Abstract
This paper examines which factor would mostly be related to the driver's braking timing by conducting indoor experiments using driving simulator. Fourteen participants drove a trailing vehicle and the lead vehicle was decelerated without notice. Participants applied brakes according to their subjective judgments on how best to prevent a rear-end collision. Various factors such as following car speed, distance between two vehicles, relative velocity, time-to-collision (TTC), rate of change of visual angle (which is the inverse of TTC) and others were examined in discriminant analysis. It was revealed that the rate of change of visual angle, which is the inverse of TTC, is most closely related to a driver's braking timing. The results were affirmed by the outdoor experimental results conducted on a test course using 7 participants. The findings can be used to determine the activation timing of adaptive braking system.
