Last summer, after an update to the P4 firmware there were quite a few threads started about the severe jerking and erratic movements of the P4 (and I think other Phantoms as well)..  I started following a bunch of them back then as mine was also doing the same thing.   It was so bad that I would also let it hover for 30 to 60 seconds just to make sure it was not going to shut off in mid flight. Usually after that short wait the jerking would subside.  I quit following the threads as new updates came out and new concerns started flooding the forum.
It's appearing that when the jerking occurs in hovering that the forward motors experience an intantaneous power reduction or the rear ones are increasing in power.  Last year the jerking seemed to suggest that only one motor (random as to which one) would jerk and it would even tip diagonally.

I was just wondering though, did anybody actually figure out what was causing this jerking?  Mine still does it and in the past week has done it even more severely, to the point of a severe motor speed surge on take off (full power) causing the P4 to tip over towards the front andthe blades contacting the ground shutting down the bird.  This actually happened to me 2 times in a row yesterday afternoon.  The third attempt to take off was normal and flew with no issues.

I'm now hesitant to fly this P4.  I really dont want to send it back to DJI repair if a fix that I might be able to do works.  I have already recalibrated the IMU several times over the past 2 months but the jerking remains..  The only thing I have NOT done is roll back the firmware and reinstall (that is if a preveous version is still available on Assistant)

Anybody have thoughts on this?

Sir, did you try to use another battery? Please provide a video of the situation. Thanks for your support.

Phantomrain.org Posted at 2018-1-27 04:49
Most likely firmware related, have you updated to the another firmware since last summer. ?

Have updated to all of the new firmware updates so far since then....  However one just showed up this morning on my Go app but have not updated yet...  Earlier this week I decided to use the Assistant and re-flash the firmware in the P4, since then it stabilized and hovered flawlessly.  I however have done that several times over the past 6 month and seen the jerking return.
Will have to watch it closely for a while.
But yes, since it started right after a very big controller and P4 update this past summer it surely is a firmware issue....  I think I’ll only use Assistant for future updates just in case the wireless connection is being interfered with during the upload process.

Thanks

DJI Elektra Posted at 2018-1-27 00:55
Sir, did you try to use another battery? Please provide a video of the situation. Thanks for your support.

Batteries made no difference in anything.  However I had used the Assistant to reflash the firmware and that seemed to have worked for the time being.  We will see how things go.

Oldmaninwva Posted at 2018-1-27 05:12
Have updated to all of the new firmware updates so far since then....  However one just showed up this morning on my Go app but have not updated yet...  Earlier this week I decided to use the Assistant and re-flash the firmware in the P4, since then it stabilized and hovered flawlessly.  I however have done that several times over the past 6 month and seen the jerking return.
Will have to watch it closely for a while.
But yes, since it started right after a very big controller and P4 update this past summer it surely is a firmware issue....  I think I’ll only use Assistant for future updates just in case the wireless connection is being interfered with during the upload process.

There were some instabilities with aircraft firmware V02.00.0106 as you describe (it was released last July), since then there have been a couple of test 'Beta' releases. And finally a few days ago an official release V02.00.0700 (this aircraft update also needs RC to be at Version V1.9.3). This appears to have resolved the instability issues.

When motors are started when sitting on ground, it's best to take off full throttle for a second or three as quickly as possible after arming motors. When sitting on ground with motors running aircraft will try and stabilize itself, and a puff of wind or uneven ground (or both) means it is more likely to tip over if sudden changes or windy conditions. This means it may try to level itself by moving sideways and 'tripping over' on ground.

Aardvark Posted at 2018-1-27 06:29
There were some instabilities with aircraft firmware V02.00.0106 as you describe (it was released last July), since then there have been a couple of test 'Beta' releases. And finally a few days ago an official release V02.00.0700 (this aircraft update also needs RC to be at Version V1.9.3). This appears to have resolved the instability issues.

When motors are started when sitting on ground, it's best to take off full throttle for a second or three as quickly as possible after arming motors. When sitting on ground with motors running aircraft will try and stabilize itself, and a puff of wind or uneven ground (or both) means it is more likely to tip over if sudden changes or windy conditions. This means it may try to level itself by moving sideways and 'tripping over' on ground.

Stability might also benefit from an IMU calibration via DJI Go 4, and a 'sensor' calibration which needs to be done using DJI Assistant 2 with aircraft connected via USB lead to computer.

Oldmaninwva Posted at 2018-1-27 05:14
Batteries made no difference in anything.  However I had used the Assistant to reflash the firmware and that seemed to have worked for the time being.  We will see how things go.

Please keep us updated if the problem continues. Thanks for your support.