Experimental Study On The Influence Of Radiation Damage Of Image Sensor On The Performance Of Star Sensor

With the increasing demand of China’s aerospace missions and the rapid development of aerospace technology,autonomous navigation has become a key technology for space probes to achieve autonomous operation and management.Autonomous attitude measurement is the basic function of autonomous navigation system of space probe.Among many attitude measurement devices,star sensor has become an indispensable attitude measurement device for multi platform navigation system in aviation,aerospace,navigation and other fields because of its high accuracy,full autonomy and non accumulation of error over time.Satellite platform star sensor has been widely used,and its star sensor technology is relatively mature.At present,the star sensor based on CMOS(Complex Metal Oxide Semiconductor)image sensor is the main direction of star sensor technology.However,with the increasing demand of satellite platform for navigation and control accuracy,its attitude and orbit control system also puts forward higher requirements for the attitude measurement accuracy and reliability of star sensor.The star sensor works in a complex and diverse space environment.The effect of various space irradiation on the star sensor will inevitably affect the performance of the star sensor.The space radiation effect mainly acts on the on orbit equipment through particles and electromagnetism,and the proton radiation effect will have a great impact on the CMOS detector.In order to explore the effect of proton irradiation on the performance of CMOS star sensor(mainly on the accuracy of star sensor),the related research work was carried out.The main research work of this paper is divided into the following three points.1.This paper presents a method for evaluating the accuracy of star centroid position of star sensor based on Star diagonal distance measurement.The position accuracy of star centroid of star sensor will directly affect the attitude measurement accuracy of star sensor.However,for a single star,it is difficult to directly measure the position accuracy of star centroid.At present,most of the existing methods evaluate the repeatability of star centroid position by theoretical calculation or measurement,but the measurement accuracy of star centroid position obtained by these methods is not accurate.Therefore,this paper proposes a new method to measure the star diagonal distance by experiment and calculate the position accuracy of star centroid by theory,and analyzes the method by computer simulation.This method is not only suitable for multi star matching star sensor,but also suitable for single star tracking star sensor,which can realize the accuracy evaluation of star centroid position.2.In order to study the influence of radiation damage of image sensor on the performance of star sensor(accuracy of star centroid position),a set of laboratory test system and evaluation scheme are designed based on the proposed evaluation method of star centroid position accuracy of star sensor.CMV4000 detector is irradiated by proton radiation source with different energy(3Me V,60 Me V)under different fluence conditions.The experimental system for measuring the centroid position accuracy of star sensor is built by using matching star sensor lens and image acquisition system.A large number of star maps are collected and processed,and the relationship between different proton irradiation effects and the accuracy of star centroid position is obtained.3.In order to avoid the error caused by the laboratory test equipment,the field observation experiment scheme is designed.The CMV4000 detector irradiated by 60 Me V high energy proton radiation source under different fluence conditions is used to carry out the field observation experiment by using the same star sensor system.The experimental results show that the performance of star sensor based on CMV4000 detector irradiated by proton will degrade;For the CMV4000 detector irradiated by different energy sources,the centroid position accuracy of the star sensor irradiated by 3Me V low energy proton is lower than that irradiated by 60 Me V high energy proton;for the CMV4000 detector irradiated by the same energy proton,with the increase of proton irradiation fluence,the dark current of the star sensor increases,the signal-to-noise ratio of the system decreases,and the detection sensitivity of the star sensor decreases When the radiation fluence is higher than 50 krad,the star image captured by the star sensor in the night sky under the same setting parameters can not correctly extract all the star centroid coordinates,and can not accurately complete the star image matching function.The research results of this paper provide a theoretical and experimental basis for the work of CMOS star sensor performance affected by space proton irradiation,and also have a certain reference value for the radiation protection design of star sensor.