Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Now Available: Innovators Under 35 2013 See The 2013 List »

35 Innovators Under 35

Ken Endo, 34

Adding spring to robotic limbs by doing away with some of the motors

Sony Computer Science Laboratories

Endo's prostheses enlist springs and other mechanisms that allow them to look more natural and feel more comfortable.

Photograph by Jeremy Sutton Hibbert

Robotic limbs are usually packed with multiple powerful motors, making them heavy and bulky. Engineer Ken Endo hit on an idea for lightening and streamlining the limbs: replacing some of the motors with a series of springs. His goal isn’t to build better robots; rather, he wants to make prosthetic limbs and orthopedic devices that can, as he puts it, “eradicate disability.” He hopes to make artificial limbs that function nearly as well as real ones, affording amputees near-effortless motion with no discomfort.

Endo had been focused on building more advanced robots until about seven years ago, when he found himself moved by the determination of a friend who had lost his legs to bone cancer. “He said he wanted to walk by himself,” Endo says. “That’s when I changed my research focus from robots to biomechanics.”

As a PhD student working in the MIT Media Lab’s Biomechatronics Group, led by Hugh Herr, Endo created the first computer program that closely simulates human walking, a surprisingly complex motion. Now back in his native Japan as a researcher with Sony, he’s enlisting that model to build legs with spring-based ankle and knee joints that he says work much like the real things. “The ankle joint also requires a motor,” he notes, “because the human ankle generates a huge amount of mechanical power.” But most of the work will be done by the springs, he says, making the legs far more efficient and leaving the wearer less tired and sore. Endo is now perfecting his joints on a walking robot. He hopes to have the bugs smoothed out in mere months, at which point he’ll start working to make the device suitable for amputees.

Another big challenge Endo has taken on is making prostheses affordable. More than half of all amputees live in poor countries, where many are victims of land mines. The price tag of $35,000 or more for a high-quality prosthetic leg in the United States is far out of reach for the vast majority of these amputees.

To address that, Endo has been working to design prostheses specifically for people in developing countries and to find ways to distribute them there. He has already achieved one breakthrough: a leg costing about $30 whose knee joint can bend when the leg is lifted off the ground but locks into place when the leg is weighted, leading to a less effortful, more natural-looking gait.

Courtney Humphries

2012 TR35 Winners

Ryan Bailey

Shining a light on faster, cheaper, more accurate medical tests

Ken Endo (video)

Adding spring to robotic limbs by doing away with some of the motors

Christina Fan (video)

Prenatal testing for genetic conditions from a sample of the mother’s blood

Abraham Flaxman (video)

Combining different types of data in new ways in order to track and slow the spread of disease in developing countries

Bryan Laulicht (video)

Finding an adhesive that protects vulnerable skin

Juan Sebastián Osorio (video)

Monitors specially designed for premature infants help detect breathing problems

Weian Zhao (video)

Spying on cells in their native habitat to develop better tests and drugs

See This Years' Winners

More Innovators Under 35