In this paper, we present the design of a novel variable stiffness ankle-foot orthosis for correcting the drop-foot condition. The proposed mechanism controls permanent magnets to provide torque assistance to the patients suffering from drop foot. The stiffness of the mechanism can be adjusted by controlling the position of the permanent magnets. The variable stiffness actuator can control the stiffness independent of the position. This enables the orthosis to provide necessary assistance during the gait cycle. The conceptual design of the proposed orthosis is verified by considering the torque and stiffness requirements for a healthy gait cycle extracted from a public dataset consisting of gait data from 20 healthy individuals. We show that the actuator can exhibit necessary stiffness during the stance phase and provide necessary torque during the swing phase. Moreover, the presence of elastic elements prevents any impact on the joints of the patients.


Design of a Novel Variable Stiffness Active Ankle Foot Orthosis Using Permanent Magnets for Drop Foot Assistance

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

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