ETHOS: A Robotic Encountered-Type Haptic Display for Social Interaction in Virtual Reality

TL;DR

ETHOS presents a dynamic encountered-type haptic display enabling natural social contact in VR by coordinating a torque-controlled robot, interchangeable props, headset-visible registration, and safety gating. The system supports static and dynamic interaction modes for handovers, fist bumps, and high-fives, achieving sub-centimetre spatial colocation ($5.09 \pm 0.94$ mm) and average contact latency of $28.53 \pm 31.21$ ms, well below many perceptual thresholds on average. The approach uses a ChArUco-based registration pipeline with high-frequency pose updates and a robust safety framework to allow unencumbered interaction while preserving user protection. These results establish a practical foundation for high-fidelity, on-demand social haptics in VR and point to future work in user studies, multi-user encounters, and adaptive prop design to enhance social realism.

Abstract

We present ETHOS (Encountered-Type Haptics for On-demand Social Interaction), a dynamic encountered-type haptic display (ETHD) that enables natural physical contact in virtual reality (VR) during social interactions such as handovers, fist bumps, and high-fives. The system integrates a torque-controlled robotic manipulator with interchangeable passive props (silicone hand replicas and a baton), marker-based physical-virtual registration via a ChArUco board, and a safety monitor that gates motion based on the user's head and hand pose. We introduce two control strategies: (i) a static mode that presents a stationary prop aligned with its virtual counterpart, consistent with prior ETHD baselines, and (ii) a dynamic mode that continuously updates prop position by exponentially blending an initial mid-point trajectory with real-time hand tracking, generating a unique contact point for each interaction. Bench tests show static colocation accuracy of 5.09 +/- 0.94 mm, while user interactions achieved temporal alignment with an average contact latency of 28.53 +/- 31.21 ms across all interaction and control conditions. These results demonstrate the feasibility of recreating socially meaningful haptics in VR. By incorporating essential safety and control mechanisms, ETHOS establishes a practical foundation for high-fidelity, dynamic interpersonal interactions in virtual environments.

Figures (4)

• Figure 1: ETHOS (Encountered-Type Haptics for On-demand Social interaction) enables corresponding virtual and physical renderings of dynamic interpersonal interactions, demonstrated here with an object handover (left), fist bump (centre), and high five (right).
• Figure 2: Interactable props of a baton (left), closed fist (centre), and open hand (right) used to render an object handover, fist bump, and high five interactions, respectively.
• Figure 3: Flowchart depicting the consistent sequencing of user and system actions for all interactions presented in this work: object handover, fist bump, and high five.
• Figure 4: Visualization of the dynamic control strategy: (a) an initial midpoint trajectory is generated as the user’s hand first approaches, (b) the trajectory is blended with the user’s current hand position as the interaction progresses, and (c) contact is reached at a unique location for each interaction.