I am trying to understand what the EKF2_*_DELAY parameters mean and how to determine their correct settings. The best documentation I have been able to find is the “Using the ECL EKF” page where it says:
The EKF runs on a delayed ‘fusion time horizon’ to allow for different time delays on each measurement relative to the IMU. Data for each sensor is FIFO buffered and retrieved from the buffer by the EKF to be used at the correct time. The delay compensation for each sensor is controlled by the EKF2_*_DELAY parameters.
For instance, the default value for GPS (EKF2_GPS_DELAY) is 110 ms. Should this setting be understood as follows: When the system receives a GPS measurement, then that measurement is expected to be delayed by 110 ms?