GPS system accuracy improved through data fusion

The system, which is based on sensor fusion, incorporates a conventional GPS signal with those of other sensors (accelerometers and gyroscopes) in order to reduce the margin of error in establishing a location. "We have managed to improve the determination of a vehicle's position in critical cases by between 50 and 90%, depending on the degree of the signals' degradation and the time that is affecting the degradation on the GPS receiver," states David Martín, a researcher at the university's system intelligence laboratory. Commercial GPS deviecs are accurate to about 15m in an open field, but decreases rapidly in urban locations, affecting their usefulness in Intelligent Transport Systems. "Applications that will benefit from the technology that we are currently working on will include cooperative driving, automatic manoeuvres for the safety of pedestrians, autonomous vehicles or cooperative collision warning systems," the scientists said. The basic elements in the system are a GPS and a low cost Inertial Measurement Unit (IMU), which integrates three accelerometers and three gyroscopes. Data is fed to a computer that merges the data and corrects the errors. Enrique Martí, from the university's applied artificial intelligence group, said: "This software is based on an architecture that uses context information and a powerful algorithm (the 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." The researchers now plan to investigate whether smartphones can be used as data collectors. According to the team, some smartphones have more than 10 sensors, in addition to WiFi, Bluetooth or GSM, and may provide the same functionality at much lower cost.