"I Have a Package For Mr. and Mrs. Smith, Can You Point Me to Their House?" - Co-Designing Bystanders' Interaction with Autonomous Delivery Vehicles

Small-size autonomous vehicles have reached a level of technological maturity that enables their use as efficient means for goods delivery. Yet, current designs of both ground and aerial vehicles fail to address potential information needs of bystanders: What is this robot doing? Can it harm me? Does it need help? Through a series of six co-design workshops (), we iteratively explore two types of autonomous healthcare delivery vehicles, namely aerial and ground robots, with a focus on bystanders' perspectives and interaction needs between bystanders and AVs. The resulting design propositions were then synthesized into functional scale-model prototypes of a healthcare delivery robot and drone. We validate our co-design findings by conducting two laboratory Wizard-of-Oz experiments (). Our results demonstrate how familiar colors and iconography support goal sharing and bystanders in recognizing the delivery vehicle's purpose and intentions. Mapping interaction needs of bystanders, we find contextual effects on bystander attitudes and the effectiveness of communication modalities. This work contributes to the design of future, socially acceptable small-size delivery vehicles fit for human spaces.