Autotune Zeta WingWing Z84

[Matthias_Hryniszak]

Hello,

I am trying to autotune my long-range Z84. I started with a quite low AUTOTUNE_LEVEL of 6, but it resulted in the plane getting vertical oscillations. So I thought maybe the value is too high and went down to 3. This changed only the responsiveness of the plane (was slower on 3 than on 6) but the oscillations didn’t vanish. In the end I tried 9 and it went much better!

The main difference that I could spot was in the D-term (over 3x smaller). I didn’t notice those oscillations when D-term was 0 (factory default) so maybe that’s the culprit?

Z84 is a pretty small (84cm) flying wing with quite big control surfaces. I was wondering if there is maybe a better procedure for tuning such a small and agile plane? Also, should I try with a higer AUTOTUNE_LEVEL value? Are there values above 10?

Cheers,
M.

[Allister (Allister Schreiber)]

I’ve noticed the same issues with high D-term values after autotune causing oscillations. I ended up manually tuning the plane but I’m not super happy with the results.

AP4.1 has a new autotune function that is supposed to address this problem so I’m hoping to try that out and see if it improves things.

[Matthias_Hryniszak]

I’m on 4.1-dev installed like a week ago. Which autotune mode should I be using to get “the new one”?

[Allister (Allister Schreiber)]

I haven’t tried it yet so I can only offer what’s posted here: (but I’m guessing you’ve probably read this link already)

New fixed wing PID system and autotune

[ArduPilotPlanePorter] Last month we finally merged the new fixed wing control code slated for the ArduPilot plane 4.1 release. This provides a major improvement in several areas: much better manual PID tuning, with clearer parameters and much improved filtering new fixed wing AUTOTUNE system which produces a much better tune for a wider range of aircraft The key change in the PIDs is we are switching to use the same PID code that is used for VTOL aircraft in ArduPilot. This leverages the g…

[Matthias_Hryniszak]

So… I have the new AUTOTUNE and it does make the D-term too high on my wing on low AUTOTUNE_LEVEL values.

[Allister (Allister Schreiber)]

I’m disappointed to hear that. I’ve been holding out for this new autotune.

I’ve moved this thread to the Plane 4.1 section. This way the dev’s will see this. Perhaps there is an issue with the autotune function in 4.1 beta.

[Lanza]

Have you tried with the new 4.1 Beta 4 ?

[Matthias_Hryniszak]

No. I switched to INAV. It’s new algo for tuning the plane works good enough. I was able to then tune the leveling in-flight with adjustments and it all works great now.