Design of an Electromechanical Ankle-Foot Orthosis with Controlled Locking and Dorsiflexion Assist

A microprocessor-controlled ankle-foot orthosis has been developed which is intended to improve ground clearance during the swing phase of gait and provide stability during stance. The design minimizes barriers to adoption related to cost, weight, size, comfort, and complexity. The AFO combines a passive dorsiflexion assist spring with a solenoid-driven ankle clutch, controlled by a microprocessor in response to real-time motion sensing during gait. Bench testing characterized the performance of the solenoid clutch and demonstrated over 50N of force, which proved adequate for reliable unlocking while consuming an average of only 5W during gait. The electromechanical AFO weighs 541g with an additional 212g battery worn at the hip.