HMI Interfaces of Unmanned Automated Taxi Services: What Is Essential Information?

At SAE Level 4, the Automated Driving System (ADS) handles all driving tasks, including emergencies, within a defined Operational Design Domain. This shift in driving responsibility has enabled the development of Unmanned Automated Taxi (UAT) services that can operate without a human driver. Since UAT services rely on system-user interactions, the role of the Human-Machine Interface (HMI) is crucial to improve the user experience. Therefore, this study aims to derive the mobile phone HMI (Human-Machine Interaction) interface for improving the UAT user experience by creating use cases in UAT services and proposing mobile phone User Interface (UI) examples. First, we created the user interaction use cases in the seven stages of the UAT service user journey (Lim and Hwangbo, 2021). And we categorized the information that can be provided in each use case based on the In-Vehicle-Information (IVI) classification criteria (Choi, 2017). A UAT mobile phone UI example was designed using the classified information. These use cases and UI examples can be utilized for future HMI interface research to improve UAT user reliability and satisfaction. In future studies, we plan to evaluate the effectiveness of the proposed UI using vehicle simulator-based experiments.