See discussion here:
https://github.com/ArduPilot/ardupilot/issues/7331
we were getting some uninitialised variables. While it only showed up in
AP_SbusOut, it means we can't be sure it won't happen on other objects,
so safest to remove the approach
Thanks to assistance from Lucas, Peter and Francisco
Previous default was to apply in-flight height origin changes to local position instead of to reported origin height. This caused problems with copters that took off before getting GPS lock.
This change means that provided the GPS_DELAY_MS parameters are set for each GPS receiver attached, the EKF will not have to wait for the configuration of each receiver to be determined before it can start.
This significantly reduces start-up times when the delay parameters are set.
If variance falls below desired minimum, set state noise to a larger value.
If variance drops below safe value, set to desired minimum and reset off-diagonals to zero.
To eliminate the possibility of editing errors, revert the covariance prediction auto-code to the original auto-code without the replacement fo the /2 and /4 operations. The compiler optimisations are able to correctly handle the /2 and /4 operations.
Also use local variables for intermediate covariance calculations. The use of class variables for these small arrays was unnecessary.
This patch ensures that covariance matrix entries for inactive states are always set to zero.
It also halves the number of copy operations from the updated to stored matrix.
All Kalman gain calculations now explicity set gains for deactivated states to zero.
Previous use of loops to set gains to zero have been replaced with more efficient memset operations.
Inhibiting gyro bias estimation during the initial tilt alignment speeds alignment.
The calculation of the maxmum state index required has been modified so that it can handle all combinations of inhibited states.
Limiting the maximum state index accessed by all EKF operations result in significant processing reductions when higher index states are not being used.
Fix rounding error bug preventing state from updating after initial convergence.
Decouple GPS reference height from published EKf origin height.
Add bitmask parameter to control update and publishing of GPS reference height.
this changes the stragegy for load levelling between EKF cores so it
works between EK2 and EK3, and with future estimators as well.
It allows us to run EK3 and EK2 at the same time with good scheduling
performance
If the GPS receiver selection changes and we are using GPS for height, the vertical position will be reset to the new GPS height measurement.
correct output observer history when doing a GPS height reset
Do not time out and provide an escalating series of messages. We may need to adjust the time thresholds used for escalation.
Do not wait if the EKF is not using the GPS.
Copter operation without a magnetometer is limited to constant position and relative position modes only (no GPS or range beacon fusion permitted)
Copter optical flow operation without a magnetometer is permitted.
The ability of planes to takeoff/launch without a magnetometer and align the yaw using the GPS velocity is retained.
Prevent bad values for GPS time delay pushing the GPS time stamp outside the range of IMU data contained in the buffer. If this occurs it can prevent the GPS measurements from being fused and cause loss of navigation.
Use the time delay returned by the GPS driver.
Wait long enough for the GPS configuration to be determined, but time out after 30 seconds and warn the user that a default value for time delay will be used.
Switch to use of an airspeed reading averaged across the raw sensor readings. since the last update.
This avoids use of the IIR which requires a larger time delay compensation and violates the assumption of uncorrelated noise.
The time delay parameter has been reduced to compensate for the removal of the airspeed IIR filtering.
This value is a compromise between what works best for a Ublox 6 which is around 200msec delay and the more recent 7 and 8 series receivers that are around 120msec delay.
Adapt the lengths of the IMU and observations buffers on startup to the specified time delays and update rates.
This does require the EKF to be re-started if time delays are changed.
bugobliterator
Peter Barker
Pierre Kancir
Andrew Tridgell
priseborough
Lucas De Marchi
Michael du Breuil
Randy Mackay
Dr.-Ing. Amilcar Do Carmo Lucas
murata
Jonathan Challinger
Jacob Walser
Francisco Ferreira