Comparing the Haptic Perception of Directional Information Using a Uni-manual or Bi-manual Strategy on a Walker

This paper evaluates the haptic perception of directional cues conveyed through one or two handles mounted on a walker, with the objective of devising haptic rendering techniques for aiding people with diverse mobility, sensory, and cognitive impairments. We designed a haptic handle composed of a cylindrical soft plastic casing, which houses five custom voice-coil actuators distributed around the handle. We carried out a human subject study enrolling 14 participants to investigate the impact of using uni-manual or bi-manual conditions and to identify the most effective tactile patterns in a navigation assistance scenario. We tested the use of either vibration bursts or pressure "taps" to convey different directions of motion, relying on the concept of the apparent haptic motion illusion. Results show that the proposed technique is an effective approach for providing navigational cues. We identified specific patterns that were highly effective both in uni or bi-manual conditions in conveying directional instructions towards the front (93.7%), the back (90.5%), the left (97.2%), and the right (84.5%) directions, highlighting the viability of both strategies and their adaptability to various single or dual-handle mobility devices. No significant difference was found between providing vibratory or tapping signals.