Bridging Gaps Among Human, Assisted, and Automated Driving With DVIs: A Conceptional Experimental Study

Partially automated driving releases the driver from controlling the vehicle, but the driver still needs to monitor the driving situation steadily and be able to take over the control in critical situations when needed. In such a situation, problems arise as to how and when should the driver be informed and how to make sure the driver understands the general situation and specifically also the intention of the system correctly. Driver-vehicle interfaces (DVIs) present the necessary information to the driver. Many studies focusing on the time for Takeover-request (TOR) and the takeover time of the driver are performed leading to various results. The question: “Can a general conclusion about upper and lower limits of these two variables be drawn, which is applicable for all drivers in all situations?” should be answered. In the situation in which the driver should take over the control of the vehicle, multiple driving modes are involved. Mode error or confusion may happen when the vehicle has multiple modes. This leads to another question to be discussed in this contribution: Is it possible to use one DVI to show the status of several autonomous driving levels and corresponding functionalities to avoid mode error or confusion? To answer these questions, two DVIs are designed considering multiple autonomous driving levels and their functionalities to increase the situation/mode awareness of the driver. A simulator study with 38 participants was conducted to study the takeover time and behavior of drivers under different critical situations as well as to compare the usability. Results show that the takeover time depends upon the sequence of experiencing the TOR and the complexity of the takeover situation. Furthermore, two proposed interfaces could contribute to increasing the situation awareness of the driver. The limits and trends of developing the TOR are concluded based on the literature review and the experiments performed. It is concluded that using an average TOR time for every individual driver in all critical situations is not appropriate. Discussion with respect to TOR to ensure a safe takeover regarding non-driving-related tasks and takeover experiences is derived from the performed experiments.