Energy-Recycling Steps Make Climbing Stairs Easier

(CN) – Walking up multiple flights of stairs could soon become less daunting thanks to a new spring-loaded device that uses a person’s own energy to make the trek easier.

The energy-recycling stairs compress when a user walks down the steps, saving 26 percent of the energy that would otherwise be lost through impact and braking forces at the ankle. When a person walks up, the stairs release the stored energy – making it 37 percent easier on the knee than traditional stairs.

When a person ascending the stairs steps on the sensor on the next tread up, the latch on the lower step releases. The stored energy in the spring is also released, lifting up the back leg. (Photo courtesy Georgia Tech)

When a person walks downstairs, each step – tethered by springs and equipped with pressure sensors – slowly lowers until it locks into place and is level with next step. The device stores energy generated by the user, which is saved until someone walks upstairs. Once a person walking upstairs steps on the sensor on the next stair, the latch on the lower step and the stored energy in the spring are released, lifting up the back leg.

“You dissipate energy to stop yourself from falling, and I thought it would be great if we could store the energy wasted during descent and return it to the user during ascent,” said Karen Liu, an associate professor at Georgia Tech and co-author of the new research, published Wednesday in the journal PLOS One.

Co-author Lena Ting, a biomedical engineer at Georgia Tech and Emory University, said walking down stairs is like “tapping the brakes of your car while revving the engine.”

The device also eases the impact of going downstairs, which the researchers did not anticipate while designing the stairs.

Energy-recycling stairs store a user’s energy during descent and return energy to the user during ascent. (Photo courtesy Georgia Tech)

“The spring in the stairs, instead of the ankle, acts as a cushion and brake,” said Yun Seong Song, who built the device while he was a postdoctoral researcher at Georgia Tech. “The gentle downward movement alleviates work by the trailing ankle, which is what keeps you balanced and prevents you from falling too fast on normal stairs.”

Liu first had the idea for the project after seeing an ankle brace that stored and released energy, which she thought could help her 72-year-old mother who has difficulty climbing steps. Since her mother did not want to wear a brace just for climbing staircases, Liu decided to create smart stairs.

“Current solutions for people who need help aren’t very affordable. Elevators and stair-lifts are often impractical to install at home,” Liu said. “Low-cost, easily installed assistive stairs could be a way to allow people to retain their ability to use stairs and not move out of their homes.”

The stairs can be placed on existing staircases and do not have to be permanently installed, which can be helpful for pregnant women and people recovering from surgery.

“It’s important to keep people walking and independent through injury and aging to maximize quality of life,” said Ting. “Maintaining mobility is very much a use-it-or-lose-it thing.”

A short video of the prototype can be viewed here.

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