Characterization, Experimental Validation and Pilot User Study of the Vibro-Inertial Bionic Enhancement System (VIBES)

TL;DR

This work advances non-invasive prosthetic sensory augmentation by characterizing and validating the Vibro-Inertial Bionic Enhancement System (VIBES) integrated with the SoftHand Pro. It combines psychophysical JND-based actuator placement studies with three active tasks (Active Texture Identification, Fragile Object, Slippage) and an embodiment assessment via Rubber Hand Illusion to quantify perceptual benefits and user experience. Key findings show that VIBES improves texture discrimination (notably across able-bodied and one prosthetic user) and enhances embodiment, while effects on dexterity are mixed and workload remains manageable. The results support VIBES as a promising approach for restoring cutaneous feedback and prosthetic embodiment, informing future refinements and larger-scale testing.

Abstract

This study presents the characterization and validation of the VIBES, a wearable vibrotactile device that provides high-frequency tactile information embedded in a prosthetic socket. A psychophysical characterization involving ten able-bodied participants is performed to compute the Just Noticeable Difference (JND) related to the discrimination of vibrotactile cues delivered on the skin in two forearm positions, with the goal of optimising vibrotactile actuator position to maximise perceptual response. Furthermore, system performance is validated and tested both with ten able-bodied participants and one prosthesis user considering three tasks. More specifically, in the Active Texture Identification, Slippage and Fragile Object Experiments, we investigate if the VIBES could enhance users' roughness discrimination and manual usability and dexterity. Finally, we test the effect of the vibrotactile system on prosthetic embodiment in a Rubber Hand Illusion (RHI) task. Results show the system's effectiveness in conveying contact and texture cues, making it a potential tool to restore sensory feedback and enhance the embodiment in prosthetic users.

Figures (8)

• Figure 1: Overview of the main components of the prosthetic device with the VIBES (Vibro-Inertial Bionic Enhancement System). A detailed view (right) shows the inner part of the socket with vibrotactile actuators and EMG sensors.
• Figure 2: The bracelet worn by an able-bodied subject in the two experimental conditions: A and B (respectively a) and b) in the figure). c) The bracelet of the VIBES for the able-bodied experiments made of a 3D-printed case with vibrotactile actuators and adjustable VELCRO bands for secure fitting.
• Figure 3: Logistic fit for the ten subjects. Raw data and model predictions for each participant are labelled as 1 to 10. Blue: A condition; red: B condition.
• Figure 4: System Validation - An able-bodied user during: a) the Active Texture Identification Experiment in which the subject matches the sandpaper beneath the SHP with the handle (detailed view on the right) by exploring five options with their real hand on the right side; b) the Fragile Object experiment in which the subject moves a fragile object with a detailed view of it; c) the Slippage Experiment in which the subject grasps a cylinder and tries to detect slippage.
• Figure 5: Pilot Experiments - The prosthetic user during: a) the Active Texture Identification Experiment in which the subject matches the sandpaper beneath the SHP by exploring five options with her real hand on the right side; b) the Fragile Object experiment in which the subject move a delicate object; c) the Slippage Experiment in which the subject grasps a cylinder and tries to detect slippage.