[Rock-dev] Standard unit for IMU mangetometer values?

[Steffen Planthaber]

Hi,

As you mentioned we decided for SI units and we should stick to that.

As the value is a float anyways, I can't see any advantages in moving 
from SI as "tansport unit".

Nevertheless it is unhandy. So I'd use the SI unit and add a getter 
methods "toNanoTesla()" to get readable values (according to 
base/time.toMilliseconds())

This way, the use of a non-SI unit is clearly visible in the source code.


Steffen

Am 07.07.2014 14:47, schrieb Leif Christensen:
> Hi,
>
> do we have a standard unit / convention for magnetometer readings?
>
> In the xsens_imu and imu_xsens drivers, we are just forwarding the
> values from the xsens, which confirms to no standard at all (arbitrary
> unit with 1 being the magnetic field strength at calibration time in
> Enschede, Netherlands). The stim300, imu_kvh_1750 have no magnetometer
> inside.
>
> Some are using Tesla, some Gauss (10^-4 T).
>
> Most of the time we are interested in the magnetic flux density of the
> (distorted) earth magnetic field, which ranges from 30µT (equator) to 60
> µT (pole).
>
> Apart from being the derived SI unit, Tesla is a little bit unhandy for
> these ranges, I think. But if we have a standard there, I would go with
> that. If not, I would either propose µT or Gauss.
>
> Total magnetic field strength today in Bremen (IGRF11 model):
> 49429.8 nT
> 49.4298 µT
> 0.494298 G
> 0.0000494298 T
>
> LG,
> Leif
>


-- 
  Steffen Planthaber
  Weltraumrobotik

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