Development of Body Weight Support Treadmill Training System Using Pneumatic Mckibben Actuator

Abstract

Previous studies suggest that body weight support treadmill training is effective to improve walking ability for incomplete spinal cord injuries. However, the moving of a patient's legs during the treadmill training represents ergonomically unfavorable and tiring work for therapists. Therefore, the purpose of this study is to develop a body weight support treadmill training system. This system consists of three parts, powered orthosis, equipment of body weight support and treadmill. The part of powered orthosis is based on Hip-Knee-Ankle-Foot orthosis with trunk support and is driven by pneumatic Mckibben actuator. Pneumatic Mckibben actuator is safe to use, obtains high power and contributes to lose weight of the orthosis. In this study, we try to develop a feedback control system which referred difference between inner pressures of actuators set up an antagonistic arrangement and joint angle of the orthosis. This control method is able to increase stiffness of hip and knee joints of the orthosis and achieves large torque for the orthosis walking. Additionally, co-contraction of pneumatic Mckibben actuators which set up an antagonistic arrangement as bi-articular muscle is able to increase stiffness of both hip and knee joints of the orthosis.