A man holding a cellphone on a busy street.
Photo credit
Michael McCarthy

Improving mobility for visually impaired pedestrians

CSE researcher works on Bluetooth system to better navigation app on city streets

An estimated 25.5 million American adults have some type of visual impairment, from “trouble seeing” to complete blindness, according to a 2016 National Health Interview Survey. With the aging Baby Boomer generation, this population is expected to grow.

After receiving orientation and mobility training, people with vision impairment can usually travel independently to known places along familiar routes by relying on a white cane or a guide dog to avoid obstacles. However, neither of these provides spatial awareness along their path (such as the presence of a work zone, traffic intersection, bus stop, or subway entrance) or guidance information to a destination. 

Understandably, traveling alone in an unfamiliar environment is often a challenge.

“Every day it’s a new experience,” says Ken Rodgers, president of the American Council of the Blind in Minnesota. “I never know what I’m going to encounter exactly.”

For University of Minnesota Roadway Safety Institute and College and Science and Engineering researcher Chen-Fu Liao, technology offers the potential to revolutionize the way people with vision impairment navigate city streets.

“To improve mobility, access, and confidence in the transportation system, it’s 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 research associate in the University of Minnesota’s Department of Mechanical Engineering who is leading research in this area.

In previous work, Liao developed the Mobile Accessible Pedestrian Signal, or MAPS, which uses smartphone technology to provide location and signal timing information to visually impaired pedestrians. (Watch our video on this study on CSE's YouTube channel.)

Developed in collaboration with Minnesota’s Vision Loss Resources (a provider of services and support for people with vision loss), MAPS received positive feedback from testers.

However, Liao discovered the GPS technology was not acceptably reliable in GPS-unfriendly environments.

“Because we provide information to the visually impaired, we cannot afford to provide wrong information [even] one time,” Liao says.

This University's Roadway Safety Institute-sponsored work is aiming to improve the app’s accuracy and reliability by developing a “self-aware” infrastructure—one that can monitor itself and ensure the information it’s providing is up to date, even in a GPS-unfriendly environment (such as indoors or in “urban canyons”).

Next steps with Bluetooth

To that end, Liao and his team have developed a standalone Bluetooth Low Energy (BLE) smart system integrating commercial off-the-shelf BLE beacons.

Since BLE beacons are primarily designed to be detected and not communicate with each other, the researchers integrated them with the necessary interface elements to sense other BLE devices within their range, Liao explains.

The BLE beacons can be placed in locations such as on light posts, traffic barrels, or barricades. Then, using a positioning and mapping algorithm, 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 beacon location has changed.

A database containing the location and message of each device is then integrated with the smartphone app to provide navigation information

An illustration of bluetooth-beacon signals
Bluetooth Low Energy beacon testing at a study site in St. Paul.

“This mapping methodology will ensure that correct audio information is provided to app users at the right location,” Liao says. “It could be used anywhere—at traffic intersections, skyways, or underground tunnels—to provide directions for travelers.”

Results of testing in a variety of environments indicate that the system can successfully detect if the location of one or multiple BLE beacons in a network has changed and detect when any of its beacons are not functioning—resulting from a loss of power or vandalism, for example.

Summer testing in Stillwater

Liao has received additional funding from the Minnesota Department of Transportation to deploy the system at six intersections in Stillwater, MN, in the summer of 2019.

The researchers will integrate the Bluetooth system with the smartphone app and then conduct real-world tests of the new technology. The University of Minnesota has also filed a provisional patent on the technology.

“The benefit of our approach is that the visually impaired need nothing more than a smartphone with a text-to-speech capability to receive traffic and location information,” Liao says.

“The intent of our assistive system is not to undermine the skills and strategies that people with vision impairment have learned for navigation and wayfinding,” Liao adds. “Instead, the system aims to support their wayfinding capability, extend mobility and accessibility, and improve safety.”

Republished from the University of Minnesota's Roadway Safety Institute Summary Report 2013-19.

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