Development of a Headlamp Dimming Request Prediction Model

This paper presents results of field studies conducted to predict headlamp beam usage and drivers' dimming request responses as a function of glare headlamp photometry, road background brightness and topography. An instrumented vehicle equipped with a variable intensity headlighting system was driven on two-lane public roads. Dimming distances were computed from separation time and closing rate measured by a radar. A long exposure photograph of each opposing vehicle was taken to determine the trajectory of the driver's eye point through the test car's beam pattern. Subsequent analysis of the film yielded an accurate time history of the glare illumination experienced by opposing drivers. The results show that the driver's dimming request behavior is dependent upon the level of discomfort glare experienced by the driver when the approaching vehicle first appears in his view and the potential glare exposure, i.e., the time-distance during which the glare could be experienced by the driver. On the basis of these results a model to predict when the driver would signal a dimming request to an opposing vehicle is proposed.