Abstract
Many hemiplegias use ankle-foot orthosis to prevent foot drop when they walk. However, it is difficult to walk smoothly because a conventional ankle-foot orthosis has high rigidity. In order to support natural gait of hemiplegias, in this study, a technique to regenerate energy is applied, and a new self-powered semi-active ankle-foot orthosis including a DC motor and step-up chopper circuit is developed. In this method, safety long-time continuous drive that is not restricted in time and the place is enabled and damping at ankle joint can be controlled. With developed ankle-foot orthosis, relation between angular velocity and braking moment at each duty ratio are derived. It is in this way shown that changing electric current of the circuit change damping force of developed ankle-foot orthosis. In addition, by experiment on the consecutive walk, it is shown that developed ankle-foot orthosis can control damping at ankle joint, charge battery by regenerating energy loss during a gait and prevent foot drop, and it is expected that developed ankle-foot orthosis provide higher effect than conventional type in ability to improve hemiplegic gait. Furthermore, as a result of estimate with measured electric current, developed ankle-foot orthosis shows high electricity recovery (86.5%).
