NRLFEATURES SPECTRA 2 Autonomous underwater vehicles (AUVs)have demonstrated many capabilities in inspection, surveil- lance, exploration, and object detec- tion in deep seas, at high speeds, and over long distances. However, the low-speed, high-maneuverability operations required for near-shore and littoral zone missions present mobil- ity and sensing challenges that have not been satisfactorily solved, despite nearly half a century of AUV develop- ment. Very shallow water and littoral environments are complex operating zones, often turbid, cluttered with obstacles, and with dynamically changing currents and wave action. AUVs need to be able to maneuver around obstacles, operate at low speeds, hover, and counteract surge and currents. To develop AUVs that can successfully navigate and oper- ate in these dynamic and challenging environments, Naval Research Labo- ratory (NRL) researchers have taken inspiration from nature — from sh, in particular — to design and develop novel underwater propulsion, control, and sensing solutions. For AUV propulsion and control, NRL has developed an actively controlled curvature robotic n based on the pectoral n of a coral reef sh, the bird wrasse (Gomphosus varius ). In the most recent n iteration, four rib spars connected by a exible synthetic membrane dene the n geometry, and control of each rib deection angle enables the shape deformation needed to generate 3-D vectored thrust. Using computational uid dynamics (CFD) tools in conjunction with experiments, sets of high-thrust-producing n stroke kinematics, or n gaits, have been identied. This kind of articial n tech- nology can adapt to varying ow condi- tions and provide the thrust control necessary for low-speed maneuvering and precise positioning. The NRL articial pectoral n has been integrated into a man-portable, unmanned vehicle named WANDA, the Wrasse-inspired Agile Near-shore Deformable-n Automaton. Four side-mounted ns, two forward and two aft, provide all the propulsion and control necessary for the vehicle. A set of custom control algorithms uses information about the vehicle motion and surrounding environment to in- form changes to the n stroke kine- matics. By weighting and combining various n gaits, the magnitude and direction of thrust generated by each n can be controlled to produce the desired eects on vehicle motion. Computational and in-water experi- mental results have demonstrated WANDA’s capabilities. WANDA can perform low-speed maneuvers includ- ing forward and vertical translation, turn-in-place rotation, and station keeping in the presence of waves. Bio-Inspired Designs for Near-Shore AUVs
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Bio-Inspired Designs for Near-Shore AUVs - Spectra 2014
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8/9/2019 Bio-Inspired Designs for Near-Shore AUVs - Spectra 2014