Matti Krüger, Vanessa Krüger, Taisuke Mukai, "Evaluation of Interfaces for Augmenting a Driver's Ability to Anticipate Front Risks in Real Traffic", 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV), 2023.

Effective alerts are often subject to a tradeoff between relevance and utility. While it is easier to acknowledge the relevance of a warning about an imminent hazard than a more distant threat, the possibilities to act appropriately in response to notifications decrease with threat distance. To benefit from the advantages of early notifications without creating annoyance and ignorance, we introduce a variety of Human-Machine Interfaces that provide driver assistance by scaling stimulus saliency in accordance with the urgency of a front risk in traffic. Further, we report an initial investigation of the influence of the HMIs on measures of front collision risk and subjective driver experience after prolonged use in real traffic. Three functional HMI prototypes were implemented in a roadworthy vehicle, equipped with additional hardware for front risk detection, stimulus presentation, assistance control, and data logging. Participants with advanced driving practice received these vehicles for 12 days in total for personal daily use, consisting of 3 guaranteed days of use for one of each HMI prototype and 3 days of driving without any added front risk notifications. Besides continuous logging of driving data and risk estimates, subjective data were acquired in the form of logbook entries and interviews. Measures of driving safety were high across all conditions, indicating no occurrence of critical situations. No HMI specific safety effects on top of high baseline levels were observed. Subjective ratings show a trend for an increasing perceivability and usefulness of a sound-based HMI with extended system exposure. Participant feedback suggests that no such adaptations may have been necessary for the remaining vision-based HMIs because intuition could be gained quickly. Future HMI iterations should refine the balance between salience and subtlety to better align with actual safety levels while future investigations might benefit from longer individual exposures or an experimental control of safety levels.