In automated vehicles, driversare only required to input high-level control commands as opposed to lower-level commands in manually driven vehicles. The conventional driver-vehicle interfaces (DVIs) such as steering wheel and pedals that function in operational level, thus, may not be utilized in higher levels of automation. A DVI that allows the driver to input tactical-level control commands, i.e., lane change and turning, by easily understanding a situation, would be potentially required for automated vehicles. We thus propose tactical-level-interaction (TLI) for lateral and longitudinal controlling of highly automated vehicles. In this study, we developed a touchscreen-based DVI prototype that allows the driver to use simple touch gestures to input tactical control commands. The screen displays an augmented map including the ego vehicle rendered from the top view. The driver can instantly input a set of lateral commands by location-based TLI, e.g., lane changing, by designating a desired location on the map, e.g., lane, by double-tapping and swiping. Situational awareness is enhanced, for e.g., when approaching an intersection, by using visual and auditory prompts. We performed experiments using a simulator to evaluate TLI compared with the operational- (OLI, level 0) and strategical-level interaction (SLI, level 4). The results show that TLI offers both the flexibility of OLI as well as the comfort of SLI, and drivers prefer to use all three interaction methods depending on the driving environment.
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