Slip-triggered wearable robot twists elderly people’s hips to prevent falls

With a slip and a twist, a robotic device that fits around an elderly person’s pelvis can avert a perilous tumble, Italian researchers report in Scientific Reports.

The device—like the shorts version of exoskeleton pants—can sense an impending fall within 350 milliseconds and apply torque directly to the erring limb. The robotic hip-twist corrects the person’s center of mass and successfully sidesteps a fall. In early trials using a prototype, eight elderly people and two elderly people with prosthetic legs were all able to stay upright while walking on a shifting treadmill designed to trigger stumbles.

The researchers are hopeful that their device, called the Active Pelvis Orthosis, or APO, could firmly improve the health of the elderly. Each year, millions of people 65 and older suffer falls. They’re the leading cause of fatal and non-fatal injuries in that demographic, causing 95 percent of hip fractures and most traumatic brain injuries. The resulting health care costs are an estimated $31 billion each year in the US alone.

For fall prevention, the APO has a leg up on the competition, the researchers argue. Unlike other mobility devices and exoskeletons, theirs doesn’t try to take over a person’s movement. The APO idles at the waist, quickly learning and then monitoring a person’s gait. It only kicks in with force when it detects that a limb is out of step. This is critical, the authors say, because most prone-to-fall elderly can and do try to counter a fall on their own. It’s just that they’re often not strong enough to pull it off.

“In this situation, it is necessary to develop ecological and symbiotic solutions able to help only when necessary,” the authors wrote.

For that only-when-needed robotic oomph, the researchers designed a waist-hugging device that connects to the thighs. Its braces are made of lightweight carbon fibers, and there are motors that sit on the side of each hip. Tethered to a computer, the APO tracks the movement and angle of the limbs and hips as a person walks. With just a few steps, a custom algorithm can figure out a person’s individual gait and detect deviations. When a hip hits a wrong angle and the wearer begins to lose balance, the device responds in less than half a second. It applies a twisting force to both hips to shove the thighs down and restore stability. The force is designed to be gentle and calculated based on the wearer’s weight.

To test the APO, the researchers had their 10 tethered subjects walk on a split-belt treadmill, in which the belts can move independently and slide apart to cause a user to slip. When that happened, the APO quickly restored the users’ balance so they could stay upright and go back to walking normally, the researchers found.

But, they note, “after this promising proof of concept, challenges lie ahead.” Far more tests and trials will be needed to see how the APO could work in real-life—with real, awkward falls and other frail elderly subjects. The researchers are also working to make the device untethered and less bulky and conspicuous. Right now, it weighs around 4.2 kilograms (about nine pounds), which may be challenging for some. There’s also no word of what a final device might cost an elderly patient, who are often on restricted budgets.

Still, so far, APO wearers have been impressed, including 69-year-old Fulvio Bertelli, who tried out the device in a Florence hospital and said it helped and protected him. “I feel more confident when I wear the exoskeleton,” he said.

Scientific Reports, 2017. DOI: 10.1038/srep46721  (About DOIs).

Related articles


Share article

Latest articles