Design, Analysis, and Control of a UserAdaptive Ankle Foot Orthosis

Abstract

This chapter presents the design and preliminary evaluation of a useradaptive ankle foot orthosis (AFO). To begin with, according to structural characteristics of the human ankle as well as foot dimensions of an ablebodied subject, the ankle orthotic device is conceived. Then, based on a common twodegreeoffreedom (DOF) foot model, a coupled AFO–human system is setup. Further, the system's DOFs are derived; the device's mechanism of user adaptation is analyzed and verified using adams software. After that, the layout of a portable orthotic system, as well as a smart insole that detects gait phases, is illustrated. Finally, the orthotic system is tested on the aforementioned subject. Results show that, during the AFObased walking with assistive torque, the foot's plantarflexion level before the swing stage and dorsiflexion level in the swing stage approximately increase by 3 deg and 4 deg, respectively, relative to the condition of AFObased walking without assistive torque. Therefore, the orthosis has the potential to aid body propulsion and control toe clearance.