科研之友
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摘要
Given that the precise pose of space non-cooperative targets is difficult to obtain during close rendezvous and docking, an efficient and reliable pose measurement method of space non-cooperative targets based on the time-of-flight (TOF) camera is proposed. Firstly, in view of the characteristic that light intensity can be stored in gray-scale images taken by the TOF camera, a dot calibration board made from retro-reflective materials is adopted to improve the calibration accuracy. Secondly, the ellipse detection method based on the combination of edge arcs is applied for calculating the inner and outer ellipse parameters of the target surface butt ring. Thirdly, the connected components of the depth image are analyzed via the region growing method based on local thresholds and the target surface connector is extracted under constraints such as area and aspect ratio. Finally, a target coordinate system is established through the docking ring and the connector and the three-axis position and attitude angle of the system in the camera coordinate system are calculated. Besides, a ground verification system is set up to verify the robustness and measurement accuracy of the proposed method. To this end, the proposed method and the ORB (Oriented FAST and Rotated BRIEF) method are compared using the experimental results of 4 groups of 100 frame images, indicating that the TOF camera has broad prospects in the pose measurement of non-cooperative targets.
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