Drones and robots – or people in an unfamiliar airport – could benefit from a navigation technique that combines Wi-Fi signals and accelerometer technology.
The technique from researchers at North Carolina State University measures speed and distance in indoor environments to track devices in near-real time.
“We call our approach Wi-Fi-assisted Inertial Odometry (WIO),” said Raghav Venkatnarayan, co-corresponding author of a paper on the work and a PhD student at NC State. “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.”
Devices such as smartphones incorporate inertial measurement units (IMUs) to calculate how far a device has moved, but IMUs suffer from large drift errors and minor inaccuracies can quickly become exaggerated.
In outdoor environments, many devices use GPS to correct their IMUs, but this doesn’t work in indoor areas where GPS signals are unreliable or non-existent.
“We created WIO to work in conjunction with a device’s IMU, correcting any errors and improving the accuracy of speed and distance calculations,” said Muhammad Shahzad, co-corresponding author of the paper and an assistant professor of computer science at NC State. “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.”
The researchers wanted to test the WIO software but could not access the Wi-Fi network interface cards in off-the-shelf devices such as smartphones or drones. To address the problem, the researchers said they created a prototype device that could be used in conjunction with other devices.
The researchers found that using WIO improved a device’s speed and distance calculations for indoor navigation. Devices using WIO calculated distance with a margin of error ranging from 5.9 per cent to 10.5 per cent. Without WIO, the devices calculated distance with a margin of error from 40 per cent to 49 per cent.
“We envision WIO as having applications in everything from indoor navigational tools to fitness tracking to interactive gaming,” Venkatnarayan said in a statement.
“We are currently working with Sony to further improve WIO’s accuracy, with an eye toward incorporating the software into off-the-shelf technologies,” said Shahzad.