Assessment of a Multimodal Feedback System for Independent Navigation of People With Visual Impairments

Introduction A wearable system provided verbal or vibrotactile feedback to guide visually impaired participants along indoor routes. Performance measures were used to compare the effectiveness of different feedback types. Methods The wearable system simulated autonomous guidance by recognizing large QR codes and then providing cues based on the detected code, to guide participants along an indoor route (37.3 to 180 m). Ten participants with visual impairment were enrolled to test the system. Each participant walked eight different routes in an office building using the wearable system. Different feedback configurations were used for each route. Feedback configurations varied based on the sensory modality (verbal or vibrotactile) and, for vibrotactile, the location of the vibration motors (head, waist, and cane handle). Multimodal feedback combining verbal and vibrotactile cues was assessed using each participant's preferred vibrotactile feedback. Results We found that vibrotactile motors placed on a head resulted in fewer incorrect responses and interventions versus other feedback configurations. Six out of ten participants agreed that combining verbal and vibrotactile feedback was preferable. Survey responses suggest that participants rated trust the highest and mental effort the lowest with the combined verbal-vibrotactile modality. Vibrotactile motors on the cane handle were difficult to interpret. Discussion Our experiments suggest that a vibrotactile interface worn on the head is the most effective means of nonvisual guidance. This configuration transmits direct, concise, and instant guidance information to the user. Combination type feedback shows similar results and may provide additional confidence to users. Our study results provide insights into user-centric design of feedback systems for navigation. Implications for Practitioners A key element of ensuring successful adoption of assistive technology will be personalized fitting and training. Practitioner involvement will be critical when developing fitting and training protocols.