What is the reason for having 2 EKF filters (EKF2 and EKF3) in the ardupilot
code? The only difference I see is the noise parameter values. I am trying
to understand the ardupilot codebase and would appreciate it if someone
could provide some insight.
We have been through a few different versions of the EKF filter - as the
names might suggest to you!
Because of how vital that code is, we like to test the filters
"ride-along" before making a new filter the one used by the aircraft for
its estimations by default.
You can fiddle with which EKF is used with the AHRS_EKF_USE parameter.