| The star tracker is widely used in military and scientific research fields due to its strong anti-interference ability and no accumulation error.But,when used near the ground,it is susceptible to strong sky background radiation during the day,causing the star tracker to malfunction.In order to expand the application field of star trackers and reduce their use restrictions,the development of daytime star trackers capable of working under daylight conditions has become a research hotspot in the field of star trackers.In this paper,the special application background of the daytime star tracker is researched.The star signal signal-to-noise ratio enhancement technology around the star tracker and the star point extraction technology under complex background conditions are studied.The main research contents are as follows:1.According to the application characteristics of the daytime star tracker,the signal-to-noise ratio analysis of star tracker starlight detection is carried out,and the technical scheme of realizing the signal-to-noise ratio enhancement of the star image is explored.Firstly,the spectral characteristics of the sky background radiation and the stellar target are analyzed,and the suppression of the sky background radiation is realized by rationally selecting the spectral band of the starlight detection.Then,the factors affecting the signal-to-noise ratio of the star images are analyzed by deriving the mathematical solution of the signal-to-noise ratio of the star image in detail.Finally,the multi-frame star image superposition method is proposed to enhance the signal-to-noise ratio of the star image,and the simulation verification is carried out.2.According to the practical application conditions of the daytime star tracker,the research on the star image superposition method under dynamic conditions is carried out.Based on the inertial navigation information,this paper proposes a star image superposition method based on pose correlation frame.The method can effectively realize the alignment and superposition of the dynamic star image,and achieve the purpose of enhancing the signal-to-noise ratio of the star image.The paper analyzes the attitude-based frame superposition algorithm by simulation and experiment,and analyzes the influence of installation angle error,gyro error and star image superposition error on the superposition method.3.The background noise of the actual near-infrared star image was researched.The background noise characteristics of the near-infrared star image and the influence of these noises on the method of superimposing the enhanced signal-to-noise ratio of the star image are analyzed.Through the reasonable selection filtering method,the background noise of the near-infrared star image is suppressed and simulated.It is verified that the method of superimposing the star image can improve the signal-to-noise ratio of the star image and the accuracy of star centroid estimation. |
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