M.I.D.A.S. Touch: Magnetic Interactive Device for Alternative Sight through Touch
Taylan K. Sen, Morgan W. Sinko, Alex T. Wilson, Mohammed E. Hoque · 2014 · Proceedings of the 16th International ACM SIGACCESS Conference on Computers & Accessibility (ASSETS 2014) · doi:10.1145/2661334.2661350
Summary
This demonstration paper presents MIDAS Touch (Magnetic Interactive Device for Alternative Sight through Touch), a novel free-space haptic interface that allows visually impaired users to feel and create digital drawings without physical contact with a surface. The system uses a Leap Motion 3D hand tracker to map a user's finger position in real space to a virtual pen on a computer-hosted drawing canvas. When the virtual pen passes over regions where ink has been drawn, an electromagnet beneath the user's hand dynamically applies force to a small neodymium permanent magnet attached to the user's fingertip, creating a sensation of touch. The key innovation is the free-space approach — unlike force feedback styluses which suffer from mechanical backlash reducing fine resolution, or mechanical surface deformation systems that only allow feeling one's own drawings, MIDAS Touch applies force through a magnetic field with no mechanical linkages. The electromagnet (converted from a 900W transformer with E-shaped laminated iron core) can deliver over ±250 mN of dynamic force across a 3cm x 3cm x 1.5cm volume at 30Hz. Pen state (drawing vs. not drawing) is controlled by finger gestures: holding index and middle fingers together activates drawing mode, while spreading them apart (scissors gesture) switches to viewing mode. Previously drawn ink older than 5 seconds becomes "feelable" during scanning.
Key findings
The prototype successfully demonstrates that electromagnet-based free-space haptic feedback can provide visually impaired users with the ability to both perceive and create line drawings on a computer. The system addresses two specific use cases that existing approaches cannot handle well together: viewing drawings made by others (not possible with mechanical surface deformation approaches) and reviewing one's own drawing progress (critical for maintaining coherent compositions). The hardware is built from relatively inexpensive components — a Leap Motion sensor, an Arduino Mega microcontroller, a modified transformer, and a standard notebook computer — suggesting potential for low-cost deployment. The Leap Motion reliably tracks fingers over a 5cm x 5cm x 5cm volume. However, this is an early proof-of-concept prototype with no user evaluation with visually impaired participants yet conducted; testing with this population remains future work.
Relevance
MIDAS Touch explores an unconventional approach to non-visual graphics access — using magnetic force fields rather than touchscreens, tactile displays, or force-feedback styluses. For accessibility practitioners, the concept of free-space haptics is interesting because it eliminates the mechanical constraints of contact-based systems and could potentially be combined with other modalities (audio, vibration) for richer non-visual information display. The specific application to drawing is compelling because art and visual expression are often inaccessible activities for blind individuals, and sharing drawings between sighted and blind family members addresses a real social need. The main limitations are the early prototype stage, the small interaction volume (3cm x 3cm), the need for a magnet attached to the finger, and the absence of user evaluation with the target population. The work serves as a proof of concept for electromagnetic haptic interfaces in accessibility applications.
Tags: visual impairment · haptic feedback · free-space haptics · drawing · magnetic interface · sensory substitution · assistive technology · Leap Motion