Filter Status Flags
The filter status flags are available in the Status (0x82,0x10)message. The assignment of the filter status flags in the Status (0x82,0x10) is device specific. The following table shows an overview of the status flags for the 3DM-CV7. The sections below it provide a detailed description of each status flag.
| Bit # | Description | Potential Cause | Recommended Action |
|---|---|---|---|
| 0-1 | Filter condition (Stable/Converging/Unstable) | Insufficient initial conditions supplied. | Verify required conditions are properly enabled. Review Filter States. |
| 2 | Roll/Pitch Warning | Sensor is not aligned with vehicle frame. | Review Vehicle Frame page. |
| 3 | Heading Warning | Heading source is not valid. For Magnetometer Aiding:time varying magnetic interference. |
For External Heading:FAQ:How to improve filter performance For GNSS Kinematic Alignment: FAQ:How to improve filter performance For Magnetometer Aiding:perform Magnetometer Calibration, check for time varying magnetic interference via Scaled Mag (0x80,0x06). |
| 6 | IMU Bias Warning | Gyro bias is high. |
Perform Capture Gyro Bias (0x0C,0x39) |
| 9 | Mounting Transform Warning | Transform is likely incorrect. | Review Vehicle Frame page. |
| 10 | Time Sync Warning | No PPS source detected, or external heading timestamp is too old. | Check PPS source is set correctly . |
| 12-15 | Solution Error | Filter computation warning flags. If any bits 12-15 are set, all filter outputs will be invalid. | Reset Navigation Filter (0x0D,0x01) |
Filter condition (bits 0-1)
Regardless of the active filter mode (see Filter Status), the Estimation Filter will report one of three Estimation Filter conditions in the status message: stable, converging, and unstable/recovery.
| Filter Condition Values | Description |
|---|---|
| 1 | Stable |
| 2 | Converging |
| 3 | Unstable/Recovering |
Stable
The Estimation Filter reports that it is stable when the error state estimates are generally consistent with the available aiding measurements and state uncertainty estimates stabilize.
Converging
The Estimation Filter reports that it is converging when the error state estimates have not yet converged to stable values. The duration of the convergence condition is dependent on the filter mode (see Filter Status), the quality and frequency of aiding measurements, and the dynamics of the sensor platform. Typical convergence times can be several minutes after filter reset for the Estimation Filter to reach Full Navigation mode.
Unstable/recovering
The Estimation Filter reports that it is unstable/recovering only if the Auto-adaptive Filtering option is enabled (the default selection). This condition is reported when aiding measurements have diverged in consistency with internal state estimates for an extended period of time. When the Estimation Filter is in this state, it will attempt to recover by adapting the state and measurement models until state and measurement consistency is achieved. When this condition is reported, the reported navigation solution will not be valid, and it may appear to change rapidly. After successful recovery, the Estimation Filter will return first to the converging, then to the stable condition.
NOTE: After initialization, the filter will report a converging condition until state estimates have stabilized. Then a stable condition is reported. If the availability of aiding measurements changes, or the filter mode changes (see Filter Status), the Estimation Filter may revert from stable to converging. If aiding measurements are highly inconsistent with internal state estimates, the Estimation Filter may report the unstable/recovering condition. When the unstable/recovering condition is reported, the filter outputs will be unreliable and the Estimation Filter will attempt to recover.
Estimate warnings (bits 2-9)
An estimate warning means that the Estimation Filter's confidence in the accuracy of the flagged estimate is low. The following table details the outputs that are impacted by each estimate warning flag.
| Estimate Warning | Impacted Outputs |
|---|---|
| Roll/Pitch Warning | Attitude DCM (0x82,0x04), Attitude Quaternion (0x82,0x03), Euler Angles (0x82,0x05) |
| Heading Warning | Attitude DCM (0x82,0x04), Attitude Quaternion (0x82,0x03), Euler Angles (0x82,0x05) |
| IMU Bias Warning | Accel Bias (0x82,0x07), Gyro Bias (0x82,0x06) |
Solution error (bits 12-15)
An error flagged by bits 12-15 indicate that there is a non-numerical value (NaN) in the navigation solution. If bits 12-15 are non-zero, the user is advised to reset the Estimation Filter (Reset Navigation Filter (0x0D,0x01)).