Four-Legged Robot Balances on a Beam

A new robotic navigation system has been designed to give robots previously unseen balance skills, with a four-legged robot able to walk along a balance beam in trials.

The system was developed by researchers at Carnegie Mellon University's Robotics Institute (RI), who say their design is one of the first of its kind. 

"This experiment was huge," said Zachary Manchester, RI assistant professor. "I don't think anyone has ever successfully done balance beam walking with a robot before."

"With current control methods, a quadruped robot's body and legs are decoupled and don't speak to one another to coordinate their movements," Manchester said. "So how can we improve their balance?"

To address this question, the team leveraged a reaction wheel actuator (RWA) system that attaches to the back of a quadruped robot, and allows the robot to balance regardless of its feet position. The team described the RWA’s effect as similar to a cat’s tail, allowing the body to balance even if one or more feet are off the ground.

RWAs are commonly used in the aerospace industry to adjust the position of satellites. 

"You basically have a big flywheel with a motor attached," said Manchester. "If you spin the heavy flywheel one way, it makes the satellite spin the other way. Now take that and put it on the body of a quadruped robot."

The system demonstrated successful results in several tests, showing the robot to be capable of recovering from knocks, as well as reorienting itself to a standing position when dropped from a height of just over a foot.

The team has predicted four-legged robots will soon enter widespread commercial use, with their system providing crucial agility skills that could be instrumental in search-and-rescue or exploration robotic applications. 

"Quadrupeds are the next big thing in robots," Manchester said. "I think you're going to see a lot more of them in the wild in the next few years."