[bmw111]

Hi, I've always gotten good help with my builds and have another issue I need an expert to help me sort out. I've posted a short video of the quad's behavior here:




It seems that no matter if I increase/decrease P or D, I get the same behavior seen in the video. The P/D were set at "400" and I moved them to "450," crazy oscillation and prop wash on sharp turns. The current settings are the best "compromise" I've found (somewhere between those settings above), but you can see there is still oscillation and "bounce" and a tiny bit of the propwash issue. Any suggestions for my settings? I've attached the UAV file.

Thanks for any help!

[TheOtherCliff]

Have you tried the OPTune/LPTune method?

Or you can try a simple ZN tuning.

First export your settings so you can go back if you want to.

(simplified ZN tuning)
Used "advanced" tab.  Set outer loop to default values and leave it there.  Set inner loop I and D to zero on roll and pitch.  Double the P on roll and pitch.  Carefully take off and see if it oscillates.  Increase or decrease roll and pitch P (just make them the same unless you want to tune roll and pitch separately).  Keep increasing / decreasing these P until it just starts to oscillate.  Now cut that P in half and start increasing both "I" until it oscillates or at least until it holds it's bank angle in turns when flying around.  If you have a some oscillation or ringing you can add a small amount of D to remove that.

[bmw111]

I used settings from a previous similar build and modified from there. I believe it's pretty close, so I'd rather not start over and do the fly/land/modify/fly/land/modify/ad nauseam thing again if at all possible. I've been doing that and don't want to get back in that frustrating loop. That's why I posted here to see if someone can look at my UAV file and relate my settings to the behavior seen in the video. Again, I feel I'm real close but the small changes I make to the settings don't seem to make any difference, but if I use larger changes, the oscillations get extreme. Just hoping someone can point to something obvious that I'm missing. Like, "Well, doh, your D's are way too high!" 

[TheOtherCliff]

That's why you should export your settings before trying it. 

Another quick thing you could try is to take your P, double it, plug it into OP/LPTune calculator and try the values it gives you.  The good thing about this is that if you want to tweak it, you just multiply all the PID numbers by something a bit bigger than 1 like 1.5 (if it feels mushy) or smaller like 0.75 (if it oscillates).  Repeat till it is the best place between mushy and oscillation.  You don't have to re-fly your UOV flight.

The simple method I described shouldn't be an endless search.  Where does P alone oscillate?  Cut that in half.  Adding I, where does it oscillate (or where does it hold bank angles correctly if you can't get it to oscillate)?  Back it off till it stops oscillating.  If there is ringing, add D till ringing stops.  At that point, if it isn't good, there may be a problem somewhere.  It shouldn't need tweaking.

What ESC protocol are you using?  You should be using PWM-490, PWMSync, or higher (= *Shot*).  Slow ESC protocol keeps you from tuning high enough to get rid of the mushy.