The driver response process in assisted and automated driving
Doktorsavhandling, 2022

Background: Safe assisted and automated driving can be achieved through a detailed understanding of the driver response process (the timing and quality of driver actions and visual behavior) triggered by an event such as a take-over request or a safety-relevant event. Importantly, most current evidence on driver response process in vehicle automation, and on automation effects (unsafe response process) is based on driving-simulator studies, whose results may not generalize to the real world. Objectives: To improve our understanding of the driver response process 1) in automated driving, which takes full responsibility for the driving task but assumes the driver is available to resume manual control upon request and 2) assisted driving, which supports the driver with longitudinal and lateral control but assumes the driver is responsible for safe driving at all times. Method: Data was collected in four experiments on a test track and public roads using the Wizard-of-Oz approach to simulate vehicle automation (assisted or automated). Results: The safety of the driver responses was found to depend on the type of vehicle automation. While a notable number of drivers crashed with a conflict object after experiencing highly reliable assisted driving, an automated driving function that issued a take-over request prior to the same event reduced the crash rate to zero. All participants who experienced automated driving were able to respond to the take-over requests and to potential safety-relevant events that occurred after automation deactivation. The responses to the take-over requests consisted of actions such as looking toward the instrument cluster, placing the hands on the steering wheel, deactivating automation, and moving the feet to the pedals. The order and timing of these actions varied among participants. Importantly, it was observed that the driver response process after receiving a take-over request included several off-path glances; in fact, drivers showed reduced visual attention to the forward road (compared to manual driving) for up to 15 s after the take-over request. Discussion: Overall, the work in this thesis could not confirm the presence of severe automation effects in terms of delayed response and a degraded intervention performance in safety-relevant events previously observed in driving simulators after automated driving. These differing findings likely stem from a combination of differences in the test environments and in the assumptions about the capabilities of the automated driving system. Conclusions: Assisted driving and automated driving should be designed separately: what is unsafe for assisted driving is not necessarily unsafe for automated driving and vice versa. While supervising drivers may crash in safety-relevant events without prior notification during highly reliable assisted driving, a clear and timely take-over request in automated driving ensures that drivers understand their responsibilities of acting in events when back in manual driving. In addition, when take-over requests are issued prior to the event onset, drivers generally perform similar manual driving and intervention performance as in a baseline. However, both before and just after the take-over requests, several drivers directed their gaze mainly off-road. Therefore, it is essential to consider the effect of take-over request designs not only on the time needed to deactivate automation, but also on drivers’ visual behavior. Overall, by reporting the results of tests of a future automated driving system (which is in line with future vehicle regulations and insurance company definitions) in realistic environments, this thesis provides novel findings that enhance the picture of automation effects that, before this thesis, seemed more severe.

automation safety

take-over request

driver behavior

response process

automated driving

driving performance

Room Beta, SAGA building - Chalmers Campus Lindholmen (for password to ZOOM email linda.pipkorn@chalmers.se (if before defense) or xiaomi.yang@chalmers.se (during defense))
Opponent: David Abbink

Författare

Linda Pipkorn

Chalmers, Mekanik och maritima vetenskaper, Fordonssäkerhet

Driver conflict response during supervised automation: Do hands on wheel matter?

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Automation aftereffects: the influence of automation duration, test track and timings

IEEE Transactions on Intelligent Transportation Systems,;Vol. 23(2022)p. 4746-4757

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It’s about time! Earlier take-over requests in automated driving enable safer responses to conflicts

Transportation Research Part F: Traffic Psychology and Behaviour,;Vol. 86(2022)p. 196-209

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Driver Visual Attention Before and After Take-Over Requests During Automated Driving on Public Roads

Human Factors,;Vol. In press(2022)

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Driver response to take-over requests in real traffic

IEEE Transactions on Human-Machine Systems,;Vol. 53(2023)p. 823-833

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This PhD thesis assesses the safety of two types of vehicle automation systems: assisted driving and automated driving. Assisted driving systems are already present in cars on public roads today. These systems help drivers to accelerate, brake, and steer their cars—but are dependent on the drivers to make up for potential limitations, such as failing to detect a stationary vehicle on the road ahead. On the other hand, an automated driving system is assumed to reliably handle the complete driving task under certain conditions (e.g., highway driving). When the conditions no longer apply, the system will notify the driver to take over the complete responsibility of the driving task. This thesis acknowledges that the human role is different in assisted and automated driving than in manual driving and investigates this new driver role: specifically, the consequences it may have on traffic safety. The novelty of the thesis, which used data collected on a test track and public road, lies in the detailed study of the timing and quality of the process that the human goes through when responding to a system limitation in assisted driving or transitioning back to manual driving after a period of automated driving. In contrast, the literature to date mainly consists of studies conducted in driving simulators focusing on a driver’s single response time. Importantly, this thesis demonstrates that what is safe for assisted driving is not necessarily safe for automated driving. Drivers coming out of a period of automated driving could handle the same event that was challenging for several drivers in assisted driving. This thesis also found that, in the same event, a hands-on-wheel requirement may not actually hasten the driver response in assisted driving. Moreover, the thesis could not confirm the safety concerns, such as delayed response to events and even crashing, that had previously been attributed to assisted and automated driving compared to manual driving. Potential reasons for the differing findings are discussed: they may stem from the difference in test environments and system designs included in the various studies. Finally, the thesis also emphasizes the importance of including drivers' visual behavior alongside the time it takes to deactivate the system when assessing the safety of automated driving. Overall, this thesis presents data-driven research that contributes to making current assisted driving systems and future automated driving systems safe.

L3Pilot - Piloting Automated Driving on European Roads

Europeiska kommissionen (EU) (EC/H2020/723051), 2017-09-13 -- 2020-09-13.

Addressing challenges toward the deployment of higher automation (Hi-Drive)

Europeiska kommissionen (EU) (EC/H2020/101006664), 2021-07-01 -- 2025-06-30.

Styrkeområden

Transport

Ämneskategorier

Tillämpad psykologi

Interaktionsteknik

Människa-datorinteraktion (interaktionsdesign)

Robotteknik och automation

ISBN

978-91-7905-724-4

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5190

Utgivare

Chalmers

Room Beta, SAGA building - Chalmers Campus Lindholmen (for password to ZOOM email linda.pipkorn@chalmers.se (if before defense) or xiaomi.yang@chalmers.se (during defense))

Online

Opponent: David Abbink

Mer information

Senast uppdaterat

2023-11-13