Drivers anticipate lead-vehicle conflicts during automated longitudinal control: Sensory cues capture driver attention and promote appropriate and timely responses

Abstract

Adaptive Cruise Control (ACC) has been shown to reduce the exposure to critical situations 12 by maintaining a safe speed and headway. It has also been shown that drivers adapt their visual behavior 13 in response to the driving task demand with ACC, anticipating an impending lead vehicle conflict by 14 directing their eyes to the forward path before a situation becomes critical. The purpose of this paper is 15 to identify the causes related to this anticipatory mechanism, by investigating drivers' visual behavior 16 while driving with ACC when a potential critical situation is encountered, identified as a forward 17 collision warning (FCW) onset (including false positive warnings). This paper discusses how sensory 18 cues capture attention to the forward path in anticipation of the FCW onset. The analysis used the 19 naturalistic database EuroFOT to examine visual behavior with respect to two manually-coded metrics, 20 glance location and glance eccentricity, and then related the findings to vehicle data (such as speed, 21 acceleration, and radar information). Three sensory cues (longitudinal deceleration, looming, and brake 22 lights) were found to be relevant for capturing driver attention and increase glances to the forward path 23 in anticipation of the threat; the deceleration cue seems to be dominant. The results also show that the 24 FCW acts as an effective attention-orienting mechanism when no threat anticipation is present. These 25 findings, relevant to the study of automation, provide additional information about drivers' response to 26 potential lead-vehicle conflicts when longitudinal control is automated. Moreover, these results suggest 27 that sensory cues are important for alerting drivers to an impending critical situation, allowing for a 28 prompt reaction. 29

A Reference Model for Driver Attention in Automation: Glance Behavior Changes During Lateral and Longitudinal Assistance

“…1) The effect of automation: The significant decrease of PRC (eyes on path) when using ACC+LKA compared to manual driving (Fig. 7a) is consistent with previous studies on the real-world effect of ACC [37], [39], [40]. The lower PRC is interpreted as a symptom of a reduction in driving task demand when using vehicle automation, because of vehicle allocation of some of the control tasks-longitudinal and lateral control.…”

“…The lower PRC is interpreted as a symptom of a reduction in driving task demand when using vehicle automation, because of vehicle allocation of some of the control tasks-longitudinal and lateral control. Note that Morando, Victor and Dozza's 2016 work [39] showed that this PRC reduction effect occurs in steadystate driving with ACC, and that glances do return on-path in response to vehicle deceleration regulation if the lead vehicle brakes. A difference in PRC in the off-path glance distribution between manual and ACC+LKA driving was also expected.…”

“…The decrease of attention to the forward path when using automation may be considered potentially unsafe. However, it is important to distinguish between eyes off-threat and eyes off-path; for example, drivers look back at the road in response to vehicle deceleration from ACC (see [39]). The detrimental effects of taking the eyes off path are somewhat dependent on whether there is a lead vehicle, which poses a potential threat.…”

“…In manual driving, the increase in attention in response to a vehicle ahead was greater. A possible explanation is that when driving manually, to keep a safe headway to the lead vehicle, the driver predominantly uses visual cues, such as looming-the optical expansion of the lead vehicle in the eyes of the driver [39], [43], [44]. Because looming perception is impaired at the eye periphery [45], [46], an increase in glances to the forward path is expected.…”

Visual Sensory and Visual-Cognitive Function and Rate of Crash and Near-Crash Involvement Among Older Drivers Using Naturalistic Driving Data

“…Prior studies on vision and driving using naturalistic driving methods have not examined visual risk factors for crash and near-crash events. 11–20 Therefore, the purpose of this study was to examine the association between visual sensory and visual-cognitive function and rates of crash or near-crash involvement among older drivers using a naturalistic study design.…”