VEEK-MT2 User Manual
45
www.terasic.com
July 4, 2016
The measurement of magnetic field will be subjected to distortion. There are two categories of these
distortions: the hard iron distortions and the soft iron distortions. The hard iron errors refer to the
presence of magnetic fields around the sensor (magnets, power supply wires) and are related to the
measurement offset errors, while the soft iron errors refer to the presence of ferromagnetic materials
around the sensor, which skew the density of the Earth's magnetic field locally and are related to scaling
offset errors. In other words, to get the correct magnetometer data you should calibrate it first. In this
demonstration, we corrected the magnetic field with the following formula:
X
calibrated
= X
– X
offset
Y
calibrated
= Y
– Y
offset
Z
calibrated
= Z
– Z
offset
where X
offset
, Y
offset
and Z
offset
area the average value of X/Y/Z magnetic field, defined as:
X
offset
= (X
max
– X
min
)/2
Y
offset
= (Y
max
– Y
min
)/2
Z
offset
= (Z
max
– Z
min
)/2
where X
max
/X
min
/Y
max
/Y
min
/Z
max
/Z
min
are the maximal and minimal value of X/Y/Z values reported by
magnetometer in the MPU9250 while the VEEK-MT2 is rotated in its X/Y/Z axes as shown in
Figure 4-20 Rotate VEEK-MT2 around each of its 3 aces
Summary of Contents for VEEK-MT2
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