Bio-inspired active soft orthotic device for ankle foot pathologies

TLDR

The design is inspired by the human foot and lower leg musculoskeletal system, mimicking its muscle‑tendon‑ligament structure. The study aims to design an active soft ankle‑foot orthotic powered by pneumatic artificial muscles to treat gait pathologies of neuromuscular disorders and improve mobility, safety, stability, and muscle use during walking. The device uses flexible soft materials and three pneumatic artificial muscles to assist dorsiflexion, inversion, and eversion, and incorporates embedded sensors for gait training and analysis. Early experiments show the prototype can achieve up to 20° dorsiflexion from plantarflexion and that ankle joint angles are controllable.

Abstract

We describe the design of an active soft ankle-foot orthotic device powered by pneumatic artificial muscles for treating gait pathologies associated with neuromuscular disorders. The design is inspired by the biological musculoskeletal system of a human foot and a lower leg, and mimics the muscle-tendon-ligament structure. A key feature of the device is that it is fabricated with flexible and soft materials that provide assistance without restricting degrees of freedom at the ankle joint. Three pneumatic artificial muscles assist dorsiflexion as well as inversion and eversion. The prototype is also equipped with various embedded sensors for gait training and gait pattern analysis. The prototype is capable of 12° dorsiflexion from a resting position of an ankle joint and a 20° dorsiflexion from plantarflexion. Results of early feedback control experiments show controllability of ankle joint angles. Ultimately, we envision a system that not only can provide physical support to improve mobility but also can increase safety and stability during walking, while enhancing muscle usage and encouraging rehabilitation.