High Vibrations in Arms

🧪 Flight Testing & Log Analysis
1

Hello!I just assembled my very first drone, and I’m really excited for the first flight. However, every time I ARM the drone, I notice some vibrations in the arms, when in Stabilized mode (Even Manual). On increasing the throttle, the vibrations become more prominent. These vibrations are present only when I try to balance the drone in its stable position. When I tilt the drone along the sides, it vanishes. I have calibrated the drone a lot of times, but the problem still persists. There is no vibration when I change it to Altitude mode. I am currently using the following components:

FC: Pixhawk 2.4.8
Motors: Emax ECO 2306 (1700kv)
Frame: 5 inch generic Quad frame
ESC: Littlebee 30A

I also don’t have an RC hooked up as I want to achieve completely autonomous flight (I know this is a bad idea, but I’m low on time and resources to purchase one now). I’m using Qgroundcontrol Virtual Joysticks to initiate flights.

I took a log and obtained the following results with default parameters.
https://logs.px4.io/plot_app?log=73141bba-8703-4618-9eab-9add677b82d7

I haven’t done any kind of PID tuning (Not sure how to go about it). I have tried smoothing the Actuator Control FFT graph by varying IMU_GYRO cutoff and MC_DTERM cutoff. However, across a wide range, the default ones seem to reduce the vibrations the most.

Would love to solve this problem at the earliest as I have to present this project at an expo.

Thanks a million!

2

@bkueng you might be able to help here.

@antonyjohne make sure to check this: https://docs.px4.io/master/en/config_mc/pid_tuning_guide_multicopter.html

3

Indeed! :slight_smile:

You need to do the PID tuning. I don’t see much from the log, but the gains are probably too high. You can try to reduce MC_{ROLL,PITCH,YAW}RATE_K, or change the airframe to ‘Generic 250 Racer’.

4

Thanks for the reply! Will try out your suggestions and reply. Are you sure you don’t notice anything weird with my Actuator Control FFT graph?

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