方案，实现了短基线高精度动态相对定位。该方案首先基于实时伪距单点定位求得移动站近似坐标，结合载波信息进行站间差分，求得单差模糊度浮点解及更高精度的移动站坐标。之后，再利用双差观测方程,并采用扩展Kalman滤波(Extended Kalman Filtering，EKF)算法获得移动站精确坐标和双差模糊度浮点解。最后，采用LAMBDA算法进行模糊度快速固定，获得最终定位结果。实验结果表明，所采用的无固定基准站差分定位方案使得基线长度均方差小于5cm，达到了较高的动态相对定位精度。

Differential Positioning Algorithm for GPS Moving Base Station

Relative navigation and positioning technology plays an important role in the air refueling missions. In this paper, aiming at the problem that the traditional differential positioning mode is limited by the fixed base station and limited coverage, an unfixed base station differential positioning scheme is studied to achieve high-precision dynamic relative positioning of short baseline. Firstly, the approximate coordinates of the moving station are obtained based on the real-time pseudo-range single point positioning, and then the single-difference ambiguity floating-point solution and higher-precision coordinates of the moving station are obtained by combining the carrier information. Secondly, based on the double-difference observation equation, precise coordinates and ambiguities of the station are obtained through EKF algorithm. Finally, the LAMBDA algorithm is used to quickly fix the ambiguities and to obtain the final positioning results. The experiment results show that the unfixed base station differential positioning scheme in this paper achieves standard deviation of baseline length less than 5cm, which meets the dynamic relative positioning requirements.