Basic study on prediction of initial contact for intelligently controlled ankle foot orthosis (I-AFO)

Ankle-foot orthoses (AFOs) are orthotic devices supporting movements of ankles of disabled persons for example hemiplegia, polio, peroneal nerve palsy, etc. In our previous research, we developed some kinds of passive controllable AFO which can control ankle torque with Compact Magnetorheological fluid brakes. One of the remarkable key points of its control is damping control at initial contacts. We think that a prediction of the initial contact is effective for its control because the initial contact usually ends very instant moment of about 0.1 s. In this paper, we describe basic control method of our controllable AFO and prediction method of the initial contact for it. Finally, we could predict instant contacts before 0.1 s with the absolute error of 0.020 s.