Path-Guided Indoor Navigation for the Visually Impaired Using Minimal Building Retrofitting
Dhruv Jain · 2014 · Proceedings of the 16th International ACM SIGACCESS Conference on Computers & Accessibility (ASSETS 2014) · doi:10.1145/2661334.2661359
Summary
This paper presents the design and evaluation of a cellphone-based indoor navigation system that provides step-by-step path guidance for visually impaired users in unfamiliar buildings with minimal infrastructure requirements. The system combines infrared (IR) beacons mounted at turns and landmarks with accelerometer-based dead reckoning to track the user between beacons — a hybrid approach that reduces the number of wall-mounted units needed compared to pure beacon systems (from 3m spacing to 8-10m spacing) while maintaining localization accuracy of ±1.6m. The system comprises three components: wall modules with IR transmitters deployed at strategic locations (about 20 per floor at ~/floor), a small waist-worn user module containing an IR receiver, accelerometer, and Bluetooth (~), and an Android mobile application that downloads building maps, calculates shortest paths using Dijkstra's algorithm, and delivers audio/vibration navigation instructions. A formative study with five visually impaired participants in Delhi — navigating tracks in an academic building and a shopping mall — revealed key needs: current location awareness, turn-by-turn guidance with step counts, obstacle warnings, and destination confirmation. Users reported high anxiety about independent indoor travel, with problems including absent or unhelpful bystanders, language barriers, and vulnerability to injury.
Key findings
A before-and-after evaluation with 10 visually impaired users (ages 17-32, navigating a 75m multi-floor track) showed dramatic improvements across all metrics. Major path deviations dropped from 1-4 per user (baseline) to zero with the system. Help-seeking events dropped from 2-6 per user to zero for 7 of 9 completers (two needed help with the elevator only). Travel time decreased significantly (p<0.01), and steps taken also decreased significantly (p<0.01) as users followed precise instructions instead of exploring. User confidence rose from 2.3/5 to 4.2/5 on a Likert scale. The system was learned in approximately 2.5 hours over 3 days. Users appreciated the balance of pushed information (landmark warnings 2-3m ahead, turn instructions) and pulled information (on-demand step counts via a button), with continuous vibration confirming they were on track. A destination buzzer module helped users pinpoint door locations. Nine of 10 users said they would buy the module at . Key design insights included the importance of cultural considerations: belt attachment was problematic for women wearing traditional Indian dress, and speech recognition struggled with regional Indian accents. Users also emphasized that applications in developing countries should support non-touch "dumbphones" given low smartphone penetration among visually impaired populations.
Relevance
This work is particularly significant for its focus on developing-country contexts, where 90% of the world's blind population resides. The low cost ( user module, /floor infrastructure) and minimal building retrofit requirements make it far more deployable than expensive systems like Building Navigator or Drishti. The hybrid IR-beacon plus dead-reckoning approach is a practical engineering trade-off that balances accuracy, cost, and installation burden. For accessibility practitioners, the formative study insights about anxiety, social embarrassment, and the real-world challenges of bystander-dependent navigation in India provide valuable context for designing wayfinding systems in diverse cultural settings. The distinction between pushed and pulled navigational information is a useful design pattern for any assistive navigation system. Limitations include the line-of-sight requirement for IR communication, the need for building-specific infrastructure installation, and the lack of a long-term deployment study.
Tags: indoor navigation · visual impairment · wayfinding · assistive technology · infrared · dead reckoning · mobile accessibility · developing countries