Kill Switch in Auto Mode

Hi All,


I've got a stock DJI F450 with APM2 (running 2.7, although I plan on moving to 2.8 soon) with a Spektrum Dx7s. I noticed that the Spektrum has a Throttle Cut option, that I've tested in Stabilize mode, and I was wondering if it couldalso bring down the quad in Auto mode.


The idea would be to stop all the motors moving (and cause the quad to crash) by pushing a button on the Spektrum transmitter. Any ideas?



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  • It would be nice to have a combination of what Jake and R_Lefebyre are saying.

    One switch that would kill the motors in one position and prevent you from killing them in the other position. If anyone figures this out let me know, I'd love to have that feature on my quad.

    One switch to rule them all... (I couldn't help it)

  • You could always program a channel 7 option to disarm motors.  That would drop it like a rock.  I already posted the changes on issue 481.  The code is untested but should work.

  • I don't think in auto-mode that switch would have any effect. I may be mistaken, but in auto mode altitude and thus throttle is managed automatically. In other modes, such as loiter, and alt_hold, throttle can be used to increase or decrease the altitude but not directly control throttle.

    Funny story, I found this the hard way when I accidentally switched my Stabilize and loiter mode function. I took off and switched it to loiter, then back.. or to.. or... anyway I somehow got it backwards. When I tried to land it did indeed land but could not get the motors to turn off (Motors will not stop in loiter mode) took me a few long seconds to realize it had it on loiter mode. I was going through my head, how will I get these motors to stop, and is it about to take off and be gone? The battery plug in too close to the blades to pull it! haha

  • Stephen and Craig,

      We want the kill switch because we plan on giving this to people who aren't pilots (scientists who would use it for gathering data) and we want a way to drop the quad if it does something that we don't want it to do. Craig is right that we want it as a better wrecked than lost feature.



      We plan on running it in Auto mode and we've found that just dropping the throttle stick to the bottom doesn't always kill it. Sometimes it makes the quad slowly descend as it continues on its path and other times it doesn't seem to have any effect.

  • Any time you drop the throttle stick all the way to the bottom, the motors will stop. (I am pretty sure, but for sure in Stab mode).  I think what you are looking at doing is a switch that simply drops the throttle stick to the bottom.  I'm not quite sure I understand how that's better than just dropping the stick to the bottom.  

    But now you've made me realize the opposite thing....  I should actually use throttle cut to prevent myself cutting the throttle accidentally.  My Octo hovers at 1/4 throttle, so it would be too easy to kill it accidentally when trying to decend.  I can use the switch to prevent me from ever dropping it too low in flight.  The only downside is that it will only arm/disarm if you flick the switch.

    I'm already flying my helicopter like this however, so it would be consistent.  Basically, switch down, arm it.  Raise switch, motors start, and will not stop until you drop the switch again.

  • Yes, it's a potentially dangerous button. I have one too. One thing it might be good for is an ARM switch. You can set it up in conjunction with your ESC calibration so that you could only arm the APM while pressing the Cut button. I set it up once but don't think I ever used it, vaguely recall some minor issue which I didn't try to fix. Might be good around/for kids etc.

    I am thinking you're thinking of using it as a "better wrecked than lost" switch...

  • Most of us go to extra efforts to prevent this.  Why would you want this Kamikaze feature?

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