In early March 2018, scientists were able to get footage of one of the Arctic’s most elusive sharks, the Greenland Shark. The footage, obtained by putting bait on underwater cameras, allowed the researchers to get a better idea of the shark’s population to better monitor their density and behaviors.
But despite underwater drones and remotely operated underwater vehicles, it is difficult to document marine life accurately. Existing autonomous underwater vehicles (AUVs) are traditionally tethered to boats or powered propellers.
So leave it to scientists to come up with a solution. At the Massachusetts Institute of Technology (MIT) Computer Science and Artificial Laboratory (CSAIL) a group of researchers created an autonomous soft robotic fish that can get up close and personal with real fish.
The scientists say SoFi was designed to be non-disruptive so it can interact and observe marine life, snapping photos and videos while it swims.
According to Cecilia Laschi, a professor of biorobotics at the Sant’Anna School of Advanced Studies, Pisa, Italy, SoFi’s creators show several technical achievements in fabrication, powering and water resistance that allow the robotic fish to move underwater without a tether.
“A robot like this can help explore the reef more closely than current robots, both because it can get closer more safely for the reef and because it can be better accepted by the marine species,” said Laschi.
Through its fisheye lens, this soft robotic fish, called SoFi, can take video and high-resolution photos as it swims alongside real fish.
SoFi “fish brains” in the head which is encased in baby oil to prevent water leakage but also because baby oil doesn’t compress as the pressure changes when the fish moves to different depths.
SoFi uses common, off the shelf materials to behave like a real fish including onboard sensors for perception, a lithium polymer battery just like the one used in your smartphone and a servo motor. SoFi also uses a waterproofed Super Nintendo controller so it can steer itself and move like real fish and a customized communications systems to pick up acoustics.
SoFi has a buoyant tail which allows it to ‘steer’ itself and move like real fish – undulating side-to-side.
The tail is comprised of two balloon-like chambers. As one chamber expands, it flexes to one side. When the second other chamber is filled with water, it flexes in the opposite direction. This action creates the undulating tail motion seen in real fish and propel SoFi forward.
SoFi has two fins on its side called dive planes which both adjust the pitch so it can dive up and down. To adjust its position vertically, SoFI has an adjustable weight compartment and a buoyancy control unit that changes its density by compressing and decompressing air.
In test swims on the Rainbow Reef in Fiji, SoFi swam at depths of more than 50 feet for around 40 minutes and was able to swim one body length per second. SoFi can swim in a straight line, turn, or dive up or down.