EKF3 origin initialization after takeoff

ArduPlane Plane 4.4
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1

Hi all,

I would greatly appreciate it if someone could help me with my understanding of the EKF origin.

  1. What is the EKF origin? From what I have read in the documentation and about the algorithm, it seems to be a vehicle’s initial location estimate at the moment t0. Then, it is used to predict the vehicle’s state at the moment t1 and so on. Is that understanding correct?

  2. What is the best time to set the origin? Should it be set only before takeoff? Can it be set during a flight?

These questions have arisen because I want to use EKF with GPS support enabled (EK2_GPS_TYPE=0 or EK3_SRC1_POSXY=GPS, depending on the EKF version I use), but I can’t afford to have a stable GPS signal during takeoff. As such, I can’t get the EKF initialized and get its origin assigned before takeoff.

My plan was to set up the plane’s location before takeoff somehow manually. Then, when the GPS signal gets stable during the flight, the EKF will get initialized, and the plane switches from DCM to EKF.

I’m not sure if this scenario is feasible or conceptually correct, though.