Snake Robots Slither Across Tough Terrain and May Aid Search-and-Rescue Missions

Sidewinder snakes have the amazing ability to quickly climb sandy slopes in the desert. Now, scientists have taken a closer look at this ability and have created a snake-like robot to test ideas spawned by observing real snakes.

Before the study, the robotic snake could only use one component of sidewinding motion. This allowed it to move across level ground, but it was unable to climb inclined, sandy trackways.

"Our initial idea was to use the robot as a physical model to learn what the snakes experienced," said Daniel Goldman, one of the researchers, in a news release. "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."

In order to create a better robot, the researchers watched several real sidewinders as they moved in a large enclosure containing sand from the Arizona desert, which is their natural habitat. The enclosure could actually be raised to create different angles in the sand, and air could be blown into the chamber from below to smooth the sand after each snake was studied. The scientist recorded their movements using high-speed video cameras.

"We realized that the sidewinder snakes use a template for climbing on sand, two orthogonal waves that they can control independently," said Hamid Marvi, one of the researchers. "We used the snake robot to systematically study the failure modes in sidewinding. We learned there are three different failure regimes, which we can avoid by carefully adjusting the aspect ratio of the two waves, thus controlling the area of the body in contact with the sand."

In fact, the researchers were able to create a robot that could pass horizontal and vertical waves through its body to move in three-dimensional spaces. It's two inches in diameter and 37 inches long, and the snake itself has a body that's created with 16 joints. With its ability to tackle tough terrain, scientists believe that the robot could be used for urban search-and-rescue operations in which robots need to make their way through the rubble of collapsed structures. Because they can also readily move through pipes, they've been tested to see their potential for inspecting nuclear power plants from the inside out, as well.

"We are interested in how animals move on different types of granular and complex surfaces," said Goldman. "The idea of moving on flowing materials like sand can be useful in a broad sense. This is one of the nicest examples of collaboration between biology and robotics."

The findings are published in the journal Science.