Watching brief

UK-developed sensor technology designed to track the indoor movements of people and objects with pinpoint accuracy has made its commercial debut at universities here and in the US.

Cambridge and Illinois universities have just completed installation of a positioning system developed by Ubisense, a UK specialist in location systems. This uses ultra-wideband (UWB) radio technology to track people and equipment to within 6in by monitoring devices known as Ubitags – credit card-sized tags that are carried or attached to objects to be tracked.

Ubisense hopes the system will open up a host of applications ranging from security monitoring to providing detailed space-planning data for building managers.

When linked to wider systems it could also open the way for ‘sentient computing networks’ in which people interact continuously with the devices around them. For example, if the system detected that someone was using a different computer from normal it could re-route their e-mails and phone calls to that desk.

The Ubisense system has been installed at Illinois’ newly opened computer science centre and, on a smaller scale, at Cambridge’s laboratory for communication engineering. Ubisense claimed this was the first time a sensor-driven system based on UWB technology had been commercially deployed.

UWB is used by Ubisense as an alternative to conventional radio frequency (RF) or infrared sensors. The technology allows data to be carried over short distances at low power without the effects of multipath distortion suffered by standard RF signals. This distortion, which occurs when radio signals reflect off walls, furniture and other objects, makes accurate tracking difficult.

UWB signal pulses are of extremely short duration, making it easier for the system to filter out the effects of multipath.

Infrared also poses problems because it relies on direct line of sight between the sensor and the object being tracked, while UWB can travel through walls and doors. The ubiquitous GPS is undisputed king of outdoor tracking but beset by problems when walls and ceilings are involved.

The Ubisense system is based on communication cell areas approximately 30m square. Within each cell wall-mounted UWB sensors receive location updates from each Ubitag up to five times per second.

This data is relayed to a master control unit, which uses custom-designed software to create detailed real-time information on the movements of people or objects.

Ubisense was founded in 2002 by a group of location technology experts including Andy Hopper, professor of communication engineering at Cambridge. A prototype of its system was tested for two years at Cambridge’s AT&T Research Labs as part of ground-breaking work into sentient computing networks.

Ubisense said the systems at Cambridge and Illinois demonstrated that it was possible to create a highly accurate indoor tracking system cost-effectively. ‘To install the system in a commercial site you have to keep the equipment down to a reasonable level,’ said Jay Cadman, Ubisense’s head of sales and marketing.

Cadman admitted that some concerns had been raised by people uneasy at being continuously tracked so precisely. He said Ubisense envisaged many applications of the system being used to monitor general high-level trends rather than specific individuals.

He said the company expected to announce the first non-university orders for the system within the next few months.

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