Drone not stable in flight

HI all, I’m kinda new to this platform and I made my first test flight yesterday with a Pixhawk 4 mounted on a custom frame, (2.2kg takeoff weight, 570mm base wheel). I used the Holybro s500 frame in the QGroundControl setup and used default gains. During my first flight I noticed low frequency oscillations and the drone was very unstable, it has been very hard to land it successfully. I guess I have to tune the PID controllers but I’m a noob with PX4 and I wonder if someone could take a look at the flight video and suggest a correct procedure in order to tune my quad.
Thank you in advance and any recommendation is well accepted :smiley:

Video of the flight:

Hi @Matte_Lanni !
Have you read this document?
After seeing the video, I would say that the overall rate gains are too high. Reducing the MC_ROLLRATE_K and the MC_PITCHRATE_K should increase stability: lowering them from 1.0 to 0.6 should stop the oscillations; then you can play around with this parameter to have the desired response/stability ratio. (The K gains are not in the document but they basically lower P, I and D at the same time)

Have fun!

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Hi @bresch thank you very much for your help!
Yes I read the document but honestly I found it a bit confusing because this is my first experience and I have a lot of things to learn yet :sweat_smile:
I will proceed following your suggestion, thank you very much :smiley:

Hello Mr. @bresch I ask for your help again, or anybody who can suggest how to solve the problem.
I followed your advices, read the document again and modified the MC_ROLLRATE_K and MC_PITCHRATE_K parameters, and here is what I obtained with my quad:




I would have proceeded bringing the two parameters both to 0.35 because I think I was getting some results but suddenly after the last crash I burnt an ESC and I’ll have to replace it. In the while I wondered if someone could tell me if my approach was correct or not and any other suggestion is well accepted :sweat_smile:
Thank you in advance

Hi @Matte_Lanni
I’m not really an PID expert but I was able to achieve stable flight on my S500 by increasing MC_ROLLRATE_D MC_PITCHRATE_D to 0.40. Let me know it it works for you as well.

Hey @Matte_Lanni Did you ever figure out the solution? I am having a similar problem.

@JaredJLG Please open a new issue, please upload the ulog from your flight to Flight Review, and make sure to share the link.


That is pretty erratic flight performance. Did you calibrate your ESCs, either individually or all at once?