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Researchers at North Carolina State University (NCSU) have developed a new soft robot design that engages in three simultaneous behaviors: rolling forward, spinning like a record, and following a path that orbits around a central point. The device, which operates without human or computer control, holds promise for developing soft robotic technologies that can be used to navigate and map unknown environments.
The new soft robots are called twisted ringbots and are made of ribbon-like liquid crystal elastomers that are twisted (like a rotini noodle) and then joined together at the end to form a loop that resembles a bracelet. When the robots are placed on a surface that is at least 55 degrees Celsius (131 degrees Fahrenheit), which is hotter than the ambient air, the portion of the ribbon touching the surface contracts, while the portion of the ribbon exposed to the air does not. This induces a rolling motion; the warmer the surface, the faster the robot rolls.
“The ribbon rolls on its horizontal axis, giving the ring forward momentum,” says Jie Yin, corresponding author of a paper on the work and an associate professor of mechanical and aerospace engineering at NCSU.
The twisted ringbot also spins along its central axis, like a record on a turntable. And as the twisted ringbot moves forward it travels in an orbital path around a central point, essentially moving in a large circle. However, if the twisted ringbot encounters a boundary, like the wall of a box, it will travel along the boundary.
“This behavior could be particularly useful for mapping unknown environments,” Yin says.
The twisted ringbots are examples of devices whose behavior is governed by physical intelligence, meaning their actions are determined by their structural design and the materials they are made of, rather than being directed by a computer or human intervention.