Substitution of motor function of polio survivors who have permanent paralysis of limbs by using Cybernic Voluntary Control

There are 10 to 20 millions polio survivors living around the world. Some of them cannot move their limbs by themselves. They feel inconveniences at several situations: climbing stairs; moving in a narrow space; walking. It is very difficult for polio survivors, who have permanent paralysis, to restore motor functions by using conventional rehabilitation approaches. Our aim is the assistance of motor functions of these polio survivors by using HAL. The movement support by using HAL with Cybernic Voluntary Control is possible if electrical signals based on intention of motions can be detected from the polio survivors. However, there are two issues to apply the CVC: First, the bioelectrical signal activity is extremely small and sparse in comparison with unimpaired person's signals. Second, we cannot apply conventional calibration methods to these polio survivors. This paper proposes a specific simplified CVC method for polio survivor with permanent paralysis or severe muscle weakness in their limbs. The method consists of two parts to solve the mentioned issues: a preprocessing algorithm for particular bioelectrical signals and a procedure for assistive torque generation without calibration. We applied the proposed method to the participant who has paralysis due to polio viral infection and confirmed the effectiveness. As a result, the HAL with proposed method generated enough assistive torque to lift up the participant's shank from extremely small and sparse bioelectrical signals. Although the participant's bioelectrical signal activity was extremely small and sparse, and also he could not move the left knee by himself. After we applied the proposed method, the participant was able to move his knee voluntarily. Consequently, we confirmed that the proposed method could assist the basic motor function of paralyzed polio survivor.