P4P moving up down on its own after takeoff.
- Thread starter KevMo Photog
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Mine does the same thing when close to the ground, the vision sensing system causes this. It should be fairly stable once you are approx. 20 feet AGL.
Hmmm. Mine did not use to do it for some reason. My P4's also never did it. But your right it's not doing it after I get up some.
KevMo, I thought it was just me but I flew my P4P+ last Sunday and again on Wednesday and noticed the same thing for the first time. Usually, I can take off and leave it at six foot in the air and it will just stay there but the last two times I noticed it dropping a foot or so and then going back up. I have done no updates recently so I blamed it on the wind. Yes, 20 feet in the air it's fine but like yourself I never noticed it at lower levels before.
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I too recently saw this, minor but annoying, the craft wanders just a bit a low altitudes, going down more than up maybe a foot?
Ok cool. Glad to know it's something that has just changed. So I'm not crazy!!! LOL I hate to do any calibration unless Im prompted from what I have heard.
Going through menu's I just noticed that I had turned off my VPS setting. So I'm sure that must be what has changed. I think I did this flying really low down a creek with trees overhead. Did it so it would not see water below and balloon up into a tree limb. So I should be good now I hope. Check it next time im up!
Some of these yoyo cases of wandering up and down as if your drone is possessed are caused by the installation of camera guards bolted to the landing gear. What happens is the guard bounces sound waves coming from your VPS sonar and confuses the VPS system. The drone can yoyo up and down up to 60' , but only when at high altitudes when in a hover. If VPS is off this shouldn't occur.
If you're craft has a yoyo anomaly with VPS off, that caused by something else.
If you're craft has a yoyo anomaly with VPS off, that caused by something else.
It is very slight John. But it just started this a few weeks ago. And its not bad in diff areas too. But I did turn off the VPS a month ago or so as I was flying down this creek in tight quarters and didn't want the balloon off the water effect into the tree limbs.
Thanks for the input John. I did check and my VPS is already turned on and I use no camera guard while flying. I wouldn't refer to it as a yoyo effect but I did notice it drop about a foot and then go back to where it was the last two flights. I was flying in the P mode and was hovering between 6-15 feet AGL. Didn't think much of it at the time but after KevMo mentioned it, I chimed in. Was hoping to try it today to see if I could duplicate the condition but 14-16mph winds have me grounded for the day. Hate when that happens, LOL.
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What I have noticed in the last couple of times out, is that if I am flying at say 5 feet, up a walkway, it will settle a little, like maybe a foot or less as it moves slowly forward. It doesn't seem to do this unless it is very low or I can't detect it when I am higher.
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Mine has been doing this far more obviously recently. Like yours, KevMo it’s only lower to ground, or at least lower that it’s noticeable. Oddly the altimeter doesn’t usually show as changing, but I’m watching the drone with my eyes and on the screen obviously losing altitude.
This is a theory, but I am pretty confident in it for this purpose. If you buy a $10 cheap helicopter, it will hover just find when it reaches equilibrium, but if you put your hand under it it will move up because you're changing the equilibrium. What I think is happening is that you're getting changing air pressure stability under the craft. If the air pressure rises a little, it will move it up until the computer realizes it and adjusts, and allows it to drift back down. That's why it will work better in open areas higher up, because the air is less turbulent and more predictable for the computer.
Mine will do it slightly. More in tighter areas, less or none in open areas. More with a breeze, less or none in dead calm conditions. It'll do it on my back porch even hovering as high as 5' where the downdraft can get turbulent around the grill and table and chairs, but it will be a lot better in the yard where it's flat for 3'-5' away, hovering as low as 3' or so.
TL;DR- if the air from the props or breeze isn't steady but is turbulent, the computer can't predict it as well and you're seeing slight overcompensation.
Mine will do it slightly. More in tighter areas, less or none in open areas. More with a breeze, less or none in dead calm conditions. It'll do it on my back porch even hovering as high as 5' where the downdraft can get turbulent around the grill and table and chairs, but it will be a lot better in the yard where it's flat for 3'-5' away, hovering as low as 3' or so.
TL;DR- if the air from the props or breeze isn't steady but is turbulent, the computer can't predict it as well and you're seeing slight overcompensation.
Agree awinn! My only concern is that my bird has not acted this way at all until the last few weeks for some reason. It's always been rock steady even at 6ft and under at times.
I don't have a lot of experience with them yet, but as a mechanically-inclined person I'll throw stuff out until the experts step for me 
I would guess it's a software calibration/sensitivity issue with the latest update because these seem pretty solid built (unless they're crashed but then it could be a lot of stuff). But if it's possibly mechanical, have you checked the sonic sensors for blockage, cleaned the VPS sensors, checked battery voltage, see if any motors seem too hot? I'm just thinking of things that I'd check if I was diagnosing it from the ground up.
Edit: and check it in other conditions. I've read that the VPS sensors are good, but need bright light and stationary objects to work correctly. Can be unpredictable otherwise. Maybe turn them off selectively and see if it has any impact on the issue. I'd also re-calibrate the IMUs and compass and all the easy stuff if you haven't yet.
I would guess it's a software calibration/sensitivity issue with the latest update because these seem pretty solid built (unless they're crashed but then it could be a lot of stuff). But if it's possibly mechanical, have you checked the sonic sensors for blockage, cleaned the VPS sensors, checked battery voltage, see if any motors seem too hot? I'm just thinking of things that I'd check if I was diagnosing it from the ground up.Edit: and check it in other conditions. I've read that the VPS sensors are good, but need bright light and stationary objects to work correctly. Can be unpredictable otherwise. Maybe turn them off selectively and see if it has any impact on the issue. I'd also re-calibrate the IMUs and compass and all the easy stuff if you haven't yet.
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KevMo, agreed, this is my concern as well. It isn't like it would be the first thing, or even the most irritating, to start working more poorly after an update.
My gimbal on my p4p drifts so much I've more or less giving up doing panoramas with it and the longer exposures I could do before are becoming blurry messes. :-/ I've done anything and everything, up to soldering iron compass degausses and changed and tweaked and isolated and tested every single gimbal and other option. The mavic gimbal, otoh, is rock solid.
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I don't have a lot of experience with them yet, but as a mechanically-inclined person I'll throw stuff out until the experts step for me
Edit: and check it in other conditions. I've read that the VPS sensors are good, but need bright light and stationary objects to work correctly. Can be unpredictable otherwise. Maybe turn them off selectively and see if it has any impact on the issue. I'd also re-calibrate the IMUs and compass and all the easy stuff if you haven't yet.
Thanks for the thoughts, always good to have different takes on it even if it doesn't result in a solution.
FWIW I have not done the detailed mechanical teardown/testing at the motor temp level. Otoh, this is actually a brand new P4P for me at least, first flight on Sept 25th. Admittedly 75 flights & 19hrs of air time since then. Never had the issue on the other P4P as far as I recognized. All of the simple calibration stuff is rock solid, I'll keep watching everything carefully on my side and see how it behaves.
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Oh, just to update, on mine it is happening at 40-70'. However, the speculation on the air pressure/temp gradients may not be too far off. I've noticed it most when flying at home, where I'm taking off from about an acre of clearing of a hillside surrounded by trees, and I'm typically on the leeward side of the hill so I can have pretty different winds at ground level. My standard protocol is to launch a cpl feet, everything is stable then immediately get up above the treeline. This is where I've noticed it, after that launch up, then watching the altimeter stay the same while I watch the bird drift down and see the trees rise up on the screen.
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