A Study on the Spatial Location of HCP and Spinopelvic Alignment when Sitting on an Automotive Seat

Abstract

The design of automotive seats is an important design factor that affects the biomechanical alignment of the driver's spinopelvic alignment when in a seated state. However, there is a lack of biomechanical studies evaluating body changes in a driver's seated state in a driving environment. Therefore, urgent research is needed on driver-specific basic data that can be used as basic data to be considered in the development and design of automotive seats.Purpose: The purpose of this study is to measure the difference in the alignment of the spine and pelvis according to the driver's sitting posture when voluntarily participating drivers sit at their preferred car seat back angle and to use this data as basic biomechanical data for car seat design.Method: A total of 15 participants were seated in their preferred posture, and the lateral view of their spine and pelvis was evaluated using X-rays. The sagittal seatback angle at the time of sitting and the distance from the HCP (hip center point) to the VBC (vertebral body center) were measured. The HCP was determined as being the center of the femoral head, which is the point where the horizontal line and the vertical line bisecting the horizontal line meet after drawing a circle enclosing the femoral head on the lateral X-ray. VBC was defined as being the point at which the lines connecting the four ends of the vertebral body with intersections met in the side view of the X-ray. Then, based on the HCP, the distance of the VBC from the 5th lumbar vertebra to the 10th thoracic vertebra was measured with the x-coordinate for the horizontal line and the y-coordinate for the vertical line.Result: When the angle of the seatback was optimized when sitting, the angle was 10.9.4°±2.997°. And the distance of all vertebral bodies (L5, L4, L3, L2, L1, T12, T11, T10) from the HCP was 128±15.96, 147.3±19.44, 167.6±22.39, 187.5±24.87, 202.9±26.93, 216.2±29.89, 226.4±32.42, and 234±33.46, respectively, and the y (mm) values were 64.67±21.93, 106.1±22.91, 143.8±24.78, 181.6±23.30, 218.1±24.32, 253.6±27.80, 283.8±30.6.57, 331.6.57, respectively. Thus, as the change in distance from the HCP from the 5th lumbar vertebra to the 10th thoracic vertebra increases, x-axis increases by 15%, 13.78%, 11.87%, 8.2%, 6.55%, 4.72%, and 3.4%, respectively, and y-axis increases by 64.67%, 35.53%, 26.29%, 20.1%, 16.28%, 11.9%, and 10.6%, respectively, were observed.Conclusion: The results of this study will be used as basic data that can be reflected in an optimal ergonomic seat design by providing the vertebral body coordinate shift in the thoracic and lumbar region from the HCP through actual X-ray imaging, not virtual simulation, for optimal car seat design.