this forces the EKF origin to the GPS alt on a height datum reset if
we have GPS lock. If we don't do this then the reported AMSL alt will
drift over time away from the GPS alt when we reset while on the
ground
this forces the EKF origin to the GPS alt on a height datum reset if
we have GPS lock. If we don't do this then the reported AMSL alt will
drift over time away from the GPS alt when we reset while on the
ground
this fixes a bug in the set of home alt while disarmed. The set had a
circular dependency which could cause a large bias to build up between
home alt and gps alt due to small fluctuations in barometer data
Thanks to Nick Allen for spotting this
this ensures we consistently fly with EKF lane1 if it is healthy at
the point we arm. Otherwise the choice of lane will be a lottery.
This is important as many systems have quite different filtering and
vibration characteristics on their different IMUs. We by default
enable fast sampling only on the first IMU for example, which means
the 2nd and 3rd IMUs are more vulnerable to high freq causing
aliasing.
this ensures we consistently fly with EKF lane1 if it is healthy at
the point we arm. Otherwise the choice of lane will be a lottery.
This is important as many systems have quite different filtering and
vibration characteristics on their different IMUs. We by default
enable fast sampling only on the first IMU for example, which means
the 2nd and 3rd IMUs are more vulnerable to high freq causing
aliasing.
this sets a limit on the difference between the earth field from the
WMM tables and the learned earth field inside the EKF. Setting it to
zero disables the feature. A positive value sets the limit in mGauss.
this zeros the delta angle and delta velocity accumulators when a
sensor is unavailable for a period of 0.1s. This prevents garbage
values being passed into the EKF when a sensor dies and then becomes
available again some time later
this we ensures we get new data for all active IMUs on each loop,
rather than sometimes returning with some IMUs not having data.
This matters as not having a sample on an IMU for a single loop can
cause an EKF IMU failover, which will degrade the learned bias
variances
The issue is usually only seen under high load, such as requesting a
loop rate beyond what the hardware is capable of
this allows us to learn the gyro biases each lane would need if it had
to switch to another gyro due to a sensor failure. This prevents a
sudden change in gyro bias on IMU failure
Andrew Tridgell
Robin Hilliard