Influence factors and improving strategies of perceived safety - an on-road study with L2 autonomous driving.

Perceived safety (PS) and trust are important factors that influence the adoption of autonomous driving. In order to study the factors influencing PS and the possibility of real-time monitoring, an on-road experiment with L2 autonomous driving with 30 participants was conducted. Participants experienced autonomous driving functions as co-drivers and rated PS through video replays. Physiological data were recorded during the experiment and analysed afterwards. It was found that PS significantly reduced during events of hard braking and bumps, whereas it was high during congestions and hard-turning events when speed was relatively lower. Analysis of geolocations and environmental data around the vehicle showed that tunnels, terrain and traffic complexity would impact PS. Physiological data showed a significant negative correlation between electromyogram (EMG) of the lower limb and PS. Through post-experiment interviews, technical and human-computer interaction (HCI) measures that are expected to improve PS are proposed.