Can Allowing Interface Customisation Increase Driver Confidence and Safety Levels in Automated Vehicle TORs?

Automated vehicles that require humans to resume control via a takeover request (TOR) in some scenarios have a specific requirement for human–machine interfaces (HMIs) designed to bring them back into the loop safely in terms of driving behaviour post-takeover. However, a single design of HMI will not be optimal for all users or circumstances. Providing the ability to customise a TOR HMI allows users to improve usability based on their needs and desires. However, it is necessary to test the effect of customisation on both driver confidence and safety. An on-road experiment was conducted featuring two trials: one using a default interface and one using a customised interface. Participants experienced multiple TORs within each trial; post-takeover performance data was recorded to analyse lateral and longitudinal accelerations, speed, and primary control inputs within the context of safety and driver confidence. Statistically significant results indicated that participants utilising a customised interface exhibited slightly higher mean speeds, slightly higher longitudinal accelerations, and slightly higher lateral accelerations. It is posited that the overall increase in speed and accelerations is due to a higher level of driver confidence and readiness as a result of the increase in usability due to customisation. In terms of safety, the increase in acceleration represents a potentially beneficial effect, while the longitudinal acceleration and speed levels remained well within the bounds that would be considered safe. Takeover times were lower when using a customised interface when inclusive of the entire protocol process; however, reaction times were almost identical.