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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Drivers’ Response to Automation Initiated Disengagement in Real-World Hands-Free Driving

Driving automation features in the form of advanced driver assistance systems (ADAS) that can control the longitudinal and lateral vehicle kinematics on sustained bases (SAE Level2) are becoming increasingly available in consumer vehicles, making the study of drivers’ behavioral adaptation and the impacts of automation central to driving safety. This study used real-world data to assess drivers’ responses to automation-initiated disengagements by quantifying changes in drivers’ moment-to-moment visual attention and vehicle control behaviors. Fourteen drivers (36% female) drove for one-month each a Cadillac CT6 equipped with a data acquisition system that recorded driving kinematics, miles driven, automation use, GPS, and video of the driver and driving environment. Cadillac’s Super-Cruise (SC) is one of the most advanced, commercially available partial automation systems that, when engaged, enables hands-free driving while directly monitoring the driver’s head orientation. A total of 265 SC initiated disengagement events were identified (mean=18.9; SD=16.5 per driver) across 5,514 miles driven with SC. In general, SC initiated disengagements were associated with substantial changes in glance distribution. Immediately after disengagement, the proportion of glances to the Road decreased from 83% to 68% and at the same time the proportion of glances to the Instrument Cluster increased substantially, from 8% to 27%. The period following SC initiated disengagement was also characterized by a 44% increase in the overall number of transitions between glance areas (from 845 transitions before to 1218 after the disengagement across events). The most dominant visual attention patterns after SC disengagements were Road to Instrument Cluster (57% increase) and Instrument Cluster to Road (222% increase). Linear quantile mixed-effects models were used to estimate glance duration before and after disengagements. Findings indicate that on-road glance duration following SC disengagement decreased significantly and was 4.86sec shorter in the 85th quantile (Q15Before=0.5, CI=[0-2.24], Q15After=0.43, CI=[0-2.11], p=.04; Q50Before=2.02, CI=[0.8-3.24], Q50After=1.45, CI=[1.02-1.88], p=ns; Q85Before=6.63, CI=[2.06-11.2] to Q85After=1.77, CI=[0-3.67], p<.001). Analysis of driver hands on-wheel behavior indicate that drivers adopted SC’s hands-free feature to a substantial degree, taking both hands off the steering wheel more than 75% of the time SC was engaged. Takeover duration when driving hands-free was significantly longer (2.4sec) compared to driving with at least one hand on the steering wheel (1.8sec). In conclusion, concerns over the phenomenon of driver out-of-the-loop, coupled with known limitations of partial automation systems, have led research to focus on driver response to automation-initiated disengagement and the ability to regain manual control. The authors find that real-world automation-initiated disengagements trigger substantial changes in driver glance behavior including shorter on-road glances and frequent transitions between the Road and the Instrument Cluster glance areas. This behavior pattern likely represents drivers’ searching for information related to the disengagement or the automation state and may be shaped by the automation design. Higher levels of automation may introduce more substantial changes in visual and vehicle control behaviors during automation initiated-disengagements. This data provides useful information to designers charged with developing assistive and automated systems and empowers regulators and safety advocates with insights needed to better guide appropriate utilization of ADAS technologies.

Language

  • English

Media Info

  • Media Type: Web
  • Features: Figures; Photos; References;
  • Pagination: 9p
  • Monograph Title: 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV): Enhanced and Equitable Vehicle Safety for All: Toward the Next 50 Years

Subject/Index Terms

Filing Info

  • Accession Number: 01888534
  • Record Type: Publication
  • Report/Paper Numbers: 23-0137
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 21 2023 5:21PM