Measurement of Postural Responses in Horizontal Perturbation Using Angular Velocity

Abstract

The decline of the balance function induces the elderly people to fall and it causes the decrease of daily activity to become bedridden or fear of falling. The fall occurs when sudden external forces such as trips or slips take place. Therefore, it is important to consider a simple evaluation of the posture balance in human to perturbation. In this study, we proposed the measurement system using gyro sensor, and measured the body sway of the pitch direction by the perturbation. The subjects are ten healthy adults and kept upright position on the table. They attached the sensor to an ankle joint, a knee joint and a back near the center of gravity. Then horizontal translation of table to the backward was given as the perturbation. The experiments were performed with 20 patterns of different acceleration from 0.6 m/s² to 4.4 m/s² by 0.2 m/s² randomly. As the result, the feature of three postural control strategies such as ankle strategy, hip strategy and stepping strategy can be confirmed by the angular velocity in the pitch direction. Additionally, the variation of the angular velocity of back for perturbation was larger than those of ankle and knee. Thus, we concluded that the sway in the back greatly influenced to the postural control for horizontal translation to the backward.