Get home position from dataflash logs

ArduCopter Copter 3.6
1

Hi,
Is it possible to get home position coordinates from dataflash logs using Mission Planner?

Thanks!

2

You can create a .KMZ file which will open in Google Earth and show you your whole flight path.

3

Thanks for the reply. I need to know the altitude in which the home position was set (from available dataflash logs), so If I’m not mistaken the flight path will not help me…

4

Home location updates are recorded in the ORGN message. There are two types. Type 0 is the EKF origin and type 1 is the AHRS home location.

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5

Thanks!!
What is the difference between the two types?

6

I am using mavlink “command_do_long” to set home before takeoff (not through MP), and my missions have relative altitude WPs. I have noticed that the actual flight altitude is different than the WP altitude and I suspect that the reason has something to do with the way I set home. The fact that there are two types makes this even more probable.

7

The EKF origin is just used internally by the EKF as a position reference, and is created when the GPS first gets a lock. The origin point itself can be arbitrary and isn’t used as a home location, rally point, etc., so yeah if you’re setting the EKF origin instead of home, that could explain it. I’m not sure if SET_HOME_POSITION can set the EKF origin, though.

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8

What is the Mavlink message in which the ORGN information is sent? I’d like to interpret it and set home altitude according to EKF home altitude. Maybe this will solve the altitude offset during flights.

Thanks for your help!

9

I see these messages being sent by flight controller:
GPS_GLOBAL_ORIGIN - This might be the EKF origin, not sure.
HOME_POSITION - Seems self explanatory.

These messages don’t seem to be streamed constantly. They might only be sent when a new home/origin is set.