基于UKF的姿态无关GPS双差整周模糊度确定

Attitude Independent GPS Ambiguity Resolution Using UKF

基于运动的GPS双差整周模糊度确定方法需要预先知道载体的姿态,为了消除对姿态的依赖,研究了一种新的整周模糊度确定方法。首先将多天线载波双差相位矢量观测方程转化为标量观测方程,消去了对载体姿态矩阵的依赖。经过短时离线观测,以中心估计算法和协方差白化算法估计和修正双差整周模糊度的近似解及协方差矩阵。再以该近似解和协方差矩阵为初值,由无迹卡尔曼滤波(UKF)实时估计双差整周模糊度的精确解。最后对该方法进行了仿真,仿真结果表明经过离线批处理算法的预处理UKF可准确收敛于真实解,证明了方法的正确和有效性。

The vehicle′s attitude should be known in advance in order to resolve GPS double differenced integer ambiguity when using motion-typed algorithm.To eliminate the dependence on the attitude,a novel algorithm for integer ambiguity resolution was investigated.Converting original vector measurement equation into scalar measurement equation,the attitude matrix of carrier vehicle was canceled out.After a short data collection period,a batch algorithm was employed to attain a coarse float estimate of the ambiguity.The batch algorithm included the centerted estimate algorithm and the whitening filter.Then the float ambiguity resolution was passed into an unscented Kalman filter as initial state value.UKF estimated the precise ambiguity resolution in real time with the initial value.Finally,simulation was implementeda and the results indicate that with the off-line batch algorithm UKF provides a correct ambiguity resolution without prior knowledge of vehicle′s attitude,which validates the proposed algorithm.