Table 2.
Comparison of discussed indoor positioning solutions for people with visual impairments
| References | Technology | System | Techniques | Tested by | Test | Feedback | Accuracy | Remarks |
|---|---|---|---|---|---|---|---|---|
| Tian et al. [29] | Computer vision | Web camera and mini laptop | Text recognition and door detection | Blinds | Door detection and door signage recognition | Voice | Medium | (−) Motion blur and very large occlusions happen when subjects have sudden head movements |
| Lee and Medioni [36] | Computer vision | RGB-D camera, IMU, Laptop | Camera motion estimation | Blinds and blindfolded | Pose estimation and mobility experiments | Tactile | Medium | (−) Inconsistency in maps |
| Manlises et al. [33] | Computer vision | Web camera and computer | CAMShift tracking | Blinds | Object recognition, navigation time | Voice | Medium | (−) Tested with 3 blinds only |
| Li et al. [37] | Computer vision | Tango mobile device | Obstacle detection, camera motion estimation by combining visual and inertial data | Blindfolded | Error occurred during navigation and navigation time | Voice and Haptic | Good | Using smart cane with the system reduced the errors |
| Kanwal et al. [38] | Computer vision | RGB camera and Kinect sensor | Corner detection using visual and inertial data | Blind and blindfolded | Obstacle avoidance and walking | Voice | Good | (−) Infrared sensor failed under strong sunlight conditions |
| Al-Khalifa et al. [40] | Computer vision and motion | Google glass, Android smartphone, QR code | QR code recognition, IMU | Blinds | Error occurred during navigation and navigation time | Voice | Medium | (+) Easy to use |
| Legge et al. [42] | Computer vision | Digital tags, Tag reader , smartphone | Digital tag recognition | Blinds and Blind folded | Tag detection, Route finding | Voice | Medium | (+) System provided independent navigation |
| Zeb et al. [43] | Computer vision | Web cam, AR markers | AR marker recognition | Blinds | Normal walking | Voice | Medium | Low cost |
| Ahmetovic et al. [48] | BLE | Beacons and smartphone | Fingerprinting, IMU | Blinds | Normal occurred events that hinder the navigation | Voice | Medium | (−) Can’t inform the users that they are in wrong way |
| Kim et al. [49] | BLE | Beacons and smartphone | Proximity detection, IMU | Blinds | Navigation time, task completion, deviation during navigation | Tactile and voice | Good | (+) Test was carried out in a large area (busy railway station) |
| Cheraghi et al. [50] | BLE | Beacons and smartphone | Proximity detection, IMU | Blinds | navigation time, Navigation distance | Haptic and voice | Medium | Improvements are required to support varying pace of walking |