A fast algorithm of attitude measurement for APS-based digital sun sensors

The centroid coordinates of the sun image on the APS is required to be worked out in APS-based digital sun sensors. The usual `centroid' algorithm wastes time, especially when the area of the sun image is far smaller than the APS's. A new and faster method is offered to calculate the centroid of the sun image. The merit of the new algorithm is that it can improve the speed of the calculation and ensure the demand of precision