To build a better crawly robot, add legs—lots of legs

When traveling on rough and unpredictable roads, the more legs the better—at least for robots. Balancing on two legs is somewhat hard; on four legs, it’s slightly easier. But what if you had many many legs, like a centipede? Researchers at Georgia Institute of Technology have found that by giving a robot multiple, connected legs, it allows the machine to easily clamber over landscapes with cracks, hills, and uneven surfaces without the need for extensive sensor systems that would otherwise have helped it navigate its environment. Their results are published in a study this week in the journal Science.

The team has previously done work modeling the motion of these creepy critters. In this new study, they created a framework for operating this centipede-like robot that was influenced by mathematician Claude Shannon’s communication theory, which posits that in transmitting a signal between two points, that to avoid noise, it’s better to break up the message into discrete, repeating units.

“We were inspired by this theory, and we tried to see if redundancy could be helpful in matter transportation,” Baxi Chong, a physics postdoctoral researcher, said in a news release. Their creation is a robot with joined parts like a model train with two legs sticking out from each segment that could allow it to “walk.” The notion is that after being told to go to a certain destination, along the way, these legs would make contact with a surface, and send information about the terrain to the other segments, which would then adjust motion and position accordingly. The team put it through a series of real-world and computer trials to see how it walked, how fast it could go, and how it performed on grass, blocks, and other rough surfaces.

“One value of our framework lies in its codification of the benefits of redundancy, which lead to locomotor robustness over environmental contact errors without requiring sensing,” the researchers wrote in the paper. “This contrasts with the prevailing paradigm of contact-error prevention in the conventional sensor-based closed-loop controls that take advantage of visual, tactile, or joint-torque information from the environment to change the robot dynamics.”

They repeated the experiment with robots that had different numbers of legs (six, 12, and 14). In future work with the robot, the researchers said that they want to hone in on finding the optimal number of legs to give its centipede-bot so that it can move smoothly in the most cost-effective way possible.

“With an advanced bipedal robot, many sensors are typically required to control it in real time,” Chong said. “But in applications such as search and rescue, exploring Mars, or even micro robots, there is a need to drive a robot with limited sensing.”