Driver's fatigue evaluation during long term driving for automotive seat development

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Driver's fatigue evaluation during long term driving for automotive seat development

Uenishi, K. / Tanaka, M. / Yoshida, H. / Tsutsumi, S. / Miyamoto, N.

Improvement of automotive safety and comfort requires the development of a seat that causes less driver fatigue during long-term driving. One of the most important aims is to mitigate forms of physical fatigue, such as low back pain. Methods of evaluating physical fatigue have generally relied on measurements of surface electromyography data and body pressure distribution, and fatigue has been estimated based on correlation analyses between the results and subjective evaluations. An important issue in automotive seat comfort is therefore reducing driver fatigue during long-term driving. In this paper, a two-dimensional human body-seat model was constructed by FEM and analyzed by using the static deformation constant of the seat as the parameter. The results showed that less hardness of the seat cushion under the thigh and the seat back under the back decreased lower intervertebral disc load and mitigated the stress on the lumbar vertebrae of a seated driver. A long-term driving experiment was carried out and multiple regression analysis was performed with urinary adrenaline level changes as the criterion variable. We found the increase in deformation under 'the thigh and the back' was important to reducing fatigue. and this result was in agreement with the result of the FEM analysis. The 1-2 Hz low frequency of Z-axis vibration also affects cumulative fatigue during long-term driving. A driver fatigue mechanism during long-term driving was clarified by the results of this study, and the structure of a fatigue-less seat was proposed.