Influence mechanism and recognition algorithm of CMOS active pixel sensor radiation damage on star sensor star map recognition

In order to analyze the causes of star sensors performance degradation and attitude measurement accuracy reduction in space radiation environment, the total ionizing dose effects on complementary metal oxide semiconductor(CMOS) star sensor performance are studied. By using an established outfield star sensor test system, the Orion Nebula and the zenith direction of the sky are imaged. Through the experimental processes of star map data acquisition, star point extraction and star map matching, the influence mechanisms of complementary metal oxide semiconductor active pixel sensor(CMOS APS) noises on background gray mean value of star map and number of identified stars are analyzed. A recognition algorithm for finding stars annihilated by radiated noise is proposed. Through theoretical derivation, the quantitative relationships between CMOS APS dark current noise, dark signal non-uniformity noise and photon response non-uniformity noise and star centroid positioning error are established. The γ radiation results show that the image gray-mean of the whole star map increases, the number of identified stars decreases, and the star point centroid positioning accuracy decreases, which seriously affect star map recognition of star sensor. This research provides a theoretical basis for the radiation-resistant reinforcement design of high precision star sensors.

60Co- γ After X-ray irradiation, the dark current noise, DSNU noise, and PRNU noise of CMOS APS increase with the increase of cumulative dose. The increase of total noise of CMOS APS will cause the average gray level of the background in the star map taken by the star sensor to increase, and the background fluctuation is obvious, resulting in an increase in the difficulty of star point recognition and a decrease in the number of star point recognition. Based on mechanism analysis, this paper proposes an algorithm for finding unrecognized star points, This algorithm can successfully identify stars that have been obscured by background noise. Research has found that the increase in CMOS APS dark current noise, DSNU noise, and PRNU noise leads to the displacement of the center of mass position of stars, ultimately affecting the accuracy of star sensor center of mass positioning. This article lays a theoretical foundation for improving the success rate of star sensor recognition and ensuring the safe and reliable operation of satellites in orbit for star sensor design units.