How to Greet Humans: Designing Opening Encounters for Functional Robots with Naive Users

Abstract

Many robots are publicly deployed as predominantly functional machines, yet they are still perceived through a social lens and are expected to comply with basic social norms such as greeting. Designing recognizable greeting gestures for non-humanoid robots typically relies on movement specialists and a costly iterative process. We examined whether a participatory, kinesthetic elicitation process can be used to design a greeting gesture for a robotic arm sharing a public space. In the first study, naive participants designed greeting gestures for a robot that interrupts its primary task to welcome a newcomer entering the environment. Most designs included a nod-like movement, and a separate group of naive reviewers recognized the majority of these behaviors as greetings. In the second study, the top-ranked gesture was validated in a naturalistic encounter where a functional robot performed a task and then paused to deliver the greeting. Most participants recognized the gesture as a greeting and perceived it as a welcoming, socially normative act. Our findings suggest that non-experts can design socially normative gestures, lowering the barrier to adding a social layer to functional robots that share public spaces.