2010 R&D 100 Winner
2010 Editors' Choice Recipient

The_Leveraged_Freedom_Chair_MIT_Mobility_LabModern electric wheelchairs are marvels of engineering, but they do not work well on rough terrain and are often unavailable to those in rural areas or developing countries. With this in mind, the Massachusetts Institute of Technology’s Mobility Lab, Cambridge, Mass., has developed the Leveraged Freedom Chair (LFC), which is maneuverable within the home and can travel long distances on rough roads far from urban centers.

The key innovation behind the LFC is its single-speed, variable mechanical advantage lever drivetrain. Instead of using multiple gears, an LFC user varies mechanical advantage and chair speed by sliding his or her hands up or down the levers. Changing user geometry instead of machine geometry allows the use of a simple, light-weight, low-cost, single-speed chain drive. Pushing forward on the levers provides up to a 4-to-1 mechanical advantage, and pulling back ratchets and resets the drivetrain for the next power stoke. Pulling the levers back further brings the brakes—small bars that protrude from the levers—into contact with the tires. The wheelchair can be used indoors simply by removing the levers.

Real-world performance tests yielded a propulsion efficiency gain of about 20%. The LFC has a targeted cost of about $200, far less than most commercial options, and has an open-source design to encourage investment.

Rough-terrain wheelchair

MIT Mobility Lab
Association for the Physically Disabled of Kenya
Transitions Foundation of Guatemala
Whirlwind Wheelchair International

Development Team

MIT-Mobility-Lab_The Leveraged Freedom Chair-team
(Top row): The Association for the Physically Disabled of Kenya
(Second row, l-r): Xuefeng Chen; Slava Menn; Harry O’Hanley; Mario Bollini
(Third row, l-r):: Danielle Delatte, Tish Scolnik with Fatuma Acan; Amos Winter; Ben Judge
(Bottom row): Transitions Foundation of Guatemala


The Leveraged Freedom Chair Development Team:
Adam Blake
Mario Bollini
Xuefeng Chen
Danielle Delatte
Dana Frey
Danielle Hicks
Ben Judge
Slava Menn
Harry O'Hanley
Nydia Ruleman
Tish Scolnik
Evelyn Wang
Amos Winter, Massachusetts Institute of Technology Mobility Lab