Fairly recently, my Pixhawk based system (running 3.3 series AC) has started flying off wildly in one direction (then often flipping) in stabilize mode. However, loiter seems to be essentially fine. Stumped. Any ideas? Thanks!
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Can you attach a data log of a flight that includes the transition from loiter to stabilize mode? What you describe does seem odd since basic copter stabilization is running in any and all modes. Loiter just uses the GPS and IMU to hold a position where as you control the position (xy&z) in stabilize mode.
How does it behave in Position Hold or Altitude Hold modes? From what you describe, I would expect it to work fine in Position hold but fly off in Altitude hold mode. Position hold and Loiter are essentially the same while Altitude hold and Stabilize are essentially the same except for the use of the barometer to hold altitude.
Check the Mission Planner "Flight Mode" screen (under Initial Setup/Mandatory Hardware) to verify that the copter is actually going into the mode you think it is when you change your transmitter Mode switch.
Doug
Just a question since you probably can help me with this: When is the compass used and how/for what?
The compass is used in any mode or function that requires navigation, such as Loiter, RTL, Auto (flying to waypoints), Guided, Circle, Position Hold and Simple mode. The compass is used to orient the copter to a heading. While the GPS may tell the copter where to go from it's current position to get to a new position, the compass points it in the right direction to get there.
Doug
Thanks for the explanation. On a copter where there is just too much electronic interference, could I fly using a Nav mode with GPS only?
I don't think so. I think a compass is required. See this article on compass setup in the copter documentation http://ardupilot.org/copter/docs/common-compass-setup-advanced.html
Are you using an external compass mounted to a mast? The internal compass on the Pixhawk will most always have problems due to proximity to the power wiring. Check your setup to make sure you have selected the external compass.
Doug
I'll try pull the logs at my next opportunity. Thanks.
Sounds like a problem with your RC transmitter settings. Perhaps recalibrate? Or check that you're not in Heli mode or some other channel got reversed?
The mode looks right but indeed the unit hasn't been recalibrated for quite some time. Worth trying. Just seems odd that loiter works but stabile doesn't! Thanks.