this is only used in one place, and that place is called from the same routine setting the persistent state. The only other place which calls readIMUData shouldn't be running the prediction step, but mmay, depending on the previous setting of the prediction step.
We are not initialising this state on filter reset, so it's possible that the state will be set when we do an InitialiseFilterBootstrap, which is probably not desired
The previous method resulted in data incest and fusion of predicted airspeed on every EKF internal time step.
This was not apparent during flight where the vehicle was turning, but during long straight legs did not constrain along track drift.
Make it user selectable.
Remove potential for a race condition between decisions based on latest data and the EKF fusion processing which operates on a delayed time horizon. This is achieved by preventing data entering the buffer if awaiting checks to pass ensuring that no EKF fusion time horizon processes can use data that hasn't passed checks.
Log the waitingForGpsChecks class variable
These changes enable the EKF to use the last observable wind velocity vector estimate to synthesise an airspeed measurement if operating without an airspeed sensor and when all other measurement types that can constrain velocoty drift are lost. This enables the EKF to use dead reckoning to continue after loss of GPS when there is no air speed sensor fitted and without the need to set a default airspeed value.
The logic used to fuse a default airspeed value has also been cleaned up and the call to FuseAirSpeed() from inside SelectBetaDragFusion() has been removed.
AP_NavEKF3: Fix error in default airspeed observation variance
AP_NavEKF3: Enable shadow fusion of airspeed when sensor is disabled
clang reports this could be a problem when compiling under some EABIs. Remove it from most places as it is just noise, replace with class where we want to avoid including Location.h
we don't need to persist this across multiple calls as we now fuse all axes on the one step.
I've moved the defintion of these variables to where they are initialised to make it clear they're not used uninitialised.
this fixes a bug introduced in #21834
this fix in #21834 was correct for getPosD, but should not have been
applied to getLLH
this caused cruise mode in plane to descend/ascend by the difference
between the public and local origins on mode entry
fixes#21984
Innovations and innovation test ratios will still be calculated and reported for an unhealthy sensor, but the EKF states wnd covariance matrix will not be modified.
When returning our last-known-position we were supplying lat/lng but not
altitude.
This usually really doesn't matter as this result generally isn't used,
especially for altitude. OTOH, it may prevent a bug into the future.
Fixes bug that prevents the vertical velocity being reset to the GPS if the position aiding has already timed out and improves sensitivity of the bad IMU data check.
