Research On Tracking Of Underwater Object Based On Forward-looking Sonar

The technology of underwater target detection and tracking based on sonar is one of the research content in the domain of Autonomous Underwater Vehicle AUV) vision, and is a difficult and significant problem. Target detection and tracking is at the bottom of vision application system, and is the base of continuing high-level disposing, such as classifying targets and analyzing behavior.The contents in the dissertation originate from the controlling and displaying system of a sort of forward-looking sonar. The problem of target tracking based on serials of sonar images is studied in this dissertation, including modules of target detection, matching and estimating motion of target. The module of target detection takes charge of judging the existence of targets in serials of sonar images, describing the shape character of the target, such as the position and the size of the least encircling rectangular. The module of target matching searches the corresponding relation of targets in serials of images to confirm the track of target. The module of target motion estimating takes charge of forecasting the possible arisen location so as to confirm the scope of target searching.In the dissertation, the hardware configuration, data format of 881A type of sonar and the existent image pretreatment software, which including coordinate transform, binds of wave inserting, switching of gray level, median filtering and display of sonar images, etc., are presented at the first. The second, two kinds of image segmentation or target detection arithmetic, self-adapting threshold arithmetic and mean-shift arithmetic, are development. In the fore method image is segmented by self-adapting threshold to get the two-value image, and then the connected areas are get by some kinds of detecting method, so as to detect targets. In the latter targets are directly detected during the process of image segmentation. Then, a kind of function is presented to evaluate the possibility that two targets in two connected frames are the same target, so as to realize the target matching. At last,a sort of target tracking method is presented based on Kalman filter, which...