The prototype transfers up to 80% of an 80-lb load, but there’s one catch: The device affects the user’s gait. The user places his or her feet in boots attached to a series of tubes running up the leg to the backpack. The person carrying the load also needs 10% more oxygen than normal for the extra effort needed to overcome gait interference.

Springs at the ankle and hip and a damping device at the knee let the exoskeleton approximate the walking motion of human legs, with a small external power input (one watt). Other loadbearing exoskeletons require larger power sources (in one case, about 3,000 W from a gasoline engine).

Hugh Herr, principal investigator of the Biomechatronics Group, envisions exoskeletons that could help people run or lessen the likelihood of leg and back injuries.

An exoskelelton developed at MIT transfers 80% of an 80-lb load directly to the ground.

An exoskelelton developed at MIT transfers 80% of an 80-lb load directly to the ground.