Perception by Palpation: Development and Testing of a Haptic Ferrogranular Jamming Surface

Area of Science:

• Biomedical Engineering
• Haptics and Tactile Sensing
• Medical Training Technologies

Background:

• Medical palpation training is crucial but often limited by expensive, static, or case-limited equipment.
• Existing palpation training tools lack the dynamic variability needed for comprehensive skill development.

Purpose of the Study:

• To develop and evaluate a novel haptic surface concept for palpation training using ferrogranular jamming.
• To assess the system's ability to render palpable irregularities with controlled shape, position, and hardness.
• To investigate user interaction and performance in characterizing these irregularities.

Main Methods:

• Development of a 260 x 160 mm tactile field using ferromagnetic granules within a vacuum-sealed chamber.
• Manipulation of granule shape, position, and hardness via permanent magnets and pneumatic vacuum control.
• A psychophysical experiment with 28 untrained participants evaluating performance in identifying and sketching irregularities.

Main Results:

• 100% of participants correctly identified irregularities, with high agreement (κ=0.723).
• High Intersection over Union (IoU) scores (79.3% Soft Lump, 68.8% Annulus, 76.7% Hard Lump) and low center distance errors (Mdn ≤ 7.4 mm) demonstrated accurate shape and position rendering.
• Participants subjectively perceived hardness differences and reported a 71% improvement in palpation skills.

Conclusions:

• The ferrogranular jamming haptic surface effectively renders irregularities with controllable position, form, and hardness.
• Users can accurately locate and characterize these rendered irregularities through palpation.
• The system shows feasibility as a dynamic and effective palpation training device, enhancing user skills.