ZED-F9R - Integration manual
is flagged as
1:INITIALIZING
in the UBX-ESF-STATUS message. Once initialized, the IMU-
mount alignment status is flagged as
2:INITIALIZED
. If no IMU-mount alignment is required,
the IMU-mount alignment is flagged as
0:OFF
. A detailed description of the automatic IMU-
mount alignment operation can be found in the
section.
•
INS initialization:
Before entering fusion mode, the initial vehicle position, velocity and
especially attitude (vehicle roll, pitch and heading angles) need to be known with sufficient
accuracy. This is achieved during INS initialization phase using GNSS which comprises an
INS coarse alignment step. As long as the fusion filter is not initialized, the status of the INS
initialization (
insInitStatus
) is flagged as
1:INITIALIZING
in the UBX-ESF-STATUS
message. Once initialized, the INS initialization is flagged as
2:INITIALIZED
.
•
Wheel tick sensor initialization:
Solution enters fusion mode (
fusionMode
field in the
UBX-ESF-STATUS message is on
1:FUSION
), even when wheel tick is not yet initialized,
following a degraded HPS mode approach described in
section. WT
sensor parameters, such as initial wheel tick factor, are estimated in parallel and are used once
estimated with sufficient accuracy. As long as the wheel tick parameters are not initialized, the
status of the wheel tick initialization (
wtInitStatus
) is flagged as
1:INITIALIZING
in the
UBX-ESF-STATUS message. Once initialized, the wheel tick sensor initialization is flagged as
2:INITIALIZED
, WT data are used by the filter and the parameters are stored in non-volatile
storage. If no wheel tick data are required, the wheel tick initialization is flagged as
0:OFF
.
•
Sensor error (e.g. missing data) detected:
Sensor timeout of more than 500 ms will trigger an
INS re-initialization.
Note that initialization phase requires good GNSS signal conditions as well as periods during which
vehicle is stationary and moving (including left and right turns). Once all required initialization steps
are achieved, fusion mode is triggered and continuous calibration begins.
3.2.6.1.2 Fusion mode
Once initialization phase is achieved, the receiver enters fusion mode. The receiver is in fusion
mode if the
UBX-ESF-STATUS.fusionMode
field is set to
1:FUSION
. The fusion filter then
starts to compute combined GNSS/dead reckoning fixes (fused solutions) and to calibrate the
sensors required for computing the fused navigation solution. This is the case when the sensor
calibration status (
UBX-ESF-STATUS.calibStatus
) is set to
1:CALIBRATING
. As soon as the
calibration reaches a status where optimal fusion performance can be expected, (
UBX-ESF-
STATUS.calibStatus
is set to
2/3:CALIBRATED
.
3.2.6.1.2.1 Degraded HPS mode
In case of WT sensor error / timeout (500 ms), or normal WT sensor initialization, the solution falls
back to degraded HPS mode. The
UBX-ESF-STATUS.fusionMode
field still shows
1:FUSION
when
the receiver enters degraded HPS mode. However, the following flags can be used to determine when
the receiver has entered degraded HPS mode:
• The
UBX-ESF-STATUS.wtInitStatus
shows
1:INITIALIZING
.
• The WT fault flag,
UBX-ESF-STATUS.missingMeas
field, is set to
1
, indicating a WT timeout
has been detected.
Degraded HPS mode is planned for short WT sensor error / outages. If the WT sensor is not available,
the customer should perform thorough testing of the degraded HPS mode.
In the degraded HPS mode, the receiver does not lock the position while the vehicle is stationary, so
the position could drift slightly, based on the GNSS conditions. The receiver needs WT for stationary
phase detection.
UBX-20039643 - R01
3 Receiver functionality
Page 24 of 105
C1-Public
Advance information
