Study on Driver's Car Following Abilities Based on an Active Haptic Support Function

A research prototype driver support system to augment perception to enhance situation awareness and control for car following applications is introduced and results from a field test evaluation are reported. The support system applies driving and braking force control and a gas-pedal push-back force whose magnitudes depend on the degree to which an undesirable region in a perceptual control space of time headway (THW) and time to collision (TTC) is penetrated (i.e. criticality based on perceptually meaningful cues [4]). Because the support system essentially extends the driver's: i) perception and criticality assessment (through dynamic force feedback on the gas pedal), ii) information processing (haptic information is provided earlier and more saliently than the visual information alone especially when visual attention is directed away from the driving task), and iii) control abilities (through automatic superposition of decelerations by the system), the system can be viewed an extension of the driver as a perceptual-motor controller. Therefore, changes in car following behavior with and without support system are quantified by identifying the coefficients of a simple practical car following model of the driver alone versus the driver plus support system.

The results clearly show that drivers who naturally follow closely, and thus operate frequently in the system's active support domain, effectively have a higher control bandwidth with the system which means that they are able to more rapidly and accurately respond to changes in the gap to the lead vehicle. These drivers exhibited an improvement of car following performance (i.e. less variability in gap at a longer target THW) as well as reported a reduction in workload. The support system effectively reduced the frequency with which drivers experienced close following and rapid gap closure situations.

The supported driver is essentially more vigilant to gap changes while following at a greater time-headway without an increase in workload.