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:

3691281226?profile=original

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

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  • Hello again!

    Sorry for the delay, I have been away for a while. I've been busy with coursework and exams.

    So I finally I got back to work on this issue, repaired my quadrotor & tested it again. This time the issue was resolved and I could successfully test a mission with automatic take-off & landing. Here's the list of things that I did:

    -Replaced my Pixhawk with another one (purchased from the same store)

    -Decreased the climb rate parameter (WPNAV_SPEED_UP) to 1.5 m/s (originally it was 5 m/s)

    -Changed the CF propellers from 13x4 to 13x6.5 (it was not intended, my local store had ran out of 13x4 CF props and the closest option was this)

    I'm not sure which one(s) contributed to fixing the problem, and I can't risk undoing them one by one until I encounter the problem again; But I feel that the only (or at least the most) effective change was replacing the Pixhawk.

    If I find out something more, I will post it here for further reference. Again, I want to thank all the community members who took the time to respond to this discussion, I really appreciate your help!

  • I think you would have better luck with some $3.00 weather stripping than that pad for vibration dampening.  Too much surface area used.

    • I'm thinking of using something similar to the "3D Printed Anti-Vibration Platform" mentioned here, as Fnoop suggested that it has worked better for him and many others. I know that doesn't necessarily mean it's going to work for me. I might try something simpler like what you suggested before going for that. Thanks Michael

      • If it flies well in Stabilize and AltHold, then your basic wiring and dampening would seem to be okay.  If it screams off only when you engage a mode that requires positioning...

        There is such a thing as too much vibration dampening:

        3702738335?profile=originalThis Pixhawk is mounted to the plate with foam tape, and I used two different density earplugs to absorb different vibration harmonics.  It rides so well that it will not complete AutoTune.

        Finally, could you tell us which Chinese copy your PX4 is?  In case your problems are in the FC,

        • joe bob your antivibration is a mess,how do you calibrate level with this?

          this is my way of complete antivibration insulation...pix must be in "Sandwich"

          3702809900?profile=original

          • orange foam-antivibration mount(with silicon rubbers)-pixhawk on silicon pads for hard disc in "sandwich"........result,vibration almost zero at full throttle

            • Emin I have similar setup but foam upside and forget vibrations :) ; yours looks better because you give more weight to the FC, How you resolve upside px wires ?

              • Just make openings on top and hope u wont need to unplug too much

                3702913994?profile=original

                • Thank's

        • If it flies well in Stabilize and AltHold, then your basic wiring and dampening would seem to be okay.

          Yes it was okay in Stabilize & AltHold, but I almost never tried to go full throttle in those modes. I was thinking that maybe the vibration problem arises only at about full throttle, could it be so?

          I don't think my FC is overly isolated, as I have used a very thin pad.

          Finally, could you tell us which Chinese copy this PX4 is?

          I bought it from here. It was performing well, and the sensor readings (including the barometer) were also reasonably accurate. But what Cala said just now makes sense too...

          Shenzhen Bate Technology Co.,Ltd
          We will serve RC models all over world
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