Abstract
This paper proposes the concept of "combined pelvic and lumbar support" as an optimum support condition for designing automotive seats that best fit the human body and minimize fatigue during long trips. This seat design concept has been derived from the standpoints of the skeletal structure of the human body and body load distribution when sitting. A body posture is described that places much less load on the lumbar region and individual posture differences are clarified. A prototype seat has been built which incorporates combined pelvic and lumbar support and maintains the desired posture so as to reduce the applied load. The results of tests conducted to confirm the effect of this seat in reducing fatigue are also presented. (A)