MIT's Robot Fish Can Blend in and Spy on Real Sea Creatures

Researchers at MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) have built a fish robot that can swim in the open water alongside the very animals it is researching.

Robotic fish have become increasingly sophisticated in recent years. They are now "secret agents" that can infiltrate schools of fish in controlled scenarios. The new CSAIL robofish called "SoFi" appears to set a new standard in its ability to blend into open water.

“To our knowledge, this is the first robotic fish that can swim untethered in three dimensions for extended periods of time,” says CSAIL PhD candidate Robert Katzschmann, lead author of the new journal article published today in Science Robotics, in a press statement. “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 can handle going 50 feet deep into open water for up to 40 minutes. It's strong enough to push back against currents, and it takes high-resolution photos. Using a waterproofed Super Nintendo controller, the SoFi can swim in a straight line, turn, and dive up or down.

SoFi's back half is made of silicone rubber and flexible plastic, while the head, which holds all the electronics, is 3D-printed. To swim, SoFi's motor pumps water into two balloon-like chambers in its tail, which function like a set of pistons in an engine. When one chamber expands, it flexes and bends to one side or the other.

Getting SoFi to swim at various depths proved to be one of the greatest challenges for Katzschmann and the team. Its fins have “dive planes” that adjust the up-or-down pitch of the fish. It does all this with minimal motor noise and low-frequency communications with the research team on wavelengths from 20 to 36 kilohertz.

“The robot is capable of close observations and interactions with marine life and appears to not be disturbing to real fish,” says CSAIL director Daniela Rus.

With a proven model, the team is now tweaking SoFi through an improved pump system and minor alterations to the body and tail. After that, they plan on building more SoFis that would use their robotic eyes to follow schools of fish.

“We view SoFi as a first step toward developing almost an underwater observatory of sorts,” says Rus. “It has the potential to be a new type of tool for ocean exploration and to open up new avenues for uncovering the mysteries of marine life.”