Conflict when several apps use the accelerometers?
hendrik.siedelmann at googlemail.com
Tue Jan 27 22:53:22 CET 2009
2009/1/27, Helge Hafting <helge.hafting at hist.no>:
> Gunnar Aastrand Grimnes wrote:
>> This page does: http://wiki.openmoko.org/wiki/Accelerometer_Fundamentals
>> Noise is around 3cm/s^2, i.e:
>> It can fill in _short_ - 3-5s gaps in GPS coverage, if the orientation
>> of the phone is known.
> Not enough for a 4km tunnel then, which is 3 min when going 80km/h.
> 5s is enough for a 111m tunnel, but 5s signal loss is usually not a
> problem anyway.
> Of course, the car speedometer readout can take care of speed and
> braking/acceleration, the accelerometer would only be needed to notice
> turning. Could be interesting to see where it thinks I am after 3 min,
> if 5s is all I can expect. I guess those 3-5s is the interval where
> precision matces the gps. But it will be useful for longer than that, as
> long as estimate is more accurate than "stopped at the tunnel entrance."
> The error increase with time, but so do the real distance from the entrance.
> Helge Hafting
Yes, I too think it would be useful for a longer period. In a time of
3-5 seconds one could propably get away with simply projecting the
route at signal loss with constant speed. And I think navit snaps to
streets anyway, so it wouldn't matter if its off by a bit.
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