Binocular Vision Measurement For Approaching Phase Targets: Research On Measuring Accuracy&Camera Calibration

The approaching phase target access to the measuring facilities from remotedistance. Limitted by the field of view, it is hard for traditional vision measuring systemto cover all the motion range of the approaching target. Hence, the research of the visionmeasuring system, which can cover all the motion region of the target and guarantee themeasuring accuracy during the whole measuring range as well, is quite meaningful,especially to the high-precision acquirement of the pose of approaching phase targets,like aerial vehicles for space rendezvous and docking and the landing UAVs.At first, based on the characters of the approaching phase target and the traditionalbinocular vision measuring system, this paper design a binocular vision relay measuringsystem, which can cover the whole motion range of the approaching phase target.Considering different parameters errors of the camera, this paper analyzes themeasuring accuracy about the relay measuring system from different measuring regionby some theoretical and artificial ways.Later, from the view of the camera intrinsic parameters, this paper does some deepanalysis about the measuring system from different measuring range. Then, establishingthe pinhole projection model with distortion, and based on this model, this paperproposes the conception of the focal length model error through the method of theoryderivation, numerical simulation and physical experiment. After that, using the focallength model error, this paper does some quantitative analysis about the measuringsystem.Thirdly, this paper proposes a distortion calibration method based on focal lengthinformation, which can decrease the influence of the focal length error to the measuringaccuracy. Meanwhile, though theory derivation and numerical simulation, comparedwith the traditional two step calibration, the above method has the advantages of thedistortion calibration.Through the above analysis, we know that the relay measuring system’s directingerror carry-over factor increases quite quickly when the measuring range is remotedistance. In order to guarantee the accuracy of the camera’s direction during the remoteregion, this paper proposes a camera’s direction calibration method based on theposition of the optical center and two control points. The above method uses few pointsduring the calibration, so that it is applicable for the camera’s direction calibration withfew remote control points. At last, through some numerical simulation, this paperverifies the rightness and robust of the method.