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squid robot

Squid-like robot propels itself using jets of water

Image credit: uc san diego

A squid-like robot that can propel itself by generating jets of water using its own power source has been developed by engineers at the University of California San Diego.

It is envisaged that the robot could be used for underwater exploration, as it also carries an array of sensors and a camera.

“Essentially, we recreated all the key features that squids use for high-speed swimming,” said professor Michael T. Tolley, one of the paper’s senior authors. “This is the first untethered robot that can generate jet pulses for rapid locomotion like the squid and can achieve these jet pulses by changing its body shape, which improves swimming efficiency.”

This squid robot is made mostly from soft materials such as acrylic polymer, with a few rigid, 3D printed and laser cut parts. Using soft robots in underwater exploration is important to protect fish and coral, which could be damaged by rigid robots. Soft robots tend to move slowly and have difficulty manoeuvring.

The research team, which includes roboticists and experts in computer simulations as well as experimental fluid dynamics, turned to cephalopods as a good model to solve some of these issues. Squid, for example, can reach the fastest speeds of any aquatic invertebrates thanks to a jet propulsion mechanism.

The robot takes a volume of water into its body while storing elastic energy in its skin and flexible ribs. It then releases this energy by compressing its body and generates a jet of water to propel itself.

At rest, the squid robot is shaped roughly like a paper lantern and has flexible ribs, which act like springs, along its sides. The ribs are connected to two circular plates at each end of the robot. One of them is connected to a nozzle that both takes in water and ejects it when the robot’s body contracts. The other plate can carry a water-proof camera or a different type of sensor.

Engineers tested the robot in a water testbed and demonstrated that it could steer by adjusting the direction of the nozzle. As with any underwater robot, waterproofing was a key concern for electrical components such as the battery and camera.

They estimated that it could travel at about 18 to 32 centimetres per second (roughly half a mile per hour), which is faster than most other soft robots, the researchers said.

“After we were able to optimise the design of the robot so that it would swim in a tank in the lab, it was especially exciting to see that the robot was able to successfully swim in a large aquarium among coral and fish, demonstrating its feasibility for real-world applications,” said Caleb Christianson, who led the study.

Researchers conducted several experiments to find the optimal size and shape for the nozzle that would propel the robot. This in turn helped them increase the robot’s efficiency and its ability to manoeuvre and go faster.

Underwater robots were recently used by UK researchers to monitor and document the daily habits of the endangered Mediterranean sperm whale.

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