Alternative options for dealing with automation failures: Automated stopping vs. Taking over manual control

Abstract

Previous research has investigated the driver’s ability to resume control after an automation failure. This study considers situation criticality, safety and difficulty between take-over and automated stop scenarios. Findings are reported of an experimental study investigating different strategies to take back control of an automated road vehicle. The study had a mixed factorial design with automation being the between-participants factor with two levels, SAE Level 1 vs. SAE Level 3. Urgency (High vs Low) and Take-Over Mode (Manual, Automated Stop) were the within participants factors. Dependent variables were: i) Minimum Time-to-Collision (TTC), ii) Self-reported Situation Criticality and Perceived Safety and iii) Percentage of Gazes to [the] Road Centre. Overall, 36 participants took part, with half assigned to either level of the Automation factor. The automated driving experience was designed to fail during participation. This required the driver to take-over manual control or have the system bring the vehicle to an automated stop. Results revealed that during manual take-over of control, measures of time-to-collision, perceived criticality and safety were worse and fixations to the forward view increased when compared to the Automated stop condition. Manual take-over of control in a high-urgency situation revealed higher criticality (shorter time-to-collision and lower perceived safety) and more difficulty (increasing fixations to the road centre) than in a low-urgency situation. The study points to an automated stopping manoeuvre being the preferable strategy to manual take-over of control.