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Analysis of eye gaze given different automated driving styles in an urban environment

When designing driving styles for automated vehicles, the situational context has a major impact on the configuration of longitudinal and lateral manoeuvre parameters. Regarding motorways and rural roads, a defensive approach is generally preferred over a dynamic approach as the former results in higher ratings of user acceptance, trust and safety. However, research in an urban environment is needed, where interactions between vehicle and environment are more complex. In this context, psychological questionnaires are usually used to evaluate automated driving styles, but often, a more objective evaluation is needed, which could be achieved by observing the gaze. To address these two issues, a driving simulator study in an urban environment was conducted with 42 participants. The participants experienced four automated drives with nine different scenarios respectively (e.g., bus stop, crossing intersection, unprotected left turn). In each test condition, the ego-vehicle performed either a defensive or a dynamic driving style. During each drive, participants were asked to observe the behaviour of the ego-vehicle while their gaze was tracked with a head-mounted eye tracker. Furthermore, an HMI was implemented to provide participants additional information about the upcoming manoeuvre of the ego-vehicle. After all drives, an interview was conducted. The results show that eye gaze holds the potential to identify trust in automated driving styles as gaze significantly differed during the two driving styles. In the defensive driving style condition, less gaze is allocated in the mirrors and more gaze is allocated in the environment. This suggests that participants do not spend as much time on assessing the manoeuvre and therefore, trust seems to be higher. This indicates that eye gaze can be utilized as an objective measurement of trust in automated driving.