对地观测星载激光测高仪在轨姿态系统误差检校方法

Calibration method of on-orbit attitude systematic error for spaceborne laser altimeter of earth observation

星载激光测高仪通过接收经地表反射的微弱激光脉冲回波,计算卫星与地表的距离;结合卫星位置和姿态数据,生成激光脚点精确地理位置和高程结果。对于高程精度10 cm量级的对地观测激光测高仪,必须对影响严重的姿态角系统误差进行标定和校正。文中推导得出星载激光测高仪姿态角误差与已知地表先验信息相关联的数学模型,设计了利用大洋表面作为地表标定场,通过卫星姿态机动方式,最小二乘估计算法校正卫星在轨系统误差的具体方法。仿真结果表明,所设计的方法能够准确估计存在的姿态系统误差,即使大规模观测值丢失,估计偏差也小于5%。这种在轨运行系统误差的标定方法对于对地观测星载激光测高仪的姿态误差检校具有参考意义。

The range between satellite and surface target was acquired by processing the weak received waveform which was transmitted from the space-borne laser altimeter and reflected by earth surface. Combined with the precise orbit and attitude data, the accurate location and elevation of laser footprint were calculated. As for the altimeter with elevation accuracy of 10 cm magnitude, the systematic error on attitude angles influencing the accuracy severely should be calibrated effectively. The analytic model of attitude angle error associated with priori knowledge of earth surface was deduced, and the calibration method used to eliminate the attitude error was designed, which utilized the ocean surface as calibration field, was by way of satellite attitude maneuver and based on least squares estimation algorithm. The results of simulation show that the designed method can estimate the systematic error precisely and effectively, even if the mass observed data were lost, the estimated bias is less than 5%. This on-orbit calibration method is beneficial to the systematic error correction for the space-borne laser altimeter, and is of reference significance.