A new technique is in development to be able to measure speed and distance in indoor environments, which could be used to improve navigation technologies for robots or drones.
This technique uses a combination of Wi-Fi signals and accelerometer technology 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 Ph.D. student at North Carolina State University. “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 technology called inertial measurement units (IMUs) to calculate how far a device has moved. However, IMUs suffer from large drift errors, meaning that even minor inaccuracies can quickly become exaggerated.
In outdoor environments, devices use GPS to correct their IMUs. But this doesn’t work in indoor areas, where GPS signals are unreliable or nonexistent.
“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 ran into a problem: They 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 created a prototype device that could end up used in conjunction with other devices.
The researchers found using WIO improved a device’s speed and distance calculations dramatically. For example, devices using WIO calculated distance with a margin of error ranging from 5.9 percent to 10.5 percent. Without WIO, the devices calculated distance with a margin of error from 40 percent to 49 percent.
“We envision WIO as having applications in everything from indoor navigational tools to fitness tracking to interactive gaming,” Venkatnarayan said.
“We are currently working with Sony to further improve WIO’s accuracy, with an eye toward incorporating the software into off-the-shelf technologies,” Shahzad said.