一种提高导航卫星星座自主定轨精度的方法研究

针对近地导航卫星仅利用星间测距进行自主定轨时，因无法消除星座整体旋转误差而导致长期自主定轨精度不高的问题，提出了利用拉格朗日导航卫星星座与近地导航卫星星座联合仅利用星间测距进行自主定轨的方法。建立了拉格朗日轨道导航卫星星座和近地导航卫星星座联合仅利用星间测距进行自主定轨的动力学模型和观测模型。利用扩展Kalman滤波（EKF）算法和星间测距信息实现了拉格朗日轨道导航星座与近地导航星座的长期自主定轨。以4颗拉格朗日卫星组成的导航星座与12颗GPS卫星组成的近地导航星座作为仿真对象进行了仿真分析，仿真结果表明本文仅利用星间测距的联合自主定轨方法可以有效提高导航卫星星座的长期自主定轨精度。

A Method for Improving Accuracy of Autonomous Orbit Determination for Navigation Constellation

An autonomous orbit determination method using only crosslink range measurement is proposed to achieve long-term accurate autonomous orbit determination for a combined navigation constellation constituted by a near-earth navigation constellation and a Lagrangian navigation constellation. This method is advised to solve the problem that rotation and translation of the entire near-Earth navigation constellation relative to the inertial reference frame can bring large error to the autonomous orbit determination using only cross-link range measurement. The model of a combined navigation constellation constituted by a near-Earth navigation constellation and a Lagrangian navigation constellation is given. EKF method and only crosslink range measurement are used to achieve long term autonomous orbit determination of the combined navigation constellation. A Lagrangian navigation constellation composed of four satellites and a near-earth navigation constellation constituted by twelve GPS satellites are chosen to verify feasibility and accuracy of autonomous orbit determination using only crosslink range measurement. Simulations show that this technique can improve the accuracy of long term autonomous orbit determination for the navigation constellation.