Abstract
Purpose:
This study evaluated the ability of blind subjects to navigate complex routes when guided with vibrotactile commands.
Methods:
The tactile feedback system consists of six vibration motors that are attached to individual points on a subject’s upper torso through a vest. The motors are connected to a push-button microcontroller system that delivers commands to the subject when the researcher presses a button that activates the corresponding motor(s). Eight navigational commands are encoded into the six-motor array, including, ‘forward’, ‘veer left’, ‘approaching left turn’, ‘turn left’, ‘veer right’, ‘approaching right turn’, turn right’ and ‘stop’. For example, ‘approaching left turn’ is coded as a single pulse of a motor, whereas ‘turn left’ is coded as two pulses of the same motor. Ten low-vision subjects were recruited from the Braille Institute, Los Angeles. Wearing the tactile feedback system, subjects were guided through indoor and outdoor courses. As a control, the subject navigated the same course using a cane for guidance. Appropriate response to commands, time to complete a trial, and reaction time were measured. Subjects were also given an exit survey that measured the usability of the feedback system. A parallel LED-array allowed alignment of a given command to video footage recorded for each trial.
Results:
Using tactile commands, subjects displayed responses consistent with 82.46% of commands and an average reaction time of 1.46 seconds. Subjects also completed routes faster than with their cane alone (p = 0.04). When using the device, subjects complained that encoding multiple commands on a single motor affected their ability to successfully comply with commands, probably stemming from a cognitive dissonance effect. They also preferred that the motors were placed closer to their skin. The device was rated 76% usable with subjects enthusiastic for its use as a street crossing guide.
Conclusions:
The tactile feedback system shows promise as an alternative to verbal-assist devices as means of communicating important information to users for mobility. However, optimal motor positioning and command encoding need to be investigated further to maximize its benefit.