An Ankle Foot Orthosis with Stiffness Change Using Spring-cam Mechanism

Abstract

Decreased gait speed is one of challenges for patients with hemiparesis to be overcome during walking rehabilitation. Joint stiffness, i.e. resistance of the corresponding joint, which is defined as the ratio of its moment variation to its joint angle variation, is an essential factor to increase gait speed on walking in patients. Here, we propose an unconventional Ankle Foot Orthosis (AFO) that enables to change the joint stiffness in response to ankle flexion using spring-cam mechanism. In this maniscript, we verified the effect of developed orthosis on walking in one healthy subject. We confirmed the synergetic effect on inter-joint coordination, where increased ankle joint stiffness indirectly decreased both knee and hip joint stiffness, suggesting effectiveness for walking rehabilitation in patients.