Design and Evaluation of an Active Ankle Exoskeleton in Gait Assistance

Abstract

Inspired by the energy storage and release mechanism of human’s Achilles tendon during walking, this paper proposes an ankle exoskeleton which is featured by adjustable stiffness of elastic elements to assist gait. The stiffness of the elastic elements can be switched to be consistent to the gait phase switching by a controllable clutch. The deformation range of the elastic element is increased by a linear driving mechanism in order to improve its energy storage ability. Plantar pressure and ankle motion are recorded to estimate the gait phase and switch the stiffness of the elastic elements. In order to evaluate the performance of the exoskeleton in gait assistance, the experiments were carried out on one subject. The result represents that whatever the stiffness of the elastic elements, the metabolic consumption of the subject can be reduced when the exoskeleton is actuated comparing with the situation of the exoskeleton non-actuation. The dominant muscle activities represent different decrease levels during walking with actuated exoskeleton.