HolyBro S500 Setup

Hello,

I have been working on setting up a HolyBro S500 ARF frame (Holybro motors, ESCs, etc) with a Pixhawk 2.4.8 (Pixhawk clone) flight controller. For some reason, even though I selected the HolyBro S500 reference frame on first setup, the oscillations were so bad, I could hardly get off the ground with the aircraft. After reducing/adjusting the roll/pitch PIDs a bit, I think it is flying a lot better, but I was wondering if anyone could take a look at this log and give any suggestions on improving performance (or explain why the S500 Reference params didn’t work in the first place.) Thanks! The log I’ve linked here is a flight with the modified PIDs.

https://review.px4.io/plot_app?log=6d712716-a8b3-4361-9b55-d893f7512ea4

Just out of curiosity, how have you mounted your Pixhawk? Any photos you may share??

Sure thing! I have used a vibration dampening mount.


@mwbb Any suggestions or ideas what could be going on?

To be honest the PIDs still look pretty bad.
I would tune it down heavily and then work your way up.

I would recommend following these guides:
https://docs.px4.io/master/en/config_mc/pid_tuning_guide_multicopter.html

(this one explains PIDs really well)
Quadcopter PID Explained - Oscar Liang.

Oh, also, what battery are you using?
If it is too high of voltage this could cause this unstableness.
I believe the suggested battery is 4 cell.

Thanks for the response, @Andrew_Wilkins. I will have another look at those guides, I know I have a ways to go with understanding the tuning process well. I am using a 3S 5000mAH battery, unfortunately do not have any 4S. This might not be a question for you necessarily, but I guess my underlying concern here is why/how are the default PIDs for this frame/setup so far from what is flyable? I understand that every setup is a bit different, but would using an older flight controller and a 3S battery have that much of an effect on the PIDs, all else being equal?

I also have similar issue but with s500 frame. After a lot of searching here and there, the wobbling and vibrations issue solve by selecting other frame type. Have you tried all the frame type? This is the cheapest and quickest solution for me. And i hope for you too.

No it would not. 3S should be fine here. If you were using a 6S that would be different.
5000mAH should be fine as well.

The older flight controller should not make a difference.

I know our S500 was a bit wild at first as well. We did have to turn down the PIDs a bit, but the oscillations weren’t so bad that we could not takeoff.

@zihad_mahmud makes a great point. I wonder what would happen if you chose the “generic quadcopter” layout.