Image processing of digital sun sensor using modified moment method

The moment method was used to estimate the centroid in a digital sun sensor to increase the angle measurement accuracy and computation speed. Since the moment method is sensitive to the image background and digital sun sensor images have large backgrounds, the moment method was modified to eliminate the background effect. A pinhole diffraction model was used to define several key indexes in the modified moment method. Results from digital sun sensor calibration experiments show that the image background is almost eliminated with the digital sun sensor having a centroid estimation accuracy of 0.02 pixels over the entire ±64° field of view.