Multi-Line Body To Vehicle Frame Rotation Calibration Routine - Novatel SMART7 Installation And Operation Manual

SMART7 with SPAN Operation
can easily be entered manually through the SETINSROTATION RBV command. If the rotational
offset is more complex (that is, rotation is about 2 or 3 axis), then the calibration routine
provides a more accurate estimation of the values.
The steps for the calibration routine are:
1. Apply power to the SMART7.
2. Configure the SPAN system including an approximate IMU Body to Vehicle frame (RBV) rota-
tion. See SPAN Configuration on page 63.
3. Ensure that an accurate lever arm has been entered into the system.
4. Perform an initial system alignment using one of the methods described in System Start-Up
and Alignment Techniques on page 66. Ensure the system reaches Solution Good.
5. Enable calibration using the INSCALIBRATE command with an optional standard deviation
target.
INSCALIBRATE RBV NEW [target_stdev]
6. To monitor the calibration, log INSCALSTATUS using the ONCHANGED trigger.
7. Start to move the system. Movement of the system is required for the observation of the
angular offsets.
Drive a straight course on level ground (remember that most roads have a crown resulting in
a constant roll of a few degrees). Avoid driving on a surface with a constant, non-zero, slope
to prevent biases in the computed angles. Vehicle speed must be greater than 5 m/s (18
km/hr) for the calibration to complete.
8. When the calibration is complete, either because the accuracy requirement has been met, or
the calibration been halted by user command, the calibrated offset value can be viewed in
either the INSCALSTATUS log or the INSCONFIG log.
To save a calibrated rotation for subsequent start ups, issue the SAVECONFIG command after cal-
ibration is complete. Each time the IMU is re-mounted this calibration should be performed again.
See also Kinematic Alignment on page 66 for details on kinematic alignment.
After the INSCALIBRATE RBV ENABLE command is entered, there are no body-vehicle
rotation parameters present and a kinematic alignment is NOT possible. Therefore this
command should only be entered after the system has performed a kinematic alignment
and has a valid INS solution.
For information about the logs and commands used in this procedure, refer to the
Commands and Logs Reference

4.5.6 Multi-Line Body to Vehicle Frame Rotation Calibration Routine

The single pass Body to Vehicle frame offset calibration feature assumes flat ground when estim-
ating the roll offsets between the IMU Body and Vehicle frames, as this component of the rota-
tional offset is difficult to observe through typical ground vehicle motion. In practice this can
result in an outstanding roll offset error as high as several degrees. For applications where
vehicle roll must be well known, or pass-to-pass accuracy of a highly offset position is especially
important, the Multi-Line IMU Body to Vehicle frame offset calibration routine offers higher
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