Design Of Dynamic Star Map Simulator Based On CCD Star Tracker

The dynamic star map simulator instrument is a kind of performance test device of star tracker on the ground.It provides reliable simulation star maps for testing the function of star map identification algorithm and the ability of attitude calculation through out simulating the real space on the ground.The precision of the ground test will have a direct influence on working accuracy when the vehicle of star tracker working in the track out of space.The thorough research on the technology of dynamic star map simulation was conducted and the system of dynamic star map simulator was designed in this paper.By using the Gaussian gray diffusion model to simulate the star imaging on CCD and using the liquid crystal light valve as the display device of simulation star map.It realized the star map simulation with high resolution and large field of view and solved the test problem of star tracker on the ground.In this paper,the overall structure,system composition and basic functions of dynamic star map simulator were discussed at first.The basic theory of dynamic star map simulation was analyzed including the basic operation principle of star tracker and dynamic star map simulator,the imaging theory of star map and the method of star map simulation.Combined with the parameters of star tracker and the specific simulation requirement,the task of dynamic star map simulation and display system can be summarized as: selecting the observed stars for simulation,coordinates transformation and displaying the simulation star map.This system is the core part of dynamic star map simulator.The simulation field of view and the principle of selecting the observed stars can be determined thought out analyzing different description method of attitude.By analyzing the stellar characteristics and the shooting process of star tracker,the method of magnitude simulation can be determined and the method that using the Gaussian gray diffusion model which is in accordance with the actual star imaging as the imaging model of star.In this design scheme,Visual C++ software from Microsoft was taken to design the overall framework and modules of the software of dynamic star map simulation system and Access database software from Microsoft was taken to make the observed stars database.The function of each module of the software and the impact of saving mode on the time cost of star map simulation were thoroughly researched and analyzed at the same time.Combined the miniaturized and dynamic demands of system and the influence of display device on the precision of angle of single star and angular distance of stars,high resolution liquid crystal light valve was supposed to be the best choice as the display device of star map.In this paper,the method of testing a few of important technical indexes of dynamic star map simulator was analyzed at last,the angle of single star and angular distance of stars were tested in the mean time.The results shows that the precision meets the system design requirement,the simulation star map is reliable and the overall design method is feasible.