The role of the future car will need not only as transportion but also how much entertainments are provided and how much comfortable to relax in the car Until now, the development of vehicle seats have been only focused on driving posture. However, the driving posture has a limit that creates large concentrated loads on the hips and waist when driving for a long time. So the purpose of this study are to develope optimal posture and to apply new seat mechanism in order to rest in the vehicle comfortably. The optimized posture is divided into ideal angles for each body this paper suggest each body angle and those got Inspired by NASA's gravity posture and recent relax furnitures such as stressless chair. But the state of the vehicle is gravity and it is a very compact space without unnecessary space. so it is a different environment from NASA's case. To find most effective posture, I recorded the body pressures of hips and upper body by changing the body angles such as angle of thigh and horizental car plane or upper body of passenger Also this need to take into account the conditions of the vehicle, such as the passenger's field of view or the space of surrounding components. When changing seat to the optimal position, there should be no interference with the surrounding components, and there should be no discomfort due to the blind field of view. Through this process, the ideal angles of vehicle rest position was proposed in this paper and the posture is defined as the relaxion posture, which is a combination word of relax and position. In the relaxion posture, the maximum loads on the hips and waist could be reduced by about 25%, with the distribution of body pressure increased by about 18%. Also, the test proved positive effects of improvement blood flow in part of thigh and hips by dispersed body pressure distribution more widely Relaxion seat can be designed with minimal changes to current seat mechanisms, and seats of this concept have been in production since 2019 This study also could be a direction of passengers posture in the autonomous vehicle.

Mr. Juyeol Kong, Hyundai Motors, REPUBLIC OF KOREA Mr. Chanho Jung, Hyundai Motors, REPUBLIC OF KOREA Mr. Seonchae Na, Hyundai Motors, REPUBLIC OF KOREA Mr. Sangdo Park, Hyundai Motors, REPUBLIC OF KOREA Mr. Gilju Kim, Hyundai Motors, REPUBLIC OF KOREA Mr. Sanghyun Lee, Hyundai Motors, REPUBLIC OF KOREA