How to Do If "Unable to get RBV Calibrated"

by HanaHana

1. Conditions for RBV calibration

To get RBV calibrated, you need to meet the following conditions:

1. Drive in a straight line (no turns);
2. Driving speed reaches 5m/s (minimum speed);
3. Flat road (the carrier cannot be inclined);
4. Drive in the forward direction (reverse driving is not allowed).

Among them, you need to pay attention: the first two conditions will be automatically detected during calibration process, and the receiver will use the data that meets the requirements for calibration; the latter two cannot be automatically detected, and must be performed in accordance with the requirements during calibration, otherwise the RBV calibration result may be inaccurate.



2. Impact of RBV calibration failure

If the RBV calibration cannot be completed, there will be an offset of several degrees between the input RBV value and the actual installation. The RBV error mainly affects the attitude of the vehicle body in the navigation information, and also affects the navigation center and azimuth to a certain extent due to the lever arm configuration.

The impact is mainly reflected in the LAND MODEL (Check with SETINSPROFILE command). When the satellite signal is good, there will be no obvious impact; when the satellites signal is lost, the error divergence is particularly obvious. At that time, the constraint deviation caused by the RBV error in the NHC processing will be increasing with time. If you are not using LAND MODEL, there is no significant difference in navigation results.



3. Solution of RBV calibration failure

If the RBV calibration cannot be completed, you can use the roughly estimated RBV value without calibration, such as [0,0,0], [0,180,90], etc. When under open sky with good satellite signals, the GNSS/INS results should not be significantly deteriorated; When under satellites signal loss, the GNSS/INS results show error divergence due to RBV error. This method is suitable for scenarios without signal loss or applications with signal loss but with low precision requirements.

An interface to modify the RBV calibration required speed can be provided in order to meet the calibration requirements of low-speed carriers, but the accuracy of the RBV calibration of low-speed driving will be not high, so it will not help significantly to improve the accuracy of the GNSS/INS results.

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