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MPP - Compass-error-large

RadioFlyerMan

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On a brand new MPP (30 flights) I’ve been experiencing, on every other flight or so, what appears to be a breakdown between the IMU and the compass. On Go4, the compass error is displayed, the GPS is then dropped, and it goes into ATTI mode. Sometimes it recovers to GPS-p mode, sometimes it doesn’t. In the flight log txt file, the reason for the failure of GPS is a “compass-error-large” and followed later by a “yaw-error-large”. No Flyxxx.dat files on this MPP.
On those flights where this occurs, the first symptom is a very slow yaw after turning 90 to 180 degrees, flying forward for a few hundred feet and then braking to hover. The slow yaw will last 30 or more seconds before it decays. Meanwhile, the GPS is 20+ and strong. If I the push the flight further, it tends to trip the compass error.
On one flight where this happened, it recovered to P mode. I then experimented by activating RTH. It landed at HP, pointing 180 deg in the opposite direction.
I have had flights where everything is fine. Flies straight instead of a crab angle, no yaw after braking. RTH to within an inch of HP.
All this in spite of numerous FW refresh, IMU and compass calibrations, and RC stick calibration. Also, the HP and flight area is where I live in the Class G boonies and flew over a 1000 flights with my other MPP (now the “nephew”) with never a problem... no magnetic/yaw issues ever.

Something is electronically unstable... compass, IMU???

Any opinions before I send it back?
 
On a brand new MPP (30 flights) I’ve been experiencing, on every other flight or so, what appears to be a breakdown between the IMU and the compass. On Go4, the compass error is displayed, the GPS is then dropped, and it goes into ATTI mode. Sometimes it recovers to GPS-p mode, sometimes it doesn’t. In the flight log txt file, the reason for the failure of GPS is a “compass-error-large” and followed later by a “yaw-error-large”. No Flyxxx.dat files on this MPP.
On those flights where this occurs, the first symptom is a very slow yaw after turning 90 to 180 degrees, flying forward for a few hundred feet and then braking to hover. The slow yaw will last 30 or more seconds before it decays. Meanwhile, the GPS is 20+ and strong. If I the push the flight further, it tends to trip the compass error.
On one flight where this happened, it recovered to P mode. I then experimented by activating RTH. It landed at HP, pointing 180 deg in the opposite direction.
I have had flights where everything is fine. Flies straight instead of a crab angle, no yaw after braking. RTH to within an inch of HP.
All this in spite of numerous FW refresh, IMU and compass calibrations, and RC stick calibration. Also, the HP and flight area is where I live in the Class G boonies and flew over a 1000 flights with my other MPP (now the “nephew”) with never a problem... no magnetic/yaw issues ever.

Something is electronically unstable... compass, IMU???

Any opinions before I send it back?

Wondering why it isn't already in a box? No but seriously...I would never fly ANYTHING that did what you describe as happening and certainly not "Every other flight". That thing isn't air worthy..It should have already been at DJI for a diagnostic and repair/replacement. IMHO ;)
 
i have to agree with other comments,there is something wrong in the IMU ,it is not getting all the info it needs from the compass or GPS module ,needs to go back to DJI not safe to fly like that
 
UPDATE:
The more I think about it, the more I believe the problem was caused by an unstable IMU.
1. During the very first flights, when I would fly forward then brake, the drone would slide to the left a few feet. When I then flew straight back and braked, it would slide right a few feet.
2. When all the aforementioned problems got worse, I noticed a red message during startup “IMU Initializing”. It would take 4 or 5 seconds. I’ve never seen that message in my first MPP.
 
UPDATE:
... I noticed a red message during startup “IMU Initializing”. It would take 4 or 5 seconds. I’ve never seen that message in my first MPP.

That may very well be the ordinary preheating of the IMU & nothing to worry about. If you calibrated the IMU in a hotter environment than when you fly the IMU needs to be heated to that temp before take off ... in order to minimize the pre-heating time it's advised to do the calibration in a similar temp as when you fly.
 
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That may very well be the ordinary preheating of the IMU & nothing to worry about. If you calibrated the IMU in a hotter environment than when you fly the IMU needs to be heated to that temp before take off ... in order to minimize the pre-heating time it's advised to do the calibration in a similar temp as when you fly.
OK, thanks. Good to know.
 
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