ViboPneumo: A Vibratory-Pneumatic Finger-Worn Haptic Device for Altering Perceived Texture Roughness in Mixed Reality

TL;DR

ViboPneumo addresses the challenge of altering the perceived texture of real objects in mixed reality without obstructing finger function. It combines a finger-around pneumatic actuator to lift the finger and reduce contact area with a top-mounted vibrotactile actuator to increase roughness, enabling bidirectional texture modulation. Technical evaluations validate precise air-pressure control, deformation response, and reduced contact area, while two user studies demonstrate that roughness modulation broadens perceptual range across materials and improves visual-haptic MR matching. The approach offers a scalable, fingerpad-free method to enrich MR texture experiences and enable versatile applications in design, education, and interactive systems.

Abstract

Extensive research has been done in haptic feedback for texture simulation in virtual reality (VR). However, it is challenging to modify the perceived tactile texture of existing physical objects which usually serve as anchors for virtual objects in mixed reality (MR). In this paper, we present ViboPneumo, a finger-worn haptic device that uses vibratory-pneumatic feedback to modulate (i.e., increase and decrease) the perceived roughness of the material surface contacted by the user's fingerpad while supporting the perceived sensation of other haptic properties (e.g., temperature or stickiness) in MR. Our device includes a silicone-based pneumatic actuator that can lift the user's fingerpad on the physical surface to reduce the contact area for roughness decreasing, and an on-finger vibrator for roughness increasing. Our user-perception experimental results showed that the participants could perceive changes in roughness, both increasing and decreasing, compared to the original material surface. We also observed the overlapping roughness ratings among certain haptic stimuli (i.e., vibrotactile and pneumatic) and the originally perceived roughness of some materials without any haptic feedback. This suggests the potential to alter the perceived texture of one type of material to another in terms of roughness (e.g., modifying the perceived texture of ceramics as glass). Lastly, a user study of MR experience showed that ViboPneumo could significantly improve the MR user experience, particularly for visual-haptic matching, compared to the condition of a bare finger. We also demonstrated a few application scenarios for ViboPneumo.

Figures (12)

• Figure 1: (a) A user wearing ViboPneumo and experiencing the decreased roughness of a virtual leather table mat in MR, (b) A visual scene in MR (HoloLens2) featuring cotton & leather table mats, glass & ceramic mugs, a wooden cube, and a piece of paper (c) The detailed view of the user sliding on a texture while wearing ViboPneumo with pneumatic actuation; (d) The bottom view of ViboPneumo with pneumatic actuation; (e-f) Two examples of ViboPneumo applications: altering the perceived roughness of the glass-shelf surface to feel like that of ancient Chinese pottery in the museum, and modifying the perceived roughness of a 3D-printed resin-based object to resemble another material (e.g., copper).
• Figure 2: (a) The structure of ViboPneumo with dimensional information: A linear resonant actuator and a 3D-printed semi-transparent housing with a layer of PDMS film with 1mm thickness, two layers of silicone rubber that were 400 $\mu$m thick, and a layer of PET film (40$\mu$m thickness) in the middle; (b) The appearance of the wearable device; (c) All the electronic components were assembled into a control box as the pneumatic-vibrotactile control system.
• Figure 3: The principle of reducing contact area through pneumatic actuation. When the pneumatic actuator is activated (right), it lifts the fingertip and causes a decrease in the contact area ($A_2$) compared to the contact area ($A_1$) when the actuator is inactive (left).
• Figure 4: The process of pneumatic-actuator fabrication.
• Figure 5: The pneumatic-vibrotactile control system.