Comfortable power assist control method for walking aid by HAL-3

We have developed the power assist suit HAL (Hybrid Assistive Leg) which provide the self-walking aid for gait disorder persons or aged persons. The power assist was performed according to the operator's intention by using myoelectricity(EMG) signal as the primary command signal. However, there remains the problem that the operator senses the discomfort while the power assist is performed by EMG-based control. The scope of the present research is to propose the control methods to reduce the discomfort which the operator sense while the EMG-based power assist is performed in walking and standing up respectively; 1) the control method that the integrated motion between HAL-3 and the operator corresponds with the particularity of operator's musculo-skeletal system while in the power assist walking, 2) the predictive control method applying feedforward controller to remove the discomfort while in standing up. As the result, the power assist walking was performed corresponding to the joint kinematics of the normal walking without the assistance. Applying feedforward controller realized the quick response while in standing up power assist. These control methods enabled HAL-3 to realize the power assist that the operator sensed the reduce of discomfort.