I'm running ArduPlane V2.76
To start with, here are my tlogs 2014-05-15%2019-40-50.tlog
and video (from a keychain cam) https://www.youtube.com/watch?v=8eqQnTWkuwg
The problem is, there is a fierce up and down shake.... in the video about at 2:15 into the Auto mission flight. I switch to RTL and changed Servo Pitch P from 1.10 to 1.05 and reset and started the mission. Again the shaking started a little beyond the first location shaking problem. Switch back to RTL, changed from 1.05 to 1.00, reset and started the mission. This third time it went a little farther and shook enough to cause the X8 to go in at 100 meters. I couldn't retrieve the plane until the next day because of the difficult terrain. BTW, the plane was never in "Manual Mode", alway in "Auto" or "RTL" modes.
My question, besides HELP, is..... I thought it was strange, the problem should have started immediate after launch, not several minutes after! Also thinking the problem might be in the PTCH2SRV_P settings...( which I was changing from 1.10 to 1.05 to 1.00) it was acting light porpoising!
Now having to take time to rebuild, if I can't find a direction to correct the problem, then I'm grounded!
Any help will be very appreciated!!
Thx, Brian
Replies
RTL and Auto are using the same attitude control loops. The gains are also scaled with airspeed, which may be an estimate in your case based on GPS speed if you don't have a pitot-static system. If your auto mission airspeed is different from RTL (is this possible?) it could be that you are so close the ragged edge with your tuning that any error in speed estimate and thus speed scalar, will push you over the edge in to limit-cycle oscillation.