Chapter 3 SPAN OperationOEM7 SPAN Installation and Operation User Manual v1 62offset is more complex (that is, rotation is about 2 or 3 axis), then the calibration routineprovides a more accurate estimation of the values.The steps for the calibration routine are:1. Apply power to the receiver and IMU.2. Configure the SPAN system including an approximate the IMU Body to Vehicle frame (RBV)rotation. See SPAN Configuration on page 49.3. Ensure that an accurate lever arm has been entered into the system either manually orthrough a lever arm calibration, see Lever Arm Calibration Routine on page 60.4. Perform an initial system alignment using one of the methods described in System Start-Upand Alignment Techniques on page 54. Ensure the system reaches Solution Good.5. Enable calibration using the INSCALIBRATE command with an optional standard deviationtarget.INSCALIBRATE RBV NEW [target_stdev]6. To monitor the calibration, log INSCALSTATUS using the ONCHANGED trigger.7. Start to move the system. As with the lever arm calibration, movement of the system isrequired for the observation of the angular offsets.Drive a straight course on level ground (remember that most roads have a crown resulting ina constant roll of a few degrees). Avoid driving on a surface with a constant, non-zero, slopeto prevent biases in the computed angles. Vehicle speed must be greater than 5 m/s (18km/hr) for the calibration to complete.8. When the calibration is complete, either because the accuracy requirement has been met, orthe calibration been halted by user command, the calibrated offset value can be viewed ineither 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 Coarse Alignment on page 55 and Kinematic Alignment on page 55 for details on coarse andkinematic alignment.After the INSCALIBRATE RBV ENABLE command is entered, there are no body-vehiclerotation parameters present and a kinematic alignment is NOT possible. Therefore thiscommand should only be entered after the system has performed either a static or kin-ematic alignment and has a valid INS solution.For information about the logs and commands used in this procedure, refer to the OEM7Commands and Logs Reference Manual (OM-20000169).3.5.7 Multi-Line Body to Vehicle Frame Rotation Calibration RoutineThe 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 canresult in an outstanding roll offset error as high as several degrees. For applications wherevehicle roll must be well known, or pass-to-pass accuracy of a highly offset position is especially
