Easy to implement safety feature

[Chrissorocr500]

Heres a idea that would be easy to implement and save a lot of props and injuries.

The problem is when landing or taking off in airmode if your drone gets caught on an angle it goes ballistic. Not trying to blame anyone but myself for almost chopping my nose off, but this sort of thing can be easily and automatically prevented with simple code.
Name anything else that can accelerate like a rocket with the throttle all the way off.

If the throttle is at zero on the stick there is no reason to have any of the motors command 100 percent throttle, particularly if the roll and yaw are also near zero. The simplest would be to simply constrain max commanded throttle to any motor when the throttle is at 0.
for example my quad hovers at 1300us, so while flying this is plenty of power to stay at the commanded angle when the throttle is 0 and more importantly not enough throttle to rocket off into something

This at least makes it so if theres an issue on landing you can release the stick and it stops freaking out.

TLDR
limit each individual motor throttle to aprox hover power when the throttle stick is under the set idle power so it cant rocket off

[sensei-hacker]

That seems like it might be a good idea.
What exactly do you mean by "gets caught on an angle"?

[Chrissorocr500]

Taking off on a non level surface, having a stick or something holding it down and airmode revs the prop to full throttle despite the throttle stick being set at 0 and next thing you know theres a drone shooting thru the air towards who knows what, all with the throttle all the way down.
Or you could even have a setup mistake where the FC, gryo, accelerometer, props are wrong and the drone goes cartwheeling thru the air with some of the motors full throttle.
This would still let it start to runaway, but as soon as things start going wild you could let off the throttle and it stays on the ground

Throttle all the way down should never result in a drone launching, but the way it is now it can and will under certain scenarios

[Jetrell]

@Chrissorocr500
This shouldn't happen if airmode_throttle_threshold is set just above the quads hover throttle.

You said your quad hovers at 1300us.. And airmode_throttle_threshold is set to 1150 by default. That means pitch/roll stabilization i-term will start to accumulate error before the quad has even left the ground. Leading to the issue you encountered. Set it to 1350us.

[Chrissorocr500]

That wont help hardly at all, all my testing shows that once you arm and pass that threshold airmode is on permanently until you disarm.
So if you lift up a little but dont take off the thing could go wild (like you might if you were on an angle and things were looking not great)

The root of the problem is when your throttle is at zero the motors are allowed to go full tilt. If my throttle is at zero there shouldnt be any possible way for the motors to go flat out and cause the drone to rocket around.
Ideally we would still have airmode to keep the drone level in freefall flight, but it dosent need full throttle to do that. A throttle cap for each motor when your throttle stick is low gives plenty of control and isnt enough to flip the drone. There is no downsides, only upsides.

It looks like betaflight has something similar
ez landing It limits how much Airmode can increase motor output at zero throttle and centered sticks.
Heres a video with a demo
https://www.youtube.com/watch?v=lhPD6dZynjw

[Jetrell]

@Chrissorocr500 Yeah true, Ez landing is a useful approach to the issue. I use it with BF on some of my quads. But it isn't perfect either. I've seen it lead to a neutral stick low throttle hang-time crash, when it caught the pilot off guard, because he forget it was active.

With INAV presently, if I'm going to spend time near the ground for too long. I turn off permanently enabled airmode. And only have it active in the modes tab with ACRO mode. This way I launch or land in ANGLE mode. And only switch to ACRO/Airmode when I'm airborne.

The simplest would be to simply constrain max commanded throttle to any motor when the throttle is at 0

That wouldn't be useful. The ideal of airmode it to provide a strong stabilaztion response when the quad is airborne. Which obviously includes low throttle inverted hang-time. Even under high wind conditions. Which may require the i-term to be wound-up considerable, to maintain strong attitude control.. Which means it many need to apply a lot of throttle to some of the motors.

[Chrissorocr500]

I am a beginner and only fly in angle mode so no high speed flips for me. I can see in very limited scenarios you could potentially need a fair bit of adjustment, but that seems to be the exception rather than the rule, and for pilots on that level it cant be too difficult to give a tiny bit of throttle or pitch to pop out of that mode.

it isn't perfect either. I've seen it lead to a neutral stick low throttle hang-time crash, when it caught the pilot off guard, because he forget it was active.

It has settings for this so most likely its just not set very good for his needs

I think its worth having as an option just for the safety factor.

[Jetrell]

I am a beginner and only fly in angle mode so no high speed flips for me.

As I mentioned. The main workaround for now is to go to the Configuration Tab > Other features and turn off Permanently enable AIRMODE. This is a recommendation under the wiki standard modes.

And only enable Airmode in the modes tab with ACRO, and not with any other flight or nav modes.
Since you're mostly flying in ANGLE mode. You don't need Airmode active. Which is causing your issue.

I can see in very limited scenarios you could potentially need a fair bit of adjustment, but that seems to be the exception rather than the rule, and for pilots on that level it cant be too difficult to give a tiny bit of throttle or pitch to pop out of that mode.

We aren't talking about the collective throttle rcData. What you spoke of would limit the rcCommand for the throttle required to control stabilization on each motor individually That should not be limited in airmode/ACRO.

[Chrissorocr500]

turn off Permanently enable AIRMODE

Thanks, thats what I will do until I have time to modify inav source to make it work good both in the air and on the ground as its not great to have the quad tumble while falling when I release the throttle all the way.