Research On Dim Star Signal Extraction And Star Tracking Algorithm

On the background of star sensor, the detection of dim star signal under two circumstances is studied. One is under the condition of strong sky background during the day, the other is under high dynamic conditions. In addition, the star tracking algorithm is studied. The main work is as follows:In-depth research is made on the distribution difference among atmospheric scattering, solar radiation and star radiation, and the significant differences of polarization properties between the sky scattered radiation and the star radiation is analyzed. The star spectrum polarized imaging device is designed, and its working process and principle is introduced.Structure elements of morphologic filter is designed according to the characteristic of isolated star spot. The background estimation and elimination technology based on morphologic operation is studied. The increase of SNR by multi frame image accumulation is analyzed. The common noise of star sensor is introduced, and calculation formula of SNR is deduced.The reason of smearing is analyzed. The smearing image restoration method based on wiener filtering is studied. A method of stellar-inertial attitude determination under high dynamic condition is proposed, and the simulation results verify its effectiveness. Star centroid extraction simulation interface and star pattern simulation interface with attitude determination function are made. The function and using method are introduced in detail.The basic principle of star tracking is analyzed. A star tracking algorithm based on star neighborhood matrix is proposed. The speed of star pattern identification is accelerated by setting two thresholds before new stars identification and attitude determination. The reliability enhances by adding validation mechanism before attitude output.