What a Robotic Snake Teaches Us About Physics [Video]

By Wesley Fenlon

Physics research at Georgia Tech have made new discoveries about the relationship of angles and motion using robotics. It's neat!

Which of these things produces less drag while soaring through the atmosphere: a boxy Borg Cube or the sleek fuselage of a Learjet? No surprise here: the angular nose of the Learjet obviously reduces drag and helps the plane slice through the air. Researchers at Georgia Tech decided to take that principle and study it in an entirely different field: robotics. To be completely accurate, physics and bioengineering researchers at Tech took inspiration from the angled snout of the sandfish lizard and tried to build a robot that moved fluidly through a granular environment.

With the goal of creating a search bot capable of navigating the dirt and rubble of disaster sites, the team got more than they bargained for when they discovered an angular head did far more than reduce drag. With minute adjustments, the angle of the head dramatically changed the lift forces applied to the robot. Need a physics lesson on why this is a big deal? Read on.

Physics professor Daniel Goldman explains the significance of the Georgia Tech team’s research:

“While the lift forces of objects in air, such as airplanes, are well understood, our investigations into the lift forces of objects in granular media are some of the first ever...

We discovered that by changing the shape of the sand-swimming robot’s head or by tilting its head up and down slightly, we could control the robot’s vertical motion as it swam forward within a granular medium.”

The robot in question is comprised of seven segments connected by servo motors. Wrapped in latex socks and a spandex swimsuit and with its wedged wooden block of a head attached, the robot looks like one high-tech snake. At first the research team was simply studying the advantages of using a wedge to reduce drag, but they soon discovered small angular changes applied negative or positive lift to the robot’s head depending on the orientation to a horizontal plane.

“The researchers investigated the vertical movement of the robot when its head was placed at five different degrees of inclination. They found that when the sandfish-inspired head with a leading edge that formed an angle of 155 degrees with the horizontal plane was set flat, negative lift force was generated and the robot moved downward into the media. As the tip of the head was raised from zero to 7 degrees relative to the horizontal, the lift force increased until it became zero. At inclines above 7 degrees, the robot rose out of the medium.”

As the video above demonstrates, the influence of the humble sandfish lizard has given researchers a new understanding of how to move objects through a granular medium with minimal effort. Slap a camera on this robot and it’ll be ready to burrow through landslides, avalanches and rubble to hunt down disaster survivors.