Inquiry about "Actuator Control FFT" and "Angular Velocity FFT" in PX4 Flight Log

PX4 Autopilot
1

Hello,

I am reviewing the flight log of my OctaQuad, which is based on the Pixhawk 6X running PX4, and I’ve noticed significant disturbances in the “Actuator Control FFT” and “Angular Velocity FFT” when viewing the log via the Flight Review tool (according to FlightLog analysis instructions).

I would like to understand whether these disturbances could be related to flight stability or if they impact the overall flight performance. If so, what could be the possible causes of these issues, and what would be the recommended solutions? Additionally, I would like to know the ideal values or trends for these graphs.

System Details:

  • Quadcopter Type: OctaQuad (Coaxial Octocopter)
  • Flight Controller: Pixhawk 6X
  • PX4 Version: 1.15.4
  • GPS: Yes
  • Airframe: Generic 10" Octocopter Coaxial Geometry
  • Body Structure: Multilayered Carbon Fiber with Removable Arms
  • Dimensions:
    • Length (Nose to Tail): 230 cm
    • Width (Right Motor to Left Motor): 352 cm
    • Weight: ~170 Kg

I am also seeking clarification on the technical aspects of the “Actuator Control FFT” and “Angular Velocity FFT” in the PX4 flight logs. I don’t fully understand these parameters, including what values are considered normal or problematic. Any insights on what constitutes good or bad values for these graphs would be highly appreciated.

I would like to:

  1. Understand whether these disturbances impact flight stability.
  2. Identify potential root causes and solutions.
  3. Clarify the ideal baseline values/patterns for these FFT graphs.

Logs:

1- https://review.px4.io/plot_app?log=2fa38ee0-4845-4a11-965f-3a014022ad19

2- https://review.px4.io/plot_app?log=90bd1fb9-a4fd-4169-b41c-02590cc2d934

3- https://review.px4.io/plot_app?log=cd51047f-156e-4e6c-97b0-f1d2a295d466

4- https://review.px4.io/plot_app?log=7720c243-6e77-4f7f-8e82-070be4cb6203

Thank you for your support!

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