Scientists Use Wi-Fi Like Sonar to Measure Distance and Speed in Indoor Settings

Scientists from North Carolina State University (NC State) have formulated a method for calculating speed and distance in indoor settings, which could be used to enhance navigation technologies for drones, robots, or pedestrians attempting to learn their way through an airport.

WIO is a software program, but researchers created a hardware prototype for initial testing with other devices. (Image credit: North Carolina State University)

The method uses a new combination of accelerometer technology and Wi-Fi signals to monitor devices in near-real time.

We call our approach Wi-Fi-assisted Inertial Odometry (WIO). WIO uses Wi-Fi as a velocity sensor to accurately track how far something has moved. Think of it as sonar, but using radio waves, rather than sound waves.

Raghav Venkatnarayan, Study Co-Corresponding Author and PhD Student, NC State

Various devices such as smartphones integrate technology known as inertial measurement units (IMUs) to measure how far a device has shifted. However, IMUs suffer from large drift faults, meaning that even trivial inaccuracies can rapidly become a huge issue.

In outdoor settings, several devices use GPS to rectify their IMUs. However, this does not function in indoor areas, where GPS signals are nonexistent or unpredictable.

We created WIO to work in conjunction with a device’s IMU, correcting any errors and improving the accuracy of speed and distance calculations. This improvement in accuracy should also improve the calculations regarding a device’s precise location in any indoor environment where there is a Wi-Fi signal.

Muhammad Shahzad, Study Co-Corresponding Author and Assistant Professor of Computer Science, NC State

The scientists wanted to test the WIO software but encountered an issue: they could not access the Wi-Fi network interface cards in off-the-shelf devices such as drones or smartphones. To resolve the problem, they developed a prototype device that could be used along with other devices.

The scientists learned that using WIO enhanced a device’s speed and distance calculations radically. For instance, devices employing WIO calculated distance with a margin of error ranging from 5.9% to 10.5%. Without WIO, the devices measured distance with a margin of error ranging from 40% to 49%.

We envision WIO as having applications in everything from indoor navigational tools to fitness tracking to interactive gaming.

Raghav Venkatnarayan, Study Co-Corresponding Author and PhD Student, NC State

We are currently working with Sony to further improve WIO’s accuracy, with an eye toward incorporating the software into off-the-shelf technologies,” stated Shahzad.

The paper titled, “Enhancing Indoor Inertial Odometry with Wi-Fi,” will be presented at UbiComp 2019, being held from September 11th to 13th in London, U.K. The work was achieved with support from the National Science Foundation, under grant 1565609. Venkatnarayan will also be showcasing WIO at ICNP 2019, which will be held in Chicago between October 7th and 10th.

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