iComp writes "Boffins at Madrid's Carlos III University have used cheap accelerometers and gyroscopes — and expensive mathematics — to improve the accuracy of GPS* by as much as 90 per cent.
The team compared their results to differential GPS — which is about as good as satellite systems get — and found that with detailed analysis of the data coming from three cheapish accelerometers and three gyroscopes they could get reliable accuracy down to below 2 metres, and critically they could do so without calibrating their kit to match the vehicle in which it was fitted.
Satellite navigation systems, including GPS, are normally accurate to 10 metres or so, but that accuracy falls off rapidly as one enters an urban environment where buildings block, and reflect, signals. In an urban setting, the boffins say, "the determination of a vehicle’s position can be off by more than 50 metres". Differential GPS, which uses a known location to monitor drift caused by atmospheric changes, is more accurate, but still can't account for passing buildings, so navigation systems fall to guessing.
The Spanish boffins aren't doing much more than that, but their guesses are very well-informed and made using accumulated data."
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