Acceptable motor vibration threshold for industrial multirotor from PX4 ULog logs? Long high-load flight observation

Flight Testing & Log Analysis
1

Hi everyone,

I’ve been bench-testing multiple brushless motor variants for heavy-payload industrial multirotors (survey, power inspection) and noticed obvious vibration differences across different stator winding, magnet grade and rotor balance designs.

From static vibration sensor testing:

  1. Motors with thinner silicon steel stator show higher high-frequency vibration under sustained 60%-85% throttle (common hover load for inspection missions);

  2. After 40+ mins continuous high-temperature operation, magnet performance decays slightly, and vibration peaks rise noticeably in ULog vibration records;

  3. Low-KV high-torque motors produce lower amplitude vibration at cruise speed, but obvious vibration spike during rapid vertical climb with full payload.

I’ve seen some guides mention acceleration peak-to-peak threshold around 2–3 m/s² as safe, but I want to confirm real field experience from long-duration industrial flights:

  1. What vibration reading range do you keep as the safe upper limit to avoid PX4 EKF divergence or PID oscillation?

  2. Does motor thermal aging shift vibration characteristics mid-flight and mess up notch filter tuning?

  3. For fleet operation with daily multi-hour flights, what motor mechanical specs help stabilize vibration logs long-term?

Thanks for sharing your ULog samples and tuning tips!