Current Work

Adaptive Ankle Foot Orthosis (AAFO)

The development of the AAFO is based on the analysis of elastic mechanisms developed by Dr. Hugh Herr.

Drop foot or passive equinus is caused by non-functioning ankle dorsiflexors which impair the subject from lifting the toe. There are two common complications from drop foot. First, the subject cannot control plantar flexion during heel strike, so the foot slaps the ground on every step. This is referred to as “slap foot”. The second complication is the inability to attain toe-ground clearance during swing. This causes the person to drag their toe on the ground throughout swing. The Actuated Ankle Foot Orthoses (AAFO) would assist during these two phases of gait:

At heel contact, it would increase the stiffness of the ankle during controlled plantar flexion to prevent slap foot.

After toe-off, it would place the ankle in slight dorsiflexion for ground clearance.

The AAFO will be powered by commercial batteries.This includes all of the devices on the AFO including the angle sensor, the force sensor, and the SEA.The computer and controller will obtain its power from a normal wall socket.In the inactive state, the AAFO is almost completely rigid.In this state, it resembles rigid AFO’s currently on the market. The AAFO has a failsafe mechanism that would revert to this inactive state in case of any failures. For further safety, there are limits to the amount of force the AAFO can produce.