星敏感器星图的高精度星点提取方法

High-precision star centroid extraction method on star image of star sensor

摘要:

星敏感器硬件电路产生的噪声以及在航天器上应用所面临的复杂恶劣的工作环境,都对星图质量造成严重影响,进而降低星点提取精度.针对上述问题,提出了一种精度高且抗干扰性能好的星点提取方法.首先,采用多窗口抽样自适应阈值分割方法对星图去噪,为后续的星点提取奠定基础；然后,基于改进的灰度交叉投影法进行星点粗提取；最后,利用局部区域生长+高斯曲面拟合法进行星点精提取.改进的灰度交叉投影法能够克服星点范围重叠带来的问题,从而快速准确找到星点的粗略区域,而且可以为局部区域生长提供可靠的“种子”点；局部区域生长法可以保证星点区域的边缘细节能够得到充分保留,这对提高星提取的精度大有益处.仿真实验表明,在噪声标准差为2的仿真条件下,该方法的星点提取精度达到了0.075 5 pixel,相比于扫描法等传统方法,该方法的星点提取精度有大幅提高,而且还具有良好的抗干扰性能,因而对于在强噪声干扰条件下提高星敏感器测量精度具有重要参考价值.

Abstract:

The noises caused by star sensor electric circuit and the complex working environment faced by the star sensor when being applied in spacecraft both have serious impact on the quality of the star image, leading to the decrease of the star centroid extraction precision. Regarding the issues above, a star centroid extraction method, which has high precision and good anti-noise performance, is presented. Firstly, a multi-window sampling adaptive threshold segmentation method was used to reduce the noise of star image. Secondly, an improved gray cross projection method was proposed for star point coarse extraction. Finally, the local region growing method and the Gaussian surface fitting were used for star centroid fine extraction. The improved gray cross projection method can solve the problems caused by star point overlap so as to quickly and accurately find the rough area of star point and provide reliable “seed” points for the local region growing method. The local region growing method can fully reserve the edge of star point, which is beneficial to improve the star centroid extraction precision. Simulation results show that the star centroid extraction accuracy of the proposed method reached 0.075 5 pixel under the simulation condition with a noise standard deviation of 2. Compared with the traditional methods such as the scanning method, the star centroid extraction accuracy of the proposed method is greatly improved with good anti-interference performance, which has significant reference value for improving the accuracy of star sensor measurement under strong noise interference conditions.