ZED-F9K - Integration manual
•
Speed data
: Data coming from this sensor type can only be delivered to the receiver via one
of the communication ports within a UBX-ESF-MEAS (data type 11). The speed data shall be
delivered in meters per second.
If speed data but no absolute or relative wheel tick data are detected, the receiver automatically uses
the speed data without the need for reconfiguring the
CFG-SFODO-USE_SPEED
key. This behavior
can be deactivated by setting the
CFG-SFODO-DIS_AUTOSPEED
key and by manually setting or
clearing the
CFG-SFODO-USE_SPEED
key. If wheel tick data (or both wheel tick and speed data)
are detected on the software interface, the receiver uses the data type (by default wheel tick data)
corresponding to the configured
CFG-SFODO-USE_SPEED
key.
To make the receiver interpret incoming speed data (data type 11 in ESF-MEAS) instead of the single
wheel tick data (data type 10 in ESF-MEAS) on the software interface, the
CFG-SFODO-USE_SPEED
key must be set.
It is strongly recommended to use the absolute wheel tick sensors to ensure robust
measurement processing even after sensor failures or outages.
3.2.4.1.3 Odometer settings
You can configure the following odometer settings:
•
Sampling frequency
: The wheel tick/speed data sampling frequency (
CFG-SFODO-FREQUENCY
)
should be provided with an accuracy of approximately 10 %. If not provided, it is automatically
determined during the initialization phase: this requires a consistent data rate and can take
several minutes. Once initialized, the sampling frequency will be stored in a non-volatile
storage. For optimal navigation performance, the standard wheel tick/speed input at 10 Hz is
recommended.
•
Latency
: For best positioning performance, the latency of the wheel tick/speed data (
CFG-
SFODO-LATENCY
) should be given as accurately as possible (to within at least 10 ms). If not
provided, the wheel tick/speed data latency is assumed zero. More details about latency can be
found in the
section.
•
Quantization error
: If absolute/relative wheel tick data are used (for example, if the tick data is
a distance), the quantization error can be defined in the
CFG-SFODO-QUANT_ERROR
key. The
quantization error can be calculated as
2*Pi*R / T
with
R
the wheel radius,
T
the number of
ticks per wheel rotation. If the quantization error is not provided, it is automatically initialized by
the receiver.
•
Speed data accuracy (software interface only)
: If speed data are used, the speed data
accuracy can be set in the
CFG-SFODO-QUANT_ERROR
key. If not provided, the speed data
accuracy is automatically initialized by the receiver.
•
Scale factor
: If the coarse WT scale factor is not configured in the
CFG-SFODO-FACTOR
key,
it is estimated automatically during the initialization (see section
for more
details).
•
Combination of multiple rear wheel ticks (software interface only)
: If wheel ticks are
being received from both rear wheels, the receiver can be configured with the
CFG-SFODO-
COMBINE_TICKS
key to use the combined rear wheel ticks rather than a single tick. It is
recommended to use combined rear wheel ticks if available, as they are often of higher quality
than the single ticks.
3.2.4.2 UBX-ESF-MEAS time tagging (software interface only)
To achieve optimal performance with the fusion solution it is essential to determine the epoch in
the receiver time frame when the UBX-ESF-MEAS sensor data were taken. This may be done in one
of the following ways:
• First byte reception: reception time of the first byte of the UBX-ESF-MEAS message
UBX-20046189 - R01
3 Receiver functionality
Page 20 of 105
C1-Public
Early production information
