Low frequency oscillation

[wynnsquad]

RCEfan,

Thanks for sharing this video. This appears to be EXACTLY what my copter does too. I’ll try tomorrow to upload a video of mine. As far as the tuning thing goes, I’ve been playing with the tune a lot and so far I can’t find a better tune than David’s default setup. I thought for a little while that lowering the I term was helping but now I’m feeling like it didn’t make a significant difference.

I’m not giving up yet though–we’ll figure this out!

[wynnsquad]

OK here’s my video clip. It’s not easy to see for most of the clip but you can definitely hear the oscillation throughout. Sorry I couldn’t keep the copter more steady and in frame.

[biggestRCEfan]

Thanks mate. Looks similar. Will look into PIDs myself to see if I can make any headway.

[wynnsquad]

RCEfan,

Just sharing a clip from my FPV flying this evening. Man I really feel like this thing is pretty locked in (or as much as you’d want it to be for a tricopter) if only it weren’t for that darn wobble. Does your FPV footage look similar?

[biggestRCEfan]

Yep, same as mine. Haven’t made any progress on my side. Love flying it though.

Nice area with the mountains? Where is it?

[wynnsquad]

Same here, still love flying my tri.

I’m in Utah U.S.A. and those are the Wasatch mountains. They are beautiful and I really enjoy them.

[Tabarish]

Hi there.
I had these issue with my tricopter and I could improve its stability by changing the PID values for pitch and roll.
My tricopter setup is the same as the shop provide, all purchased in rcexplorer.se except for the receiver of course.
I started with the PID values that David posted in the guide, then I raised P values a lot and its behaviour improved.
Here you have my PID setup:
And some videos of the result:

I hope this information help you 😉

Attachments:

1. 

   TricopterPID.jpg
   

[biggestRCEfan]

Sweet, thanks mate. Will give it a try.

[wynnsquad]

Cool! Thank you I’m excited to try your gains. I never would have guessed that I might need to increase my gains so much but it looks like it might be the ticket! I’ll give it a try and report back.

[biggestRCEfan]

I upgraded to triflight 0.7 Beta 2 and increased the P gains on pitch and roll. It did appear to improve the low-frequency oscillation. Haven’t pushed them as high as Tabaris but will play more to see the best I can get. But first trying to get the tail dynamics sorted that came with the new firmware.

[wynnsquad]

RCEfan,

Great to hear! Unfortunately I’ve been slacking on my side and haven’t been able to try out the new gains or anything yet 🙁 Hopefully soon.

In a support ticket with David I asked him about parameters that might need changing in order to get the 0.7 tail behavior improved and this is what he said:

Try disable tri_motor_acceleration, tri_motor_acc_yaw_correction and tri_yaw_boost

You can also probably reduce tri_dynamic_yaw_maxthrottle quite a bit.

Fly it, tune the PID’s on the tail and then try enabeling the tri_yaw_boost first to see how that performs you can try the other parameters as well but try one at a time to see how it makes the copter feel.

Anyway maybe this can be helpful for you as you try to improve tail performance. Hopefully I’ll be able to try it out and get some work done on my side soon too.

[biggestRCEfan]

Cheers Wynn.

Lauka suggested:

I would advise to try out the new yaw control branch.

Do you have airmode on? It should help with the pitch control

Will flash v8 of his alpha firmware he just sent out (I have 0.7 Beta 2). Will see if that helps.

[biggestRCEfan]

Just came back after I maidened my V4 with the 0.7 Beta 2 v8 firmware. Lauka was right, the jumpiness in pitch with sudden yaw inputs are gone. Had a blast flying LoS. Couldn’t do the in-flight tailtune as it was too windy.

Thanks Lauka, your work gives us much pleasure!

I now need to work on the yaw PIDs, as the yaw channel is a bit soft. Step inputs does not give the same sharp, crisp response as on the pitch and roll channels (my PIDs are the same as I used in 0.7 Beta 2). But first I need to figure out how to add yaw D gain to the lua script as for quads this parameter appears to be ignored and hence not included in the lua script. I am expecting that the D gain will have to play a roll in getting yaw response crisper.

[wynnsquad]

Just tried the gains from @Tabarish on my V4 running 0.5 and the oscillation magnitude I think has gone down, and the frequency has gone up. These seem to be a good set of gains. Overall I’d say it’s a significant improvement as now the oscillations may be in range where the vibration-damping camera tray can do its job. Haven’t tested it with the camera rolling, but seems like it may be the case.

Still looking forward to trying Betaflight and 0.7 though

[Siclair]

Have you tried the old trusted Triflight 0.5?

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