PNI FieldForce Trax - Manual (Page 24)

PNI Sensor Corporation DOC#1016505 r06
TRAX User Manual Page 20
Note: While the TRAX is shown removed from the host system, the Accelerometer
Calibration may be performed with the TRAX mounted in the host system.
Figure 5-2: Accelerometer Calibration Starting Orientations
5.2.2 Mag-and-Accel Calibration
The TRAX allows for a simultaneous magnetometer and accelerometer calibration. This
requires a good calibration pattern, stable measurements (not handheld), and installation
in the user’s system such that the appropriate local magnetic environment is present. PNI
recommends 18 to 32 calibration points for a Mag-and-Accel Calibration. The Accel-
Only Calibration pattern discussed in Section 5.2.1 also will work for a Mag-and-Accel
Calibration. Optimal performance is obtained when all rotations of the cube are
performed towards magnetic north to achieve the widest possible magnetic field
distribution.
Note that combining calibrations only makes sense if all the host system’s magnetic
distortions (steel structures or batteries, for instance) are present and fixed relative to the
module when calibrating. If the Accel-Only Calibration is performed, the user’s system
distortions are not relevant, which allows the TRAX to be removed from the host system
in order to perform the Accel-Only Calibration.