Research On Videometrics Technology In The Aircraft Transformation Collision Avoidance System

During the process of airplane transforming in the airport, once the crash happens, considerable economic losses and casualties follow. Therefore, the study of Aircraft Transformation Collision Avoidance System(ATCAS) has great significance to prevent the accidents at the airport. In recent years, Videometrics technology has developed rapidly, which provides an efficient solution for the ATCAS. In this article, the author introduced his researches in the Videometrics technology to build the measurement module of an ATCAS.In the first chapter, the background and the domestic and overseas development of the ATCAS is introducted. The key technology of author's research and the meaning creative work of the article is described.The second chapter describes the camera optical model, the calibration of camera intrinsic parameters which is adapted to the airport and the effect which is taken by the protective glass of the camera. Among them, the establishment of an imaging camera model is the basis for the measurement. We can understand the internal geometry of the camera, the light propagation path inside the camera and the videometries principle through the establishment of the camera model.When we calibrate the intrinsic parameters of a camera in the airport, we must consider the different situations with different number of the control points in the view of the camera. If there is enough number of control points we can calibrate the intrinsic parameters on site. While the number of control points is limited, we have to calibrate the intrinsic parameters in the lab at first. This thesis aslo do some search on the imaging measurement model and the corresponding equation of the light path from camera to space target after the installation of protective glass. At last, simulation experiments on different methods are carried out to verify the accuracy of their calibration.In chapter three the thesis studies on the problem of camera pose estimation in details, which has a high researching value. Extrinsic parameters of a camera can be given by camera pose estimation, and the most representative camera pose estimation algorithm is the orthogonal iterative algorithm. However, if there are only two control points in the view of a camera, most camera pose estimation algorithms are no longer useful. For this situation, the thesis provides a new optimized algorithm with Rodrigues rotation matrix and conducts simulation experiments to compare the precision with the orthogonal iteration algorithm.In chapter four the thesis studies on photogrammetry technique with single camera. We usually use two or more cameras to measure in phtogrammetry, because at least two cameras are needed to give the 3-D coordinate of the space target without additional information. In airport every camera has its own work field, so we have to use monocular camera to measure the target. Therefore some more position information of the measurement target has to be added. In this dissertation the height of the target is measured at first, the collinear equation method is used to measure the initial coordinate value and then optimize the initial result by the pyramid method. Traditional pyramid method needs three control points at least. To reduce the number of control points, the thesis provids an improved method of pyramid method with two control points and the camera optical axis. In the final, the thesis analyze the accuracy of the improved pyramid method.In the chapter 5 the thesis introduces the solution of ATCAS with videometrics technique. Airport collision avoidance system is a large system, and this thesis is only focus on the measurement part. The camera calibration method, pose estimation and target measurement is depending on the different circumstance of each camera. If there are only two control points in the view of a camera, the intrinsic parameters can be calibrated in the lab, the pose of camera in the measurement site can be estimated by the Rodrigues method, and the pyramid method with optical axis can be used to measure the position of the target. If four control points are provided, both of the intrinsic and extrinsic parameters can be calibrated in the measurment site, and the camera's pose can be optimized by the OI method.