Design and Integration of Thermal and Vibrotactile Feedback for Lifelike Touch in Social Robots

TL;DR

The paper presents a multimodal enhancement of the PARO zoomorphic SAR by integrating a flexible thermal interface and embedded vibrotactile actuators to deliver biologically plausible warmth, heartbeat-like rhythms, and purring. The design process combines iterative user feedback and expert input to establish a reproducible methodology for multimodal haptic cue integration. Pilot evaluation shows that mild warmth improves realism without compromising comfort, while expert-driven vibrotactile cues significantly boost perceived life-likeness. The work offers practical guidelines, a low-cost integration path, and a generalizable framework for deploying life-like touch interactions across SAR platforms in care, education, and home settings.

Abstract

Zoomorphic Socially Assistive Robots (SARs) offer an alternative source of social touch for individuals who cannot access animal companionship. However, current SARs provide only limited, passive touch-based interactions and lack the rich haptic cues, such as warmth, heartbeat or purring, that are characteristic of human-animal touch. This limits their ability to evoke emotionally engaging, life-like physical interactions. We present a multimodal tactile prototype, which was used to augment the established PARO robot, integrating thermal and vibrotactile feedback to simulate feeling biophysiological signals. A flexible heating interface delivers body-like warmth, while embedded actuators generate heartbeat-like rhythms and continuous purring sensations. These cues were iteratively designed and calibrated with input from users and haptics experts. We outline the design process and offer reproducible guidelines to support the development of emotionally resonant and biologically plausible touch interactions with SARs.

Figures (4)

• Figure 1: Multimodal Prototype, integrating an electric heating pad controlled via a manual temperature regulator. It includes multiple vibrotactile actuators that simulate both purring and heartbeat sensations.
• Figure 2: Thermal and Vibrotactile Interfaces. The electric heating pad is sewn into a layer of soft white faux fur and controlled via a manual temperature regulator. The vibrotactile actuators are used to simulate both purring and heartbeat sensations.
• Figure 3: Stacked bar charts of perceived comfort and realism ratings (1 = lowest, 5 = highest) across four temperature settings: Baseline ($28^\circ C$), Mildly Warm ($35-36^\circ C$) , Warm ($38-39^\circ C$), and Very Warm ($40-43^\circ C$). Each bar represents 100% of responses, segmented by comfort/realism rating.
• Figure 4: Waveforms of the final vibrotactile cues. Top: heartbeat. Bottom: purring.