Research On Methods To Improve The Accuracy Of Single Star Simulators

Star sensor is a type of high precision attitude sensor that uses stars in space as a reference source to provide flight attitude information to all types of spacecraft.Before entering orbit,they need to be tested and calibrated by a star simulator on the ground to ensure that their accuracy meets the requirements for orbital operation.As the accuracy of the star sensor increases,the star simulator,as the main equipment for its ground-based parameter testing,also needs to meet higher accuracy requirements.To this end,a study of methods to improve the accuracy of the single star simulator has been carried out to meet the needs of the star sensor test work.This paper analyzes and summarizes the factors influencing the accuracy of the single star simulator,and gives an optimization method to improve the accuracy of the calibration error,which mainly restricts the accuracy of the emitted light parallelism,and the environmental influences,which affect the long-term stable accuracy.This method uses CMOS camera to replace the traditional penta-prism method of theodolite and combines the high-precision centroid location algorithm based on the weighted optimization of bicubic interpolation to overcome the human eye reading error and improve the tuning accuracy to0.5″.The accuracy of the emitted light parallelism of the single star simulator is improved by guiding the installation of the single star simulator with a high precision calibration method.A real-time parallelism monitoring system based on a pentaprism is designed to improve the long-term stability of the parallelism of the e mitted light by monitoring the parallelism of the emitted light from a single star simulator in real time,overcoming the degradation of accuracy due to environmental factors.The results of the image quality evaluation indicate that the distortion is at a low level of 0.001863%,the MTF curve is close to the diffraction limit and the imaging quality of the parallelism monitoring optical system is good.Finally,the simulation experiments of the high-precision centroid location algorithm were carried out by building a single star simulator experimental device,and the results showed that the algorithm has good accuracy and stability,and its location error is below0.05pixel;the theoretical accuracy analysis and actual measurement of the single star simulator emitted light parallelism were carried out,and the results showed that the single star simulator emitted light parallelism after the high-precision adjustment method improved to 0.63″,which meets the requirements of technical index.