Robotic exoskeleton could prevent falls among the elderly

When someone wearing the device starts slipping, it counteracts to prevent a fall.

Falling is the leading cause of fatal injury for older adults in the United States, with a quarter of Americans over the age of 65 falling each year. A new robotic device that can be worn around the waist could one day help prevent these incidents and provide greater independence to people with limited mobility. The Active Pelvis Orthosis (APO) was originally developed after Italian researchers Maria Chiara Carrozza and Nicola Vitiello noticed many amputees preferred wheelchairs to prosthetics, which meant they were sacrificing mobility for a lower risk of falling. They reached out to Silvestro Micera, an expert in the biomechanics of slipping, to find a solution. After developing the device, they tested it on both amputees and elderly volunteers and found it helped improve balance. The results have been published in Nature Scientific Reports. We asked bioroboticist Vito Monaco, who contributed to the research, to tell us more about it.

ResearchGate: What does this device do?

Vito Monaco: The device is a robotic exoskeleton, a brace that wraps around the pelvis and both thighs. Thanks to a couple of electric motors, the device can assist hip flex-extension during walking, thus reducing overall effort for the user. It is also able to identify unbalance from an unexpected slippage and counteract it.

RG: Whom could such a device help?

Monaco: The APO has been primarily designed to help fragile persons during their daily activities. Both the elderly and subjects affected by neuro-muscular-skeletal disorders could take advantage of our device for a safer and more autonomous lifestyle. This is critical, since it allows these people to enjoy social relationships, experience emotional benefits, and avoid a sedentary lifestyle and its more dangerous consequences.

The device could also be updated to one day support manual laborers with their work, reducing their overall physical burden and lessening the risk of falls.

A prototype of the exoskeleton at a rehabilitation center in Florence, Italy. Credit: Hillary Sanctuary / EPFL

RG: How did you test it?

Monaco: We have been working on “falling” for several years. One of our first steps was developing a big treadmill to deliver movements that cause test subjects to slip while they’re walking. This platform represents our main experimental setup. People are asked to walk on it (with a safety harness) at constant speed until a sudden and unexpected slippage is triggered.

To test whether the APO helps with balance recovery after a slippage, we asked elderly people and transfemoral amputees to recover from slipping while wearing the device on the treadmill. The volunteers didn’t know whether they’d be caused to slip, or whether the balance-assisting function of the device they were wearing was activated. During the trials, the whole-body kinematics was recorded by a camera-based motion capture system for analysis. Results revealed that the stability against falls improved when the APO acted in assistive mode.

RG: What did the participants think of the device?

Monaco: This is the first prototype of the exoskeleton, so while it works well in testing, it’s not exactly cute. Before using it, many participants didn’t like it because it looked bulky. But after using it, participants were usually surprised to feel the assisting contribution of the robot. Several improvements have since been implemented. The current and most advanced prototype of the APO is totally comfortable, well finished, autonomous, and works fine even outside the lab.

RG: Have you worn it yourself?


Monaco: Actually, I’ve never worn it. The prototype of the exoskeleton can comfortably fit people up to 1.7 m tall. I’m 1.9 m tall, so it doesn’t fit me.

RG: How does it work?

Monaco: The APO assists with hip flex-extension thanks to two independent electric motors provided with an elastic element. The control strategy driving the platform can switch between motor tasks like walking and climbing stairs, and counteracting the lack of balance due to a slippage. When a lack of balance is detected, the assistive strategy is triggered, and the APO acts on both thighs in order to increase stiffness at hip joints against limb movements. The limb that is slipping is slowed down, while the other one is forced to push on the ground. This strategy is effective for the recovery of balance.

RG: When do you think this kind of balance device could be available commercially?

Monaco: Our device will be extensively tested in the next three years within the framework of the EU-funded CYBERLEGS Plus Plus project. This project aims to demonstrate the effectiveness of several robotic platforms in real-world conditions, with the ultimate goal of fostering its market exploitation. If successful, the device will be commercially available in the next years.