Performance Of Snake-Like Robot Benefits From Analysis Of Real-Life Sidewinders

Chuck Bednar for – Your Universe Online
Observing sidewinder snakes as they use their unique talents to climb sand-covered slopes has helped both biologists and the engineers behind the development of snake-like robots gain new insight into their respective fields, according to research appearing Friday in the journal Science.
In their study, experts from the Georgia Institute of Technology, Carnegie Mellon University, Oregon State University, and Zoo Atlanta reported that, by studying the snakes in a unique bed of inclined sand, they were able to learn that sidewinders climb by increasing the amount of their body that comes in contact with the surface.
[ Watch the Video: Robots Learn From Sidewinder Snakes ]
According to Reuters reporter Will Dunham, the study authors then took that knowledge and applied it to an existing snake robot so that it could mimic the sidewinder’s technique. Their research, he added, is a prime example of how scientists are applying knowledge of biology to improve technology, and their snake-like robot could be used for dangerous tasks such as search-and-rescue operations in collapsed structures or inspecting nuclear power facilities.
At the heart of the experiment is Elizabeth, a serpentine robot designed by Carnegie Mellon’s Howie Choset, said Ed Yong of National Geographic. Elizabeth, named in honor of Choset’s wife, was specifically designed to slide over rough terrain, slither through tight cracks and traverse other areas inaccessible to humans. During a field test in Egypt, however, the researchers found that the robot was unable to scale sandy slopes.
While Elizabeth could sidewind, it wasn’t able to do it very well, Yong explained. So Choset joined forces with Georgia Tech’s Daniel Goldman and other experts in the field to investigate what the robotic snake was doing wrong. The research team worked with six sidewinders from Zoo Atlanta, and observed their ascent up a sandy trackway that could be inclined at different angles. They even had sand from Arizona’s Yuma Desert brought in to mimic the creatures’ native conditions as closely as possible.
“At first, the team assumed that as the track got steeper, the sidewinders would respond by digging their bodies more firmly into the ground, just like we would if we climbed a steep dune. They didn’t,” the National Geographic reporter said. “Instead, they kept more of their body in contact with the ground, giving themselves more purchase on increasingly treacherous slopes. As the researchers raised the flat track to a 20 degree incline, the sidewinders compensated by laying down twice as much body.”
They went on to test 13 other species of rattlesnake, and found that none of the non-sidewinders were able to negotiate the slopes the way that the sidewinders could. So they reprogrammed Elizabeth to mimic the sidewinders, and found that the robot suddenly had far more success at climbing up the slopes. The findings revealed that snakes must narrow the range of their contact lengths as slopes become steeper in order to successfully ascend.
“Sidewinding just seems so weird and unnecessary,” Goldman, corresponding author of the study and an associate professor of physics at Georgia Tech, told Rachel Feltman of the Washington Post. “Why use this crazy movement pattern? But as it turns out, they have a good reason.”
“Our initial idea was to use the robot as a physical model to learn what the snakes experienced,” he added in a statement. “By studying the animal and the physical model simultaneously, we learned important general principles that allowed us to not only understand the animal, but also to improve the robot.”
The study, which was funded by the National Science Foundation (NSF), the Army Research Office and the Army Research Laboratory, revealed that both horizontal and vertical motion had to be understood and then replicated in Elizabeth for the snake-like robot to be useful on sloping sand. However, Goldman told Feltman that the study didn’t just help the scientists build a better robot, but provided them with new insight into the efficient hill-climbing mechanics of the real-life sidewinder as well.
“The snake is one of the most versatile of all land animals, and we want to capture what they can do,” said Ross Hatton, an assistant professor of mechanical engineering at Oregon State University. “The desert sidewinder is really extraordinary, with perhaps the fastest and most efficient natural motion we’ve ever observed for a snake.”
“This type of robot often is described as biologically inspired, but too often the inspiration doesn’t extend beyond a casual observation of the biological system,” Choset added. “In this study, we got biology and robotics, mediated by physics, to work together in a way not previously seen.”
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