US Navy Researchers Develop Bio-Inspired Autonomous Vehicles

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Researchers at the U.S. Naval Research Laboratory (NRL) have designed and developed novel underwater propulsion, control, and sensing solutions for near-shore and littoral zone missions, inspired by the bio-mechanics of fish.

NRL Laboratories for Computational Physics and Fluid Dynamics aerospace engineer Jason Geder recently told UST: “Expeditions in near-shore environments are complex, often proving turbid, cluttered with obstacles and plagued with dynamically changing currents.” Inspired by the pectoral fins of the reef fish, bird wrasse, NRL researchers have developed an actively controlled curvature robotic fin that provides scaled down Autonomous underwater vehicles (AUVs) with a novel low-speed propulsion system.

AUVs have demonstrated many successful capabilities in inspection, surveillance, exploration, and object detection in deep seas, at high speeds, and over long distances. However, operations in littoral zones requiring low-speed and high-maneuverability present mobility and sensing challenges that have not been satisfactorily resolved.

Inspired by the pectoral fins of the reef fish, bird wrasse, NRL researchers have developed an actively controlled curvature robotic fin that provides scaled down AUVs a novel low-speed propulsion system.”

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According to UST, the artificial pectoral fin has been integrated into a man-portable, unmanned vehicle named the Wrasse-inspired Agile Near-shore Deformable-fin Automaton, or WANDA (with an obvious reference to the 1988 film). Four side-mounted fins, 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 inform changes to the fin stroke kinematics, or fin gaits. This kind of artificial fin technology can adapt to varying flow conditions and provide the thrust control necessary for low-speed maneuvering and precise positioning.

Geder added: “Computational and in-water experimental results have demonstrated WANDA’s capabilities. WANDA can perform low-speed maneuvers to include forward and vertical translation and turn-in-place rotation, and we are currently evaluating station-keeping in the presence of waves.”

Aimed at operating at speeds of 2k, or hold position in the presence of 2k currents, WANDA can also coordinate maneuvers for waypoint navigation. The AUV is now being prepared for payload testing, which will start this year.