Lots of scientists use animals to make robots better, but a new study published in Science uses a robotic model to better understand the animal that inspired it.
Sidewinder snakes are unusually good at climbing sandy slopes. But their methods look as unusual as they are effective -- they seem to hoist themselves up one body segment at a time, like a slithery sideways trench crawl (see the video above for footage of their slinky "sidewinding" locomotion). But researchers wanted to figure out how this sand-friendly movement worked.
"Sidewinding just seems so weird and unnecessary," said corresponding author Dan Goldman, an associate professor of physics at Georgia Tech. "Why use this crazy movement pattern? But as it turns out, they have a good reason."
Goldman and his colleagues -- a group of researchers from Georgia Tech, Carnegie Mellon, Oregon State, and Zoo Atlanta -- observed the movement of the snakes in a special tank designed to simulate sand dunes.
The movement pattern turned out to be surprisingly simple: The sidewinders move using an undulating wave down their body. At the same time, they make the same motion at a 90 degree angle from the first. By controlling the waves independently, the snakes can change how much of their body comes into contact with the sand, allowing them to adjust their gait for different angles of slope.
To test that motion, the researchers used a snake-inspired robot developed by Carnegie Mellon. The robot could move sort of like a sidewinder on flat sand, but struggled with the same sandy inclines that the real snakes could easily manage.
When the researchers programmed the dual-wave control into the robot's locomotion, it reached new heights.
This experiment wasn't about making a better robot, Goldman emphasized. He's just excited to have a better understanding of the sidewinder's super-efficient way of traversing sandy hills. But the study does have some practical robotics applications.
A limbless robot could be used in search-and-rescue missions where space was cramped. Sand-crawling robots could prove useful on missions to other planets with strange terrains. In an upcoming companion paper, the researchers will describe how the sidewinder motion allows them to control robots more effectively. "You can almost drive them around like a car," Goldman said.
In focusing more on learning about snakes than in making an efficient robot, the researchers got closer to nature than most animal-inspired bots.
"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," study author and Carnegie Mellon professor of robotics Howie Choset said in a statement. "In this study, we got biology and robotics, mediated by physics, to work together in a way not previously seen."