The unique movement of jellyfish has made them a popular model of study for robotics researchers, who hope to develop advanced new machines that move with great efficiency. Scientists are now showing off a new breed of soft robots inspired by these marine creatures, which uses air channels to swim at great speeds.
This new type of soft robot was developed by scientists at North Carolina State University and Temple University, and actually builds on their earlier work that produced a fast-moving robot inspired by a cheetah. That machine alternately pumped air in and out of two actuators to cause a stiff spine to instantly spring from one flexed state to another. The latest robot is an adaptation of this approach, as study author Jie Yin explains.
“Our previous work focused on making soft robots that were inspired by cheetahs – and while the robots were very fast, they still had a stiff inner spine,” says Yin. “We wanted to make a completely soft robot, without an inner spine, that still utilized that concept of switching between two stable states in order to make the soft robot move more powerfully – and more quickly. And one of the animals we were inspired by was the jellyfish.”
Jellyfish swim with an energy efficiency that is unparalleled in the ocean environment. The team sought to recreate this through the use of a polymer disc, which was pre-stressed by being stretched out in four different directions and then combined with two other non-stressed layers, one of which features an air channel.
This stack of polymer discs makes for a soft robot that can switch between a relaxed state in which it curves up like a bowl, and a flexed state in which this bowl-shape quickly reverses itself into a dome, by filling the empty channel with air. This causes the machine to push away water and move itself forward.
“We can make the robot ‘flex’ by pumping air into the channel layer, and we control the direction of that flex by controlling the relative thickness of the pre-stressed layer,” Yin says.
In testing, the soft robot demonstrated an average speed of 53.3 mm per second, while none of the three jellyfish species studied as part of the research traveled faster than 30 mm a second.
Air-powered robotic jellyfish outpaces its real-life rivals [New Atlas]