A Portable Ankle-Foot Rehabilitation Orthosis Powered by Electric Motor

Yang Bai*, 1, Xueshan Gao1, Jun Zhao2, Fei Jin3, Fuquan Dai1, Yunqi Lv1
1 School of Mechatronical Engineering, Beijing Institute of Technology, Beijing, 100081, China
2 Department of Neurological Rehabilitation, China Rehabilitation Research Center, Beijing, 100068, China
3 Rehabilitation Engineering Research Institute, China Rehabilitation Research Center, Beijing, 100068, China

© 2015 Bai et al

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the School of Mechatronical Engineering, Beijing Institute of Technology, Beijing, 100081, China; Tel: 86-13581927345; E-mail:


Powered ankle-foot orthosis can not only prevent foot-drop and assist patients’ walking but also improve the ankle joint movement for patients with dysfunction caused by the various injuries and nervous system diseases. Common ankle rehabilitation devices limit the ankle injury patients’ rehabilitation training within fixed places, so a portable powered ankle-foot orthosis is presented in this paper to enable the patients to continue their work normally with the treatment. The orthosis employs electric motor drive mode to provide ankle dorsiflexion and plantar flexion assistance during patient’s walking. First, the ankle-foot dynamics model is established and the gait is analyzed for the powered ankle-foot orthosis system. Then, a new mechanical structure including wearing parts, analogous ankle joint and transmission is described. For the small installation space between the instep and the knee, the compact transmission mechanism has been given more attention and the finite element method is adopted to optimize the key structure after the force analysis. In addition, the closed-loop control system is chosen for the orthosis position and speed control. At last, wearing and movement experiments on the prototype are carried out, which validates the stability and rationality of the structure design and the effectiveness of the motion control. It has great significance in promoting patient's rehabilitation to help them return to the society.

Keywords: Ankle-foot, ankle rehabilitation, dorsiflexion, plantar flexion, powered orthosis.