Adaptive Ankle-Foot Prosthesis with Passive Agonist-Antagonist Design

Abstract

The development of prosthetic feet that closely replicate the natural biomechanics of the human foot remains a significant challenge in prosthetics engineering. This paper presents the design and testing of a novel agonist-antagonist architecture for the ankle joint of a passive prosthetic foot featuring an adaptive sole. The ankle mechanism, inspired by the dynamics of the human leg-ankle-foot complex, utilizes compliant elements in an agonist-antagonist configuration to passively achieve an ankle torque close to that of a sound ankle without the need for external actuation. Concurrently, the adaptive sole adjusts its shape in response to different terrains, potentially improving stability and comfort for the user. The theoretical model underlying the proposed design is presented, followed by a preliminary validation through simulations. Finally, a prototype based on the new architecture is tested by a healthy subject using customized walking boots, demonstrating its potential to improve the functional performance of prosthetic feet in diverse environments.