Shape-Changing Interfaces as eHMIs: Exploring the DesignSpace of Zoomorphic Communication between AutomatedVehicles and Pedestrians

External human-machine interfaces (eHMIs) are shown to support Automated Vehicles (AVs) in interacting with vulnerable road users such as pedestrians. Typically, eHMI concepts are light- or sound-based designs that communicate the AV's intention with abstract visualizations, which are unfamiliar, not fully intuitive, and require learning. In the natural world, animals are shown to communicate their intention or disposition with a variety of visible reactions, using posture, gesture, or other means, which have implicit meaning by association with centuries of evolution. We explore the design space of biomimicry-inspired communication between AVs and pedestrians using external Shape-Changing (eSC) interfaces. We created six distinct concepts of eHMIs that employ external shape change and evaluated them in a focus group. Results show that zoomorphic, shape-changing-based eHMI concepts are promising in achieving intuitive communication about an AV's intention in traffic. This may help in reducing the learning effort associated with abstract eHMIs, and ease the integration of AVs.