Sofi harnesses a suite of relatively low-tech approaches in an ingenious harmony — and could permanently change access to marine wildlife. Image supplied by MIT CSAIL.

MIT’s CSAIL lab has unveiled a soft-bodied, acoustically controlled swimming robot that has major implications for AUV technology and submarine wildlife monitoring.

Announced in a paper in Science Robotics on March 21, ‘SoFi’ and comprises of a suite of innovative technologies.

To start with, SoFi uses ultrasonic acoustic communications — sound waves, that travel much farther underwater than radio or radar, and elmininate one of the main needs for a tether, that keep many AUVs bound to a surface vessel. SoFi’s comms operate on a wavelength of 30-36 kilohertz, producing minimal disturbance, and mean SoFi can be controlled by a diver around 20 metres away.

Secondly, propulsion — SoFi is not driven by propellers, impellers or electric motors — but a simple system of water pumps and chambers that create lateral motion of SoFi’s ‘tail’ that mimics how real fish swim.

Sofi is designed to get as close as possible to aquatic wildlife, and the communications and propulsion systems create far less disturbance than traditional equivalents — a characteristic that should be enticing to any submarine application that requires extreme delicacy.

Such a simple propulsion system is made possible by the robot’s soft body — a tail of elastomer enables gentle force to produce the ‘swimming’ motion that pushes it through the water, with a set of ‘dorsal’ fins that can control pitch for diving or ascending, in conjunction with an internal buoyancy system that can also be controlled remotely.

“To our knowledge, this is the first robotic fish that can swim untethered in three dimensions for extended periods of time,” said lead author of the study, CSAIL PhD candidate Robert Katzschmann.

“We are excited about the possibility of being able to use a system like this to get closer to marine life than humans can get on their own.”

SoFi is composed of relatively low-tech, inexpensive components, including 3D-printed parts, a linux microprocessor, a Super Nintendo controller, and a Li-Ion battery similar to those in laptops and smartphone — which means that this elegant, disruptive mix of materials and approaches could also revolutionise access to marine photography in a manner akin to the way consumer drones have permanently altered aerial photography.