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For an automobile seat, lateral support is considered to be one of the most essential elements for comfort. This report examines lateral support with two selected seats. Driver's movement while cornering was observed by seat pressure distribution (S.P.D.), and muscle activity was simultaneously recorded in electromyogram (EMG). S.P.D showed larger lateral movement of driver and EMG showed higher muscle activity on a poor lateral support seat than on a good lateral support seat. The higher muscle activity on the poor seat was explained as an effort to compete against the larger lateral movement of the body. Thus, poor lateral support was proved to lead to heavier physical burden.

Drivers' fatigue during long hour driving comes from various causes. The purpose of this study is to clarify the mechanisms of drivers' fatigue in relation to seat performance. The drivers' posture was examined on the assumption that an optimal seating posture against fatigue should exist. As a first step, laboratory test was conducted to grasp fatigue analysis viewpoints. Then, as a next step, road test with seat pressure distribution (S.P.D.) and Electromyogram (EMG) was implemented to clarify fatigue process. Results show that seat support condition is found to be one of the factors behind uncomfortable postures and physical burdens, which leads to subjectively felt fatigues.

Relationships between vehicle's high speed stability during a steering action and following aerodynamic coefficients have already been reported in the past: coefficients for time-averaged aerodynamic lift, yawing moment, side force and rolling moment. In terms of the relationships, however, we have occasionally experienced different high speed stability during steering input even with identical suspension property and almost the same aerodynamic coefficients. A vehicle during high speed cornering shows complex behavior due to unsteady air flow around the vehicle and unintentional steering input from a driver. So it is supposed that the behavior is too complex to be fully described only with those aerodynamic coefficients. Through on-road test [1] and CFD analysis [2,3,4], we have studied unsteady aerodynamic characteristics around a vehicle for pitching motion during straight-line high speed driving.