不同坐标系下航空重力扰动估算比较分析

针对捷联式GNSS/INS组合航空重力测量系统，比较在当地水平坐标系和惯性坐标系下重力扰动的估算方法及精度。结果表明，惯性坐标系下基于加速度更新的卡尔曼滤波方法比当地水平坐标系下基于位置、速度更新的卡尔曼滤波方法模型简捷且重力扰动的估算精度相当，在半波长分辨率为7.5 km时，6条重复测线重力扰动差值的标准差平均分别为1.21 mGal和1.27 mGal；对于相同测线，两种方法计算得到的重力扰动差值的标准差平均为0.65 mGal；两种方法求得的重力扰动中都存在明显的系统误差，将其按时间进行线性补偿后明显减小，测线间的最大差值分别由8.20 mGal、8.19 mGal减小到2.70 mGal、2.54 mGal，平均内符合精度分别从1.21 mGal、1.27 mGal提高到1.06 mGal和1.10 mGal。

Comparison and Analysis of Airborne Gravity Disturbance in Different Coordinate Systems

The estimation method and accuracy of gravity disturbance in local horizontal coordinate system and inertial coordinate system are compared for the strapdown GNSS/INS combined airborne gravity measurement system. The results show that the accuracy of the Kalman filter method based on the acceleration update in the inertial coordinate system is equivalent to the Kalman filter method based on the position and velocity update in the local horizontal coordinate system. However, the former algorithm is simpler. By using the two methods, the mean standard deviation of the gravity disturbance difference of the six repeatlines are 1.21 mGal and 1.27 mGal respectively, with half-wavelength resolution of 7.5 km. For the same lines, the standard deviation of the gravity disturbance difference calculated by the two methods is 0.65 mGal. The gravity disturbance of the repeatlines obtained by the two methods have evident systematic error, which can be obviously reduced by linear compensation according to time. The maximum difference between the lines is reduced from 8.20 mGal, 8.19 mGal to 2.70 mGal, 2.54 mGal respectively, and the mean internal accuracy is increased from 1.21 mGal, 1.27 mGal to 1.06 mGal, 1.10 mGal respectively.