FlowMotion: Exploring the Intuitiveness of Fluid Motion Based Communication in eHMI Design for Vehicle-Pedestrian Communication

External Human-Machine interfaces (eHMIs) are typically proposed to facilitate explicit communication of vehicle intent to pedestrians. However, implicit communication through vehicle kinematics or movement patterns is shown to be the primary indicator of driving behavior and intention in traffic, for both manually-driven and automated vehicles. Unfortunately, subtle changes in kinematics are often hard to perceive and make it difficult to comprehend a vehicle’s consequent intention. We created a novel eHMI concept by using fluid movements to highlight and exaggerate the movement of the vehicle, and therefore emphasize this movement-based implicit communication. Preliminary results showed that the movement of the fluid called attention to subtle changes in the acceleration and deceleration of the vehicle, and was able to effectively indicate the nature of the change of vehicle speed, which in turn alluded to its intentions in traffic. This approach explores design solutions to highlight vehicle kinematics in facilitating communication of vehicle intention in traffic, for both automated vehicles of the future, and manually-driven vehicles of today.