Hexacopter tilting

PX4 Autopilot Multicopter 🛸
1

Hello all,

My hexacopter is equipped with a Cube Orange flight controller and is currently running the firmware version 1.13.3. Generic Hexarotor X is the configuration of the hexacopter. As soon as the drone autotuned in the QGC, it started flying flawlessly. Afterwards, I added a 135g weight to the second motor and autotuned the drone to make it stable.
Even with the additional weight, the hexacopter was performing admirably until today. Now, as the hexacopter takes off, it keeps tilting in the direction of motor 2 (rolling in the direction of the added weight) which leads to a crash. Subsequently, I adjusted the PID parameters to default and took out the weight, but the problem persisted. Even trying to go back to the autotuned numbers I had before the extra weight didn’t help, though. Nothing worked when I attempted recalibrating all of the sensors and ESCs.

I’ve attached the log files for your convenience. The 4th link is the log file of a good flight with additional weight (I am aware that vibrations are huge and I am getting a vibration mount for that).

Any help in resolving this issue will be helpful. Thanks in advance.

Flight Log link:

  1. https://review.px4.io/plot_app?log=c89a8497-a9e8-4727-b1f6-9133129daa0d
  2. https://review.px4.io/plot_app?log=b7cf84f4-5bf6-4f66-9e18-0d42702e568a
  3. https://review.px4.io/plot_app?log=956a2ad5-cdee-4c42-9429-fd3d783c369f
  4. https://review.px4.io/plot_app?log=d2a963a4-0dce-41c9-81ad-51d2520dc25c
2

that is interesting that it suddenly started failing.

but if you change the cg, dont you need to make a config change so that the autopilot knows where the new cg is? did you do that? and what portion of the total weight is 135g?

3

@MasterChief It was working fine until yesterday, even without doing the configuration. I didn’t do anything other than autotuning and don’t know what other changes to make. I didn’t get what you mean by " what portion of the total weight is 135g?"

4

I didn’t get what you mean by " what portion of the total weight is 135g?"

What is the take-off weight? If 135g is small compared to total take-off weight, then the CG is not moved by much and maybe configuration is not needed. But if it moves the CG significantly, then the CG shift should be accounted for somehow. I don’t know how well PX4 handles CG shifts yet, but there must be some parameters to at least partially account for CG shift.