At each new valid range measurement, the time derivative of the distance
to the ground is computed and compared with the estimated velocity.
The average of a normalized innovation squared statistic check is used
to detect a bias in the derivative of distance measurement,
indicating that the distance measurements are kinematically inconsistent
with the filter.
- ekf2: expose dead reckoning as control status flags
- commander:
- add GPS validity check
- in AUTO MISSION if dependent on GPS then a loss of GPS will
- Also use the delayed current data instead of newest that might not be
available (gps buffer is sometimes empty if the dt between samples is
larger than the delayed horizon).
- Separate "baro fault" from "baro intermittent": intermittent is a
temporary failure and should prevent from switching to baro right now,
but "fault" means that it should never be used anymore
- In case of height timeout, check for metrics but not for consistency
as the filter is likely to have diverged already.
- remove class _mag_sample_delayed
- update mag fusion call graph to use mag sample delayed functionally
- Ekf::resetMagHeading()
- use low pass mag directly, but check if valid (magnitude)
- MAG_FUSE_TYPE_INDOOR treat like auto if heading required
- introduces new parameter EKF2_PREDICT_US to configure the filter
update period in microseconds
- actual filter update period will be an integer multiple of IMU
The existing logic using the angle between velocity vectors failed to
determine a yaw failure in practice because the state velocity is often
too small compared to its uncertainty to be used. In all the failures
reported, the yaw emergency estimator converged properly and yaw reset
would have fixed the issue.
A much simpler check using the yaw difference between the main EKF
and the emergency estimator is now used to tell if the vel/pos update
failure is most likely caused by a wrong heading.
