MultiWii

Had this idea when I missed low battery alarm & came down hard. Just lucky only 3 metres high!
As even 328 based FC boards have ability to monitor battery voltage, has anyone tried modifying code so that quad will do a controlled descent when critical voltage
point detected? May only be possible with GPS but Baro + ACC should be able to handle this even if landing might be a bit hard using only these sensors .

Cheers..B
brewski Posts: 22Joined: Tue Apr 29, 2014 10:04 am

It is a great idea. I vote for it. I think we need an autolanding procedure, like in nav code version, and enable it when the vbat is under the critical voltage. Or enable RTH when vbat reaches critical voltage and autoland when it goes under critical voltage.

Sounds r3asonable. It would need a time threshold like failsafe has and possibly trigger same emergency state as with failsafe.

Any possibility of implementing in next release?

If timing permits.

When it hits critical it should already be unable to keep thrust and start falling fast

triggering the failsafe seems reasonable after a configurable delay, if the failsafe works. this feature should be user selectable.

however, if the failsafe triggers gps return to home then you might damage the batteries more than if it just landed immediately.

I guess it depends which is more expensive to loose, your battery if it dies, your quad if it's over water at the time or your quad if the battery catches fire deffo have to let the user decide.

dominicclifton wrote:however, if the failsafe triggers gps return to home then you might damage the batteries more than if it just landed immediately.

Then you have not set your failsafe corretly. My point of view is that you set your failsave according to your mission objectives.

When your mission is to fly in your backyard you can set your failsave to a trigger point where your battery is almost empty.
If your mission is to fly in a radius of 10km than do some calculation and set your failsave to a trigger point where your multirotor can always RTH without damaging the battery.

Using the voltage threshold to trigger the emergency landing could lead to a jojo effect.
I also don't like to set the threshold everytime I start a new mission.
"landind in water" is just one scenario, but landing in a group of people ( say I'm hired for a wedding-ceremony to take airial pictures ) is a different kind of danger.

I would better like to set a capacity-% as threshold for RTH. This requires voltage and current monitoring and integration. It will avoid a jojo effect and RTH is the safest way to find a safe place to land.

I like the capacity % used to trigger RTH. Is it possible to add this to current MW 2.3Navi b7 as provision is already there in code to monitor voltage & current or do we have to wait for V2.4?
Another way to really play it safe especially on a quad, if something like a prop comes off/disintergrates or motor/esc fails is to deploy a chute.

Have you seen the rescue chute for multirotors http://www.opale-paramodels.com/index.p ... dji-s800-2
Uses a servo to deploy so can easily be done with MW & even if battery critical there should be enough left to operate a servo. Wouldn't be too hard to make one either as the chutes are available from the guys that sell stuff for model rocketry.

If multis continue to get bad press I can see time in near future that this type of failsafe could become mandatory.