Research On Rapid Matching Technology Of Star Map In Astronomical Pointing Direction

With the increasingly fierce competition in human space exploration,the field of space observation has also received increasing attention from all countries.The photoelectric telescope system is one of the main equipment in this field.For photoelectric telescopes,pointing accuracy is an important technical indicator for evaluating its performance,and it has an extremely important impact on the quality of the observed image and the accuracy of target tracking and positioning.Although the pointing model correction method can improve the pointing accuracy,there is still the defect that the pointing model coefficients have a certain life span and cannot be corrected in real time.The pointing correction scheme based on star matching can overcome the limitations of the pointing correction model method.Under passive guidance conditions,the photoelectric telescope can correct the pointing accuracy of the telescope in real time,which can be carried out at the same time as the observation task,and maintain high precision pointing for a long time.Among them,the star matching algorithm is a key link in the overall plan.However,due to the high complexity of the stellar matching algorithm,its implementation and operation efficiency at the software level is low,its punctuality is poor,and the time drift is often more than hundreds of milliseconds.Therefore,it is of great significance to carry out research on the fast matching technology of star maps.After comprehensive investigation and analysis of the hardware platform,this article combines laboratory technical conditions to carry out the technical research on the FPGA platform.After a detailed analysis of the small field of view star matching algorithm based on the error vector matrix,the overall hardware structure of the star matching algorithm is given.The communication between upper and lower computers in the structure is designed to effectively ensure the accuracy of data transmission.Different from the relatively independent development of software and hardware in the traditional hardware design process,this paper designs the relevant modules in the hardware structure based on the system-level development method.The sine and cosine calculation module commonly used in the calculation of astronomical spherical coordinates is designed using the System Generator development tool,so that the calculation angle is extended to the full real number domain.And based on the classical error theory of CORDIC algorithm,the theoretical error upper limit of the design module is given.After simulation verification,the accuracy of the module has reached the theoretical estimate,and the performance is better than the sine and cosine calculation module of the System Genearator.Based on the design of the sine and cosine calculation module,the FPGA model for solving the local true sidereal time has been continuously implemented.Compared with the software running results,the simulation waveform display calculation speed is significantly improved.Use the Vivado HLS development tool to design the error vector matrix calculation module in the hardware structure of the star matching algorithm.The algorithm implemented in C language is converted into an RTL-level implementation.After the optimization strategy,the simulation verification is passed.The simulation verification results are compared with the software level,and the computing efficiency has been significantly improved.Both Sys Gen and HLS system-level development prototype designs have passed the hardware synthesis,which can automatically generate HDL hardware description language and reliable IP cores for subsequent development and design.In this paper,aiming at the technical problems in the fast matching project of the small field of view star image,the hardware structure of the star matching algorithm is researched.Using Xilinx's two system-level development tools to carry out hardware prototype design for related modules,and pass the simulation comprehensive verification,which improves the performance of the star map matching system to a certain extent,and corrects the overall design of star matching point in real time.It has a positive meaning.