US Naval Research Laboratory (NRL) researchers have designed and developed a new bio-inspired, actively controlled curvature robotic fin, which aims to deliver a low-speed propulsion system to scaled-down autonomous underwater vehicles (AUVs).

The vehicle, based on pectoral fins of reef fish, is integrated onto a man-portable, unmanned Wrasse-inspired agile near-shore deformable-fin automaton (WANDA) AUV.

NRL Laboratories for Computational Physics and Fluid Dynamics aerospace engineer Jason Geder said: "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 AUVs [with] a novel low-speed propulsion system."

Using data related to vehicle motion and surrounding environment to notify changes to the fin stroke kinematics, the four-side mounted fins, two forward and two aft, will deliver the propulsion and control the vehicle.

"Computational and in-water experimental results have demonstrated WANDA’s capabilities."

Geder added: "Computational and in-water experimental results have demonstrated WANDA’s capabilities.

"WANDA can perform low-speed manoeuvres 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 manoeuvres for waypoint navigation.

The AUV is now being prepared for payload testing, which will start this year.

Image: NRL researchers have designed and developed a new robotic fin. Photo: courtesy of US NRL / Jamie Hartman.