Why is my video twitching when there is no wind?

erkme73 · Nov 15, 2016

Stupidly simple question. I don't really know how to describe it. When the P2V+ is stationary, in no wind conditions, at any altitude, the video looks like someone is rocking/flicking the camera. I don't mind the slight perspective change of a never-perfectly-still P2V+, but the abrupt twitching/shaking is really noticeable.

This happens whether looking straight ahead, down, or anywhere in between.

Here's a sample video:

When I compare this to others' videos, which seem like they're on a tripod, mine really looks like it's not even on a gimbal.

I first noticed the problem after shipping my P2V+ in its Pelican case. I'd forgotten to attach the gimbal guard, and two of the four white rubber grommets were torn - and one of the clear plastic pegs was broken. I've since replaced all four grommets, and both pegs. There is no binding, and it floats freely within the full range of the grommets and pegs.

When I have the P2V+ on a table, powered but no blades spinning, the camera is perfectly still (so it doesn't appear to be an electrical/gimbal motor cause). When it's hovering, I can't notice any movement of the camera that isn't directly compensating a P2V+ movement.

I've not balanced the blades, but since this isn't the classic "jell-o" style vibration, I've discounted that as a cause.

Any ideas? Ultimately this will be resolved if/when I finally receive my Mavic

J Dot · Nov 15, 2016

Hello,
If it was transported without guard, the ROLL driver circuit board Potentiometer may have been damaged.

Here is a link to what im talking about

https://www.ebay.com/itm/112202587991

Just for reference, you can find them for $10-15 us.
But that is where I would start.

J Dot

erkme73 · Nov 15, 2016

J Dot said:
Hello,
If it was transported without guard, the ROLL driver circuit board Potentiometer may have been damaged.

Here is a link to what im talking about

https://www.ebay.com/itm/112202587991

Just for reference, you can find them for $10-15 us.
But that is where I would start.

J Dot

Thanks for the suggestion. Sucks that it involves parts. I did a quick search and, aside from the one you linked to, there doesn't seem to be much out there. I'm a bit hesitant to replace a board (not knowing if it really is bad) with a used one from a crash. Seems like Murphy has several opportunities to strike.

Do you know of a way to actually test the POT, or clean/realign it?

J Dot · Nov 15, 2016

Not sure,
They are super delicate, as they have SEVERAL points of contact, look at it like this

You have 5 marks, equal distance in a straight line, #3 mark is dead center, #1 is full left, # 5 is full right, and so on, now you want to find center, but center is gone ( damaged ), so you move from 1, to 2, then to 4? Wait where is 3?, so you go back to 2, wait where is 3?, so you see, you now have a constant tug-of-war going on frantically going from 2 to 4 and back, simply looking for 3, but it no longer exists, this is basically what is happening, it is trying to center out, but cannot.

So if any of those points are damaged, can cause a conflict. Not saying that is 100% YOUR issue, but I can't see anything else causing it, unless the gimbal is binding somewhere, which you stated it was not.

Where are you located? If in country, I can send you one to test. As I have several of them.

J Dot

erkme73 · Nov 15, 2016

That's awfully kind of you Jerry. We're practically neighbors. I'm in Tampa. Your suggestion nudged me in the right direction, I think. I watched a video or two, and read some of the threads on adjusting the gimbal. That gave me the confidence to open and examine the roll axis motor. Right away I noticed that the black retaining clip on the ribbon harness was standing up (release mode).

I also never seemed to have a perfectly level horizon (even before the shipping incident). Seeing how easy it is to hold the rod and turn the camera to realign it properly, I gave that a go too. Now, I'm perfectly level (as best I can tell indoors).

I won't know if the shaking is gone until daylight. I'm hopeful that there was just a lose/intermittent contact on the ribbon cable that might have cause the stuttering. If not, I may well take you up on your offer to try the pot.

I'll post back here tomorrow, unless my test flight is overcome by other events...

Eric

J Dot · Nov 15, 2016

Lol,
Glad you braved it, they are quite simple once you look at it for a bit, you know that clip, may have been your problem! I've not come across that before, but did come across a repair where camera would turn on-off, at its pleasure, I opened to find a clip BROKEN OFF COMPLETELY, and a ribbon cable scotch tapped into place! Real Sanford and son repair, I replaced the guys board, and sill going to this day, it was a p2V+ like yours, but it would boot up, and work, then the slightest so BUMP or NUDGE, the camera would just go limp, it was crazy, all over that clip.

J Dot.

erkme73 · Nov 16, 2016

Well, so much for wishful thinking...

What is interesting is that the twitching/shaking happens at the same rate/intensity whether I'm stationary, or rolling left or right. That is, the 'center' on the pot is dynamic as it compensates for the P2V+ movement. If it was just a single bad spot on the pot, you'd think that the shaking would be noticeable only when it was trying to center on that spot.

Another thought... while watching the artificial horizon on the vision app on my phone, it looks like it is twitching just like the video - in other words, the P2V+ is experiencing (or thinks it's experiencing) subtle rolling movements. Could that be a gain issue? Shouldn't the gimbal compensate for that?

Oh well...

J Dot · Nov 16, 2016

Hmmmmm,
Well if you want to try the roll board, I'd be glad to send it to you. At least it will delete one possibility!

Are all your jello-balls in tact? None torn or broken? And are your props balanced? These usually don't cause that, but worth a look!

Let me know, as I have some other stuff to send out anyhow!

J Dot

erkme73 · Nov 17, 2016

Jerry, the roll driver showed up today (a day earlier that USPS said it would). I installed it, and here are the results:

I must admit, I had my reservations about bad spots on the POT being the culprit since the shaking happened at various roll angles. But, by God, you're a genius!

J Dot · Nov 17, 2016

Lol
Awesome, is that a still shot or video?

Ha ha, well could not ask for more than that, what a difference!
Great job my friend! I'm really excited it all worked out, really nice video, and super stable! Good show!

And Thank you, for the kind words!

So,
You are Back in action!

A+ on the repair!

J Dot

erkme73 · Nov 17, 2016

J Dot said:
Lol
Awesome, is that a still shot or video? Ha ha, well could not ask for more than that, what a difference!
Great job my friend! I'm really excited it all worked out, really nice video, and super stable! Good show!

And Thank you, for the kind words!

So,
You are Back in action! A+ on the repair!

J Dot

It's funny you say that. I have constant freeze ups on my vision app - where the screen freezes for about 5 seconds, then Phantom disconnected, then reconnects. It's always done that. But when I was watching for the shaking on the feed, it was so still, I thought it had frozen again... Almost makes me want to cancel my Mavic order... Nah... I just got shipping notice. It'll be here on Tuesday.

Thanks again!