Quantitative Motion Control Analysis Method for Power Assist System Based on Human Motion Property

Abstract

This paper describes quantitative analysis method to extract the properties of the feedforward control and the feedback control for power assist system based on human motion property. A force pattern and a feedback gain are introduced as the property of the feedforward control and the feedback gain as the feedback control, respectively. Experiments were conducted on the task of subject to keep the inverted pendulum stably from the initial condition that the angle of the inverted pendulum was set large. It is difficult to perform the feedback control in this condition. While the inverted pendulum was controlled stably, the force pattern of the beginning motion and the feedback gains were collected during the motion learning process. The force patterns were similar and the feedback gains were approximately constant as the subject's skill was improved. The feedforward control was characterized by the force pattern quantitatively, and also the feedback control by the feedback gain. These results indicate a power assist and a rehabilitation are performed according to the feedforward control and the feedback control using the control properties obtained by this quantitative analysis method. The power assist of standing up motion was performed using the feedforward control based on a normal person's torque pattern of his hip and knee joint in standing up. As the result, the operator could obtain the accurate power assist.