The compass being damaged or misaligned is one of the main factors which can affect maintenance of position during yaw. Have a good look at it, make sure it is not damaged, and is correctly positioned. Do a compass calibration in the usual way. If the compass or its mounting look damaged, replace it.
Yaw drift issue
- Thread starter Jeff48920
- Start date
One other question. Have you changed any of the ESC's on any of your motors. Also have you done an RPM check (with props off) at idle and high speed. I had one motor that was 900 RPM short of the others at full speed. Definitely caused my drift.
No changes to stock except gimbal saver and camera shield. Just got my laser tach today so your response is really timely.
As before I assigned the motors numbers as follows: with the uav in launch position (pilot looking at the battery):
Motor 1: Front right
Motor 2: Front left
Motor 3: Rear left
Motor 4: Rear right
Results compare with yours and indicate a bit of a problem
Motor 1: idle=3556. Full throttle=10787
Motor 2: idle=3586. Full throttle=10965
Motor 3: idle=3615. Full throttle=10777
Motor 4: idle=3510. Full throttle=9558
I am open to suggestions. Change ESC, Motor? Try DJI support?
Thanks
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Sorry I did not reply earlier. Check my last post I think we have the source of the problem with the rpm issue.+1
Motor temps would be much farther apart if there were an issue there.
Please upload a video of your issue.
Any additional info will only result in a more rapid resolution.
We're here to help.
N017RW
Premium Pilot
Swap motor #4 with any other motor.
This will determine if the [RPM] difference is due to the motor or ESC.*
*However, with this test [above] you're not just testing the motor/ESC... I assume you have the a/c strapped down, applying full throttle, and tach-ing the motors from above.
If so the FC is active, so, what if... the FC/IMU sense that arm 4 is a bit higher than the other 3? Would it not attempt to level the a/c by reducing power there?
Just a thought... let us know about the motor/ESC swap if you do it.
This will determine if the [RPM] difference is due to the motor or ESC.*
*However, with this test [above] you're not just testing the motor/ESC... I assume you have the a/c strapped down, applying full throttle, and tach-ing the motors from above.
If so the FC is active, so, what if... the FC/IMU sense that arm 4 is a bit higher than the other 3? Would it not attempt to level the a/c by reducing power there?
Just a thought... let us know about the motor/ESC swap if you do it.
I am taching the motors with reflective tape on the sides of the motors with the props off. FC is active.
However I just got your point. I will retest RPM with the uav in the same position I use for the IMU Recalculation. That way I know all 4 arms are level and the ESC is not compensating.
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N017RW
Premium Pilot
Consider trying it with the props on too.
You need to elimiate variables between test and flight conditions.
Can you set the tach for a two blades or do you need to uses the ref. tape?
More data!!!
Retested three times in the exact position used for IMU calibration. Each test was done with different reflective tape placements (side of motor, top of motor, end of prop). All tests report within + or - 50 RPM of previously reported numbers at both idle and WOT.
I am waiting for a relatively windless day to do a video of the drift from the drone perspective. Right now I have either rain or winds in excess of 15 mph on the ground.
I am waiting for a relatively windless day to do a video of the drift from the drone perspective. Right now I have either rain or winds in excess of 15 mph on the ground.
Jeff, from what you have said the motor heat is not an issue and the RPM of the motors is 50 RPM's or less you are good there. ECU'S and motors are not the issue for drifting. That only leaves IMU and compas calibration. If those two are correct and the figures are in specifications tolerance then you have only one item remaining as I see... The GPS module. Hate to say this but you may need to talk to DJI support and tell them what steps you have been through and what your Phantom is still doing. If you have to send it in its 5-6 weeks repair time. Ugh !!!
Just to be clear, the retest of the RPMs on each motor were within 50 RPM of the original test. However, the difference between motor 4 and the others at WOT remains at close to 1000 RPM. ........ I wrote DJI a couple of days ago and am now waiting for a response. (sigh).
Just a thought, try to open the slow motor, I wonder if the shaft or the ball bearing needs to be adjusted, as I mentioned in an earlier post, one of the motors on my bird was stopping earlier then the others (didn't have rpm meter ) I simply opened the motor and noticed that the shaft was bent and wouldn't come out, applying little bit force I was able to allign it again and this took care of the issue.
I had my p2v+ suddenly start moving in an elliptical circle when yawing. More pronounced one way than the other. No crashes etc. Checked everything and found that somehow my GAIN settings had changed - maybe an update or an IMU calibration that went wrong.
Anyway once I changed the gains it went back to yawing correctly. As I recall there's one set of gains relating to your sticks and one set for automatic positional changes done by the quad. It's the second - if you don't have a record of your old gain settings - make sure that you make very small changes at a time.
Anyway once I changed the gains it went back to yawing correctly. As I recall there's one set of gains relating to your sticks and one set for automatic positional changes done by the quad. It's the second - if you don't have a record of your old gain settings - make sure that you make very small changes at a time.
What were your gain settings? At this point I will try anything that is noninvasive.
Thanks
Just received the following "help" from DJI
"
Thank you for contacting DJI.
The issues that you're describing require for you to send in your unit for repair.
In order to be issued an RMA (Return Merchandise Authorization) number, we encourage you to call our support staff via phone to discuss your options.
You may contact us Monday-Friday, 9:00am-5:00pm PST at 818-235-0789.
Thank you for choosing DJI,
"The Future of Possible!”
"
Thank you for contacting DJI.
The issues that you're describing require for you to send in your unit for repair.
In order to be issued an RMA (Return Merchandise Authorization) number, we encourage you to call our support staff via phone to discuss your options.
You may contact us Monday-Friday, 9:00am-5:00pm PST at 818-235-0789.
Thank you for choosing DJI,
"The Future of Possible!”
While I agree that it is likely the motor rpm difference you found, out of curiosity what version of firmware are you on? I ask because my phantom was fine with a stable yaw before an update in firmware. I could spin it like a top and it would drift very little. Now I have the same issue during yaw as you describe of drifting excessively. I also now have an somewhat unstable forward flight in that the phantom tends to sink in altitude where before I did the update it did not. It is probably just coincidence but both issues occurred after I updated from 3.08 to 3.10 firmware. The phantom had never been crashed when it started these issues and had about 60 flights on it. I should probably order a tach and test motor speeds. Has anyone else seen this issue after updating the firmware?
Just throwing this in...The motors have a bearing spacer (under the motor) that could give you results like you are describing; yaw, heat and rpm for motor 4. I would consider this another point to evaluate, since you've exhausted common resolutions.
It could be as simple as adding lubrication to the bearing washer. To this point, motors on the Phantom have had few conversation here on this forum. They seem reliable and durable, but again they are mechanical and will fail at some point. The question has always been, what maintenance is required for the motors. This may be that indicator.
Good luck!
It could be as simple as adding lubrication to the bearing washer. To this point, motors on the Phantom have had few conversation here on this forum. They seem reliable and durable, but again they are mechanical and will fail at some point. The question has always been, what maintenance is required for the motors. This may be that indicator.
Good luck!
I gave up!!!! The Phantom is on the way to DJI for warranty repairs (I hope). I'll let you all know how it turns out.
You probably did the right thing... Get it taken care of under warranty. I sent mine back after the last upgrade when my gimbal stopped working. Thought it was a software issue. Just received an email telling me they replaced the camera. Don't know how the upgrade could brick the camera but .... Warranty and its fixed. They expect to ship it within the next 10-14 days as they are behind and backed up. I'm in week 8 right now. I've asked them if they are going to extend my warranty for the time they have had it. Waiting to see. Good luck!
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