3DR X8+ successfuly completed an automission, but lost one prop. Need help analysing consequences


X8+ lost a prop in a 10 min mission. Still it perfectly completed it and did RTL.

I have checked Auto Log Analysis and apart from Battery Failsafe (which I have no problems with) I have noted IMU Mismatch - VIBRATION warning.


Log File D:/…/X8+/Logs/2016-06-05 09-40-19.log
Size (kb) 11438.015625
No of lines 152019
Duration 0:10:43
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = NA -
Test: Balance/Twist = NA -
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (14.02%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FS_BATT (This is OK and expected)

Test: GPS = GOOD -
Test: IMU Mismatch = WARN - Check vibration or accelerometer calibration. (Mismatch: 1.25, WARN: 0.75, FAIL: 1.50) (This one worries me a lot! Is this just because X8+ flew with only 7 props on?)
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = GOOD -

Is there anything else, apart of putting the missing prop back, I should do to get the IMU Mismatch back to GOOD?


The X8+'s 8-10 minutes auto mission logs analysis show everything as GOOD, but always indicate IMU Mismatch.

I’m afraid to mess with the accelerometer calibration. I sure it will ask to also calibrate the compass. And I had a hard time calibrating the compass on Iris+ very recently, and it crashed due to accelerometer issue.

What would you advise?


Have you checked the vibration levels in the log?

An Accelerometer calibration should not upset the compass calibration.

What make is the controller - 3DR?

The problem is that there is no VIBE section in the Logs.

I’ve purchased it from the US. It is 3DR. I belive it is not a clone.

Diagnosing problems using Logs

Telemetry logs (also known as “tlogs”) are recorded by the Mission Planner (or other ground station) when you connect ArduPilot to your computer via a telemetry link.

I am connecting to X8+ using Tower to do an automission. I can find NO telemetry logs in there. Do I have to use PC-based Ground Control Station to have the Telemetry Logs?

Tower has tlogs too. They are actually in the Services app and not Tower. There hard to find but should be in the Droid planner services folder. They should be in “Android/data/org.droidplanner.services.android/files/tlogs/org.droidplanner.android/” folder.


logs are also created and stored on the SD-Card inside the pixhawk itself. you can take the SDCard out, stick it in a PC, and inspect them there too. :slight_smile: