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You might think the above image shows a couple of pieces of string, but these unassuming little things are so much more than that. They’re actually robots, created without “brains” or computerized intelligence, but capable of wiggling their way out of some very complex spaces.
The team behind this breakthrough, from North Carolina State University, first unveiled their rotini-like soft robots in 2022, demonstrating how they were able to navigate mazes without computer or human input. Instead, the tech relies on the concept of physical intelligence.
Physical intelligence refers to the idea that the materials the robots are made from, combined with their structural design, dictate their behaviors. There’s no computer or human operator guiding the robot – it just does its thing.
Now, the team has built on their earlier success with a new and improved version that can navigate even more complicated scenarios.
“In our earlier work, we demonstrated that our soft robot was able to twist and turn its way through a very simple obstacle course,” said Jie Yin, associate professor of mechanical and aerospace engineering, in a statement. “However, it was unable to turn unless it encountered an obstacle. In practical terms this meant that the robot could sometimes get stuck, bouncing back and forth between parallel obstacles.”
“We've developed a new soft robot that is capable of turning on its own, allowing it to make its way through twisty mazes, even negotiating its way around moving obstacles. And it's all done using physical intelligence, rather than being guided by a computer.”
The team used the same material as before, a liquid crystal elastomer. When exposed to a surface temperature of at least 55°C (131°F), the portion of the material touching the surface contracts, causing the noodly robot to roll. The warmer the surface, the faster it goes.
But while the materials were unchanged, the design had a key difference this time. The new robot is asymmetrical: one half is a twisted ribbon that can stretch into a straight line; the other is a tighter twist that also twists around on itself.
This asymmetry creates a difference in the forces exerted by each end of the robot, so it will no longer roll in a straight line. You can see this in action – and how this unique property helps the robot get itself out of some tight spots – in the video below.
“The concept behind our new robot is fairly simple: because of its asymmetrical design, it turns without having to come into contact with an object,” first author Yao Zhao explained. “So, while it still changes directions when it 'does' come into contact with an object – allowing it to navigate mazes – it cannot get stuck between parallel objects. Instead, its ability to move in arcs allows it to essentially wiggle its way free.”
Even mazes with moving walls and gaps smaller than its body size are no match for the robo-string, which the authors christened “maze escaper”.
Beyond simply being an awesome example of what can be achieved with soft robotics and physical intelligence, Yin talked about the potential applications of this technology: “This work is another step forward in helping us develop innovative approaches to soft robot design – particularly for applications where soft robots would be able to harvest heat energy from their environment.”
The study is published in the journal Science Advances.
