Development of an Improved Driver Eye Position Model

SAE Recommended Practice J941 describes the eyellipse, a statistical representation of driver eye locations, that is used to facilitate design decisions regarding vehicle interiors, including the display locations, mirror placement, and headspace requirements. Eye-position data collected recently at University of Michigan Transportation Research Institute (UMTRI) suggest that the SAE J941 practice could be improved. SAE J941 currently uses the SgRP location, seat-track travel (L23), and design seatback angle (L40) as inputs to the eyellipse model. However, UMTRI data show that the characteristics of empirical eyellipses can be predicted more accurately using seat height, steering-wheel position, and seat-track rise. A series of UMTRI studies collected eye-location data from groups of 50 to 120 drivers with statures spanning over 97 percent of the U.S. population. Data were collected in thirty-three vehicles that represent a wide range of vehicle geometry. Significant and consistent differences were observed between eye-position data collected before and after driving, indicating that actual driving is important protocol feature for accurate measurement of driver eye position. In six vehicles, eyellipses obtained with two-way and six-way seat-track travel were only slightly different. Comparisons between mean preferred and design seatback angles show that design seatback angle does not accurately predict mean driver-selected seatback angle. On average, drivers select seatback angles that are about 1.6 degrees more upright than design. Stepwise regression techniques were used to identify the vehicle variables that have important effects on the distribution of driver eye locations.