Assessing the Effects of Failure Alerts on Transitions of Control from Autonomous Driving Systems

Autonomous vehicle systems and their users need to collaborate to navigate the driving environment, particularly during an unstructured transition of control from automation, when the system releases control and expects the human to immediately assume driving responsibility. We investigated how such transitions affect the user's trust in the system and subsequent performance. In a full-vehicle driving simulator, participants encountered two system failures: the first varied in severity (mild or severe failure), and the second required a transition of control that was either detected and alerted (loud failure) or not (silent failure). We observed (i) significant changes in user trust in the system over time and between events, and (ii) that the first failure's severity level did not affect user performance in the subsequent failure; rather, the system's detection and alert both times was sufficient to successfully complete the transition of control.