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Can a faulty GPS module cause the drifting problem in P4P?
785 23 2019-2-20
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FlyinLo
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There has been alot of discussion and multiple threads on the drifting problem with a Phantom 4 Pro. I mainly do mapping so I noticed it when my drone was yawing in the flight (not drifting off course). When it was flying parallel to a street or long row of buildings, I noticed the further it went the yaw seemed to get worse and worse. The drone ALWAYS turns to the West. I read a thread that stated it was best to calibrate the gimbal with the drone leaning on the rears motors (camera looking straight up). After that I ran another mapping mission down a straight street and the same problem exists.

So then I tested by free flying the drone. I lined up over the street with the street dead center and directly north and south (literally and straight up and down on my ipad). Whether I flew north or south, the drone drifted to the east. And this makes sense because in the autonomous mapping mission the drone keeps turning to the west to counter the drift (I guess that is why it is turning to the west).

I have reset the drone. I have calibrated the Controller, IMU, Compass, Gimbal, and today I calibrated the Gimbal with the P4P leaned back on the rear motors. Today I also put new props on. This same drifting problem has happened to many P4P users and it seems absolutely crazy that there is not a solution or definitive reason why this is occurring.

I am wondering if a faulty GPS receiver could be causing this?? If not, could a failing or faulty motor/ ESC cause the drift?

Any help will be greatly appreciated.
2019-2-20
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Labroides
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I am wondering if a faulty GPS receiver could be causing this?? If not, could a failing or faulty motor/ ESC cause the drift?
GPS can only affect position.  It has no effect at all on direction.
It's also unlikely to be a motor/esc failure.
Is your drone the V2.0 model?
There have been many reports of a yaw issue for the V2.0.
2019-2-20
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FlyinLo
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Labroides Posted at 2-20 14:51
I am wondering if a faulty GPS receiver could be causing this?? If not, could a failing or faulty motor/ ESC cause the drift?
GPS can only affect position.  It has no effect at all on direction.
It's also unlikely to be a motor/esc failure.

Thanks Labroides.  Good info.
My problem drone is a V1 (silver sticker).  Since I could not get this resolved I purchased another V1 (Drone B)  to use and it works fine.  But I still need to figure out what is going on with Drone A.  It is driving me nuts to say the least
2019-2-20
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Bashy
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My v1 does this also,  Ive always wondered if its trim* is slightly off

*trim being the only word i know, that i am thinking of its from cheap RC cars when i was a kid lol
2019-2-20
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FlyinLo
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Bashy Posted at 2-20 19:43
My v1 does this also,  Ive always wondered if its trim* is slightly off

*trim being the only word i know, that i am thinking of its from cheap RC cars when i was a kid lol

@Bashy I am 99.99% certain it is not the controller.  I purchased a second P4P (v1) and it does not do this.  So I swapped controllers to see if it would occur in the "new/2nd" P4P and it did not.  So I can rule out the contoller trim being the problem.

Once I realized that the drone will always vear off course to the east when free flying, that makes perfect sense that the autonomous app is rotating the bird to the west to counter this.  I am hoping that DJI will provide the cause of this so I can fix/replace the part.  

Here is the flight log for 3 flights for anyone (DJI) who can take a look.  I have more logs if needed.  The first two flights are autonomous which fly parallel to the street and the P4P rotates to the West.  The third flight is a free flight where I fly straight down the street and it drifts off course to the east.

https://drive.google.com/drive/f ... afpEOzb?usp=sharing
2019-2-21
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Anokadrone
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Are you on the latest firmware?
2019-2-21
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FlyinLo
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Anokadrone Posted at 2-21 06:34
Are you on the latest firmware?

I am the latest.  FW 1.05.0600
2019-2-21
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fanseacc58a6
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Canada
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Same issue since day one on my p4p v2. My p2v p2v+ p3p all fly perfect but this p4p v2 has a strange yaw drift at all times. www.opspeculate.com
2019-2-21
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Edward J Smith
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My P4P does this also. It is not limited to the P4P because my Mavic Air does it too. I have also so been cursed with gimbal horizon tilt on my P4P.
2019-2-21
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FlyinLo
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Edward J Smith Posted at 2-21 19:18
My P4P does this also. It is not limited to the P4P because my Mavic Air does it too.

I have this posted on the phantompilots forum as well.  
https://phantompilots.com/thread ... 142299/unread?new=1

This is what is happening:
2019-2-21
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FlyinLo
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In the above photo.  I started at the south end of the street.  I had it perfectly lined up with cross hairs (using Litchi) to fly to north end of street.  I simply gave forward stick and did not touch anything else.  It literally drifted to the east by 75+ feet in a relatively short distance.   I am not sure if a faulty compass can cause this??    The drawing shows this, but if I use autonomous software, then the drone will fly to the destination point but it will "yaw" a considerable amount to the west to correct for the easterly drift.  If the autonomous apps applied "left" or "right" stick instead of yaw to correct this, then it would not be noticed.  But since a yaw is used to correct the heading, the aircraft will be rotated a significant amount.  The drift to the east, and correction yaw to the west occurs whether I am flying north or south.

