Communicating Issues in Automated Driving to Surrounding Traffic - How should an Automated Vehicle Communicate a Minimum Risk Maneuver via eHMI and/or dHMI?

Kurzfassung

Cooperative automated vehicles (CAV) are not able to drive automated in all situations. Each vehicle has or is going to have its own operational design domain (ODD), which exactly specifies which situations can be handled, and which cannot. Vehicles of higher levels of automation according to SAE J3016 will try to take the driver back into the control loop if the vehicle approaches the border of its ODD by issuing a transition of control (ToC). If the driver is not responding, the vehicle will perform a minimum risk maneuver (MRM), where the CAV is stopping. Instead of looking at the internal HMI of single CAVs, the H2020 project TransAID focusses on the effects of automation limitations on traffic efficiency and safety. Besides helping the CAV to reduce negative impacts of such situations by infrastructure measures, also informing the surrounding vehicles about a CAV’s current issues and about its plans to solve them will most likely improve such situations. To approach this assumption, DLR conducted a first virtual reality study, where e.g. a 360° externally mounted LED light-band as external HMI (eHMI) of a CAV and specific vehicle movements as dynamic HMI (dHMI) are used in case it needs to perform an MRM. In the study, ten participants tested different variants and combinations. Preliminary results show that the use of an eHMI is a useful and informative approach.