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Multicopter Self-Stabilization Question

colorex

Rotor Riot!
Mentor
#1
If you angle all the motors a few degrees inward, so that the thrust goes at an outward angle (or just warp the arms upwards a bit), won't this make the multicopter a bit self-leveling?

Meaning that when you let go of the sticks it returns to a neutral position.
 
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JimCR120

Got Lobstah?
Site Moderator
#2
I want to say no but then when I think of how dihedral works I must reconsider. So now, I'm thinking yes but I've got as much mutli-copter experience as you have aircraft available to fly.

Now I'm very curious about this too.

Dadde? Someone?
 
#4
Here are my experiences...

I have been flying Tricopters and Quadcopters for a while...

I have flown with bent arms (upwards) making motor tilt a bit but that really does not matter much.
I have flown with arms loose without knowing it and it caused vibrations in 1 axis only - the other was rock stable.

Up to a certain degree I think it does not matter much at all.

//UndCon
 

JimCR120

Got Lobstah?
Site Moderator
#5
You seem less than totally convinced. I'm guessing then that you probably weren't checking for tilt stabilization as it would relate to center canted props.

I think this would have to be an experiment to do unless it's been done.
 
#6
Multiwii compensates for a lot - including reduced thrust as it is still level in auto mode when flying with a bent arm.
It also compensates for not being balanced at COG so I can add weights to 1 arm and that motor just increases RPM to maintain level.

However - It might be more noticeable on a gyro-based *Copter where there is no intelligence built in to compensate for such things.

I can do series of tests this Sunday when our indoor season begins (3 hours of fun every Sunday)
1 of my current arms is slightly bent upwards...


All this makes me want to build a thrust-meter...my current kitchen-scale only go up to 1000g
 

jetpackninja

More combat please...
Mentor
#8
Make a tricopter sandwich
Scale - tricopter - brick (may be better to strap or some other way attach the tricopter to the scale...)
Measure the total weight, fire up the tricopter at full throttle, get another weight reading.
I don't have a tri- but it seems like it should work?
 

Yair

Junior Member
#11
I didnt check about the "quad dihedral" but my guess is that the only thing you will get is shorter flights( not all thrust gives you lift) and i immagine some oscilation( the quad will not be "flat" anymore and will have some pendulum effect)
Just a guess...
 

colorex

Rotor Riot!
Mentor
#12
I didnt check about the "quad dihedral" but my guess is that the only thing you will get is shorter flights( not all thrust gives you lift) and i immagine some oscilation( the quad will not be "flat" anymore and will have some pendulum effect)
Just a guess...
Indeed it will.
 

JimCR120

Got Lobstah?
Site Moderator
#13
My unqualified idea for a test would consist of the following:

1) Obtain a gyro equipped tricopter or quadracopter.
2) Turn down the gains on the gyros to see what level of oscillations are experienced, looking for light to moderate. Note number of turns on potentiometers.
3) Return to normal gain settings.
4) Angle in the motors 15 degrees.
5) Repeat step 2 & 3.
6) Angle in the motors 30 degrees.
7) Repeat step 2 & 3.
8) Report findings.

As I said I don't consider myself qualified to just come up with steps but maybe someone who does have the knowledge and experience can chime in and help out.