[Wishlist] Auto-soft-landing on accidental throttle down

This is a public letter to APM developers:

I wonder if it's possible in the future to add a flight mode to APM where if you accidentally pull the throttle down the system engage a failsafe landing

a simple algorithm like (pseudo code):

var t1 = listenTo (apm.throttle1)

var t2 = listenTo (apm.throttle2) after 000.1sec

var diff = t2 - t2

if ( apm.altitude > 5m && diff > 400) 

do soft lower.altitude

else linear.throttle

my point is that we should have a mode, especially for aerial photography, not acro, where an accidental throttle decrease while flying at high altitude shoudl be prevented.


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  • T3

    As of 3.1.5 (the current "standard" firmware) you can arm and disarm in alt hold/loiter.  

    (Some experienced pilots will hate this but) you can simply avoid stabilize altogether and take off in alt hold or loiter mode.  I have tried it on 3DR's X8, it works great.  The copter takes off when you bump the stick above 50% throttle.  On landing, it automatically cuts the props once it touches down- no intervention required.  As an experiment, while in flight I dropped the throttle to 0%.  The copter descended at a decent speed, but not too fast too land safely.  It landed with a satisfying thump and cut the props.

    Please note you need a well tuned copter for this to be reliable.  And wind doesn't help.

    • that's interesting. it's basically solve for my thinking. 

      I actually also have a NAZA hexa and i love the auto-take of of the NAZA V.2 which sounds similar to what you mentioned.

      • Moderator

        @Stephen you are right ;-) IMHO there are already too many parameters and people are adjusting all of them all the time and stuffing up their gear. Better just to learn how to fly. It only takes a week if you go out every day. 

    • Agree, works really great. With AC3.2-rc5 even better . But another one of my favourite fool functions, ResetToArmedYaw, got lost :-(

  • Why ?

    I mean, the "Throttle" stick on your typical RC TX is a pretty obvious "thing".......

    Or should be.

  • You already have at least two modes that do this, AltHold and PosHold, both excellent for aerial photography.  In either mode if you put the throttle to zero, accidental or otherwise, the craft will descend at its maximum allowable programmed rate. Set that rate to whatever value you like. It works fine. Try that in Stabilize, Drift or Acro and it will fall from the sky.

    • Out of interest,  is this applicable to just ac3.2 or earlier versions too?

      • Pretty much. That variable has been around for quite a while. Of course Position Hold is new to 3.2, but the variable applies to any guided mode, such as AltHold and Loiter. It simply caps the maximum descent rate. There are similar parameters for both horizontal velocity and climb rate, but descent rate seems to be the most important for a lot of people.

    • that's fantastic... how / where do you set that "rate" you mentioned?

      • That would be the "Speed Down" parameter in the WPNav section of the "Extended Tuning" tab. You can also change it in the "Full Parameter List"  where it's listed as the WPNAV_SPEED_DOWN parameter. Same parameter, just two ways of adjusting it.

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Shivchand Jaysaval liked Shivchand Jaysaval's profile
Aug 25