For an amputee using a prosthetic leg, a crack in the pavement or a divot in the grass can cause a stumble that leads to a fall and serious injury.

So Carnegie Mellon University assistant professor of robotics Hartmut Geyer and his team are developing a robotic prosthetic, one that will enable above-the-knee amputees to feel less susceptible to stumbles. The prosthesis would work the same way natural legs do, including the way they recover their balance after a trip or stumble, an action that doesn’t require a second thought for most people.

By studying human reflexes and other neuromuscular control systems, the research team has been able to simulate stable walking gaits over uneven terrain, and better recovery from stumbles. It’s still in the early phases, but the implications of the research show promise for better understanding an area about which much is still unknown.

“We actually know much less about how humans control our limbs than many would assume,” Geyer says. More than a million Americans have had a leg amputation and that number is expected to quadruple by 2050. Half of the amputee population reports a fear of falling, he adds.

“The focus of this project is the idea that amputees can use a prosthetic, and if they walk in Schenley Park and they accidentally trip or slip, or if someone bumps into them, they can automatically recover their balance and there’s no fear of falling down,” reports Geyer.

Over the next three years, as part of a $900,000 National Robotics Initiative study funded through the National Science Foundation, this technology will be further developed and tested using volunteers with above-the-knee amputations. Joining Geyer on the research team are Steve Collins, associate professor of mechanical engineering and robotics, and Santiago Munoz, a certified prosthetist orthotist and instructor in the Department of Rehabilitation Science and Technology at the University of Pittsburgh.

The hope is that a robotic prosthesis would allow the amputees to enjoy a fuller range of motion beyond everyday walking, which could eventually include dancing and skiing.

Geyer recently presented his findings applying the neuromuscular control scheme to prosthetic legs via full-size walking robots at the IEEE International Conference on Intelligent Robots and Systems in Hamburg, Germany. And while he said the research has implications beyond prosthetic devices, to development of legged robots, it’s not going to lead to bionic men and women anytime soon.

The science fiction aspect of robotics is only a small part of the research in the field, Geyer says; he finds this area of research a great opportunity to help people as well. “Often times robots are seen as dangerous machines, and people are concerned about some kind of robot revolution,” he says. “But these machines interacting and collaborating with humans can have a large impact on the quality of life for all people.”