ZED-F9K - Integration manual
Phase
Procedure
Indicator of success
IMU calibration
(gyroscope and
accelerometer)
Drive curves and straight segments for a few
minutes by including a few stops lasting at least
30 seconds each. This drive should also include
some periods with higher speed (at least 50 km/
h) and can typically be carried out on normal
open-sky roads with good GNSS signal reception
conditions.
The calibration status of the used sensors
UBX-ESF-STATUS.calibStatus
shows
2/3:CALIBRATED
.
Table 10: Accelerated calibration procedure
Note that the calibration status (
UBX-ESF-STATUS.calibStatus
) of some used sensors might
fall back to
1:CALIBRATING
if the receiver is operated in challenging conditions. In such a case,
fused navigation solution uncertainty increases until optimal conditions are observed again for re-
calibrating the sensors.
In the presence of significant temperature gradient affecting the gyroscopes, the fused
navigation performance might also depend on how well the temperature compensation
table is populated. The table is gradually filled in while the vehicle is stationary and by
observing gyroscope biases at different temperatures. Therefore the quality of the
gyroscope temperature compensation depends on how many temperature bins could be
observed while the vehicle was stationary and on the duration of the observation for each
bin.
3.2.6.3 Automatic IMU-mount alignment
3.2.6.3.1 Alignment solution output
The IMU-mount misalignment angles are shown in UBX-ESF-ALG messages.
•
IMU-mount angle initialization
: During IMU-mount angle initialization the (
UBX-ESF-
ALG.status
field is equal to
2
), and the published angles (
yaw, pitch and roll
)
correspond to the current estimated values but are not yet applied for rotating the IMU
observations.
•
IMU-mount angle initialization complete
: After initialization the (
UBX-ESF-ALG.status
field
is equal to or higher than
3
), the published angles correspond to the estimated value and are
applied for rotating the IMU observations.
•
Automatic IMU-mount alignment disabled
: If automatic IMU-mount alignment is disabled, the
published angles correspond to the IMU-mount angles configured by the the user (see
section) and are applied for rotating the IMU observations.
CAUTION
If user-defined IMU-mount misalignment angles were configured by the user
using CFG-SFIMU-IMU_MNTALG keys (see
User-defined IMU-mount alignment
section) and
automatic IMU-mount alignment is active, the angles output in the UBX-ESF-ALG message
still correspond to the definition given above: they represent the full rotation required for
transforming IMU data from installation frame to IMU frame. This means that the output
misalignment angles are computed from the composed rotation of the user-defined rotation
and the internally-estimated rotation.
3.2.6.3.2 Alignment progress
The progress of the automatic IMU-mount alignment can be monitored by checking the
UBX-ESF-
ALG.status
field.
•
IMU-mount roll/pitch angle initialization ongoing
: The alignment engine is initializing the IMU-
mount roll and pitch angles (
UBX-ESF-ALG.status
is 1). Both angles can only be initialized if
vehicle encounters left and right turns (as during a normal drive).
•
IMU-mount yaw angle initialization ongoing
: The alignment engine is initializing the IMU-
mount yaw angle (
UBX-ESF-ALG.status
is 2). IMU-mount yaw angle can only be initialized
UBX-20046189 - R01
3 Receiver functionality
Page 26 of 105
C1-Public
Early production information