I switched out controllers and the same thing occurred.  So the error is with the aircraft, not the controller.
2019-2-21
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Edward J Smith
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The drift to the east, and correction yaw to the west occurs whether I am flying north or south.

If you fly east to west does it still turn? My P4P has always turned counter clockwise from the day I got it. My Mavic Air turns clockwise. They both do it at a hover too. I don't know what can be done to fix it. Many Operators have had the same problem for a long time and I haven't seen a solution for it yet!
2019-2-21
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Bashy
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I have read folks saying that the gimbal being slightly off center can cause this too, now, whilst that may be true in some cases, its not for me, i have stood behind mine and sent it down a straight track using eyes on the drone only, NOT using FPV (no screen/goggles) anf it veered to  the right and by about the same amount as your drift had i carried on....
2019-2-21
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FlyinLo
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Edward J Smith Posted at 2-21 19:47
The drift to the east, and correction yaw to the west occurs whether I am flying north or south.

If you fly east to west does it still turn? My P4P has always turned counter clockwise from the day I got it. My Mavic Air turns clockwise. They both do it at a hover too. I don't know what can be done to fix it. Many Operators have had the same problem for a long time and I haven't seen a solution for it yet!

I am going to test that in the morning or the very first break in the rain.  I should have already done that.  I have tested the north/south because the street is straight and right beside my house   Shame on me for not already flying east/west to compare the results.

If I have time I will also test flying at 45° (NE, to SW, etc).  and see if there is a point at which the drift is almost unnoticeable.  
2019-2-21
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FlyinLo
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Bashy Posted at 2-21 19:49
I have read folks saying that the gimbal being slightly off center can cause this too, now, whilst that may be true in some cases, its not for me, i have stood behind mine and sent it down a straight track using eyes on the drone only, NOT using FPV (no screen/goggles) anf it veered to  the right and by about the same amount as your drift had i carried on....

My gimbal is spot on.  I even calibrated it standing the P4P back on the motors.    So I don't think that is it.  
2019-2-21
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Bashy
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Was just an idea as you tested your using fpv so best not to rule it out  and worth checking, the best way to check its 100% square is to look at it top down and eye it up that way, also using the flat part of the gimbal clamp/guard helps, i can take a pic in a bit to show the way i mean (if needed) but im sure you can figure it out
2019-2-21
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CHASCOADMIN
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Is the whole bird rotating or just the camera? What about the compass? Have you tried recalibrating it a couple of times?
2019-2-22
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FlyinLo
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CHASCOADMIN Posted at 2-22 04:36
Is the whole bird rotating or just the camera? What about the compass? Have you tried recalibrating it a couple of times?

The whole drone is rotating.  The gimbal stays aligned with the drone.  You can observe it in the sky and see that it has rotated alot.  We have rain solid until Saturday night.  So Sunday afternoon I will do some test flying East/West and diagonal to the poles as well so see if there are differences in the rotation.  

I have calibrated the compass multiple times.  I am wondering if the compass could be faulty.  The compass is located in the landing gear and not exactly wanting to take it apart to replace but if that is the only likely culprit, then it needs to be done.    What I can't do is spend hours and hours trying to run down the problem.  
2019-2-22
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CHASCOADMIN
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FlyinLo Posted at 2-22 06:01
The whole drone is rotating.  The gimbal stays aligned with the drone.  You can observe it in the sky and see that it has rotated alot.  We have rain solid until Saturday night.  So Sunday afternoon I will do some test flying East/West and diagonal to the poles as well so see if there are differences in the rotation.  

I have calibrated the compass multiple times.  I am wondering if the compass could be faulty.  The compass is located in the landing gear and not exactly wanting to take it apart to replace but if that is the only likely culprit, then it needs to be done.    What I can't do is spend hours and hours trying to run down the problem.

Kind of what I was thinking. The antenna for the compass are easy to get into, but the P4P is like an iPhone unless you have the specific tools. One would think that you would have seen some compass errors in DJI Go4 though...
2019-2-22
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FlyinLo
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CHASCOADMIN Posted at 2-22 11:12
Kind of what I was thinking. The antenna for the compass are easy to get into, but the P4P is like an iPhone unless you have the specific tools. One would think that you would have seen some compass errors in DJI Go4 though...

No compass errors.   So if no other likely causes surface, I will swap out the compass antennas and see if that works.  if it does not, it will be time to part it out
2019-2-22
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Bashy
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FlyinLo Posted at 2-22 11:30
No compass errors.   So if no other likely causes surface, I will swap out the compass antennas and see if that works.  if it does not, it will be time to part it out

Could you please let me know ow t goes, i have a pair of new landing gear here perhaps quote me in this or PM  so i dont miss it, thanks
2019-2-22
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fanseacc58a6
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Same issue here... I have the pvp2 pvp2+ p3p and all fly in a straight line. Mine yaws just like yours.
www.opspeculate.com
2019-2-23
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Opspeculate_2nd
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Canada
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You can try

Opspeculate's Yaw Drift Fix
2019-4-6
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BagoDJIoperator84
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I would try and calibrate your ESC and see, if that does the trick. How close are hovering over the ground sometimes the updraft can cause it to drift?
2019-4-7
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