Study On Key Technique Of Very High-Precision Star Simulator

Star sensor is a kind of high precision space optical sensor, which has been widely applied in aerospace field. With the development of aerospace technology, the precision of star sensor has been put forward higher requirements, high precision of star sensor development has been imminent, the accuracy of the star sensor calibration is the indispensable important link to achieve accurate measurement of its attitude, so, deep space guide star sensor calibration with high precision is the problem in deep space exploration and navigation field. However, at present domestic and foreign ground calibration methods used in precision can only achieve10" above, can not meet the high accuracy calibration requirements of the star sensor precision (less thanl"). In this paper, based on exploring precision calibration method and solution of the star sensor, in order to improve the calibration accuracy, high precision star simulator and its key technology research are carried out. Design a very high-precision star simulator which has an accuracy of better than0.5"(la) to solve the problem of ground high precision calibration.The simulator can be used for ground calibration and simulation test in measurement precision of high precision star sensor, it has important significance and application value to study the high precision of star sensor, deep space exploration and high precision navigation.Based on the study and analysis of the various calibration method and the characteristics of sensor home and abroad, used high imaging quality collimating optical system with long focal length and single point controllable star image simulation method and control technology, put forward a design program of very high accuracy star simulator, which realizes dynamic simulation and displays of a number of maps. The simulator is mainly composed of a high imaging quality collimating optical system with a long focal length and a standard target source with high precision and variable magnitude. High precision variable magnitude target source which has a plurality of transparent microporous with a certain size and distribution is placed on focal plane of the collimating optical system with high imaging quality and a long focal length. Each star’s position and brightness can be set and controlled, multiple stars can be combined to form the different area of particular star map, the star map is exited through high imaging quality collimating optical system with a long focal length in parallel light, and is produced on the exit pupil of the optical system, achieving star map simulation with a small celestial body full vision field and high precision. According to the problem of star position accuracy of the image, designed a kind of high imaging quality optical system with a long focal length. Collimating optical system is the most important part in very high accuracy star simulator; following the principle of designing a simulator, optical system with a long focal length, large field of view and calculation method is used. Use ZEMAX to optimize the collimating optical system, strictly control of system distortion and deviation of energy center and the main light, determine the structure parameters of the system, and give optical tolerance analysis and evaluation of image quality of the optical system, obtain deviation value of design of the distortion and energy center and the main light analyze its effect on the precision of star simulator. Design basis is provided for the study of very high accuracy star simulator by the design calculation and analysis, and for very high accuracy star simulator which establishes the basis.The star map display mode of star simulator is comprehensively analyzed and researched. In order to improve the positioning accuracy and the realization of the map star transformation, based on star map display technology principle of static star simulator, put forward a method which uses a static target standard source to achieve chart dynamic simulation and display, design high precision variable target standard source.Using the technology of laser direct writing scoring aster ion (the position precision is less than or equal to0.5u m), and breaking through the traditional mode for illumination of static star simulator, use the lighting technology of a single point controllable matrix LED as light source of star tester, control each star’s light and brightness, realize a small area of the sky star map of dynamic transformation. This method can simulate the dynamic star map, although its style is limited, overcome the problem of traditional simulation accuracy of dynamic star map by effecting of the pixel size, and the map display system is also without adding complicated calculation and controlling software, simplifies design difficulty of the system, achieves very high precision star simulator lay theoretical foundation for achieving very high precision star simulator, and has engineering application value.Accuracy evaluation method of the very high accuracy star simulator is analyzed in detail. Exiting accuracy of starlight is used as accuracy evaluation index of star simulator, collimated optical system error introduced by collimating optical system and display mode of star map effect on exiting accuracy of starlight. Error source which effects emitting accuracy of starlight is analyzed and calculated in the aspect of theory from theory results and actual machining and assembling the results of optical system. The results showed that: very high accuracy star simulator emitting accuracy of starlight can reach0.065" under the theoretical design; accuracy reached0.2312"after actual processing and alignment, can meet ground calibration requirements of the high accuracy of star sensor.In a word, the very high accuracy star simulator in this paper can be capable of simulating different forms of Star map, and the emitting accuracy of starlight is better than0.5"(1σ), can be used for ground calibration and simulation test of high accuracy star sensor, solves the problem of high precision calibration of star sensor, laid the foundation for the development of high precision star sensor.