Pixhawk [2.1] Firmware [3.5.2] - Wobbles and out of control

Hi guys,

I am trying to set up my new Pixhawk 2.1 board, but when I try to fly it is so wobbly and becomes out of control.
When plugged on the computer, I sometimes have the warning Bad Gyro Health.

Here is what I tried to do without any success:
Flash another type of vehicle and reflash 3.5.2 quad firmware
De-activate the GPS
Lower the PIDS to minimum
Tried the board on another functional quad
Change battery, it worse with a 4S one than with a 3S
Calibrate successfully a few times the ESCs

I have also noticed the light below the cube is not green when powered, is this showing an issue?
Here is the log of my lastest try where I lost control and crashed 2m away from me…
2017-09-20 10-07-30.log (225.4 KB)

Anyone has ran into this crazy wobbling issue?

Why did you lower the pids to minimum? Have you tried flying with defaults?
Crazy wobbling is either bad tuning or bad vibrations.

Yes I first tried to take off with normal PIDs values, but it is really bad, I cant even fly…
I tried to lower them down to see if it improved, my quad is a 280mm, smaller than everyone else I guess.

Set your gains to 1/3 default and raise your filter values to 30 or 40, then see if it is flyable. If it is, do a pos hold autotune.

the log is a bit too short to tell something useful. Are you able to post a longer log?

I have done the firmware upgrade to 3.5.3, set gains to 1/3 and raised up filter values to 30.

Here some updates (not necessarily linked to the changes IMO)

5” props + 3S battery = No oscillations ( or not noticeable)
5” props + 4S battery = No oscillations ( or not noticeable)
6” props + 3S battery = bad oscillations
6” props + 4S battery = very bad oscillations to control loosing.

And here is a video of what happening on 6” props + 4S:
Link to video

Any other idea? I will post a longer log of the bad setup soon.

Thank you!

for the 6"/4S setup, half the gains yet again, then try poshold autotune. You may have to increase the filters again: do this incrementally (10Hz at a time), but you want this figure as low as possible so try decreasing the gains and autotuning first.

Also: vibration isolation for the flight controller! Just a little, but it really does help.

Sorry stupi question…
How can i lower the gain ?

Thanks in advance.

Kind regards: Jan

Here are the PID values I manually tuned on a 210 mini quad with a soft mounted PixRacer. I’m not suggesting you copy them its just to give you an idea of the direction you will likely have to take with respect to Rate Roll/Pitch PID and filter.

On the advanced tuning page in missionplanner is easiest if using windows. Read the wiki on tuning though - it’s pretty useful.