Abstract

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.