Pose Measurement System Of Space Non-Cooperative Target For Close Range Rendezvous And Docking

Once the spacecraft fails,it will seriously encroach on the precious earth orbit resources and threaten the safety of other on-orbit spacecraft.Therefore,countries actively carry out research on on-orbit service technology for the maintenance and recovery of failed spacecraft.Due to the difficulty in establishing communication connections,the lack of markers,and unknown structural dimensions,the failed spacecraft exhibits typical non-cooperative target characteristics.Accurately obtaining the pose information of non-cooperative targets is the important prerequisite for the success of close range rendezvous and docking.Therefore,this paper combines ellipse detection and vanishing line strategy to study the pose measurement method of space non-cooperative target for close-range rendezvous and docking.The specific research contents and results are as follows:(1)To solve the occlusion problem of non-cooperative target ellipse detection in close-range rendezvous and docking stage,an occlusionresistant ellipse detection algorithm based on multiple arc combination is proposed.The threshold adaptive Canny detection algorithm is used to extract the edge information of the target image under noise interference and uneven illumination.According to the gradient direction and gray scale,the edge points are classified and spliced,and then arc length and chord height ratio are further utilized to eliminate the pseudo arc interference such as short arc and straight arc.An arc combination method combining triples and two-tuples is designed to improve the detection accuracy of the occluded target circle.The experimental results show that compared with the existing ellipse detection algorithms,the proposed method has the highest F-measure on both the public dataset and the experimental dataset in this paper.(2)Aiming at the lack of prior information such as the radius of the non-cooperative target circle and the ambiguity of the solution,a circular feature pose measurement algorithm based on the vanishing line is proposed.The geometric method is introduced to establish the projection conic model,and the ambiguity of circle normal vector is eliminated by binocular vision coordinate system transformation.The projection coordinates of the circle center are obtained by combining the concentric circle characteristics and the vanishing line of the satellite nozzle and the docking ring,and the three-dimensional coordinates of the circle center are reconstructed by using the triangulation technology of binocular stereo vision,so as to overcome the problem of lack of priori information of the target circle.The experimental results show that the normal vector angle error is about 1°,and the center coordinate position error is less than 20mm.(3)Combined with the actual application requirements,while based on the Qt development environment,a space non-cooperative target pose measurement system for close-range rendezvous and docking is built.By introducing OpenCV and Eigen basic library,three functional modules of image acquisition,ellipse detection and pose measurement are designed and implemented.Finally,the system is tested and verified.