What is Position Quality?

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The Position Quality channel, created by a VBOX 3iS or VBOX 3i (with firmware v2.5 or later), is a numerical confidence indicator of the quality of the GNSS position based on the kalman filter estimated standard deviation. This channel is only present when IMU integration is enabled and will be logged, sent over serial or output via CAN on byte 7 of ID 308.

It is used for RTK robot path following applications, typically to verify position quality before starting a test.

10 = Difference between GNSS and KF estimated position is better than 5 cm.
9 = Difference between GNSS and KF estimated position is between 5–10 cm.
8 = Difference between GNSS and KF estimated position is between 10 cm and 1 m.
7 = Path following position confidence is between 1–2 m.
2 = When the IMU filter has been enabled and IMU has sync'd but is not yet initialised. Once initialised it should report as per the above values.
1 = When the IMU has not sync'd or if the KF has not been enabled (note if KF has not been enabled, then the value will only be present on CAN).