See thread here for current discussion.
http://diydrones.com/forum/topics/fine-tune-pid
So I've read and tuned and tried a number of things, but I can't seem to remove this problem. I'll try my best to describe what's happening. Running quad in X formation.
- I give the copter forward stick input and fly the copter down a long field, overtime (say 10 seconds, it feels like my forward pitch control input is lessened, but it still moves forward).
- When I remove all control input, and the copter does this giant pull back; it pitches back 30+ degrees and moves 1-3 meters backwards, levels out, and is then again stable.
Replies
I get this exact behaviour when DMP is enabled
Here's a video, more details edited in the top. When I decreased Pitch Rate IMAX from 5 to 1, the problem got worse. So when I went the other way, up to 20 on IMAX, it didn't act much different than 5. You see that it doesn't really appear when I roll, but it's very clear with pitch. This is occurring in stabilize mode. The more forward flight I do, the worse it gets.
Surely someone else has had this problem.
http://youtu.be/qt5UDB-Z4k0?hd=1
This is the exact problem I'm having on my quad, only pulling to the right as well as back, and it doesn't level out, it keeps going... if you have a wireless link, check what the level is in the hud immediately after you land it, and see if it registers down. On my quad, the accelerometers aren't holding level, the level "changes" or resisters on the HUD that it has changed when I land on a level surface. It places the quad as tilted forward and to the left.
This is solved with Pitch Rate I, and Imax. What are your values?
What mode does this happen in? I have seen similar resistance to flying when I use Loiter and force it to change locations. In those cases I find it much more natural to switch to alt-hold, fly, then re-engage Loiter.
If this is happengin in Stabilize mode, I would think you have possibly a low Stab I term with a high max I value. The very low gain builds up against you and can only unwind slowly if the gain is too small. When you relax the stick it pulls you back until the I term can reduce. If it is too high, you would get oscillations.