Motors running rough

ArduCopter Copter 4.1
1

Hi

I’m having a strange thing happen. I did a flight and found the performance not that great. Landed due to the battery running low. Changed to a new pack, then found the motors running really rough at idle and the motors not wanting to spin up. Sounded like rusted nails in a tin can.

My system did report software updates and I upgraded both Mission Planner as well as Copter to the latest versions.

The same issue persisted so recalibrated everything including the ESCs. Problem persists.

If I rotate the motors by hand then there are no obstructions.
if I test the motors one at a time motor 1 runs ruff consistently. Motors 2,3,4 runs smoothly every time.

Arming the system and getting initial idle speed, all the motors run rough.

Logfile of a short bench test at https://drive.google.com/file/d/1-rvPZ0cG5K8j550ub7LdBIwERfGAQKyc/view?usp=sharing

Regards
Kobus

2

MOT_SPIN_MIN is lower than MOT_SPIN ARM. You don’t want that. You have a reason for MOT_THST_EXPO at 0.2? Is this log with no props I suppose? It would be more useful to see the log from it flying.

3

Thanks for the response. Not sure where the MOT_SPIN_MIN and MOT_SPIN ARM values came from. I reset them to their defaults (0.15 and 0.10 respectively.

The motors do not spin up fast enough to get the drone in the air, even at 100% forward stick.

I did another motor test with motors 2, 3 and 4 running smooth but 1 sounds like its timing is out.

I’ll try run some more tests a bit later.

4

How to set MOT_SPIN_MIN and _ARM
https://ardupilot.org/copter/docs/set-motor-range.html#setting-spin-armed-and-min-throttle

5

Thanks Alisteri set the values as they should be and still had strange behaviour

I defaulted the FC and reran the entire setup process, fligt settings, radio calibration, esc calibration, etc. The immediate motor test had all four motors run smoothley and i took the drone for a flight. All seemed fine in stabalise mode, tried alt hold and position hold. In position hold the drone drifted a bit and the controlls become progressivley worce.

I reset the the FC and set to stabalise. Spun the motors up a little and they sounded like a car misfiring, smooth cough, cough, smooth. I could not take off in this state.

Ive uploaded two log files. One testing stabalise, alt and position hold, the other of the irratic motor behaviour.

https://drive.google.com/file/d/10-9lWsI8Jps28Wfz6OkS09YgXbeIJ91J/view?usp=sharing
https://drive.google.com/file/d/1016zmySREmjen1XKTSpQi4pFSKBN5WmP/view?usp=sharing

This is very odd.

6

PS
I try to run auto tune while I was in position hold but this had no effect on the drone. it did not seem to do anything so I disabled it again.

7

OK, it seems my issues are far from over. Since my last post the motors ran fine. This changed this afternoon though.

I flew with one battery without any issues.

Then changed the battery pack. No settings were changed between the two flights.

After arming the system the motors run rough and then settles after a few seconds. After a disarm and arm all seems fine (somewhat) until I take-off, the drone loses power and dropped to the ground.

During the next test flight, the drone seems better but then does a ground-loop, all on its own.

I’ve uploaded the bin file of the flight with the second battery pack as well as two short videos from the onboard GoPro. You can hear the motors running rough and settle to smooth.

Bin file - https://drive.google.com/file/d/1DOdCEN5orjMlySrFw6eN69l7t6xG_LyE/view?usp=sharing

Motor running rough then settles to smooth - https://drive.google.com/file/d/1szVThnrwi_j_woKXvSXntp9eJBZa-VFk/view?usp=sharing

Motor inconstant drone loses power after take-off - https://drive.google.com/file/d/1d_J7PcFklGi9p1vz2QT7MnFlKxkixiEd/view?usp=sharing

PS. The Drone seems to oscillate quite a lot when it hovers. As soon as I climb or descend this stabilises.

Some help will be greatly appreciated

8

My Advice: Follow the tuning wiki and do some alt hold tests. I think tuning them position controllers will resolve the issue about drone not being stable and oscillating when hovering.

9

whats your esc? do you have video

10

Thanks, yes I’ve tried autotune but that had no effect at all - none that I could see anyway. I’ll check out the tuning wiki.

11

The ESC is a 4-in-1 T-Motor P60A

12

Yes please follow the the tuning wiki because you have to set the input shaping parameters before autotune unless autotune does literally nothing

13

I’ve uploaded another short vid showing the vibrations in hover. This seems to go away if i change the motor speed.

https://drive.google.com/file/d/16qLGXifIa0qpjltCq7WJoaNRjRMO9JHt/view?usp=sharing

14

Thanks’ ill have a a look at the tuning wiki to sort out the vibrations.

This still does not explain the strange motor behaviour - just running rough and losing power for no reason.

15

I would say that your battery is sagging but you said you changed battery. BTW we also had that problem motors were turning like they have something in them we overcame that problem when we discovered that our motor cables were not soldered well to the 4in1 esc also we used a hair dryer to blow some air into the motors and it was resolved. We also had that issue but probably we had something in our motors but it is worth giving a shot

16

Thanks, I’ll have a look at the motors but don’t think there is anything in them. It is time for a bit of a cleanup. The cables from the ES to the motors are soldered properly without any dry joints. I’ll disassemble the drone and check the cables between the FC and ESC. There might be some issues there as this is the only link I cannot check without taking the drone apart.

17

Good luck on that my guy

18

Also this an other way we tried if you soldered it well. Run a motor test without propellers on Mission Planner just start with %15 throttle for 2 secs and start increasing slowly with %10 untill it removes the sound. Actually it works we also tried this and it works. But I dont know if it will damage the motors or smth. so it is experimental

19

Thanks. Yes, I’ve done that before. running on the bench it either runs well or runs rough. increasing the spin % while running rough does not change anything. While running roughly the motors will typically only spin up to around 10-15% power and nothing beyond that.

I’ll have proper look. The motors running rough is really starting to sound like a physical connection issue rather than a programming fault.

20

Turn off LOW RPM POWER PROTECT in Blheli32 settings in the ESC