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为提高星点图像的质心提取精度,针对星点亚像元定位的系统误差和随机误差提出了一种改进补偿方法。采用三次样条插值函数表示质心位置与系统误差之间的关系,利用该函数进行系统误差补偿,极大地减小了误差采样点的数量和计算量。为了进一步抑制随机误差的影响,在系统误差补偿的基础上,采用非线性加权算法计算星点质心位置,并通过仿真实验确定了该算法的最优加权系数。在没有加入噪声的情况下,改进算法可以将质心法的精度从1/50 pixel提高到10-4pixel;加入服从N(0,22)分布的高斯白噪声后,改进算法可以达到0.0054pixel的精度,远小于质心法的0.0184pixel。实验结果表明:文中提出的改进补偿算法计算简单,精度高于质心法,满足了高精度星敏感器质心提取的要求。
In order to improve the centroid extraction accuracy of star image, an improved compensation method is proposed for systematic error and random error of satellite sub-pixel location. The cubic spline interpolation function is used to express the relationship between the position of the centroid and the system error. The function is used to compensate for the system error, which greatly reduces the number of error sampling points and the amount of calculation. In order to further suppress the influence of random error, based on the systematic error compensation, the non-linear weighted algorithm is used to calculate the centroid position of the star and the optimal weighting coefficient of the algorithm is determined by simulation. Without adding any noise, the improved algorithm can increase the accuracy of centroid method from 1/50 pixel to 10-4pixel. After adding Gaussian white noise with N (0,22) distribution, the improved algorithm can achieve the precision of 0.0054pixel , Much less than the 0.0184pixel of the centroid method. The experimental results show that the improved compensation algorithm proposed in this paper is simple and accurate, and the accuracy is higher than that of the centroid method. The proposed algorithm satisfies the centroid extraction requirement of high-precision star sensor.