Research On Image Stabilization System Of Full-disc Vector Magneto Graph

Full-disc vector Magneto Graph is one of the main loads of the ASO-S satellite.The solar magnetic field will be measured with high resolution and high sensitivity to study the occurrence,development,interaction,and consequences of the solar magnetic field through continuous and stable observations.Full-disc vector Magneto Graph will study the mechanisms of energy accumulation,triggering,release and transmission during flare and coronal mass ejection to provide observation basis for space weather event forecast.The motion and micro-vibration of the satellite platform are the biggest factors affecting the resolution of the space optical system.Full-disc vector Magneto Graph adopts deep integral observation mode,which requires multiple images for superposition observation,and the image shall be stable within 0.25" in the maximum observation time of 30 s.Compared with foreign countries,the research of space telescope and other space astronomical observation equipment in China is still relatively backward,and the research on image stabilization technology of space optical system is still in the exploration stage.Spatial image stabilization technology integrates many disciplines,such as optics,mechanics,electricity and computing,involving many key technical difficulties.In this paper,based on the image stabilization requirements of Full-disc vector Magneto Graph(FMG)and referring to the image stabilization schemes of spatial optical systems at home and abroad,a closed loop system composed of deviation detector,bias mirror and image stabilization controller is proposed for the image stabilization work.According to the engineering science index,the design index of each subsystem of the image stabilization system is calculated step by step,and the key technology in the image stabilization system is analyzed and studied.This paper focuses on the mathematical modeling and development of the deviation detector in the image stabilization system.Based on the analysis and comparison of the traditional bias detection methods,a bias detection method based on edge detection is proposed.Compared with the correlation calculation algorithm based on CCD or CMOS and the detection method based on the four-quadrant detector,the photodiode has a simple structure,less error sources introduced into the system and is convenient for compensation and correction.When working in orbit for a long time,it has strong ability to resist irradiation,static electricity and single particle,and is suitable for complex working environment of space.This paper analyzes the output characteristics of the bias detection device in ideal uniform incident light and actual solar observation,and completes the structure,software and hardware design of the deviation detector.Each subsystem of the image stabilization system is tested and the closed loop test of the whole image stabilization system is carried out.After testing,the resolution of the deviation detector can reach 0.05",and the linear measurement range can reach 50".The resolution of the bias mirror can be up to 0.05",and the stroke is up to 4.5'.The image stabilization accuracy of the whole image stabilization system reaches 0.2 "/30 s in the horizontal axis and 0.23" /30 s in the vertical axis.The disturbance suppression bandwidth reached 58 Hz on the horizontal axis and 55 Hz on the vertical axis.The test results accord with the design indexes and can be applied to the actual scientific observation of Full-disc vector Magneto Graph.