Effects of Non-driving Task Related Workload and Situational Awareness in Semi-autonomous Vehicles

Abstract

Recent advances in autonomous and semi-autonomous vehicles have resulted in more efficient vehicle maneuvers, which causes drivers to be less involved in operational driving, thus leading to increased drivers’ engagement in other non-driving related activities. High levels of automation arise concerns such as a decrease in situational awareness (SA) and driving performance as drivers are likely to undertake a non-driving related task during vehicle maneuvers. For cars with conditional or higher automation (SAE Level 3 or up), there is a need to study and monitor drivers’ level of engagement/involvement with the vehicles. Considering the key factors for safety when drivers perform a non-driving related task (NDRT) during conditional automation, issues concerning drivers’ SA and takeover performance in absence or failure of automation need to be addressed. In this study, we designed and conducted driving simulator experiments to investigate drivers’ SA while they were performing a NDRT during the conditional automated driving. We also investigated drivers’ takeover time and takeover quality in different NDRTs. We found that drivers’ vigilance levels are different while performing different NDRTs during semi-automation. Our results show that the response time was typically between 5–8 s and the deviation of distance to the center of the lane ranged from −0.66 m to −0.3 m which might suggest the variability in takeover quality during different NDRTs.