Voluminous Fur Stroking Experience through Interactive Visuo-Haptic Model in Virtual Reality

TL;DR

This work addresses reproducing the tactile sensation of stroking voluminous fur in VR without using real fur. It introduces an interactive visuo-haptic pipeline that combines CG fur rendered via UnityHair with a non-contact ultrasound haptic display (STM) to map hand motions to both visual deformations and tactile cues. Through two experiments, the study shows that interactive haptic parameters alone can evoke fur-like sensations and that pairing dynamic CG fur with adaptive ultrasound feedback significantly enhances perceived fur sensation, softness, comfort, and enjoyment—approaching realism close to real fur in VR. The findings suggest practical potential for fur-inspired therapy, entertainment, and retail experiences, while noting limitations such as missing skin resistance and thermal feedback that warrant further development.

Abstract

The tactile sensation of stroking soft fur, known for its comfort and emotional benefits, has numerous applications in virtual reality, animal-assisted therapy, and household products. Previous studies have primarily utilized actual fur to present a voluminous fur experience that poses challenges concerning versatility and flexibility. In this study, we develop a system that integrates a head-mounted display with an ultrasound haptic display to provide visual and haptic feedback. Measurements taken using an artificial skin sheet reveal directional differences in tactile and visual responses to voluminous fur. Based on observations and measurements, we propose interactive models that dynamically adjust to hand movements, simulating fur-stroking sensations. Our experiments demonstrate that the proposed model using visual and haptic modalities significantly enhances the realism of a fur-stroking experience. Our findings suggest that the interactive visuo-haptic model offers a promising fur-stroking experience in virtual reality, potentially enhancing the user experience in therapeutic, entertainment, and retail applications.

Figures (10)

• Figure 1: (A) Top view of the measurement system for observing visual behavior and resistive force when stroking fur of width 25cm. (B) Side view of the measurement system stroking voluminous fur. Two vertical rows of pictures show the transition of visual behavior when the fur is stroked along and against the growth direction, respectively.
• Figure 2: Results of the measured vertical force when the force sensor comes in contact with the fur at the point designated as $x = 0$. The horizontal width of fur is 25cm. Each line in the graph represents six distinct conditions, a combination of three velocity conditions and two movement direction conditions.
• Figure 3: (A) Top view of the implemented fur CG model stroked in the growth direction. The fur is pressed down by the hand. (B) Side view of the fur CG model stroked against the growth direction. The fur is lifted by the hand and it stands up after the hand passes.
• Figure 4: Schematic depicting fur behavior when stroked against the fur growth direction. (A) When the hand moves, (B) it first comes in contact with the initial fur bundle, (C) lifts it while entangling next bundles in the deformation phase, (D) slides across the bundle width during the rubbing phase, and (E) then releases it, showing a cyclic behavior.
• Figure 5: Comparison of the measured force at 1.25cm/s and the intensity of the speaker calculated by the proposed model when fur-stroking against the growth direction. The left y-axis represents force indicated by the black dashed line, while the right y-axis represents intensity of the ultrasound haptic feedback indicated by the green solid line. The x-axis shows the distance ($x$) from the initial point of contact. The proposed model demonstrates similar characteristics to the measured force, with a sharp rise and gradual decrease during the deformation and rubbing phases, respectively.