APM 3.2 Strange Nav issues

I recently got auto mode working on my quad and it has generally been working well except from a few occasions.

This strange issue has arisen several times, usually at the end of flights. The copter just seem s to either give up and just start drifting around, land, or go wildly off course. I have reviewed the logs, (and uploaded 2 examples) of this issue. I have found that the problem is somehow related to the NAV. At the points where it goes off course, the NAV DPosX and DPosY either flat lines, or the actual PosX and PosY drift way off target. You can see for yourself. In EXAMPLE A, the copter should keep in a strait line heading east, but then gradually drifts off worse and worse. In EXAMPLE B, the copter should have landed about 10~15 meters surther west when the Nav gave out.

I dont know why the NAV has these issues or even more how to fix them so any help is greatly appreciated.

If you have any questions dont hesitate to ask.


Need to turn logging up so we have more data to work with. I do see the drift though as it gets close to the last way point.


Alright here is another flight with full datalogging turned on. The same issue happens. The flight is perfect except fo the end where it should have landed 15 meters further west.

NOTE: The GPS glitch that goes off the the northwest occurs after I landed and must be from me touching.interfering with something. It did NOT occur inflight. Otherwise the GPS data is accurate to what actually occurred.

Does this help?


I can’t quite see what the problem is. I do notice that your PID tuning isn’t quite right. DesRoll/Roll and pitch don’t match well. This will affect auto performance.

Looking at your Example A, I see you fly some waypoints, and it appears to be doing well. You reach Waypoint 17 (Command #18 after the Takeoff), and then you have a Land command with no coordinates. This tells the copter to land exactly where it is now, which is basically that 17th waypoint. It does exactly what it’s supposed to. It does show it drifts off NorthEast into somebody else’s back yard. Does it really do that, or that’s just because it landed under some trees?

Your 3rd log is exactly the same.

Its not doing what its supposed to do. The problem is it lands early. It gets close to the end of a mission and just kinda gets lazy, gives up and start descending. Itas weird cause its a problem with the DPosX and Y that tells it to stop. I dont mind that so much, but I really dont want this to happen when its farther away and harder to recover.

The divert into the other yard occurs after landing… disregard that.