针对传统静态误差分析方法忽略目标运动对测量影响的不足, 本文在分析运动对目标形状影响的基础上建立了灰度质心算法误差与灰度噪声、动态目标尺寸的数学模型, 该模型表明当曝光时间内目标移动量远小于目标静态尺寸时, 动态误差与静态误差接近; 而当目标移动量与目标静态尺寸的比值大于 6%时, 灰度质心算法动态测量误差方差将比静态测量误差方差大 20%以上, 此时必须减小 CCD曝光时间、增加光源出射光功率, 以减小测量误差。

The Linear Measure Instrument (LMI) based on image processing techniques is the major equipment for measuring the swinging mirror fixed on space infrared camera. Traditional error analysis methods neglect the facula streaking effect, so the measure uncertainty is increased. A model of facula displacement, pixel noise and facula gray centroid algorithm is established. The model indicates that if the facula displacement in exposure time is far less than the static facula size, the dynamic measure error is closed to static measure error. However, if the ratio between facula displacement and facula static size is bigger than 6%, the variance of dynamic gray centroid algorithm error will be 20% more than static error variance. Then the exposure time shall be reduced and emergent power of light source shall be increased to reduce the dynamic measuring error of gray centroid algorithm.