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
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.
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.
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.
AP_NavEKF3: Implement same maths as PX4/ecl EKF
Replace attitude vector states with quaternions
Remove gyro scale factor states
Add XY accel delta velocity bias estimation
Initial tuning
Add GPS body frame offset compensation
AP_NavEKF3: Fix bugs and consolidate aiding switch logic
Switching in and out of aiding modes was being performed in more than one place and was using two variables.
The reversion out of GPS mode due to prolonged loss of GPS was not working.
This consolidates the logic and ensures that PV_AidingMode is only changed by the setAidingMode function.
AP_NavEKF3: prevent multiple fusion mode changes per filter update
AP_NavEKF3: Update tuning defaults
AP_NavEKF3: Fix bug causing switching in and out of aiding
If the GPS receiver was disconnected and no data received, then then the gpsGoodToAlign check did not get a chance to run and becasue it was previously true the EKF would switch back into aiding.
This prevents this by ensuring that gpsGoodToAlign defaults to false when the check is not being performed.
An additional check has also been dded to ensure that there is GPS data to fuse before we declare ready to use GPS.
AP_NavEKF3: Fix bug preventing planes recovering from bad magnetometers
This bug created a race condition whereby if the EKF had to reset the yaw to the GPS ground course to recover from a bad magnetometer, the new heading could be over-written by the bad magnetic heading when the plane reached the height for the scheduled reset.
AP_NavEKF3: Improve switch-over to backup magnetometer
When switching over to a back up magnetometer, ensure that the earth field estimate are reset. Otherwise mag earth field estimates due to the previous failed mag could cause data from the new mag to be rejected.
AP_NavEKF3: enable automatic use of range finder height
AP_NavEKF3: Fix bug in handling of invalid range data
AP_NavEKF3: Fix height drift on ground using range finder without GPSAP_NavEKF3:
AP_NavEKF3: Handle yaw jumps due to core switches
AP_NavEKF3: Enable simultaneous GPS and optical flow use
AP_NavEKF3: fix console status reporting
AP_NavEKF3: send messages to mavlink instead of console
This allows the GCS to better handle the display of messages to the user.
AP_NavEKF3: replace deprecated function call
AP_NavEKF3: Compensate for sensor body frame offsets
AP_NavEKF3: Fix bug in median filter code
AP_NavEKF3: save some memory in the position offsets in EKF3
We don't need to copy that vector3f for every sample. A uint8_t does the job
AP_NavEKF3: Add fusion of range beacon data
AP_NavEKF3: Bring up to date with EKF2
AP_NavEKF3: Misc range beacon updates
AP_NavEKF3: Add mising accessors
AP_NavEKF3: remove duplicate include
AP_NavEKF3: Prevent NaN's when accessing range beacon debug data
AP_NavEKF3: Update range beacon naming
AP_NavEKF3: updates
AP_NavEKF3: miscellaneous changes
AP_NavEKF3: misc updates
AP_NavEKF3: misc range beacons updates
AP_NavEKF3: add missing rover default param
1) Do not switch to a core until its states have been updated.
2) Distinguish between mandated switches required for health failure and optional switches required due to innovation checks failing.
3) Apply hyseresis to innovation check levels
This can improve position hold performance where it is not practical to have the IMU located at the centroid.
Although this enables the effect of IMU position offsets to be corrected, users will still need to be instructed to place the IMU as close to the vehicle c.g. as practical as correcting for large offsets makes the velocity estimates noisy.
Correction requires the body rates averaged across the flow sensor sampling interval. This data has been added to the sensor buffer.
The body rate data from the flow sensor driver does not contain the Z component, so an equivalent value sampled from the navigation IMU has been used instead.
The variable omegaAcrossFlowTime has been moved out of the class and into the only function that uses it.
The EK2_RNG_USE_HGT parameter sets the height (expressed as a percentage of the maximum range of the range finder as set by the RNGFND_MAX_CM parameter) below which the range finder will be used as the primary height source when the vehicle is moving slowly.
When using a height reference other than GPS, the height datum can drift due to air pressure changes if using baro, or due to terrain height changes if using range finder as the primary height source. To ensure that a consistent height datum is available when switching between altitude sources, the WGS-84 height estimate of the EKF's local positi norigin is updated using a
single state Bayes estimator,
If rngfinder or gps height data is lost whilst being used, there will be a fall-back to baro data.
Switching in and out of aiding modes was being performed in more than one place and was using two variables.
The reversion out of GPS mode due to prolonged loss of GPS was not working.
This consolidates the logic and ensures that PV_AidingMode is only changed by the setAidingMode function.
The filter status logic calculations were being repeated every time the get function was called.
The logic is now updated once per filter update step and a separate get function added
If we start GPS aiding before the gyro bias variances have reduced, glitches on the GPS can cause attitude disturbances that degrade flight accuracy during early flight.
Remember the mag bias and earth field states learned during flight when the vehicle lands.
This improves performance for vehicles that do multiple flight on one power cycle
IMU data was being corrected before being used by the co-variance prediction, whereas the delta angles and velocities in the derivation were supposed to be uncorrected.
This patch creates separate variable for the corrected data
Automatically use the highest gain consistent with a 5% overshoot to minimise RMS tracking errors.
Provide an alternative correction method for the position and velocity states that allows the user to specify the time-constant. This can be used to fine tune the output observer for for platform specific sensor errors and control loop sensitivity estimation noise.
Randy Mackay
priseborough
Michael du Breuil
Andrew Tridgell
Mathieu OTHACEHE