Which partially automated driving function do drivers prefer? Results from two field studies on public highways

Abstract

The use of partial driving automation is intended to increase both safety and comfort. However, the interaction with vehicle automation and the changing driving task, from steering to monitoring, can challenge the driver and compromise safety. To investigate driver-automation interaction, we conducted two field studies using two different SAE level 2 vehicles and involving a total of 132 drivers. In both studies, drivers drove on a public highway and gave insights on their trust and experiences in interacting with driving functions for longitudinal control (adaptive cruise control, ACC) and lateral control (lane-keeping assistance, LA). Participants of the second study could further experience lane-change assistance (LC). Our results confirm that trust increases with the use of automation. Comparing the driving functions, we found in the first study that drivers trusted and used ACC more than LA. Moreover, drivers were more positive about ACC and more critical about LA, but reported more interaction difficulties with the ACC. The data from the second study confirms the findings that drivers liked and trusted ACC more than LA. However, LC was liked and trusted even less than the LA. Our results indicate that drivers prefer driving functions that provide longitudinal vehicle control (ACC) to those that offer lateral vehicle control (LA). The lower preference for LC as identified in the second field study confirms our results, as LC forces the vehicle to move more sideways when changing lanes.