Visually impaired pedestrian walking with cane

Traveling alone in an unfamiliar environment can be a challenge for anyone, but especially for people who are blind or visually impaired. More than 3.4 million Americans 40 years and older are legally blind or visually impaired—and according to some estimates, that number will double by 2030. For RSI researcher Chen-Fu Liao, helping this growing population to more easily navigate is a top priority.

“In order to improve mobility, accessibility, and confidence in the transportation system, it is important to remove not only the physical barriers but also the information barriers that can impede mobility for people who are visually impaired,” says Liao, a senior systems engineer at the Minnesota Traffic Observatory who is leading research in this area.

In previous work, Liao developed the Mobile Accessible Pedestrian System, or MAPS, which uses smartphone technology to provide location and signal timing information to visually impaired pedestrians. Liao collaborated with Vision Loss Resources (VLR), Minnesota’s largest provider of rehabilitation services for people with vision loss, throughout development of his system.

Kate Grathwol, president and CEO of VLR, explains that the agency teaches blind and visually impaired people how to cross streets, where to catch light rail, how to use the bus—skills that give them independence—“but then the world changes, and there’s road construction, or a sidewalk closed,” she says. Since pedestrians with vision impairment are unable to read signs giving directions, they may need to ask for help. “That’s not a bad thing, but nobody else has to—they can see. The real impact of this app is that it allows the same access for the blind and visually impaired that sighted people have,” she says.

Although MAPS received positive feedback from testers, Liao discovered the GPS technology was not as reliable as it needed to be. “Because we provide information to the visually impaired, we cannot afford to provide wrong information [even] one time,” Liao says.

“Smartphone GPS can usually provide good guidance in open areas. However, in indoor or ‘urban canyon’ conditions GPS receivers encounter interference and the positioning results often become inaccurate,” says Liao. “We realized the need for a self-aware infrastructure that can self-monitor and make sure the information it provides is always correct, even in a GPS-unfriendly environment.”

Liao’s team is currently developing a system that uses a standalone Bluetooth smart device to provide trustworthy information to people with visual impairment. Researchers began with commercially available Bluetooth low-energy (BLE) beacons, such as the kind that can be used to locate a misplaced purse or keychain. These beacons, however, are primarily designed to be detected or discovered and do not typically communicate with each other. To develop the new smart system, the team is integrating these commercial off-the-shelf beacons with the necessary interface elements to sense other BLE devices within their range of communication, he says.

The BLE beacons can be placed on traffic barrels, barricades, or signs in work zone applications or at decision locations such as store entrances. Then, using a positioning and mapping algorithm, the smart system creates a local map of the unfamiliar or hazardous environment. The BLE smart beacons remember and check with other BLE smart devices within their communication range to ensure the local map is correct and provide accurate positioning information in areas where GPS signals are unavailable. The system can estimate a user’s location based on nearby Bluetooth signals, share information among nearby devices, and inform the system administrator if any information has changed. For example, the system can detect when any of its beacons are not functioning—due to a loss of power or vandalism, for example.

“Our goal is to provide reliable situation awareness and navigation information to assist with wayfinding for people who are visually impaired,” says Liao. The team’s mapping methodology, he says, will ensure that correct audible information, such as signal timing and intersection geometry, is provided to users at the correct location.

For the project’s final phase, researchers will integrate the Bluetooth system with the smartphone app and then conduct real-world tests of the technology.

Editor’s note: Liao will be presenting on this work on Dec. 10, 2015, as part of the Roadway Safety Institute’s seminar series. The seminar will be streamed live and archived for later viewing. Visit the RSI seminar web page for more information.

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