Researchers from the Georgia Institute of Technology are working to create and advance the field of “terradynamics,” also known as the study of how small legged robots move on and interact with sand and other granular materials. Terradynamics could improve legged robots working in a variety of environments such as space explorations or search-and-rescue missions.
“We now have the tools to understand the movement of legged vehicles over loose sand in the same way that scientists and engineers have had tools to understand aerodynamics and hydrodynamics,” said Daniel Goldman, a professor in the School of Physics at the Georgia Institute of Technology, in a statement. “We are at the beginning of tools that will allow us to do the design and simulation of legged robots to not only predict their performance, but also to optimize designs and allow us to create new concepts.”
According to Goldman, robots may eventually need legs to operate in complex environments. Currently, the Mars Curiosity rover relies on wheels to maneuver through sand and rocky terrain on the Red Planet. Smaller robots, however, may need legs to successfully navigate over granular materials.
The field of terradynamics is advancing rapidly because Georgia Tech scientists discovered a simple way of describing the motion of legged robots on granular surfaces. The researchers used a 3-D printer to design the legs of a small legged robot in different shapes and studied how varying configurations impacted the robot’s speed along a track bed. They also predicted forces on the robot’s legs.
“We discovered that the force laws affecting this motion are generic in a diversity of granular media, including poppy seeds, glass beads and natural sand,” said Chen Li, now a Miller postdoctoral fellow at the University of California at Berkeley. “Based on this generalization, we developed a practical procedure for non-specialists to easily apply terradynamics in their own studies using just a single force measurement made with simple equipment they can buy off the shelf, such as a penetrometer.”
In addition to new information about the force laws impacting the movement of legged robots on granular substances, researchers discovered that convex legs designed in the shape of the letter “C” work better than other variations they tried.
The field of terradynamics could have a significant impact on the design and ultimate success of robots sent to Mars. The legged robot used in this experiment was only 13 centimeters long and weighed approximately 150 grams. Robots of that size could eventually be deployed on the Red Planet to explore new terrain. Terradynamics could also help scientists learn more about how sand lizards and kangaroo rats move through sand.
The study’s findings were described Friday in the journal Science.