Effect of differences in automobile seat frame material on human’s anxienty and comfort

Abstract

There are many factors that cause fatigue to passengers while riding a car. Among them, vibrations are always present during driving, so it is regarded as one of the main causes. Various products have been developed to reduce vibrations, but the car's seat frame material is still made mainly of iron. Therefore, in this study, changes of the state when changing the seat frame material were evaluated using muscle fatigue parameter, heart rate parameter, etc. in order to reduce fatigue of passengers on board. In the experiments, electromyogram (EMG) and electrocardiogram (ECG) were measured when the subject seated on the seat vibrated using ball-vibrator combined to air compressor. In order to measure the frequency, simultaneous parallel measurement of the acceleration in the front and rear direction of the seat (longitudinal vibration), the lateral direction of the seat (lateral vibration) and the vertical direction of the seat (longitudinal vibration) were also estimated. Furthermore, the subject's MPF (Mean power frequency), the RR interval of the electrocardiogram, and the accelerations of the three axes placed on the seat were analyzed from the data oriented by measurement using biomedical amplifier. In addition, Lorentz plot was performed at the RR interval of electrocardiogram. Both the new seat and the old seat (new seat: sheet using lightweight material. old seat: current seat using iron) showed the same tendency when vibrating in MPF, there was, however, no dominant difference between them in both cases. In the Lorentz plot of the electrocardiogram RR interval, sympathetic nerves dominated when the old seat shifted from non-vibration to vibration, whereas in the new seat the parasympathetic nerve dominated and there was a dominant difference.