Hi everyone,

I m quite use to read logs but i cannot manage to get anything from this one...

The hardware :

Iris+ with 3dr gimbal

Nexus 7+droidplanner

What happened : I started to fly in stab, then in althold when it suddently goes really fast up and start to fly away.

On the log we can see that i had a good gps lock.

On the log it seem that i flew out of fence.

I didnt get that because the iris was 20m in front of me and the fence param radius is 100m.

Then it went up like I've never seen an iris climbing, it did get its rtl alt, then in RTL went in the opposite direction loosing altitude.

It ended in a tree with 2 broken arms + gimbal.

It looks like IMU was wrong few seconds before the fence breach, but i didnt understand why the rtl (fence breach)?

RelAlt goes down i dont know why.

Thanks for the help.



2015-08-01 18-51-32.log

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  • From the logs it looks like you had a GPS glitch.  At the end it shows your relative altitude as being 80 Meters in the ground and flying off into the woods while the actual altitude and barometer altitude stayed normal.  It flew up to 30 meters for the RTL but the GPS show it going down 80 meters.

    Normally see this when someone is to close to a building or trees and the GPS gets a reflection of the signal causing the GPS to suddenly drift off in one direction.

    • Thanks,

      but i can't get why i didn t see anything on logs like a bad position or a position jump.

      I was flying in the middle of a field with some small trees.

      Does the gps glitch protection works on ac3.2 iris+? http://copter.ardupilot.com/wiki/configuration/gps-and-gcs-failsafe...

    • There is no fix for GPS drift.  If it happens and you are in a GPS assisted mode the copter will fly in the opposite direction to correct for this movement.

      I have had several flights that when near a obstruction caused the copter to fly right at me or right into my house trying to correct for this drift.

      The GPS and software don't know this is happening only that the new position that it has calculated is now several meters away from it current location.

      It usually only last a few seconds but that's enough to cause a crash.

      Now in your case where you were out in the open I have no idea what happened there except that a plot of your GPS data shows it going off into the woods several meters from your location and only you can determine if that's what really happened.

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