Chapter 3 SPAN OperationOEM7 SPAN Installation and Operation User Manual v1 61We recommend that you measure the lever arm using survey methodology andequipment, for example, a total station. Only use calibrations when precisemeasurement of the lever arm is not possible.Initial estimates and uncertainties for the lever arm may be entered using theSETINSTRANSLATION ANT1 command. The calibration routine uses these values as the start-ing point for the lever arm computation.The Lever Arm Calibration routine is not available for the IMU-CPT, HG-1930, ADIS-16488, G320, IMU-IGM or STIM300.The steps involved in the calibration are:1. Apply power to the receiver and the IMU.2. Configure the SPAN system, see SPAN Configuration on page 49.3. 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.4. Enter the initial estimate for the lever arm using the SETINSTRANSLATION ANT1 com-mand.Ensure the standard deviation values entered for the antenna offset are not overly optimistic(i.e, err on the side of a larger standard deviation).5. Enable calibration using the INSCALIBRATE command wit an optional standard deviationtarget.INSCALIBRATE ANT1 NEW [target_stdev]6. To monitor the calibration, log INSCALSTATUS using the ONCHANGED trigger.7. Start to move the system. The lever arm is not observable while the system is stationary.Immediately, drive a series of maneuvers such as figure eights. The turns should alternatebetween directions, and you should make an equal number of turns in each direction. Someheight variation in the route is also useful for providing observability in the Z-axis.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 lever arm for subsequent start ups, issue the SAVECONFIG commandafter calibration is complete. If the IMU or GNSS antenna are re-mounted, re-run the calibrationroutine to compute an accurate lever arm.For information about the logs and commands used in this procedure, refer to the OEM7Commands and Logs Reference Manual (OM-20000169).3.5.6 Body to Vehicle Frame Rotation Calibration RoutineKinematic alignment requires that the rotational offset between the vehicle and IMU Body frame(RBV) is known. If the angles are simple (that is, a simple rotation about one axis) the valuescan easily be entered manually through the SETINSROTATION RBV command. If the rotational
