Diagnosing vibration related issues

ArduCopter Copter 4.6
1

I am using a quadcopter with 15-inch propellers in X configuration with square tube arms to maintain alignment. The flight controller is mounted with damping.

During hover in Loiter mode, the drone is stable and no significant vibrations are observed. However, during aggressive pitch and roll maneuvers, vibration spikes appear. These vibrations are more noticeable during pitch-up and roll-right movements.

I have already performed the following checks:

  • Replaced propellers to rule out imbalance

  • Inspected motors — no visible shaft damage or dents

  • Verified arms — no twisting or misalignment found

  • Adjusted center of gravity to exact center — no improvement observed

  • Observed during tuning that Motor 1 consistently runs at higher PWM compared to other motors

Logs of recent flights

Current observation:
Motor 1 always operates at higher PWM, suggesting thrust imbalance or higher load on that motor, which may be contributing to vibration during aggressive maneuvers.

Request:
Looking for guidance on identifying the root cause of vibration spikes during aggressive maneuvers, especially related to motor thrust imbalance, frame resonance, or tuning/filter settings.

2

TBH those plates look thin and the mount appears to be fairly short meaning it likely isn’t stiff enough.

2 Likes
3

May I know why you choose silicone washer over a metal solid washer for the arm joint? Do you think is a potential cause of vibration?

Screenshot_2026-03-23-13-01-33-96_e2d5b3f32b79de1d45acd1fad96fbb0f
Screenshot_2026-03-23-13-01-33-96_e2d5b3f32b79de1d45acd1fad96fbb0f641×666 62.9 KB

4

Arm holder is 3d printed ABS, and has some irregularities with it, to overcome those irregularaties nylon washers were added.

No, i’m in disagreement with you on washers causing vibrations, as of those were added in last flight. I’m facing same issue since long back.

Though we are replacing those Mounts with new once, upon testing ill update you on same part.

Thank you.

5

Thank you @LupusTheCanine , will take you suggestion as an consideration for development.

Will adding supports between all arms help??? Or the braces holding arms ???

Or what else i can do you resolve this.

6

Importantly i want to know on what part shall i focus more.

Mechanical or Parameters, from my side i think that i have played with parameters a lot and hardware part is what need to be focus upon.

7

How deeply the tubes are seated in the blocks? I have seen boom blocks spaced noticeably further on smaller frames.

8

Hardly 20-30mm, that too with single through bolt

9

Are they tightly pressed into the mount? I have experienced that a bolts prevents “large” movements (and rolling) but will allow a tiny amount of play, making the arms able to vibrate.

I would personally use something like a clamp with the arms going in at around 30mm.

10

What fc are you using?

11

You can get that from the log
Pixracer

12

You should spend some time configuring RPM filtering, LPF 30 is not enough.

13

Will give a try

14

I have a holybro 650, and experience significant image vibration, and am trying to limit the problem for better video when the camera is zoomed in. I have found that the highest angular motion (not angular rate) is at about 60 Hz (propeller rotation frequency). This with measured with an external BMI160 IMU mounted on camera. When I attached 8mm carbon fiber stiffeners between the motors (using 3d printed soft tpu mounts), the 60 Hz went down greatly as well as other vibration frequency amplitudes.