针对数字天顶仪在定位过程中存在的的轴系偏差, 研究了如何对光轴与旋转轴、旋转轴与垂直轴之间的角度偏差进行补偿的方法。为了高精度地解算出测站点位置垂直轴的天文坐标, 采用对称位置的两幅星图直接解算旋转轴的坐标, 从而避免了光轴与旋转轴之间的补偿。采用双轴倾角仪测量倾角, 并对旋转轴进行倾角补偿得出垂直轴的位置坐标。考虑进行轴系补偿时, 转台误差会对旋转轴坐标和倾角补偿造成影响, 分别研究了转台误差对于旋转轴以及倾角补偿的影响, 并得出了转台误差的范围。实验结果表明: 当测站点纬度的绝对值小于或等于88.3°时, 转台误差必须小于或等于35″; 当测站点纬度的绝对值大于88.3°时, 转台误差值要小于|1 166.8cos δ|″。在对称位置解算测站点位置坐标时, 必须提高转台的精度, 以减小转台误差对于定位精度的影响。

There are axis errors in orientation processing of a digital zenith camera. This paper focuses on how to compensate the axis errors among optical axis, rotation axis and vertical axis. To calculate the astronomical coordinate of the vertical axis in a measuring station position, two star images in an opposite direction were used to calculate the coordinate of the rotation axis. Thus, the compensation between optical axis and rotation axis was avoided. A two-axis tilt sensor was used to measure the inclination between rotation axis and vertical axis and the position coordinate of the vertical axis could be obtained by compensating the angle error of the rotation axis. As the turntable error could impact on the coordinate of rotation axis and tilt compensation, the influences of turntable error on the calculation of rotation axis and tilt compensation were analyzed, respectively and the range of turntable error was gained. The experimental data demonstrate that when the absolute value of the latitude of the measuring station is below 88.3°, the turntable should be below 35″. Otherwise, the turntable error should be below |1 166.8cosδ|″. The precision of rotation angle should be improved to eliminate the influence of turntable error when the coordinate of the measuring station is calculated in the opposite direction.