GPS accuracy given big boost

Posted by Ken Kola

Spanish researchers say they've found a way to improve cars' GPS in cities by as much as 90 percent with a new low-cost device.

The Universidad Carlos III de Madrid (UC3M) prototype works by adding data from accelerometers and gyroscopes to the conventional GPS signal to reduce the margin of error.

"We have managed to improve the determination of a vehicle's position in critical cases by between 50 and 90 percent, depending on the degree of the signals' degradation and the time that is affecting the degradation on the GPS receiver," says researcher David Martín.

The margin of error of a commercial GPS, such as those that are used in cars, is about 15 meters in an open field, where the receiver has wide visibility from the satellites. In an urban setting, though, it can be off by more than 50 meters, due to signals bouncing off buildings.

The new system, though, is claimed to improve accuracy dramatically, bringing the margin of error down to one or two meters. It includes a low cost Inertial Measurement Unit (IMU) that integrates three accelerometers and three gyroscopes to measure changes in velocity and maneuvers performed by the vehicle.

Software then merges the data and corrects errors in the geographic coordinates.

"This software is based on an architecture that uses context information and a powerful algorithm (called Unscented Kalman Filter) that eliminates the instantaneous deviations caused by the degradation of the signals received by the GPS receiver or the total or partial loss of the satellites," says Enrique Martí of UC3M.

The team's built a prototype that, they say, can be installed in any vehicle. The next step, though, is to get smartphones to do the job.

"We are now starting to work on the integration of this data fusion system into a mobile telephone so that it can integrate all of the measurements that come from its sensors in order to obtain the same result that we have now, but at an even much lower cost, since it is something that almost everyone can carry around in his pocket," says Martí.