Lessons learned from studying sidewinder rattlesnakes have been used to improve enable an existing snake robot climb sandy hills.
A modular snake robot developed at Carnegie Mellon University in the US had previously been able to use one component of the sidewinding motion to move across level ground, but had been unable to climb an inclined sand slope that real snakes could readily ascend.
But by recording the motion of snakes using high-speed video cameras in an enclosure at Zoo Atlanta filled with sand from the Arizona desert that had an adjustable incline, the researchers discovered that the secret to their ability to climb the slopes was increasing the amount of their body that makes contact with the granular surface by using a unique wave motion.
“Think of the motion as an elliptical cylinder enveloped by a revolving tread, similar to that of a tank,” said Howie Choset, a Carnegie Mellon professor of robotics.
“As the tread circulates around the cylinder, it is constantly placing itself down in front of the direction of motion and picking itself up in the back. The snake lifts some body segments while others remain on the ground, and as the slope increases, the cross section of the cylinder flattens.”
The study, published in the journal Science, details how the robot was then programmed with the unique wave motion discovered in the sidewinders, which enabled it to climb slopes that had previously been unattainable.
Before this study, the snake robot had trouble in climbing even moderate sandy slopes of about 10 degrees, but after reprogramming it could tackle inclinations of up to 20 degrees on loose sand.
The snakebot is made up of a series of 17 aluminium links with 16 joints, measuring about 94cm long and 5cm in diameter and contains a motor, electronics, computer and sensors.
“Our initial idea was to use the robot as a physical model to learn what the snakes experienced," said Daniel Goldman, a professor at Georgia Tech's School of Physics. "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."
Snake-like robots, rather than robots that move on wheels, offer unique capabilities for such complicated tasks as search-and-rescue operations in collapsed structures and inspecting nuclear power plants, the researchers said.
"The snake robot can thread through tightly packed space to access locations that people and conventional machinery cannot," said robotics professor Choset.
Carnegie Mellon robotics researcher Hamid Marvi, who worked on the study while at Georgia Tech, explained snakes' unique abilities.
"Snakes are the champion animal for moving on a wide range of complex terrain," Marvi said. "They have different gaits and can switch between them as needed. They have a special gait, sidewinding, for successfully climbing on sandy hills."