I have performed a hover learn and shared the results here for reference. I have also enabled INS_RAW_LOG. Kindly review the logs using the ArduCopter Review Tool and provide your recommendations on what can be improved, along with the best possible parameter changes that can be applied from your end.
Please review your compass calibration and tune it with magfit.
It’s worth to update ESC to something more modern with bidirectional dshot support for more bulletproof filtering.
Not sure about your MOT_SPIN_MAX, 0.8 is there a reason for limit?
Thank you for your feedback. I would like to provide some background on our setup and the observations we are facing, and seek your guidance for further clarity.
Previously, we were operating the following configuration:
Motors: T-Motor MN501-S 300KV
ESC: Hobbywing 40A
Propellers: 24-inch foldable
Flight Controller: CUAV X7+
Total All-Up Weight: 5600 g (5.6 kg)
With this configuration, we experienced sudden crashes, which we initially suspected were related to the 24-inch propellers. Based on this assumption, we decided to reduce the propeller size and switched from 24-inch foldable props to 21-inch Tarot propellers.
To validate this change, we performed bench tests on both ESCs at approximately 70% throttle. During these tests, we observed that the Hobbywing 40A ESCs were heating up significantly, and the motors were also getting quite hot. In contrast, when we conducted similar bench tests using EMAX BLHeli ESCs, the heating was considerably lower for both the ESCs and motors.
Based on this observation, we considered upgrading to a 60A ESC.
However, one issue we are not able to clearly understand is the inconsistent motor heating pattern. At times, motors heat up diagonally, and at other times, only a single motor (often the 3rd motor) shows excessive heating. This behavior is not consistent across flights or bench tests.
We would appreciate your guidance on whether this issue could be caused by:
Inadequate or improper filtering (e.g., lack of RPM-based filtering due to non-bidirectional ESCs), or
Some other factor such as mechanical imbalance, ESC timing, motor condition, or power distribution-related issues.
Regarding MOT_SPIN_MAX = 0.8, we have currently limited it as a precaution to avoid pushing the motors and ESCs to saturation during testing. If you recommend revisiting this value, please let us know the best practice for our configuration.
The best practice is to use the correct MOT_SPIN_MAX for your ESC/Motor/Prop combo. And that is the value at wich the output has a non-linear saturation.
If you want to increase safety reducing that value artificially is not the correct way.
The correct way is to limit the MOT_*_SLEW. That will limit the amount the motors heat up.
I guess you have not used AMC software yet.
If you were using AMC software, it would have suggested you to do that already and you would not be in this situation.
Got it! So, to avoid overheating and ensure safety, I should focus on setting MOT_SLEW_UP and MOT_SLEW_DN instead of artificially limiting MOT_SPIN_MAX.
What values would you suggest for MOT_SLEW_UP and MOT_SLEW_DN for my ESC/ Motor/Prop combo?
I am facing the error “AutoTune: Twitch Size Determination Failed.” I have attached the flight log below for reference.
Earlier, I applied QuickTune using values derived after configuring the harmonic notch filters. Compared to the previous flight, the drone’s vibration levels and motor sound were noticeably smoother. After this, I performed QuickTune and obtained the new tuning values.
However, I observed that the motors were heating diagonally, so I initially reduced the D gain by 20% to reduce motor load. Even after QuickTune, motor heating was still present. I then reduced the P and I gains as well, but although the heating reduced slightly, it did not fully resolve the issue.
When flying in Loiter mode, the drone felt aggressive but not loose, so I decided to proceed with AutoTune, keeping the AutoTune aggression at the default value. The tuning started normally, and the Roll rate D tuning completed successfully, but repeatedly after that, I encounter the error message:
“AutoTune: Twitch Size Determination Failed.”
Could you please guide me on why this issue is occurring and what changes are recommended to resolve it?
Harmonic notch filter is OK.
There’s some other minor adjustments I would have made (via Initial Parameters) but that will be OK how it is.
I would make these PID changes though:
it was observed that when aggressive pitch and roll inputs were given through the joystick, the aircraft started oscillating. Due to this behavior, these parameters were reverted to their default values, after which the oscillations were no longer present.
A test flight was conducted at an altitude of 100 meters with a forward speed of 8 m/s. Kindly review the setup and provide feedback on any further parameter adjustments that could be made to achieve a smoother flight experience.
I could not notice a big difference between having the ATC_LAND parameters set and not, they are really just related to being landed.
You could probably just try Autotune now and see what that produces.
