Designing Humanoids: How Robot Posture Influences Users’ Perceived Safety in HRI

In human-human interaction, posture serves as a critical non-verbal cue that subconsciously shapes first impressions and perceptions. Given the preference for anthropomorphism of robots acting in socially intensive situations such as caregiving, the influence of posture is expected to increase in interactions with humanoid robots. This study aims to identify the most preferred default position for the assistive humanoid robot GARMI, ensuring users' perceived safety in human-robot interaction (HRI). In a preliminary study, 30 participants evaluated ten different arm postures of the robot GARMI regarding their perceived discomfort. From these evaluations and direct rankings, three arm positions were selected for further analysis alongside the current default position in the virtual reality (VR) study. In this subsequent study, 50 participants assessed their perception of safety using both objective measures of comfort distance, grounded in proxemic theory, and two subjective measures, i.e., Godspeed questionnaire and Robotic Social Attribute Scale (RoSaS). The results indicate a significant impact of the robot's arm postures on users' perceived safety. A polite, butler-like posture is recommended as the default position, aligning with the role users typically attribute to the robot GARMI.