While some modern robots can demonstrate impressive agility—dancing, flipping, running, and jumping, to name a few—they often fall short of efficient at performing useful field tasks such as carrying a payload at consistent speed long-distance. While their legged characteristics make them more suitable than wheeled robots for traversing stairs, rough terrain, and other terrestrial obstacles, wheeled robots maintain a solid lead when it comes to speed and strength.

MechSE Assistant Professor Justin Yim aims to develop legged robots that can emulate the speed and efficiency of their wheeled counterparts, and he has won a prestigious CAREER Award from the National Science Foundation to pursue this evolution of walking robot capability.

“[We want to] make legged robots that are somewhere in between current wheeled robots and current legged robots,” Yim said. “We want these robots to be better at getting over rough surfaces than current wheeled robots can, but also with more endurance and better ability to keep up with humans over long distances and at higher speeds than current legged robots can manage.”

One challenge the project aims to address is the difference in motor requirement between the two types of robots. While wheeled robots typically only require enough motors to drive their wheels (often as little as one motor), legged robots require a larger system of motors to operate their jointed limbs—sometimes as many as thirty motors for a single robot. While the abundance of motors grant conventional legged robots impressive agility, it also makes them bulkier, more expensive, and power hungry.

“The first thing we’re working on is to figure out how to build leg mechanisms that use a smaller number of motors to traverse the same rough terrain,” Yim said, noting that members of his research group, the Novel Mobile Robots Lab, will prototype and test leg linkage systems this summer.

Yim credits nature with being a great model for legged agility in robots. “Animals are still the best locomotors, the best at getting around in lots of different, complicated places—from beaches to treetops to mountains,” he said. “We can play to engineering strengths to build legged robots that can do some things that legged animals can do, but also take advantage of the amazing things engineering devices can do that animals can’t. I think it would be really exciting to make a legged robot that could walk as fast as a human runs.”

The NSF’s Faculty Early Career Development Program (CAREER) “supports early-career faculty who have the potential to serve as academic role models in research and education and to lead advances in the mission of their department or organization.”

Yim’s study is titled “Extreme Robot Walking: Speed, Agility, and Efficiency via Reduced Degrees of Freedom” and is estimated to be funded through April 2030.