Hand Dominance and Congruence for Wrist-worn Haptics using Custom Voice-Coil Actuation

TL;DR

The paper introduces CoWrHap, a wrist-worn haptic device based on a custom voice-coil actuator that renders single-bump force feedback to support stiffness discrimination in VR. It investigates how hand dominance (dominant vs non-dominant) and hand-wrist congruence (congruent vs non-congruent mapping) influence perceptual performance and user experience. Results show no significant effect of hand dominance on discrimination accuracy, while non-congruent mapping yields better psychophysical performance (PSE) and congruent mapping yields more favorable user experience. The work demonstrates the viability, low cost, and customization potential of voice-coil wrist actuators for conveying mechanical properties in VR, informing design strategies for wrist-worn haptics.

Abstract

During virtual interactions, rendering haptic feedback on a remote location (like the wrist) instead of the fingertips freeing users' hands from mechanical devices. This allows for real interactions while still providing information regarding the mechanical properties of virtual objects. In this paper, we present CoWrHap -- a novel wrist-worn haptic device with custom-made voice coil actuation to render force feedback. Then, we investigate the impact of asking participants to use their dominant or non-dominant hand for virtual interactions and the best mapping between the active hand and the wrist receiving the haptic feedback, which can be defined as hand-wrist congruence through a user experiment based on a stiffness discrimination task. Our results show that participants performed the tasks (i) better with non-congruent mapping but reported better experiences with congruent mapping, and (ii) with no statistical difference in terms of hand dominance but reported better user experience and enjoyment using their dominant hands. This study indicates that participants can perceive mechanical properties via haptic feedback provided through CoWrHap.

Figures (7)

• Figure 1: Experiment Conditions: The participant receives either congruent haptics (on the same side as the dominant or non-dominant hand interacting with VR (a-b)) or non-congruent haptics (on the opposite side as the dominant or non-dominant hand interacting with VR (c-d)). The yellow box represents the virtual object, while the blue arrows indicate the haptic location.
• Figure 2: Custom-made CoWrHap representation. (a) It can render a single bump square signal. (b) The stimulus intensities can vary with an adjusted duty cycle between 50 % and 100 %, as indicated by force measurements.
• Figure 3: Confusion matrix showing the user performance to discriminate two consecutive haptic stimuli with CoWrHap rendering randomized duty cycles.
• Figure 4: Experiment setup: The participant wears an Oculus headset to experience VR, CoWrHap to receive interaction-based haptic feedback, and noise-canceling headphones to minimize the environment and actuation noise.
• Figure 5: Virtual task and the environment: the participant (a) selects the start button to initiate the trial, (b) explores Box 1 (on the left) by pushing from the top, (c) explores Box 2 (on the right) by pushing from the top, and (d) chooses the box which feels stiffer by clicking on the related button.