Cause of heavy vibrations

ArduPlane VTOL Plane
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1

Hi everybody,

I am just about to start testing my new VTBird 4+1, which I purchased as kit including the motors, ESCs, props, etc.

Even with freshly balanced propellers, I experience heavy vibrations when speeding up the VTOL motors and in the air. I put a link of a short video here for reference - short video of maiden hover. I thought that seeing and hearing the heavily vibrating aircraft would bring better indication for the origin, rather than providing a flight log, as I believe that the reason might not be a software issue but rather a failing component.

Can it be, that the fact that I fixed the FC directly on the board without any damping could result in such high vibrations?

Thanks in advance for your help

2

On-board flight logs are always better.
This seems tuning issue more than a vibration to me.
Follow the corresponding wiki.

3

Please find the .bin file of one of the maiden “hoppers” here : .bin file

4

Almost certainly. Look at these motor outputs oscillate:

RCout
RCout1688×517 79.4 KB

5

Hi Dave,

thanks for your help.
Don’t you think that the oscillation could be the result of an other anomaly (e.g. bad ESC timing), i.e., that the FC tries to compensate for something by adjusting accordingly the motor speeds?

6

I don’t think so. I find default ESC values to work OK in most cases. I should say I have most experience with multirotors but in this case that’s the mode it’s in so hopefully I can offer some relatable advice. If it was a multirotor I would suggest reducing the Q_A Rate Pitch/Roll PID’s until the oscillation is gone. Cut them in half or back to default and see how that looks.
You may as well set these so at some point you can configure the Dynamic Notch filter:
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4

7

Did you try loading the VTBIRD VTOL Parameter and Configurations 20201201 to see if that works?

Good luck.

8

Thanks, I did as you proposed some tests with lower PID values and got good improvements regarding the vibrations. At least, the VTOL is now flyable without any risk of structural failure due to the vibrations.
At this point, I think that I will be able to do some autotuning on the hovering before getting into the hard stuff of transition flights.
Thanks again for pointing me in the right direction.

9

Yes, I used the values from the mentioned parameter files, but a) it is from an old ardupilot version, i.e., it lacks quite a few parameters, and b) you saw the result of those parameters.
Some manual tuning improved the situation so I might go on with fine tuning now.

10

I would suggest you configure the Dynamic Notch filter before Auto Tuning.