UA/Gimbal Stability

Vector_Joe · Apr 12, 2021

Hi All, Looking for some guidance.

I just inherited a P3P for use with our Emergency Management Agency. Prior to this, it has been sitting in someone's office for an unknown amount of time. I have no idea how much it was used (or abused)

The majority of my flying has been with a Mavic Air (2+ years).

So I charged the 3 batts and the controller. Everything seemed to charge and connect properly. I'm not sure how much of a charge they'll hold, but the 3 batteries were able to go for <10 min flights so far each.

Anyway, from a handling perspective, it seems a bit jittery. Much less stable than my MA. I know that they are quite different airframes, motors, etc. but seems like more than I'd expect.

So I put together a couple minute video comparing the video output (from the SD cards) from both drones, side by side. I don't think that there is anything in the settings that is vastly different from the default on the P3P. In looking at the video, it definitely seems like there is something wrong with the gimbal, but just hovering, it seems like there also may be an issue with the flying. It has a bit of a hard time just flying a straight line.

But I'm not very familiar with the P3P, so I'm not sure where to start to diagnose the issues. Any help would be appreciated.

Edit to add: from about 0:20 - 0:35 seconds, the P3P is just hovering.

Thanks, Joe

KachemakDiver · Apr 12, 2021

Yeah, that’s not right! I would do a IMU calibration just because it sat for so long. Check the 4 white rubber gimbal vibration dampers, make sure the camera isn’t held too tight with the plastic pins. There should be only two of them total, located at opposing corners. Maybe look at prop balance also.

cheddarman · Apr 13, 2021

Little bit jittery and as has been said, possibly gimbal assembly too tightly attached to frame. Check mount, it should just hang loosely from the frame on the rubber mounts. The cable ties should just be loose, there to catch the mount should the rubber mounts become detached from a heavy landing.
I'd expect much more vibration if the props were unbalanced, but yes, check their balance if you've got some way of doing it.
When you turn the P3P on, does the gimbal do its dance routine? With drone off, is the camera free to move on its two axis, nice and smooth?

Vector_Joe · Apr 13, 2021

KachemakDiver said:
Yeah, that’s not right! I would do a IMU calibration just because it sat for so long. Check the 4 white rubber gimbal vibration dampers, make sure the camera isn’t held too tight with the plastic pins. There should be only two of them total, located at opposing corners. Maybe look at prop balance also.

Yes, did the IMU and gimbal calibration again this morning. Not much if any improvement. The gimbal seems free to float and is attached by 2 pins. I'm probably going to order new props, but the old ones don't seem that bad.

Latest flight:

Vector_Joe · Apr 13, 2021

cheddarman said:
When you turn the P3P on, does the gimbal do its dance routine? With drone off, is the camera free to move on its two axis, nice and smooth?

Yes, it does it's range of motion test and it is free to move while off. Not sure what else to check. While hovering, it won't hold position very well (at least not compared to my Mavic Air).

cheddarman · Apr 13, 2021

Um, older technology than the Mavic, my P3A is rock steady (I think). Flew last week in a strong wind and no problem holding position.
Props might look oK but it is possible for them to be out of balance slightly and at the RPM they do this can cause vibration. Be interested to know whether new props solve the issue.

KachemakDiver · Apr 13, 2021

I would also loosen the set screw on the yaw arm and adjust it so it’s not rubbing on the plastic filler plate. In the pictures it looks like it’s rubbing a lot. Might be picking up some vibration there.

KachemakDiver · Apr 13, 2021

You’re also getting some “ jello effect “ in your video. Maybe the set screw for the yaw arm is loose and causing the whole problem.

cheddarman · Apr 13, 2021

May I respectfully suggest you put a loosely tied cable-tie through the two mounts without the pins! Save the camera in a hard landing?

KachemakDiver · Apr 16, 2021

@Vector_Joe , any progress on your video problem?

Vector_Joe · Apr 16, 2021

KachemakDiver said:
@Vector_Joe , any progress on your video problem?

Yes. Thank you all for the help. It did end up being the yaw arm. I loosened the set screw, adjusted the arm so it moves freely and re-tightened the set screw. Then re-calibrated the IMU and gimbal. Here's the latest video. Might not be totally perfect, but so much better.

KachemakDiver · Apr 16, 2021

Great, yes it’s much better!

cheddarman · Apr 17, 2021

Excellent, great improvement and quite acceptable. Never calibrated my IMU, must look it up but then I'm a great believer in "if it ain't broke, leave it alone"?

While on the subject, should on routinely calibrate the IMU, as one does the Compass? I have never done it. My firmware is: