A hybrid ankle-foot orthosis with soft pneumatic actuation

This paper presents the design, development, and analysis of a powered ankle-foot orthosis for dorsiflexion assistance which aims to improve gait restoration by addressing issues related to orthosis misalignment, limited degrees of freedom, restricted range of motion, and muscular disuse. The proposed orthosis utilizes a novel hybrid design with a combination of both traditional and soft robotics for compliant and unrestrictive ankle dorsiflexion assistance for sufferers of footdrop. This article describes the complete design of the orthosis including analytical modeling and experimental testing of the soft pneumatic actuator and the development of gait phase detection and ankle angular feedback systems using wearable sensors for accurate and responsive control. Preliminary analysis was completed which validates the orthosis as a lightweight, unrestrictive, and compliant device that is capable of dorsiflexing the ankle of a person up to 100 kg, and at walking speeds appropriate for safe and effective community ambulation of up to 1.04 m/s. The novel design of the device demonstrates the potential for improved rehabilitative outcomes for patients with footdrop, due to the ability to adjust the assistive force of the device, throughout the progression of rehabilitation, which encourages muscular participation of the user and therefore reduces issues caused by muscular disuse.