A Positioning and Mapping Methodology Using Bluetooth and Smartphone Technologies to Support Situation Awareness and Wayfinding for the Visually Impaired

Principal Investigator

Chen-Fu Liao, Senior Systems Engineer, Mechanical Engineering

Project Summary

Bluetooth low energy (BLE) technology has become an important component of many Internet of Things (IoT) applications, such as data communications, remote sensing, positioning, and providing location based services. We have developed a smartphone based assistive system that uses a network of BLE beacons to provide location specific traffic and navigational information for people who are visually impaired. To ensure information integrity and security, a self-monitoring methodology was developed by reprogramming the firmware of each BLE beacon to monitor its peers in the Bluetooth network. A multi-regression technique was implemented to model the relationship between Bluetooth Received Signal Strength (RSS) and the actual ranging distance. This methodology reduces the environmental uncertainty and dynamic nature of RSS measurements in an outdoor environment. An extended Kalman filter was used to provide positioning and mapping solutions in the absence of GNSS. In addition, several statistical techniques were implemented to evaluate their effectiveness in detecting location changes of one or multiple BLE beacons in a network based on Bluetooth signal strength indications. Our results indicated that our approach is able to successfully detect the changes of a BLE network that would indicate a problem (such as vandalism or loss of power) with the network. With the self-monitoring network, we can locate the smartphone and ensure information associated with each BLE beacon provides the correct location to reliably support wayfinding for the visually impaired in a transportation network.


  • Roadway Safety Institute (USDOT)
  • Minnesota Department of Transportation

Project Details

  • Start date: 07/2014
  • Project Status: Active
  • Research Area: Transportation Safety and Traffic Flow
  • Topics: None