Motor slow spin down on throttle down behavior

ArduCopter Copter 4.0
1

Hi!
I found similar topic (Motor still spin after shut off) , but will ask for clarification here as well.
So, the issue is, that after putting throttle all the way down, motors stop spinning only after couple of seconds.
MOT_SPIN_ARM is set to 0 as well as MOT_SPIN_MIN is also set to 0.

Consider situation:
Copter crashed and you need quickly show down the motors.
There are few possibilities:

  1. Disarm - 2+ seconds for proper stick movement and disarm delay.
  2. Motor emergency stop - 1+ second for reaching correct switch and use it.
  3. Just move throttle to 0 - <0.5 second, but it does not work :(.

I have cheap Chinese drone for training and on throttle down it stops spinning of the motors instantly.

Currently I worked around 3) using Taranis features:
On Throttle > 0 -> Motor Interlock ON via aux channel
On Throttle ~0 -> Motor Interlock OFF via aux channel
Having this, motors stop pretty quick, but I feel there is better way to achieve this, rather such hacks.

So, question is - is there a way (by tuning some parameter or so) to enable behavior of instant stopping of the motors?

Thank you!

2

You 2nd option - motor emergency stop on a switch/RCchannel is the only safe way to do this. You just have to be aware of where the switch is so your fingers can quickly flick the switch.

Other options will cause disarm or motors to stop inflight when you dont want to.
MOT_SPIN_ARM and MOT_SPIN_MIN should be set correctly to realistic values.

3

Thank you for so quick reply!

After taking a look at code: https://github.com/dronekit/ardupilot-releases/blob/master/ArduCopter/motors.cpp#L80

I think, I can set disarm_delay to 0, so essentially disable auto disarm, so it (disarming in flight) will never happen.

I think there are already too much of safety features:

  1. Safety switch of the controller
  2. Arm/Disarm
  3. Throttle@0

Adding another layer here would just add unnecessary complexity…