Effects of scheduled manual driving on drowsiness and response to take over request: A simulator study towards understanding drivers in automated driving

• Published in: Accident analysis and prevention Vol. 124; pp. 202 - 209
• Main Authors: Wu, Yanbin, Kihara, Ken, Takeda, Yuji, Sato, Toshihisa, Akamatsu, Motoyuki, Kitazaki, Satoshi
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2019
• Subjects: Adult; Age difference; Automated driving; Automation; Automobile Driving - psychology; Drowsiness; Electrooculography; Eye-blink duration; Female; Humans; Male; Middle Aged; Protective Devices; Reaction Time - physiology; Sleepiness; Takeover; Task switching; Wakefulness - physiology; Drowsiness; Task switching; Takeover; Automated driving; Eye-blink duration; Age difference
• ISSN: 0001-4575; 1879-2057
• DOI: 10.1016/j.aap.2019.01.013

•Eyeblink durations were used to evaluate drivers’ drowsiness in automated driving.•The effect of scheduled manual driving on drowsiness did not persist for 10 min.•Scheduled manual driving delayed older drivers’ responses to take-over requests. Because current automated vehicles have operational limitations, it is important to ensure that the fallback-ready driver is able to perform appropriately when required to take over control of the vehicle. However, time-related increase in driver drowsiness is well-known, and drowsy driving can affect response to take-over request (TOR). It was previously reported that a scheduled period of manual driving during automated driving was beneficial in maintaining driver arousal level. The present driving simulator study investigates the effects of scheduled manual driving on driver drowsiness and performance, as well as age differences therein. A total of 115 participants, whose gender was balanced and age was distributed uniformly from 20 to 70 years, drove an automated vehicle for 31 min, and a TOR was prompted before a collision event. A between-subjects design comprised two conditions: with versus without a scheduled 10-min interval of manual driving that ended 10 min before TOR. The Karolinska Sleepiness Scale and eyeblink durations estimated from electrooculograms (EOG) were used to subjectively and objectively measure participant’s drowsiness. Reaction time, standard deviation of steering wheel angle, and minimum Time-to-Collison (TTC) were extracted to measure driver performance in response to TOR. The alleviating effect on drowsiness of 10-min scheduled manual driving became non-significant after another 10-min period of automated driving. Although the scheduled manual driving had no significant effect for younger drivers, older drivers reacted significantly more slowly in both steering and braking at the critical event. These findings provide essential insights for human-vehicle interactions: Scheduled manual driving cannot maintain drivers’ arousal level for 10 min afterwards, and for older drivers, it would be better to avoid unnecessary task-switching between manual and automated driving.