Human-Machine Interfaces in Safety-Related Cooperative Driving Automation Systems

The main objective of connected vehicles is to signif-icantly improve safety for travel participants and nearby people. Cooperative Driving Automation denotes the set of autonomous applications requiring cooperation among connected vehicles, including those with driving automation features engaged. As the operational purpose of the cooperation depends on the application class and the level of driving automation, it follows that the communication strategies and, therefore, the design principles of the human-machine interfaces of participating vehicles must change as well. However, the literature is missing a standardized and coherent strategy for the design and implementation of these interfaces, which may have undesirable impacts on the risk reduction profile of cooperative applications. This paper wants to be a first step in the definition of suitable design principles for such interfaces. We contribute an overview of related solutions providing a selection of relevant works, and we synthesize a set of fundamental human-machine interface design principles for safety - related cooperative applications, hypothesizing an inverse relationship between the level of driving automation and the need for active approaches to maximise the safety of connected vehicles and nearby road users.