Using Human-Machine Interfaces to Convey Feedback in Automated Vehicles

The next decade will see a rapid increase in the prevalence of partial and conditional vehicle automation, specifically SAE Levels 2 and 3. These automated systems are designed for specific operational conditions, such as driving on mapped highways with clear lane markings, and, within these defined contexts, can control both the speed and the lateral lane position of the vehicle. In these levels of automation, the driver is expected to act as the fallback in situations that exceed the operational capacity of the automation or during unexpected automation failures. A human-machine interface (HMI) that can both keep the driver aware of the driving situation and vehicle state and effectively ease control transitions is therefore very important. This study investigated how aspects of the vehicle HMI design, specifically feedback provided about the confidence of the automation and presentation of non-driving secondary tasks, influenced aspects of the takeover process. The results demonstrate the complexity of reengaging a disengaged driver in the context of partially automated vehicles.