FixPosition Vision-RTK 2 - Step 10: Calibrate the IMU; Pre-Calibration Requirements; Performing IMU Calibration; Confirming IMU Bias Convergence

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Step 10: Calibrate the IMU
The Vision-RTK 2 requires a start-up procedure before being fully operational. The user must
ensure the following requirements are fullled to start the calibration procedure:
1. Ensure both receivers obtain RTK xed status
2. Start the Fusion engine, and ensure extrinsics are correct
3. Move the sensor under RTK xed status with some dynamic motion
▪ Move in the shape of eight roughly sized at 10m
▪ Move back-and-forth a few times over a stretch of 10m
◦ After converging, the IMU biases will be saved to be used on the next initialization procedure. Thus, the
calibration will be signicantly faster
◦ The IMU biases will continue to be estimated any time the sensor is under
”RTK xed”
◦ IMU’s
“Excessive noise”
only indicates that the measurements present signicant mechanical vibrations;
however, this is not necessarily noise (e.g., moving on rocky terrain)
Additional information
Fusion Status
Fusion engine
Unknown
Running (Car)
Stopped (Car)
Fusion status
Unknown
Not started (wait for GNSS)
Initialized (wait for IMU)
Initialized (wait for WS)
Initialized (wait for IMU/WS)
Initialized
IMU status
Unknown
Converged
Not converged
IMU noise
Unknown
Excessive noise
Medium noise
Low noise
Wheelspeed status
Unknown
Not configured
Not used
Converged
Not converged
State estimate
Output StdDev
Position
n/a n/a
n/a n/a
n/a n/a
Orientation
n/a
n/a
n/a
Velocity (2d) n/a

+
−


Fusion
GNSS 1
GNSS 2
Velocity
30 m
Downsample Traces
Limit Points Plotted
Plot Line
Leaflet | Map data © OpenStreetMap, Imagery © Mapbox
10 m 10 m
4. Calibrate until IMU biases are converged (
IMU status
must show
“Converged”
)