Language-based multimodal displays for the handover of control in autonomous cars

Abstract

This paper presents a first evaluation of multimodal language-based warnings for handovers of control in autonomous cars. A set of possible handover situations varying in urgency is described. A set of multimodal, language-based warnings for these situations is then introduced. All combinations of audio, tactile and visual warnings for handovers were evaluated in terms of perceived urgency, annoyance and alerting effectiveness. Results showed clear recognition of the warning urgency in this new context, as well as low perceived annoyance overall, and higher perceived effectiveness for critical warnings. The time of transition from self-driving to manual mode in the presence of the warnings was then evaluated. Results showed quicker transitions for highly urgent warnings and poor driving performance for unimodal visual warnings. These results provide a novel set of guidelines for an effective transition of control between car and driver in an autonomous vehicle.