Tethers are used to supply power and transfer data for teleoperated robots. They are known to limit the robot's workspace and could have the effect of hampering its motion. What if we could take advantage of the tether? In this paper a new visual servoing scheme for catenary shaped deformable objects is introduced in order to control the tether parametric shape by properly moving its fixation point. In most of the visual servoing approaches the target object is rigid and distant from the controlled robot. On the contrary, in this paper, the object is deformable and attached to the robot, thus its 3D shape changes while the robot is moving. The experimental system is composed of two terrestrial mobile robots of the same motion capabilities linked with a slack rope. Simulation and real experiments validate the proposed control scheme for proper tether handling.
Purpose of Review This paper addresses the benefits and challenges of mixed reality (MR) for the exploration of deep-sea environments with remotely operated vehicles. The approach is twofold: virtual reality (VR) let the scientist explore the environment via a visual 3D model, overcoming limitations of local perception. Augmented reality (AR) concepts are designed in order to improve environment perception and interaction.
Recent FindingsThe key to such concepts is the implementation of 3D visual geo-referenced terrain models from the imaging feedback gathered by the vehicle exploring its unknown surroundings. Image processing, underwater vehicle navigation, and user-friendly displays for robotic intervention are addressed in an integrated concept. A broad development programme carried out at the French Institute for Ocean Science, IFREMER, is described and illustrates technical topics and use cases. Summary 3D perception derived from camera vision is shown to enable AR concepts that will significantly improve remote exploration and intervention in unknown natural environments. Cumulative geo-referenced 3D model building is in the process of being taken to reliable functioning in real-world underwater applications, accomplishing a milestone change in the capacity to view and understand the obscure and inaccessible deep-sea world.
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