Implementing automated driving features in vehicles (SAE Level 3) in urban areas is a challenge due to the constant and often unpredictable interaction between vehicles and vulnerable road users (VRUs). To tackle this problem, in BRAVE we have designed an HMI feature that keeps the driver constantly informed about the presence of VRUs in the nearby environment. This way, the driver has enough time to disengage from other tasks (e.g. watching a video) and co-monitor with the system until it is safe again to resume the task.
This system has recently been tested in a moving-base simulator at VTI Gothenburg office. Participants with and without prior experience with driver support features (SAE Level 2) drove in an urban environment while watching a video on a tablet. The level of information about VRUs around varied across four conditions: a) no information, b) a take-over warning when the collision was imminent, c) a pre-warning message informing about the presence of VRUs nearby and, d) warning and pre-warning features together. The results showed that an HMI strategy integrating pre-warning and warning messages is the best solution to increase safety while also enhancing driver trust in the overall system. However, results also showed that prior experience with automated vehicles is necessary for this to occur.
These results support the design of HMI for automated driving features based on the needs, preferences and capabilities of users to ensure higher levels of acceptance and safety.