Vision Based Station Keeping and Docking for Floating Robots
نویسندگان
چکیده
This thesis describes a method of vision based station keeping and docking for floating robots. Due to the motion disturbances in the environment, these tasks are important to keep the vehicle stabilized relative to an external reference frame. A vision-based tracking system is used to measure the image deformations, as the vehicle moves with respect to a docking station. A planar surface is chosen as a reference plane which allows visual tracking of a naturally textured region, based on planar projective transformations. The tracker integrates optic flow computation within the region with a correlation based method using motion models that sample the expected image deformations over time. These models are updated by the robot history of motion so as to accommodate predicted/future camera motions. The information provided by the tracker is then used to calculate inter-image homographies that register the current viewed image with some initial reference image. These transformations reveal the real camera motion in 3D space and allow to reconstruct the camera trajectory. This information can then be used to control the robots. Both 3D visual servoing as image based visual servoing approaches are studied. The resulting control strategies are illustrated with real experiments with a blimp and an underwater robot. Key-words: visual tracking, optic flow, planar projective motion models, visual servoing, underwater robots, blimp, station keeping, docking.
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