Research On High Precision Vision Measurement System Of Turntable Attitude

Image Navigation and Registration is one of the key technologies of FY-4.It involves multiple systems such as satellite population,attitude control,payload,and ground applications.The performance of satellite imagery directly determines the quality of satellite remote sensing images.It is impossible to meet the development requirements by simply relying on the key technology of a certain system to take measures.It must be considered from a system-wide perspective and integrated verification under the whole star condition.It is the most effective way to solve this problem by iterating the design scheme with the full physical simulation test of the three-axis air floating platform.The air-floating platform is the most ground-based device that can realistically simulate satellite motion.Therefore,the research on attitude measurement and related technologies for air-floating stations(analog satellites)is very useful for satellite research and development.The high-precision attitude determination scheme of the analog satellite aims to provide a high-precision and high-reliability measurement system for the three-axis air-floating turntable experiment.A visual measurement method based on laser indicating line is proposed to complete the high-precision measurement of the attitude.The system first analyzes the rigid body attitude measurement methods commonly used in engineering practice,and proposes a vision measurement scheme through different methods comparison and actual conditions of the project.The system installs a laser pointer on the surface of the air-floating turntable,and the projection line and the fixed screen generate intersection points(spots)to construct feature points,and use a high-speed camera to collect the spot displacement at different times,thereby calculating the three-dimensional posture of the air floating platform at any time;The mathematical model of the air-floating turntable attitude and the laser spot is verified by simulation.For the mathematical model of the measurement scheme,the world coordinate system is established by using the laser tracker,and all the measurement results are unified in this coordinate system.Determine the rotation center of the three-axis air-floating turntable under this coordinate system,perform high-precision calibration fitting on the reference screen plane and laser indicator line,and propose a full-field point-by-point calibration camera based on coplanar feature points to establish a calibration table.And gave a detailed calibration plan.For the attitude measurement method and spatial layout,the factor determining themeasurement accuracy of the system is determined by the center three-dimensional coordinate positioning accuracy of the spot.A detailed analysis of the factors affecting the centering of the spot is performed to quantify some of the errors.The error model of the centroid of the spot pixel is analyzed in detail,and the compensation model is given.According to the proposed vision-based measurement scheme,the complete equipment construction and system software design were carried out.Monte Carlo simulation was used to estimate the accuracy and uncertainty of the measurement system.The system was calibrated at the experimental site and tested on a three-axis air-floating turntable.Finally,the final experimental results were analyzed.