2014-01-13%201-14.kmz

2014-01-13%2016-14.log

2014-01-13%2016-14.kmz

All 3 crashes the same thing happened. took off in stable went to about 40 elevation switched to loiter, then flew about 150 yds into a 10mph wind. The best I can tell it appears that the quad rolls on its side and drops to the ground. Breaking a prop or two and frame once.  At least 8 good flights between these wrecks. Changed motors. Using apm 2.6  Could someone look at my log and give me an opinion. 

ThankYou

Tracy

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  • Connected receiver directly to each esc one at a time. Drove motors with props on aggressively moving throttle.  I could not make any go out of sync.  I don't know what to do put fly it and keep an eye on any development in esc's.

  • Have you checked for vibrations. i recently had a crash and the screws holding my apm case popped out. I did nt notice but this caused the actual board to vibrate making the copter do weird things. Once i glued the case tight everything was fine. Why am i telling you all this because im suggesting perhaps the board is still moving about inside the case. In my case vibrations were big up and not down, which resulted in my copter shooting up. Once fixed everything is back to sweet.

  • Moderator
    Are you using SimonK flashed ESCs? If so, while any if the physical issues is possible, swinging such a large prop does admit for the very distinct possibility of a loss of sync. The ESC is sending pulses to spin the motor, but the pulse tries to change the speed of the motor/prop faster than it can achieve, too much torque, so the motor and it's magnets get out of sync, and the motor and prop go weird.... Like trying to ride your bike downhill, only to suddenly have your front wheel transform from a circle to a triangle.

    This issue is exaduraring by SimonK firmware on ESC's. This firmware is aggressively tuned and intended for smaller craft... Up to 8, 10, many 12 inch props. Slow, big combinations like 480kv, 14 inch are known to sometimes experience sync failure with agressive throttle changes .... The Dev lists are alive right now with smart people setting out this issue, it appears often in the agressive autotune process, but can also happen spontaneously in gusty winds. With your props.... 17 inches, it might be a given in many situations. Definitely look at your ESCs, and if they are flashed for SimonK, swap or reflash. Look at the Dev lists for other solutions. There are several. A slow throttle parameter option, finding the right ESCs and programming them for your massive props, and more ideas to come. People are actively working on this issue.
  • Moderator
    Can you please detail the hardware? Did you perform any post-crash testing? That might be relevant? As Andre said, the quad desired roll and actual roll diverged, suggesting some form of lateral stabilization failure. In addition to the causes he mentioned, certain hardware combinations are known to sometimes suffer from a loss of sync, a form of propulsion failure. But unless you are swinging large props, that isn't likely.

    When faced with this type of issue, I work the problem independently. I do look at the logs, but I try not to form too much speculation from them at first. I look at the crash and gear afterwards, and I make notes about what I see. I usually start with the physical, and I make notes about what is broken, what is loose, I check the physical... Supports, screws, prop condition, collette condition, shafts bent, then move onto the electromechanical, do the motors feel right when spinning by hand, are all the cables firmly seated or do any look loose? Are the cables intact?

    I look at the logs and form a theory here.

    Then I tie it all down (zip ties) especially loose motors and perform powered tests to see if the diagnostics, ESCs, are ok... I'm looking for (invisible) wiring problems post-crash... A motor that will not spin up, etc.

    Something went wrong with the roll axis. The question is, was it physical, electrical, or more complex, like a sync issue? My (too quick) suggestion for how to approach the issue.
  • At log lines ~3870  you can see your "roll" and "desired roll" go in opposite directions.

    This indicates that APM does command correction, but there is an ESC, motor, propeller or motor-mount problem.

    Unless that was ESC or ESC connection,  your wreck probaply had a loose motor or propeller.

    - and - please use ardupilot.com forums for support.

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