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Anti crash - cartwheeling

Posted by Crispin on January 28, 2012 at 12:22pm

Hi folks,

Tell me to go away if this has been covered before. I know crash prevention has and I've read a bunch of posts but not seen anything like this.

Today while flying, a prop came off while I was about 40m up. On a quad this is pretty terminal.

As I watched it falling, throttle off but cartwheeling like mad, I was thinking. I still have 3 good motors and forms of lift. Why not use the good motor on the dead axis to try keep it level by speeding up / slowing down. Failing that, why not speed it up and cause it to flick right way up. As it tumbles over again, flick it the right way up. The idea is that it would spend more time the right way up than just random and you have a better chance of landing on your feet rather than head.

If it is not possible because of torque effects, cool, it was just an idea from a noob ;)

Cheers,

Crispin

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Replies

  • Jimmy Donadio June 8, 2015 at 7:31pm

    There are people working on algrothms to maintain control of pitch and roll in the event of a motor/prop failure on a quad https://youtu.be/ek0FrCaogcs

    They also have one for loss of 2 opposite motors https://youtu.be/t369aSInq-E

    • ShafieMukhre > Jimmy Donadio June 8, 2015 at 7:41pm

      good sharing

  • ShafieMukhre June 8, 2015 at 6:32pm

    Dear Dave C, with full humbleness to learn, have anyone done crash prevention for copter using Airbags? 

    Cheers,

    SM

  • Dave January 29, 2012 at 3:40am

    Perhaps one possibility is to use Car ESC's that have a Reverse function.  So, when your prop falls off / motor fails, the opposite motor could apply upwards or downwards thrust to re-stabilise the quad.

    The torque reaction from the other two opposing motors should cancel each other (I think), so Yaw control might also be possible?  Maybe.

    Reversible motors could make for an incredibly responsive quad.

  • Rob_Lefebvre January 28, 2012 at 12:28pm

    Yeah, basically impossible.  The yaw will be uncontrollable for one thing since you have for example 2 motors going CW and only one going CCW.  And then it would be impossible to prevent pitching, because the motor opposite the failed one will make the copter flip anytime it is powered.  The only way it could even begin to be possible is if it could go forward or reverse to try and get the copter upright.  But... really it's just impossible.

    I think the best that could be hoped for is if the AC2 recognized the condition, and killed the motors.

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