NIST research into indoor tracking for first responders

Numerous firefighter fatalities can be attributed to the lack of indoor location tracking systems. In 2016, a United States stakeholder group of public safety, government, industry and academic experts agreed that first responders need indoor positioning systems that are accurate within one metre, not just approximate.

Even if concrete walls and underground settings block outside signals, Internet of Things (IoT) infrastructure such as pre-installed sensors, Wi-Fi access points or Bluetooth beacons could render a first responder’s indoor location. But what happens if IoT data is proprietary or if power goes out at a scene? First responders need an indoor tracking solution that they can rely on, even when infrastructure-based circumstances are subject to change.

NIST funded the University of California Irvine to research an infrastructure-free localisation system as part of its Public Safety Innovation Accelerator Program (PSIAP). Researchers have found a breakthrough in how a microchip with motion sensors and cell signals may determine someone’s position with impressive accuracy. UC Irvine’s Ultimate Navigation Chip (uNavChip) aims to design, build and demonstrate a personal navigation system (PNS) that works for hours in GPS-denied environments.

The novel approach uses three different algorithms: deterministic, probabilistic and cooperative. These approaches merge them into a single platform with inertial sensors mounted in the sole of a boot. The device can locate the wearer within a metre.

But inertial sensors can only determine where an individual is relative to where they were, not the actual location. The uNavChip project combines inertial sensors with other technologies to achieve location tracking for the first time from the sole of a shoe. Transmitters on the shoes use signals such as cellular, AM/FM radio, Wi-Fi and low earth orbit satellites, which are powerful indoors but not intended for navigation.

Shoes are unique when it comes to walking. While in motion, the uNavChip uses foot-to-foot ranging to detect the distance from one shoe to another. The chip’s ranging-measuring capabilities are used for relative distance measurements between team members to generate an infrastructure-free signal and improve the location accuracy of the foot-mounted sensors.

The team was able to miniaturise and integrate their components into a single cubic-centimetre system, about the size of a cube of sugar. The team also demonstrated the feasibility of using cellular signals of opportunity for location, obtaining within 1.5-metre accuracy by leveraging a chip-scale PNS.

At the moment, uNavChip mostly stands to benefit the research community, but the chances are good that the technology could be commercialised for construction, defence, underground mining and underwater vehicle industries.