Twitching when hovering and hot motors after flight

Hi, For the past 2 days I have been trying to figure out why my drone is all of a sudden twitching while flying. I initially thought this was a vibration issue as when I take the props off and give it some throttle the motors twitch, but if I hold the Pixhawk the motors seem to work fine. Today I tried to fly and it was twitching so bad that it was hard to keep it in the air. After trying to fly the drone a few different time the latest flight was much better, but only lasted a few minuets and it still had some twitching and the motors were very hot afterwards. I will attach a video link as well as the flight log from my latest flight.

Flight Log:

Set up your dynamic notch filter, then continue with the tuning.

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Thank you for the recommendation. Ill try to set that up tomorrow and let you know!

Hi, I was testing to see if my motor screws were possibly too long. I have a multimeter and tested continuity from the motor screw to all motor wires and got no continuity. After that I tried seeing if there is continuity from screw to screw and there was. I removed the screws and checked if there was continuity from screw hole to screw hole on the motor and there wasn’t. I’m guessing this is not ok but I can clearly see that the screws are not touching the motor when there are all the way screwed in. I was wondering if you knew anything about this. Thank you!

Screw to screw seems like there should be continuity, because the base plate of the motor is a single metal part. I’m a little surprised you didn’t get continuity when you tested directly. I suspect there is a coating or paint on the part that might have created a high enough resistance that your meter didn’t beep. I would be curious to know what the actual resistance was. If you can clearly see the screws aren’t touching anything in the motor then you’re fine there.

Like wise, you shouldn’t get continuity across the screws to the wires.

Now I’m curious what the resistance would measure too. I’ll check when I get home and let you know. After looking into it a little more I’m pretty positive the screws are not touching the inside of the motor. The only reason I was concerned is because the bottom of the motor is not conductive. Guessing they have a insulating coating on them. If I measure continuity from screw whole to screw hole though I do get continuity so the coating has probably worn off in the screw holes.

The reason they are hot is because the outputs are oscillating like crazy.

Pitch and Roll Rates looks terrible:

This craft needs tuning not a multimeter.

Thank you for the reply! I’m pretty new at tuning these could you point me in the right direction? Or can you not tell from that log?

I did set up the harmonic notch filter but haven’t been able to fly it since it’s been raining the past couple of days

You want to get to a point where you can run Auto Tune. It likely won’t run now. It looks like you increased the Rate Pitch/Roll P&I from default. That’s probably going the wrong way. Set them back to default (.135) for now or a bit lower (.120). Then you need to establish a proper MOT_THST_HOVER value by hovering for awhile in AltHold or Loiter. Then set these:

Then do a test flight and see if the RCouts have stopped oscillating.

That’s good if done correctly. Let’s see the pre-filter configuration Hover flight you did.

Thank you for the advise! I was able to get the quad to fly in an acceptable manor for auto tuning. I did attempt the auto tune today but It was very windy and I did not have too much room in my backyard. I’m going go to an open field tomorrow and hope for the best!

And those logs are from the pre filter hover flight.

The log you posted doesn’t have INS_LOG_BAT_MASK enabled so it would be useless for determining Notch Filter configuration.

Yea, don’t bother attempting Auto Tune if there is any wind to speak of.

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So unfortunately the wind has been pretty bad the past couple of days so I couldn’t do the autotune. I do have a question though if you don’t mind. The drone I have build is being used for object tracking using openCV. A problem im having is that in guided mode I have it go up to 6 feet and it will reach 6 feet but then occasionally drop down a few feet then back up. Is the altitude fluctuation a part of the PID’s not being tuned or something else. I linked the log file from the last flight and a video of the drone from that same flight.

log file:


These are not set correctly:

MOT_THST_HOVER is .146 and I should be 2X P as stated above and in the Tune Wiki. And while you are making these flights you may as well set INS_LOG_BAT_MASK to 1 to collect data for Notch Filter configuration. That needs to be done before Auto Tune is run.

Ok will do thank you!