Hi,
Just a quick update for the thrust vectoring coaxial drone project,
Config:
Maxxprod Himax contra-rotating brushless motor CR2805,
7x5 props replaced by T-Motor carbon fiber 9x3 resulting in more efficiency.
Flight time is about 15 minutes with Fatshark HD pilot and 12 minutes with a Gopro 3. Could be even better with a more adapted motor. The advantage of this system is to allow large props with little frame (the 3D printed frame of this coax weights less than 30 grams) resulting in a very good efficiency.
Flight controller is a CC3D revolution with a standard coaxial vehicle config.
The system seems to not accept too much the integral (often resulting in a counter pendulum effect during fast pitch forward translation but maybe it can be a variable overshoot??) but no pendulum effect with a simple P (no I nor D) for the inner loop (acro) and a simple P (no I) for the outer loop (attitude). With this config, the system reacts very good and is very stable and controllable even with wind.
Next step will be to remove the clevis in the commands because the system could maybe accept a direct servo in the roll and pitch plates and take advantage of a larger roll and pitch travel (-45°, +45° for ex) and more room in the frame (or a lighter one). CC3D will be replaced by a SP racing F3.
Thanks for your comments if you have!
Comments
@Robert (and the others),
3D design is available on thingiverse with some advices for the mounting. Enjoy!
http://www.thingiverse.com/thing:1721441
Hi, very impressive... About motors - did You see this? Man make it fly with multiwii.
@TheSun, yes but at least I will try to log the integral values in order to figure out why there are these violent counter reactions when in ACRO mode with a big Iterm. thks a lot!
a vtol solution with aspects of this frame would be interesting.
Very interesting, theoretically I term should never affect the transient performance of a system, especially not make it unstable. There are exceptions to this, you may find that introducing the zeros from your I term in your transfer function is somehow producing a very odd root locus. I doubt changing controllers will affect this in any way
thks all,
@Paul, you're right, the disk loading is still very high, even if the flight time is pretty good due to the the low weight of the frame (less than 30g). But it's the max i can get from this motor from Himax without firing it (I tried...:)). Contra-rotating motors are quite rare and especially designed for planes (high Kv). That's why i'm working on a new experimental motor which is a little beyond my "garage" capabilities but no matter! I'm trying to transform two T-motor antigravity 4004 motors in one 4004 contra-rotating motor in order to have a very high torque low kv CR motor which can drive a 15" carbon prop. With this new design and a GEB8043125 1C Lipo, I'm sure it's possible to lift a go pro for one hour and take a real advantage from the global design comparing to an average quad! And for the flight dynamics, I don't like theory so we'll see in flight test! I'll keep you inform in this blog! thks for your comment!!
Though you have enlarged the prop diameter I still think the disk loading is pretty high in comparison to an average quad. And that really matters in terms of flight time.
Basically you could double your flight time, if you double the props diameter. So you need motors with more torque to turn the larger props etc. And the other question is, how does it effect the flight dynamics. You may should test even larger diameter to increase performance!?
I could see a lot of applications in very quick point inspections!
excelent news!
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