A Literature Review on Additional Semantic Information Conveyed from Driving Automation Systems to Drivers through Advanced In-Vehicle HMI Just Before, During, and Right After Takeover Request

In-vehicle human-machine interface (HMI) plays a significant role in accomplishing effective interactions between driving automation systems and drivers, especially during the transition of control. For this reason, different in-vehicle HMIs have been designed to convey additional semantic information from the driving automation systems to the drivers to realize safer, smoother, and better control transitions. This review summarizes and analyses 86 previously published studies that researched the effects of additional semantic information delivered through in-vehicle HMIs just before, during and right after takeover request (TOR). The additional semantic information mentioned in this review refer to the information beyond simple alerts to not only gain drivers' attention but also additionally communicate contextual content and explanation to the drivers regarding its own purpose. In this review, the additional semantic information are categorized according to their purposes and effects into three aspects: mode awareness enhancement, situation awareness enhancement, and takeover maneuver assistance. The specificities and the corresponding concerns when applying additional semantic information to in-vehicle HMIs have been detailed analyzed throughout the entire article. Further suggestions are proposed for what should be carefully considered when adding additional information for better takeover. Prospects into future in-vehicle HMI possibilities are also raised that could be applied in both academic research and industry.