Autonomous soft-robot is as swift as a fish

MIT researchers have developed an aquatic robot that can change direction in 100 milliseconds, a manoeuvre comparable to that of a fish.

The self-contained autonomous soft robot, claimed to be the first of its kind, is detailed in a paper published in Soft Robotics.

The robotic fish was built by Andrew Marchese, a graduate student in MIT’s Department of Electrical Engineering and Computer Science and lead author of the paper.

Each side of the fish’s tail is bored through with a long, tightly undulating channel. Carbon dioxide released from a canister in the fish’s abdomen causes the channel to inflate, bending the tail in the opposite direction.

According to MIT, each half of the fish tail has two control parameters: the diameter of the nozzle that releases gas into the channel, and the amount of time it’s left open.

In experiments, Marchese found that the angle at which the fish changes direction is almost entirely determined by the duration of inflation, while its speed is almost entirely determined by the nozzle diameter. That decoupling of the two parameters is something that biologists had observed in real fish, he said.

A new version of the fish that should be able to swim continuously for around 30 minutes will use pumped water instead of carbon dioxide to inflate the channels.

‘We’re excited about soft robots for a variety of reasons,’ said Daniela Rus, a professor of computer science and engineering, director of MIT’s Computer Science and Artificial Intelligence Laboratory, and one of the researchers who designed and built the fish. ’As robots penetrate the physical world and start interacting with people more and more, it’s much easier to make robots safe if their bodies are so wonderfully soft that there’s no danger if they whack you.’

In many robotic motion-planning systems, avoiding collisions with the environment is the highest priority, a situation that leads to inefficient motion, because the robot has to choose collision-free trajectoriess. With soft robots, however, collision poses little danger to either the robot or the environment.

’In some cases, it is actually advantageous for these robots to bump into the environment, because they can use these points of contact as means of getting to the destination faster,’ Rus said in a statement.