Parameters optimization of image sensor for star sensors

A star sensor realizes 3-axis attitude measurement by star imaging and star recognition, and is widely used for the spacecraft. Image sensor is the core device achieving photoelectric conversion (P-E) in the star sensor and its parameters such as exposure time and gain affect the performance of accuracy and dynamic. Therefore, a star sensor in the design phase is faced with the problem of how to determine the parameters of image sensor reasonably. The existing method for that is “trial and error method” that lacks the necessary theoretical basis. This paper proposes a parameters optimization method of image sensor for a star sensor. Firstly, the imaging model of star sensor, which has a clear physical meaning, is established, and the effect of imaging parameters on SNR is analyzed based on the corresponding theoretical derivation and simulations results. And the optimal parameters can be obtained when the SNR reaches the maximum value. Then results of experiments using a real star sensor, rotating platform and star simulator validate the simulations results. The summarized method in this paper should prove helpful for setting imaging parameters of other star sensors.