Hi all,

I'm attaching my log from our last flight as our little quad went completly bonkers before it crashed.

Short after takeoff it went completly out of control, no response at all from RC or Telemetry and then crashed near a pond (thank god).

But the mistery was about to begin when we started reviewing the log and found out that the trigger was the failsafe error  Err: EKF_CHECK-2 / Err: FAILSAFE_ EKF-1. 

In understand these two were recently added to APM, but this ain't the first time I see this sort of thing happening.

I'm attaching my log in hopes for some guidance.

Thank you all!

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I have just had a similar issue. At a certain point the log is full of EKF_CHECK-2 and FAILSAFE_EKF-1. I am running an APM2.5 with onboard magnetometer and external GPS. I have never had this error before I changed gimbal mount and used a mroe "solid" connection to the F450 frame. I must anticipate that the gimbal's batteries were nearly dead so it was "glitching" every now and then trying to keep the camera stabilized. Maybe the glitch (a "twitch" in pitch, not roll) influenced the EKF error or maybe not. I must also say I had disabled the EKF check completely and used a "relaxed" setting for the Yaw/magnetometer variance check (never logged any bad DCM failsafe alarms). The quad was on a mission and at the 3rd waypoint it failsafed to LAND so I triggered it back to stabilize and Auto again to resume. After the 3rd attempt I couldn't get it back to RTL or Stabilize (RTL was sent via Tower App) from radio or PAD. It just drifted off and set to LAND, unfortunately on some trees. I could not find it as it became dark and the GPS had lost fix (telemetry was lost at a certain point butwalking towards it I got a signal) but recovered it this morning with daylight. I downloaded the logs and attached them FYI. I also have the footage from my gopro if anyone is interested in the mission "FAIL" :)

https://www.youtube.com/watch?v=jlvdIQP82gg

From 0:47 the mission starts. At 1:12 waypoint 2 is reached and Waypoint 3 is targeted. You will notice the gimbal twitch the pitch now and then as the batteries are dieing but when it does FAILSAFE is not triggered apparently so maybe the 2 things are unrelated. At 1:40 LAND is triggered so I switch to Stabilize and Auto again for it to resume the mission which it does (1:54). The gimbal battery is now practically too weak to keep the gimbal stable and the twitching increases. @2:27 the waypoint is reached but LAND is triggered again due to EKF Failsafe. I switch to stabilize and auto again but it fails to LAND again. A@2:52 my friend (from the Samsung Note) triggers RTL but the drone flies off in the wrong direction. I switch to Stabilize again and try to bring it back but have a hard time figuring out where the front is (it was dark and grey). I see it fly away behind a tree and try to give throttle to bring it up but nothing happens (3:40). I switch to Auto and stabilize but I get not response. I see it fly further away (4:00) and lose altitude. Telemetry is then lost behind the trees (it was about 800meters from us by now). The drone continues to drift (why?) and just "lands" on a tree.

I have just had a similar issue. At a certain point the log is full of EKF_CHECK-2 and FAILSAFE_EKF-1. I am running an APM2.5 with onboard magnetometer and external GPS. I have never had this error before I changed gimbal mount and used a mroe "solid" connection to the F450 frame. I must anticipate that the gimbal's batteries were nearly dead so it was "glitching" every now and then trying to keep the camera stabilized. Maybe the glitch (a "twitch" in pitch, not roll) influenced the EKF error or maybe not. I must also say I had disabled the EKF check completely and used a "relaxed" setting for the Yaw/magnetometer variance check (never logged any bad DCM failsafe alarms). The quad was on a mission and at the 3rd waypoint it failsafed to LAND so I triggered it back to stabilize and Auto again to resume. After the 3rd attempt I couldn't get it back to RTL or Stabilize (RTL was sent via Tower App) from radio or PAD. It just drifted off and set to LAND, unfortunately on some trees. I could not find it as it became dark and the GPS had lost fix (telemetry was lost at a certain point butwalking towards it I got a signal) but recovered it this morning with daylight. I downloaded the logs and attached them FYI. I also have the footage from my gopro if anyone is interested in the mission "FAIL" :)

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Thanks for the feedback Paul! I know EKF is not being used as it only is applicable to the Pixhawk and I disabled it in the settings so it's an incorrect "labeling" as you say. Could these increasing errors be due to the gimbal that was glitching? I suspect it shouldn't happen anyhow as the DCM should keep it's bearing in time despite of the external mechanical influences (but not EM). I will try recalibrating the compass and see if the errors are reduced. Also I'm planning on purchasing a Neo GPS with magnetometer so I will be able to mount it further away from the DCM and fields. ATM the DCM is on the APM even if it is mounted on top of the drone. I do have a couple of HMC5883Ls around with 3.3V support (they use 2 transistors to adapt the 2 signal voltages instead of a dedicated TTL-3.3V IC but they work fine) and will try disabling the onboard one and mounting it externally if I don't see any improvements after the recalibration.

   FYI, I previously only had bad DCM errors and never say EKF errors. My GPS is mounted 10cms from the APM so it should be free. I have however encountere GPS glitches in the logs before, though not recently. BAD DCM errors come up when I rotate 360degrees and shortly after go away, but then again, these last 2 flights did not log any bad DCM errors (I did set the DCM/yaw divergence to "relaxed") apart from these incorrectly labeled EKF errors.

    I think I know why it didn't respond: falling behind the wet trees we lost telemetry and it fails to forced LAND when this happens apparently even if radio signal is good as I saw in the settings that this option was set to 1. Maybe I should disable it (I use a 433 MHz telemetry and it should reach over 1km in line of sight @ 20mW output which I set it to) so I can keep the drone in control at max without TX signal it will fail to LAND anyhow.

    I guess I have to run further tests to sort things out! Thanks again for the heads up!

Hello, I had the same problem and my EKF4.SM are high, up to 2.0. What does that mean? What EKF4.SM are? How GPS velocities are used? And what do you mean by GPS velocities? The SoG coming from GPS?

It seems the vibrations were fine and no big error on yaw.

I attached the log.

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Yeah, perfect analysis...in fact close to the ground the magnetometer goes crazy...from 40 to 70 degree offset.

Thanks

Paul

I am new to the forum and need to find someone with expertise in interpreting error.  I seem to get servo fluctuation while on the ground in FBWA mode as well as other auto modes.  I think this is traced to my IMU2 being noisy.  Any D that I add to Roll seems to be amplified by the noise.  I am not sure if this is normal noise or not.  I can see the plane twitch in the air from the gyro noise being modulated though the servos.  Any idea how I can filter this out?  I have attached a file of my plane sitting on the ground, no wing, no wind, no motor.  I did lift the tail at one point in the file.

Any help would be much appreciated.

Scot

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Hi All,

I've had a similar issue where my quad wouldn't respond and it ended up slamming into the side of a concrete building right before narrowly missing a parking lot of cars. Luckily nothing or nobody else was hurt but the quad. The 3 axis gimbal, Hero4 black, frame, etc are a total right off. The logs show similar Err: EKF_CHECK-2 / Err: FAILSAFE_ EKF-1 errors. I would appreciate any help root causing what went wrong. It was cold day in January and I'm not sure if this contributed to crash. 

 

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i had same errors today. in gps mode, a sudden lost of altitude.

I have had same thing before, so i was high enough to have time to change to STAB mode and make a save.

Any info what is causing this? magnetic interference ?

here´s log

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