Design Of Embedded Star Simulator System

Star sensor is a celestial sensor with very high accuracy.Compared with other celestial sensors,it has a great improvement in accuracy.It is very important to the development of China’s space industry.Because the working environment of star sensor is limited by various factors,it is possible to develop a device that can calibrate and test star sensor.Throughout the history of the star simulator,we can summarize most of the existing problems.First,the star simulator accuracy and real-time performance is poor.Secondly,the star simulator’s volume is so large that is inconvenient to carry and test anytime and anywhere.The embedded star simulator designed in this paper is similar to the traditional s tar simulator,which solves the problem of limited testing environment of star sensor.In this paper several disadvantages of traditional star simulator mentioned above,in order to improve the accuracy,real-time performance,miniaturization aspects,we consider not only the pure-two-body problem,but also added the earth non spherical gravitational perturbation and atmospheric drag perturbation,direct solar radiation pressure perturbation,and lunisolar gravitational perturbation analysis.A high precision simulation algorithm is designed in this paper.In view of the algorithm research in this paper,after calculating the orbital parameters,the perturbation equations of motion with high accuracy are derived first;Secondly,by RKF,AC,KSG integrator three methods of processing high precision equation is deduced,and compared with the results of STK standard software simulation.The error curve is drawn,comparing the precision.From the simulation results,the error of the AC algorithm is minimum,the KSG algorithm is the second,and the RKF is with the maximum error.Meanwhile,with repeating simulation tests,we compared the average simulation time of the algorithms.From the simulation results,we found that AC algorithm which is finally applied has the highest accuracy with less time cost.For the calculation of attitude parameters,firstly,the attitude kinematics and attitude dynamics equations are introduced,and then the coordinates of star under the orbit coordinate system and star sensors are calculated.Searching in the star catalog,we used a method called Interpolation Searching(IS)that the rate of star search can be greatly improved.For calculation of star coordinates,firstly using star sensor imaging principle,calculated the attitude of star sensor in the inertial coordinates,represented by the Euler angle.Then we can search in the star catalog with Interpolation Searching and calculated the ideal star coordinate.Finally,the algorithm is applied to the embedded hardware platform designed in this paper for function test.The experimental results show that the embedded star simulator system designed in this paper has higher accuracy and very good real-time performance and smaller size.The whole design of the system meets the requirements above,has the theoretical significance and practical significance.