A Shallow-Torque Haptic Device for Wrist Postural Guidance: Design and System Evaluation in a Virtual Rehabilitation Task

This research presents a new glove-shaped wearable device, designed to deliver torsional cues on the wrist as a tactile guidance tool. The device integrates four tactile modules that apply modulated shallow torque to the anatomical wrist articulation, providing torsional hints for both ulnar–radial deviation and flexion–extension degrees of freedom (DOF). The aim of this research is to evaluate whether this new type of stimulation can convey accurate directional cues on 2-DOF wrist movements, with the main target application as a guidance and support tool in virtual motor rehabilitation. Effectiveness was tested in virtual reality (VR) serious games designed to exercise wrist movements through a virtual navigation task. The glove-shaped haptic device was introduced to guide the user by directional cues provided through the shallow-torques approach. Results showed that the tactile sensations were effective in conveying accurate directional cues, reliably guiding subjects’ wrist movements on 2-DOF. This research highlights the potential of a compact, non-bulky glove-shaped device for providing clear directional cues at the wrist across 2-DOF. The shallow-torque approach, combining the natural interaction of force feedback with hardware simplicity and lightness closer to vibrotactile devices, has the potential of scalability on other body segments, and shows promise for applications in rehabilitation, postural guidance, and virtual interaction.