Hey. I have a quadrotor with Pixhawk, APM:Copter V3.3.3 (acf2e10c). I have tested it in Stabilize & AltHold modes, works fine. Also tried switching to Land mode from Stabilize & AltHold, and the drone lands perfectly.

I wanted to try AUTO mode, as a first test I defined this mission based on the tutorials here:

1. Takeoff to 10 meters

2. Loiter there for 5 seconds

3. Land

I went out for a test, as soon as I raised the throttle in AUTO mode, the copter started climbing VERY quickly, and it kept climbing up until it was about 60 meters above the ground. I waited for like 10 seconds and it kept climbing, so I panicked & switched to AltHold mode. I'm a newbie pilot so I could not control it properly at that altitude and...crash!

I thought maybe it was a bug in my planned mission or a gps glitch or something, so I fixed the copter and tried agian. This time with this mission:

1. Takeoff to 3 meters

2. Land

Again, same thing happened. This time, I switched to Land mode, but it kept climbing like crazy. Switched to stabilize and eventually...another crash.

I reviewed the logs, DAlt (desired altitude) does not match my planned mission altitude (figure below). I have attached the log, can someone please help me with this?

DAlt Plot:


2016-03-10 08-28-02.bin

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          • Do you have logs from your previous flights?

            INS_USE,  parameter is the param that you need to diasble the IMU, only for test but not desirable to use like that, If works, better to replace the controller.

            Looks here too, baro alt and climb rate don't have sense too, I hope the controller is confused.

            3702858362?profile=originalyou can try to isolate too as others recomended, perhaps the noisy IMU works better but see your logs after flying in auto modes.

        • If not original from 3DR write to your reseller 

  • I hope you have some troubles with imu 1, It's a new 3dr pixhawk?

    • Not sure what you mean by "new", I bought it about 6 months ago from a reseller located in China. And since then, I have flied with it less than 10 times, each shorter than 5 minutes in duration. Why does it matter?

      • I refer if never fly in auto modes or Loiter earlier

        Looks the difference between Imu 1 and 2, if your problem is vibrations the two imus have to be similar

        3702738316?profile=originalI hope that you have a failed controller, you can do two things:

        Write to 3DR services sending your log and this picture to confirm this.

        Try to disable IMU 1 (at night I check if it's possible, I hope something like IMU 1 disable in full params list) and try to do what Fnoop recommends: stab--alt hold---Loiter, then try to move side to side in Loiter or Pos hold, if mantain alt (up and down) then try auto from Loiter as Fnoop says. Good Luck.

        • Developer

          I'd say Cala has found the issue here.  The only thing is that it might not be a hardware issue.  It could be really high vibrations coming through at frequencies that only affect one IMU or the other.  The two IMUs have different update rates (1000hz and 1600hz) so it's possible (although rare) for them to be affected by vibrations differently.

          Getting vibration dampening right is still important (it was *really* important on the older APM2.x boards) and we have a wiki page on it.  I personally recommend the Hobby King Orange foam (because the 3M foam apparently isn't available any more in the 3DR store).

          • Nice antivibration compilant, thank's Randy I didn't saw up to now.

          • Thank's Randy to clarificate, I didn't have good results with orange foam (the first I try) but I used under the hole controller, I hope four little pads under corners like 3dr pads looks a better idea, I'm going to give another opportunity on my following build.

            HK have a similar pads than 3dr ones but not try it yet  http://www.hobbyking.com/hobbyking/store/__73571__Vibration_Absorpt...

        • if your problem is vibrations the two imus have to be similar

          Are you sure about this?

          Mission Planner's Log Analyzer detected this mismatch between the two IMUs & it said check the vibrations & calibration.

          But if you're right, all I need to do is to change the FC. I will try to get another Pixhawk & test this hypothesis. Thanks for pointing out!

  • Posting pictures of how the FC is mounted, wiring etc. can help diagnose the problem..

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