PNI CompassPoint Prime - Manual (Page 33)

Prime User Manual r08 Page 27
Table 6-1: Magnetic Calibration Pattern
Sample # Yaw Pitch Roll
First Circle
1 0° ±5° 30° to 40°
2 90° ±5° -30° to -40°
3 180° ±5° 30° to 40°
4 270° ±5° -30° to -40°
Second Circle
5 30° > +45° 30° to 40°
6 120° > +45° -30° to -40°
7 210° > +45° 30° to 40°
8 300° > +45° -30° to -40°
Third Circle
9 60° < -45° 30° to 40°
10 150° < -45° -30° to -40°
11 240° < -45° 30° to 40°
12 330° < -45° -30° to -40°
6.2.2 Accelerometer Calibration Procedure
The requirements for a good accelerometer calibration differ from the requirements for a
good magnetic sensor calibration. For example, a level yaw sweep, no matter how many
points are acquired, is effectively only 1 accelerometer calibration point. PNI
recommends 18-32 calibration points for Accelerometer Only Calibration.
Figure 6-2 shows the two basic starting positions for Accelerometer Only Calibration.
Calibration can occur within the user’s system or with the module alone. It is not
necessary to place the Prime on a hard surface as shown, but it must be held very still
during calibration, and holding it against a hard surface is a way to help ensure this.
Starting with the Prime as shown on the left in Figure 6-2, rotate the module such
that it sits on each of its 6 faces. Take a calibration point on each face.
Starting with the Prime as shown on the right, take a calibration point with it
being vertical (0°). Tilt the module back 45° and take another calibration point
(+45°), then tilt the module forward 45° and take another calibration point (–45°).
Repeat this 3-point process by holding the module on each of its 4 corners.