Nudging the Safe Zone: Design and Assessment of HMI Strategies Based on Intelligent Driver State Monitoring Systems

Dangerous driver behavior can arise from different factors: distraction, sleepiness, and emotional states like anger, anxiety, boredom, or happiness. The Driver Monitoring Systems (DMS) collect data on driver behavior and emotional states, which can help design safer driving systems. Human-machine interfaces (HMIs) can leverage the detection of altered states and foster a safe driving style. To this end, we presents two visual HMI prototypes designed to assist drivers in countering distraction conditions and emotional states of too high or too low activation. The HMI prototypes combine voice assistance, ambient lighting, and visual displays. The HMI visual strategies are designed to indicate the dangerous conditions to the driver and to provide the driver with additional information about the type of dangerous state detected. This work provides details on the design and of the methodology applied to evaluate the two HMI prototypes and presents the results of a user assessment with 26 participants, showing insights into user attitudes and helping to identify future design directions.