Extraction methed of the motion blurred star image for the star sensor under high dynamic conditions

Star sensor is beyond dispute the most accuracy absolute attitude determination sensor and it is widely used in deep space exploring and earth observing. Star image spots captured in the image sensor of the star sensor will elongate when it is under high dynamic conditions especially the rotation motion resulting in the blurred star images. The motion blurred star images with low SNR lead to the increase of difficulty in the extraction of the star areas. Normal processing procedures as the estimation of background threshold, image binarization and connected components analysis are not profitable anymore. A extraction method of the motion blurred star image based on template-correlation matching of the star sensor under high dynamic conditions is proposed in this paper. Parameters of the motion degradation function is precisely measured with the strap down laser gyro unit. So the template is generated in real time according to different dynamic conditions through the degradation model of the motion blurred image. Correlation matching criterion like minimum correlation difference and maximum correlation product are alternatives. Simulation and experimental results show that this method readily identifies and extracts the star spot area and removes the noises outside its region simultaneously. It is effective in extracting faint blurred star images unless they are totally submerged by the noise.