Zhao Shufan, Wang Xingshu, Tan Wenfeng, Dai Dongkai, Qin Shiqiao
Appl Opt. 2021 Mar 10;60(8):2372-2379. doi: 10.1364/AO.416080.
A star tracker should be well calibrated before it is equipped in order to achieve high accuracy. There exists, however, the coupling problem between the internal and external parameters for most commonly used laboratory calibration methods, which affect the star tracker's performance. We theoretically analyze the major aspects of the coupling mechanism based on the star tracker laboratory calibration model, which means the coupling between the principal point and the installation angle. The concept of equivalent principal point error, which illustrates the effectiveness of the calibration even with poor decoupling accuracy between the principal point and the installation angle, is introduced. Simulation and bench experiments are conducted to verify the laboratory calibration method and its coupling mechanism. The decoupling accuracy can be improved with more samples during calibration. In addition, the equivalent principal point error converges quickly and hardly affects the attitude of the star tracker, which is verified by both theory and experiment. The comprehensive calibration accuracy can still reach a high level even with poor decoupling accuracy.
星跟踪器在安装前应进行良好的校准，以实现高精度。然而，对于大多数常用的实验室校准方法，存在内部参数和外部参数之间的耦合问题，这会影响星跟踪器的性能。我们基于星跟踪器实验室校准模型，从理论上分析了耦合机制的主要方面，即主点与安装角度之间的耦合。引入了等效主点误差的概念，它说明了即使主点与安装角度之间的解耦精度较差，校准仍然有效。进行了仿真和台架实验，以验证实验室校准方法及其耦合机制。在校准过程中增加样本数量可以提高解耦精度。此外，等效主点误差收敛迅速，几乎不影响星跟踪器的姿态，这在理论和实验中都得到了验证。即使解耦精度较差，综合校准精度仍能达到较高水平。
