4.9
Calibrating the Sensors
This section describes how to calibrate the accelerometer and compass of the ProMove-mini.
First create a logfile as described in Section 4.3. While logging, rotate the node(s) a few times
very slowly
around all three axes, at distance from any metal object. For the accelerometer,
make sure that all three axes reach -9.8 to 9.8 m/s
2
. A logfile of 30 s should suffice. For the
accelerometer, all nodes can be stacked and calibrated at once. For the compass, it is recom-
mended to calibrate only one node at a time, to minimize the influence from other nodes.
Open the
Calibration Configuration
shown in Figure 34 via the menu (
Configuration
,
Sensor
Calibration...
). Browse to the calibration logfile created earlier and click
Parse File
. The file is
analyzed, calibration results are calculated, and detected nodes are added to the
Node ID
box.
Select a node and sensor and press
Calibrate
to calculate the required
Scale
and
Offset
for each
axis. A plot is shown to show the effect of the scale and offset on the normalized sensor signal.
The scale and offset can be applied to the node by pressing
Use Results
. The calculated values
are loaded into the
Calibration
settings of the sensor and node in the
Sensor Configuration
window (Section 4.8). Press
Apply Settings
in this dialog to apply the settings to the node.
Note: Calibrating and applying results has to be done for each node and sensor separately. In
general, the calculated scale should be around 1 and the offset around 0. If not, the calibration
source file is likely invalid (e.g. no rotation around the y-axis).
Figure 34: Calibration Configuration
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