SRL Proxemics: Spatial Guidelines for Supernumerary Robotic Limbs in Near-Body Interactions

TL;DR

This study explores spatial guidelines for supernumerary robotic limbs in near-body interactions, revealing that perceived safety and trust depend on spatial behavior calibration rather than autonomy level.

Contribution

It introduces SRL Proxemics, a spatial design framework for SRLs, emphasizing the importance of proximity zones and behavior clarity over autonomy for safety and trust.

Findings

Participants preferred clear spatial zones and coordination rules.

Higher autonomy did not increase perceived safety or trust.

Behavioral calibration in space is key to user acceptance.

Abstract

Wearable supernumerary robotic limbs (SRLs) sit at the intersection of human augmentation and embodied AI, transforming into extensions of the human body. However, their movements within the intimate near-body space raise unresolved challenges for perceived safety, user control, and trust. In this paper, we present results from a Wizard-of-Oz study (n=18), where participants completed near-body collaboration tasks with SRLs to explore these challenges. We collected qualitative data through think-aloud protocols and semi-structured interviews, complemented by physiological signals and post-task ratings. Findings indicate that greater autonomy did not inherently enhance perceived safety or trust. Instead, participants identified near-body zones and paired them with clear coordination rules. They also expressed expectations for how different arm components should behave, shaping preferences around autonomy, perceived safety, and trust. Building on these insights, we introduce SRL Proxemics, a zone- and segment-level design framework showing that autonomy is not monolithic: perceived safety hinges on spatially calibrated, legible behaviors, not higher autonomy.