Research On Three-Dimensional Imaging Technology Of Space Debris Based On Terahertz Radar

With the further advancement of space activities,the amount of space debris also increases rapidly with the increase of space activities.The rapidly increasing space debris threatens space exploration more and more seriously,and the human need for space debris protection is increasingly urgent.Imaging,identifying and cataloging space debris can effectively deal with the unknown risks brought by space debris,and the micro-motion characteristics of space debris include the motion information of space debris,the structure and size of space debris and other information.In the terahertz band,short wavelength,large bandwidth,obvious doppler effect,and high precision of the extracted target fretting features,which can provide strong support for target cataloging,identification and imaging.At the same time,with the maturity of terahertz technology,terahertz radar has great research value and potential.Therefore,it is necessary to carry out in-depth research on high-resolution imaging of space debris and micro-motion feature extraction.This thesis focuses on the micro-motion feature extraction and 3D imaging algorithm of space debris.The main work and contributions include the following aspects:Firstly,according to the unique motion characteristics of space debris,the space debris motion model and radar echo model are established,and the radar signal echo of space debris is deduced? It lays the foundation for dynamic feature extraction and 3D imaging algorithm research.Secondly,in order to solve the problem of fretting feature extraction of space debris,a method combining time spectrum and random Hough transform is introduced.Firstly,the micro-Doppler effect of space debris echoes is analyzed,and the correlation between micro-Doppler characteristics and its motion is studied? then a method of extracting time spectrum curve points by edge detection is given,which can effectively extract space debris.Finally,on the basis of the extracted space debris time spectrum curve points,the standard RHT detection curve parameter method is used to realize the rapid extraction of the space debris fretting characteristic curve.Based on the standard RHT algorithm,the error of space debris micro-Doppler characteristic parameters is further reduced by the improved RHT algorithm.Thirdly,a 3D imaging algorithm of space debris based on the combination of backprojection transformation and CLEAN technology is given.This algorithm is a parametric imaging algorithm considering the echo phase.It estimates the position and scattering coefficients of the strong scattering center in the space debris target,and then use the obtained positions and scattering coefficients of all scattering centers to reconstruct the 3D image of space debris.At the same time,the estimation of scattering point position parameters is accelerated and solved based on SSA,thus effectively realizing the 3D imaging of space debris.