Exploring Immersive Social-Physical Interaction with Virtual Characters through Coordinated Robotic Encountered-Type Contact

This work presents novel robot-mediated immersive experiences enabled by an encountered-type haptic display (ETHD) that introduces direct physical contact in virtual environments. We focus on social-physical interactions, a class of interaction associated with meaningful human outcomes in prior human-robot interaction (HRI) research. We explore the implementation of this interaction paradigm in immersive virtual environments through an object handover, fist bump, and high five with a virtual character. Extending this HRI paradigm into immersive environments enables the study of how physically grounded robotic contact and virtual augmentation jointly shape these novel social-physical interaction experiences. To support this investigation, we introduce ETHOS (Encountered-Type Haptics for On-demand Social interaction), an experimental platform integrating a torque-controlled manipulator and interchangeable props with a headset-mediated virtual experience. ETHOS enables co-located physical interaction through marker-based physical-virtual registration while concealing the robot behind the virtual environment, decoupling contact from visible robot embodiment. Both technical characterization, through spatial alignment and interaction latency tests, and experiential evaluation, through a 55 participant user study, were completed. Overall, the findings demonstrate the feasibility and experiential value of robot-mediated social-physical interaction in VR and motivate further development of dynamic encountered-type approaches for immersive HRI.