Design of A Variable-Stiffness Ankle-Foot Orthosis Emulator

Abstract

Ankle-foot orthoses (AFOs) are passive devices used to improve gait in children with cerebral palsy. They are characterized by a torsional stiffness and ankle neutral angle. For this project, a lightweight ankle exoskeleton was designed to emulate the spring-like behavior of a traditional AFO for a wide range in torsional stiffnesses and neutral angles. This was achieved by utilizing the principles of a cantilever beam to generate a desired stiffness profile and lightweight hydraulics to transmit forces from a power source worn at the waist to the device at the ankle. The proposed device was evaluated using FEA and CAD modeling and met most design requirements. The next stage of design evaluation will involve a physical prototype before the final product is implemented in a clinical trial at Gillette Children’s Specialty Healthcare.