Contribution of Visual Feedback Control during Standing on a Board Moving Horizontally

Abstract

Visualization of balance evaluation during standing is important issue for diagnosis of disease and determination of training effect. Although there have been many studies of the balance evaluation, these evaluation methods are insufficient in terms of a saving of work and its reliability. This study tries to evaluate the balance characteristics based on a mathematical model from the response of human body to an external stimulus. We applied frequency analysis to the response to horizontal sway of the support surface as the external stimulus, and identified personal balance characteristics by fitting an assumed balance control model to the result. The balance control model assumed in this study is multiple feedback loop system which is composed of the delayed state feedback control system as an inner-loop and posture control system according to the velocity of the support surface as an outer-loop. From the feedback parameters for inner-loop control, we found individual balance characteristics by calculating equivalent damping ratio and natural angular frequency. As a result, the present method can evaluate individual balance characteristics by using the assumed feedback model when external stimulus is acted.