Danger!

Posted by Paul N Braida M.E on March 7, 2015 at 2:04pm

I could use some input on this dangerous issue.

I have my quad spooling up now no problem.however I found out  that there is a dangerous issue at hand. Seems that even if the throttle stick is at zero then I turn off the transmitter the motors all fully spool up on their own..I'd have to always remember to disconnect the battery before turning off the TX.

Is there any parameter that would allow me to keep motors off when the TX is turned off?

Thanks.

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Replies

  • Jake Stew March 11, 2015 at 9:59pm

    I think you got bit by the PPM encoder bug.  There used to be a bug where the APM would always go into "flyaway mode" whenever a failsafe happened or signal was lost.

    Probably the majority of APMs out there have this bug.  So unless you've flashed the PPM encoder chip you probably have this problem.

    You can find details how to fix this here...

    http://copter.ardupilot.com/wiki/common-autopilots/common-apm25-and...

    • 3D Robotics
      Chris Anderson > Jake Stew March 11, 2015 at 10:06pm

      Jake, that was resolved more than two years ago. All APMs shipped after March 2013 had the newer PPM firmware that did not have this issue. So the vast majority of APMs out there do not have that bug.

    • Jake Stew > Chris Anderson March 11, 2015 at 10:53pm

      Thanks for clearing that up Chris.  Not sure what version the OP is using.

      Did the bug make it all the way to v2.5 or was it caught in v2.0?

  • MR60
    Forrest Frantz March 7, 2015 at 5:18pm

    The following are the issues because this particular issue is deep. The reason why it's deep is because you don't want to disable failsafe for the following reasons:

    - The ship wanders outside the range of the Tx so the signal is lost.  What do you want the ship to do?  If you tell it to stop the motors, will it fall on someone?

    - Some idiot on a bike side swipes you, you fall and break your antenna.  Tx is lost.  The ship was flying in a park with people not too far away.  What do you want the ship to do.

    - You accidentally turn off the Tx before disabling the motors.  Your face is right above the ship.  What do you want the ship to do?  If you told it to go to a safe height and return to home ... I hope wearing safety goggle is on your checklist.

    - You are testing failsafe mode and turn off the Tx while it is in flight (not near anything; your hand ready to turn the Tx back on)

    - others

    In of those cases, the ship only knows that the Tx signal was lost and it's now no longer under control of the pilot.  What do you want the ship to do automatically?

    Attached is a Pilot Checklist in a Word format that looks like the picture shown here.

    3692841090?profile=original

    Make one for yourself that speaks to the options that you have on your ship. Print off one for every flight. Don't read each line. Instead read them out loud just like professionals do (so they don't scan and skip). Check the boxes with a pen each time you fly.  Create a log.  This will help you track battery usages and motor hours to change the bearings before they cause damage to your ship.

    Flight Check List.docx

  • Paul N Braida M.E March 7, 2015 at 3:18pm

    I'm thinking the scenario if the transmitters goes low on battery power and shuts down or if radio contact is lost?

    Presto! Instant full throttle.If I was to turn off the failsafe,then what?

  • Developer
    Bill Bonney March 7, 2015 at 3:18pm
    The other advice is correct. But you can also disable the fail safe of you rc receiver to send no output on power off, or set the fail safe to be low throttle. See http://copter.ardupilot.com for more instructions on setting failsafe correctly
  • mark whitton March 7, 2015 at 2:16pm

    Chris is right, you should disarm before turning off the transmitter and you should set the RC Failsafe function and test it with the props off.  Modern RC transmitters do not use much battery power so there is not much advantage in turning them off right after a flight.

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