The inability of the GPS signal to reach inside buildings has prompted researchers to look for novel solutions

'GPS' systems for indoors based on everyday tech

Ubiquitous technology such as smartphones or Wi-Fi could be used to create a precise indoor navigation system, overcoming the limits of GPS but also offering a powerful marketing tool.

At the International Navigation Conference, organised by the Royal Institute of Navigation, teams from around the world introduced their concepts that could be used in future to help guide crowds through airports and shopping centres or assist firefighters in action inside buildings.

“In today’s world, the use of GPS is ubiquitous in both military and consumer applications,” said Roger McKinlay, president of the Royal Institute of Navigation (RIN).

“In contrast, indoor navigation technologies are very much in their infancy – just a few apps exist, and many of those simply try to amplify weak GPS signals.”

While highly reliable and accurate for outdoor use, satellite-based navigation systems provide little in indoor environments. However, researchers have proved, other technologies could be used in their place, rendering printed maps, floor plans and navigation signs obsolete.

One of the most promising systems presented at the conference in Manchester relies on the Wi-Fi signal from one or more access points installed inside a building. The system calculates the position of the user based on the characteristics of the surrounding signal, its strength, proliferation and reflection from hard surfaces.

To improve accuracy of the method, a team from the University of Nottingham has created what they call a Wi-Fi fingerprint database that could be used as a reference comparing the actual strength of the signal received by the user to the expected values.

“The problem is that this ‘fingerprint’ varies a lot over time - objects in the space might move or the access point hardware might be changed,” the team said. “We are working to keep ‘fingerprint’ maps up to date through a collaborative database of Wi-Fi fingerprints, which will allow improved indoor positioning.

Looking at the most convenient ways of indoor navigation that would not require installing any additional equipment, a team from Portugal discovered positioning information could be accurately extracted by a regular smartphone using a loudspeaker installation inside a building.

Some of the techniques could also be used by robots and autonomous vehicles to create maps of their environment and determine their position.

At the conference, Chinese researchers from Harbin Engineering University introduced the first ever mapping system using the Microsoft Kinect sensor. Relying on the audio as well as visual data from the sensor, the system would function even in low light, allowing the robots to operate at night.

According to Roger McKinlay, the technologies could be market-ready within five years.

“Many of those methods, including Wi-Fi fingerprinting or dead reckoning, that is deducting a person’s position by monitoring his or her motion including attitude and acceleration, have been tested previously,” he said. “But whereas in the past, all of these might have used a room-full of equipment, these new sensors can be built in to your smartphone, making them inexpensive and ubiquitous.”

Unlike the military-driven development of GPS, the indoor navigation systems will most likely be prompted by commercial demand. In addition to emergency response teams, hospital staff and firefighters, retailers may be interested in the technology to allow new ways of advertising.

Unlike GPS receivers, which provide information only to the users, the smartphone based technology will probably allow others to learn the subject’s position.

“I think overall though, users will be happy to provide their location in return for navigation services,” McKinlay said. “The situation might be very similar to that of the Internet cookie – you will have to give permission in order to have your location known.  You will be able to navigate around a shopping centre but you might also be notified as you are walking past the mannequin wearing the shirt you were looking at online last night.”

Last year, Google announced development of a 3D mapping smartphone Tango that could be used by blind people to navigate inside buildings.

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