Researchers have created soft robots that can navigate difficult situations such as mazes without the assistance of people or computer software. The soft robots are built of liquid crystal elastomers twisted into the shape of a twisted ribbon, similar to translucent rotini pasta.
North Carolina State University (NCSU) and the University of Pennsylvania (Penn) researchers have created soft robots capable of navigating difficult situations such as mazes without the assistance of people or computer software.
“These soft robots demonstrate a concept called ‘physical intelligence,’ meaning that structural design and smart materials are what allow the soft robot to navigate various situations, as opposed to computational intelligence,” says Jie Yin, corresponding author of a paper on the work and an associate professor of mechanical engineering.
The soft robots are composed of translucent liquid crystal elastomers in the shape of a twisted ribbon, similar to pasta rotini. When you set the ribbon on a surface that is at least 55 degrees Celsius (131 degrees Fahrenheit) hotter than the ambient air, the section of the ribbon that is in contact with the surface compresses while the portion of the ribbon that is exposed to the air does not. The ribbon begins to roll as a result of this. And the quicker it rolls, the warmer the surface.
“This has been done before with smooth-sided rods, but that shape has a drawback – when it encounters an object, it simply spins in place,” says Yin. “The soft robot we’ve made in a twisted ribbon shape is capable of negotiating these obstacles with no human or computer intervention whatsoever.”
This is accomplished in two ways by the ribbon robot. To begin, if one end of the ribbon comes into contact with an item, the ribbon spins slightly to avoid the obstruction. Second, if the core component of the robot comes into contact with an item, it "snaps." The snap is a sudden release of accumulated deformation energy that causes the ribbon to leap and reposition itself before landing. The ribbon may need to snap many times before finding an orientation that permits it to navigate the barrier, but it always finds a clear path ahead.
“In this sense, it’s much like the robotic vacuums that many people use in their homes,” Yin explains. “Except the soft robot we’ve created draws energy from its environment and operates without any computer programming.”
“The two actions, rotating and snapping, that allow the robot to negotiate obstacles operate on a gradient,” explains Yao Zhao, the paper's first author and a postdoctoral researcher at NC State. “The most powerful snap occurs if an object touches the center of the ribbon. But the ribbon will still snap if an object touches the ribbon away from the center, it’s just less powerful. And the further you are from the center, the less pronounced the snap, until you reach the last fifth of the ribbon’s length, which does not produce a snap at all.”
The team conducted many trials to show that the ribbon-like soft robot can navigate a variety of maze-like settings. The researchers also proved that the soft robots will perform effectively in desert situations, ascending and descending loose sand slopes.
“This is interesting, and fun to look at, but more importantly it provides new insights into how we can design soft robots that are capable of harvesting heat energy from natural environments and autonomously negotiating complex, unstructured settings such as roads and harsh deserts,” Yin adds.