Finger Tendon Vibration: Finger Movement Illusions for Immersive Virtual Object Interaction

TL;DR

This work introduces finger tendon vibration (FTV) as a lightweight kinesthetic haptic illusion to enhance immersive VR object interactions. Through three perception studies, it establishes a minimum effective duration of 0.75 s and shows that short FTV does not significantly alter perceived voluntary force but increases perceived involuntary movement with duration, informing rendering strategies. The authors design six VR interaction scenarios and compare four FTV rendering methods (Collision vs Predicted triggers; Full vs Fixed durations), showing that FTV improves body ownership and overall VR experience compared with no vibration or simple vibratory feedback. The study yields practical design guidelines for applying FTV in VR and discusses limitations and avenues for future work, including multi-finger FTV and alternative actuators.

Abstract

The absence of physical information during hand-object interaction in a virtual environment diminishes realism and immersion. Kinesthetic haptic feedback has proven effective in delivering realistic object-derived haptic cues, enhancing the overall virtual reality (VR) experience. Here, we propose kinesthetic illusion through a novel application of finger tendon vibration (FTV), which creates an illusory sensation of finger movement. To effectively apply FTV for virtual object interactions, we first examine the effects of short-duration FTV (<5 s) through 3 perception studies. Based on study results, we design 6 exemplary VR scenarios, representing the overall design space of VR object interactions, and 4 different haptic rendering strategies for FTV. We evaluated these rendering methods on each VR scenario and derived a design guideline for FTV application. We then compared FTV with no vibration and simple vibration, observing that FTV enhances VR experience by providing realistic resistance on the finger, greatly improving body ownership.

Figures (11)

• Figure 1: Overall system configuration. (a) We placed vibration motors on the proximal phalanx of the left index finger. Vibrating the dorsal side of the finger results in a perceived flexion movement illusion, while the palmar side results in a perceived extension movement. (b) We used a microcontroller, motor driver, and 2 eccentric rotating mass motors to form FTV.
• Figure 2: (a) An example of double random staircase procedure (P17, extension). Black squares mark reversals. (b) Boxplot of final stimulus duration for the extension and flexion directions. Circles denote outliers.
• Figure 3: Perception Study 1 setup and results. (a) To measure the perceived index pinching force, participants held a $2.5$ cm$\times2.5$ cm$\times2.5$ cm cube with the pressure sensor between their index finger and the side of their thumb. (b) Example force difference (P13) between the right hand (matching hand) and the left hand (FTV).
• Figure 4: Perception Study 2 setup. (a) We attached motion tracker markers on the MCP, PIP, and DIP joints and fingertips. Using 8 motion capture cameras, we recorded how participants perceived the FTV-induced movement illusion. (b) To compute perceived finger movement, we form phalange vectors using joints and fingertip markers. Then, we calculate the rotation angles of the proximal, middle, and distal phalanges.
• Figure 5: Perception Study 2 results. (a) We observed clear direction distinction for short-duration FTV. (b) The perceived proximal phalanx movement had a significant difference between 0.75 s, 1.5 s, and 5.0 s for both flexion and extension. The middle (c) and distal (d) phalanges did not show increased perceived movement as vibration duration increased. Numbers above the bar indicate average and standard error, which is also shown by the error bars. * indicates p<0.05 and ** indicates p<0.01.