Err: EKF_CHECK-2 Bad Crash

Have Err: EKF_CHECK-2 twice in 1 flight. First time I got it to RTL and error was gone so I decided to fly some more and switch to PosHold mode (which was a misstake and flew some more then error happened again the quad went sideways and crashed. Before error both times the quad gained some serious altitude without me telling it to. I really need someone smarter then me to check my log and tell me what is causing the altitude gain and Err: EKF_CHECK-2.

Can’t seem to get this site to upload a bin file.

https://drive.google.com/file/d/0B0rpgSpsm0DVLUJ3d19aYUN5TDg/view?usp=sharing

https://drive.google.com/file/d/0B0rpgSpsm0DVZFNOMWt2bVFoQ2s/view?usp=sharing

You haven’t said what flight controller you are using.

Just before your EKF error there is a big increase in vibration.
Could something have come loose?

It was a predator 650 where the booms snap in place. Maybe it snapped out but I doubt it. It’s a pixhawk clone. I checked a borameter in logs also and can’t see why it suddenly would gain 80 feet or more in altitude. Half wondering if this fc clone is bad.

Any and all suggestions would be very welcome. Just totaled an expensive frame and really want to have an idea of a fix before putting this on another frame and possibly destroying another one.

The vibration increase seems to be what triggered your FS_EKF and it happens that a lot of Z axis vibration causes rapid changes in altitude.

That rapid vibration increase also corresponds to large spikes in current draw and a maxing out of motor outputs.

This is all happening prior to the EKF error.
Looks like a mechanical failure.

Your RC input is also very noisy as an aside.

The autoanalysis right away reveals this:

12 6-18-2016 9-18-14 AM.bin.log
Size (kb) 9681.9853515625
No of lines 119474
Duration 0:06:35
Vehicletype ArduCopter
Firmware Version V3.3.3
Firmware Hash acf2e10c
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = NA -
Test: Balance/Twist = NA -
Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 5.50m
Test: Compass = GOOD - mag_field interference within limits (15.33%)
Max mag field length (571.40) > recommended (550.00)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FLT_MODE
Test: GPS = GOOD -
Test: IMU Mismatch = FAIL - Check vibration or accelerometer calibration. (Mismatch: 5.63, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = GOOD -

The IMU mismatch line right away indicates you have vibration issues. In looking further, the Z axis vibrations (up and down) look terrible. Have you got the FC mounted on any antivibration materials or mounts?

Mounted same as my other apm boards. In a case on foam sticky pads on the corners. Props are balanced both by blade and hub. Fpv camera doesn’t seem to have vibration in the video. Though that is from memory and could be wrong. Forgot to hit record on dvr :frowning: Could this be caused by a bad accelerometer. Reason I ask is because sometimes when I boot this up it has bad accelerometer error and won’t are so I’ll reboot again and it’s fine. This FC is only about 4 to 6 flights old.

boot this up it has bad accelerometer error and won’t and won’t arm*

Other question is why would motor be maxing out when I’m never really leaving mid throttle?

Ok so I checked just before failure and CH3 RC in shows now throttle up but seems the FC throttled motor (judging by curr motor graph all the way up) The alt graph is showing the climb. So my way of thinking is if FC showing a climb in alt without input from CH3 going up in PosHold mode the FC should be telling motors to slow down, not speed up. I see the vibration too but that is coming after FC is going full speed with motors. Question is why is it going full speed. Please currect me if I’m wrong and point out what I’m missing here???

I’ve updated my belheli firmware which automatically changed my PWM output Dither from 15 to 7. Could this cause ESC to missinterprate FC signals and cause motors to spin up?

I had nothing but problems with blHeli and Pixhawk. Dumped it and went to Xrotor 40A with their firmware on it and no modifications. Given I’m flying a big 800mm hex that’s not a racer.

Do ya think PWM output Dither setting could be the problem BigTulsa? Are you seeing the same thing as me with motor spinning up. Need people with more expieriance then I have looking at logs to make sure I’m not seeing something that isn’t there.

I wouldn’t mind suggestions on a new frame either. Was running this http://www.hobbyking.com/hobbyking/store/_51512__HobbyKing_174_Predator_650_Folding_Quad_Copter_Carbon_Fiber_Version_Kit.html, but have a feeling I’ll be crashing a few more times before I sort this problem out so thinking of something like this http://www.getfpv.com/multi-rotor-frames/qav500-fpv-quad/qav500-v2-fpv-quadcopter.html Problem with that is I run 2 batteries, a little one for my FPV and main and it’s kind of small (used to running 12-13" props). But want durable and room for electronics.