People using prosthetic legs have to be constantly vigilant about potential obstacles in their way. That is because if they stumble, there’s a pretty good chance that they’ll suffer a fall.
Prosthetic legs, even powered ones, don’t have the capacity to recover from a stumble, as this is a very challenging task for a mechanical device to perform. Researchers at Vanderbilt University have now taken on this challenge and they hope that they will soon be able to provide a new level of safety for amputees walking on a prosthetic leg.
To make this happen, the team decided that they need to understand how those of us with both legs still intact get back to a normal gait after encountering an obstacle. They built a special treadmill that can place steel bricks onto the walking surface, forcing people to trip. The device doesn’t simply throw bricks onto the treadmill at will. It actually monitors the person walking on a treadmill and places the bricks so that they interrupt that person at a specific point in a step.
Each of the volunteers walking on the treadmill was tripped dozens of times and at different stages of their walking gait. They had optical markers attached to their bodies, which were used by a camera-based tracking system to create accurate models of how they were able to recover from near-falls.
The team has gathered a great deal of actionable data that can now be used to help design smart powered prostheses that respond to unexpected events, saving their users from nasty falls. “So now we understand what the stumble reflex should look like,” said Michael Goldfarb, principal investigator of the study. “The next phase is to take that information and program it into computer-controlled prosthetic legs. After that, we will safely stumble amputees wearing both commercially available prostheses and the ones we’ve designed with these reflexes and learn whether ours can prevent more falls.”
Here’s a Vanderbilt video presenting the research. Fans of slapstick comedy should find this amusing:
Study in Journal of NeuroEngineering and Rehabilitation: A novel system for introducing precisely-controlled, unanticipated gait perturbations for the study of stumble recovery