星点亚像元定位中系统误差的改进补偿方法

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10-4 pixel；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。

Modified systematic error compensation algorithm for star centroid sub-pixel detection

In order to improve the accuracy of centroid location for star images, a modified systematic error compensation algorithm was proposed. First, the cubic spline interpolation function was used to represent the relationship of the systematic error and the actual position and compensate the systematic error. By using the cubic spline interpolation method, the number of error sample points and computational complexity was reduced greatly. Finally, after compensating the systematic error, the nonlinear weighting method were applied to reduce the effects of random error and the optimal weighting coefficient was obtained by the simulation experiment. The simulation results show that the accuracy of star position can be enhanced from 1/50 pixel to 10-4 pixel by using the modified compensation algorithm. When the additive Gaussian noise in the star image obeys N (0,22) distribution, the accuracy of modified compensation algorithm 0.005 4 pixel, which is far less than 0.018 4 pixel from the common centroid algorithm. The conclusions show that the modified compensation algorithm can satisfy the requirement of the high accuracy centroid location for star images due to its simple calculation and accurate result.