Abstract
The causes of passengers' seasickness and fatigue have not been clarified. Our previous studies found that variabilities in heart rates were generated by passengers' postural control. However, passengers' standing postural motions caused by their postural control have not been analyzed enough. The purpose of this study is to elucidate the characteristics of passengers' standing postural motion against ship motion.Our measurement system consists of 3 orientation sensors. They were placed on the head and the waist of a subject, as well as on the floor of a small craft. They measured linear and angular acceleration. The frames of these sensors were transformed to a fixed coordinate system to compare the motion of the floor with subjects’ postural motion. Linear and angular acceleration were analyzed by the root mean square (RMS). RMS values of the subjects and a vertical standing rod were compared.The values of subjects' angular accelerations were larger than the floor values (p<0.05) and were changed along with the floor vertical acceleration. However, the values of the rod’s angular accelerations were smaller than its linear accelerations. These results suggest that passengers control their posture using rotational motion of the head and the waist against the floor vertical acceleration.
