24KG Quad light crash after manual PID tuning advice needed

ArduCopter Copter 3.6
1

Hello, we maidened a 23kg quad this morning. Started with default pid and while a little sluggish it flew. I than started cranking up P and I (and a little D to avoid wobble on recentering). All went well.

Than recharged and cranked up the PIDs even more, probably i got a bit carried away and went over.

At about 1 meter after a little comanded transition to the right when it stopped it started what it looked like a big wobble and hit the ground.

Quad has 28 inch props and P80 120kv T-motors with flame 80 Esc
12S
Black Cube on 3.6.6

I think the light crash was induced by to high pids but would like an opinion from somebody more skilled than me.

Please ask if you need any more details.

Log: https://mshelisrl-my.sharepoint.com/:u:/g/personal/davide_monti_mshelisrl_onmicrosoft_com/EW6i9iWVXhhKljwGoKA9cZEBapXqlgjUYTL2bY7r_HmqDw?e=Va6DfJ

Thanks,

Corrado

2

that’s what it looks like to me

why did you make ATC_ANG_YAW_P = 7?

3

Tried to have yaw a bit more reactive on input.

4

I’m pretty sure you want to adjust acro_Yaw_P. That used to affect all flight modes… Or at least it did for Stab as well as acro. I’m pretty sure that hasn’t changed.

5

Thanks will do that.

We made some more flights and noted the quad makes a big wobble when applying fast full collective.

Maybe something wrong with min mot??

I read that tmotor esc have a linear output from factory, should i change mot exp?

6

Built a 12S quad myself last month, with Alpha ESCs and almost crashed it in a loiter takeoff after the first succesful autotune. One ESC is responding slower then the other three, at low RPM.

I’ve since bought the pricey Tiger ESC programming tool, to try fix the issue.

7

Can you please post your pids after autotune?

1 Like
8

What’s your ATC_RAT_RLL_FILT, ATC_RAT_PIT_FILT values?
Change it 10 and try flying it!

9

Why manual pid tuning? With a proper filter and agressivity settings Autotune works like a charm with large and heavy copters. Tuned a 25kg and a 28kg heavy lifter and sprayer without any problems.

1 Like
10

i usually start with default pids and tune it a bit manually from there before attempting an autotune.

11

AutoTuning a 2kg quad (680mm frame/15 inch) still gave me what seemed like i-term buildup while descending on ‘land’ mode. Thankfully I had ‘acro’ mode ready to switch into it, otherwise wobbles continued to get worse and would have crashed. I tuned down i-term and descend speed and it worked much better after that.