Researchers are addressing the tendency to stumble in lower-body prosthetics by understanding the way people with two legs catch themselves. They accomplished this by covering test subjects with motion-capturing sensors. It also required tripping them over and over — 190 times, to be exact — for a study. But because humans are so mentally geared to resist stumbling, the team first had to design a stumbling device.

This graphic shows how a device aimed at stumbling people works. (Credit: Vanderbilt)

Not only did the treadmill device have to trip them, it had to trip them at specific points in their gait. People stumble differently depending on when their foot hits a barrier. The device also had to overcome their fear of falling, so they couldn't see or feel when the block was coming.

In addition to protecting test subjects, the harness included a scale. If a subject put 50 percent or more of their weight on it during a stumble, that counted as a fall. The team's design for the machine and outcomes of their tests are available for other labs to use in the open-source journal.

The next phase is to take that information and program it into computer-controlled prosthetic legs.

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