Research On Relative Navigation Algorithm Of Non-Cooperative Spacecraft Based On Vision Measurement

With the rapid development of space technology,there is a great demand for the acquisition,maintenance and other space operations of non-cooperative target spacecraft that have lost motion control due to malfunction.Using vision measurement technology to detect the pose parameters of the non-cooperative target is the basis of relative navigation,is the key to achieve the task of docking and acquisition,and is directly related to the completion of the space operation task.This project aims at the requirement of future space operation task,based on visual measurement technology.Based on visual measurement technology,the pose measurement technology of non-cooperative spacecraft relative navigation with known structure information,unknown motion information and no information exchange is studied.The main research contents are as follows.Firstly,an experimental platform is set up and a three-dimensional structure model of the non-cooperative target spacecraft is established.On the basis of studying the relationship between the camera imaging model and the related coordinate system,the camera is calibrated by Zhang Zhengyou calibration method,get the camera’s internal parameters.Secondly,several methods of feature point extraction are studied,including Harris corner detection algorithm,SIFT feature extraction algorithm and ASIFT feature extraction algorithm.In order to solve the problem of threshold setting of Harris corner detection algorithm,an adaptive Harris algorithm is proposed,which is more adaptive than Harris algorithm and has better corner detection effect.Based on RANSAC algorithm,ASIFT algorithm is optimized to meet the full affine invariance,get more matching point pairs,and eliminate the wrong matching point pairs,and get the high-precision matching results.A 3D-2D-2D feature matching algorithm is proposed to detect and extract feature points based on the target detection image captured by virtual camera.Forward and inverse template images are obtained by using the known 3D model information of the target.Feature points are extracted and matched from the forward and inverse template images and the detected images.Feature points are matched between the 3D model and the detected images by 3D-2D-2D matching algorithm.The effectiveness of the algorithm is verified by simulation experiments.Thirdly,the perspective n-point problem is studied.Given the camera internal parameters,the coordinates of n feature points in the target coordinate system and the imaging coordinates of feature points,the pose parameters of the target in the camera coordinate system are solved.To solve this problem,several methods are studied,such as the orthogonal iterative LHM algorithm based on the collinear error in the target space,and the non-iterative method,such as EPn P algorithm,Gauss-Newton iterative optimized algorithm based on EPNP,RPn P algorithm with stronger robustness.These algorithms are verified by simulation,and the influence of each parameter on the algorithm is analyzed.The advantages and disadvantages of each algorithm are compared.Based on the above research,in order to achieve the attitude measurement of noncooperative target,this paper presents a non-cooperative target spacecraft attitude estimation scheme.Firstly,the physical model of the space non-cooperative target is established,then the original model picture is acquired by a monocular virtual camera.The features are extracted and matched by using RANSAC optimized ASIFT algorithm and 3D-2D-2D matching algorithm.Finally,the pose parameters of the target relative to the camera(rotation matrix and distance parameters)are calculated using the EPn P algorithm and Gauss-Newton iterative optimization.Experiments are carried out to verify the feasibility and effectiveness of the design scheme,and the experimental results are analyzed.Aiming at the relative navigation requirement of non-cooperative target spacecraft based on vision measurement,this paper carries out relevant research,improves the key technology and algorithm,and carries out simulation verification,an attitude measurement scheme for non-cooperative target spacecraft is proposed and verified by simulation,which lays a foundation for future non-cooperative spacecraft relative autonomous navigation and other space missions.