Think of a robot. Chances are you imagined one with legs like C-3PO of “Star Wars” fame or something with wheels like NASA’s Mars rover Curiosity. Neither of these rigid body types are particularly flexible and certainly can’t move through water well. But what about a robot with a tail? Scientists at the Massachusetts Institute of Technology have designed a soft robot based on a fish, which can bend its body and quickly flee the way that real fish do to escape predators.

Typical robots are rigid with exposed mechanisms and unnatural movement, but the fish described in the first issue of the new journal Soft Robotics is covered in a soft silicone skin. This sea-green skin protects the robot’s hard parts – the power source, the computational hardware, the actuating mechanisms that make it move – in the front and allows for a soft tail in the back. In some ways, it’s a lot like the animal it’s modeling, said lead author Andrew Marchese, a graduate student in MIT’s electrical engineering and computer science department.

“When we thought about it, a fish makes sense. It has a very similar structure,” Marchese said in the video above. “In the head of the fish, where the brains are held, it’s a little bit more rigid. But in the rear of the fish, where the undulatory motion happens, it’s quite soft and compliant.”

Other scientists have also been working on creating robots that swim and fly -- and they’ve found that soft-bodied flying and swimming animals have distinct advantages that they all seem to share. Some are even working on a manta-ray robot.


For this project, the MIT researchers managed to make a fish that was capable of moving with extreme speed and at high angles, able to turn on a dime in less than a blink of an eye. They did this in part by using a novel form of actuator (or motor) that basically uses carbon dioxide gas to inflate the soft tail at different points to make it move in specific ways.

The resulting robot is able to turn as sharply as 100 degrees on the order of 100 milliseconds, comparable with real fish that suddenly flit away as a hungry predators swims up, said Daniela Rus, who heads up the lab where the fish was built and co-wrote the paper.

The robo-fish “pushes the envelope on what machines could do today,” said Rus, who was also behind these cute-yet-creepy colorful jumping robot blocks.

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