Compact Four-Degree-Of-Freedom Fingertip Feedback Device with Large Range of Motion
Seongju Byeon, Jayhyun Kwon, Amy Kyungwon Han
AI summary
Problem
Designing compact multi-degree-of-freedom fingertip haptic devices remains challenging due to inherent size and range-of-motion trade-offs that typically limit feedback to only shear or rotation.
Approach
The authors developed a 4-DoF fingertip device using a tendon-driven truss structure that converts motor-driven tendon lengths into precise rotational and shear motions, augmented with z-axis actuation for normal force feedback.
Key results
- High motion repeatability (<±0.35° for rotation, <±0.1 mm for shear)
- Large operational range (up to 98° rotation and 6.79 mm shear)
- High user perception accuracy (98.3% normal force, 91.2% shear, 77.5% rotation)
- Ultra-compact prototype footprint (12 mm diameter, 15 mm height)
Why it matters
Demonstrates a feasible mechanical foundation for compact, multi-modal handheld haptic devices that can significantly enhance immersion and precision in virtual and teleoperated environments.
Abstract
This work presents a compact, four-degree-of- freedom fingertip cutaneous feedback device capable of ren- dering normal force, shear, and rotational cues over a large range of motion. Based on a tendon-driven truss mechanism, the device achieved high repeatability in rotational and shear mo- tions, with consistent positional errors that could be addressed through feedforward compensation. A proof-of-concept user study with additional z-axis actuation demonstrated reliable perception of all three tactile cues, achieving accuracies of 98.3% for normal force, 77.5% for rotation, and 91.2% for shear. These results support the feasibility of the proposed mechanism as a compact multi-modal tactile interface for a future handheld haptic device.