Open Source AHRS project: giving away hardware

[joerg Reisenweber]

On Sun 11 May 2014 09:25:37 Pascal Gosselin wrote:
> Indeed. When you taxi an airplane on the ground in a straight live or drive
> a car in a straight line, GPS TRACK (adjusted for magnetic declination) =
> Magnetic Heading.
> 
> The other complementary magnetometer calibration techniques involve driving
> around in a full circle in about 60 to 75 seconds or doing a 360 degree
> turn and stopping every 30 degrees.
> 
> -Pascal
> 
> Sent from my iPhone
> 
> > On May 11, 2014, at 4:47 AM, "Jake" <jake42 at rommel.stw.uni-erlangen.de> 
wrote:
> >> On 05/11/2014 07:08 AM, joerg Reisenweber wrote:
> >>> On Sat 10 May 2014 11:57:30 Pascal Gosselin wrote:
> >>> calibrate the compass via GPS track by an easy calibration or
> >>> self-calibration method
> >> 
> >> GPS doesn't offer any data to calibrate magnetometer from.
> >> magnetometer aka compass is about orientation of device, GPS is
> >> about position and movement vector. They are 100% unrelated.
> > 
> > In a static situation this is correct, but while moving it is possible
> > to get the current heading from GPS.
> > 
> > Jake
> > 

This all assumes a locked and defined mounting situation for the magnetometer. 
Then yes. For an embedded device however this method tells you nothing about 
the magnetometer heading. The embedded device can change relative orientation 
to the vehicle that's driving.
PS: you must be very sure about the vehicle moving exactly straight ahead as 
well, for anything but a non-sliding car that's not guaranteed, think boat, 
even airplane
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