Development of ankle foot orthosis (AFO) using artificial muscle

Abstract

We developed a new ankle foot orthosis (AFO) using artificial muscle. In AFO two pressure sensors are arranged in the bottom of the foot. One is located on the toe and other is located on the heel. We arranged one artificial muscle on AFO in order to functionalize or to rehabilitate musculus tibialis anterior of human foot. At this stage, the AFO with artificial muscle and two pressure sensors is used for a disabled patient at the rehabilitation center at Faculty of Medicine of Oita University to gather the medical data. The control is the four control sequences such that (1) when the heel touches down on the floor, the pressure of artificial muscle is zero, (2) when the toe touches down on the floor after the touch down of the heel, the pressure of artificial muscle is still off, (3) when the heel leaves from the floor, the pressure of artificial muscle is zero, (4) when the toe leaves from the floor, the pressure of artificial muscle becomes a certain value, hence, the artificial muscle is shortened. This control law yields a disabled patient, who is not able to walk because of the toe’s hanging down, to walk smoothly.