This is the new folding frame Project I am working on.
Can anyone tell me if it´s possible to control the eight counter rotating motors with ACM.
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This is the new folding frame Project I am working on.
Can anyone tell me if it´s possible to control the eight counter rotating motors with ACM.
You need to be a member of diydrones to add comments!
Comments
I.S. is right
a BIG negative point joint coaxial has: interferences
as you are running 2 propellers in the same direction on top of each other, the first one needs more power -> it runs slower -> the propellers overlapping from time to time which causes oscilations (big vibrations)
so if you ask me: stay away from joint coax configuration!
I'm sorry to disagree, unless your using a speed controller that can tell the motor to spin in reverse, which direction the motor spins is just flipping one of the three outpu wires coming from the esc... So to further go on
top motor spins ccw, bottom motor spins cw in relation to itself, but since its flipped upside down, its still ccw in relation to the frame.
The top prop is a normal prop, and the bottom is a normal prop but flipped upside down on the motor shaft.
So the two motors will complement each other.
@Darren, Peter
Lets name it "joint coaxial configuration":
No, the simple X4 to X8 conversion with each arm 1signal to 2 ESC+motor is looking for props in each arm turning the same way (ok, each motor will be wired to turn counter but the props will turn in the same way).
This way each arm will do have yaw moment and APM will function as regular X4.
2 Lets name it "counter coax config":
In a X8 counter coax copter each pair of props on each arm counter rotate so it doesn't produce yaw moment.
That's way APM has to balance each CW and CCW prop speeds to achieve the yaw movement thus requiring 8 different signals.
Hope I manage to explain myself.
In short:
X8 joint coax: Yaw achieved as X4 --> 4 different signals enough
X8 counter coax: Yaw achieved balancing between CW and CCW props --> 8 different signals required
Anyone has any kind of experience with coax? Is counter coax more stable and/or precise? should be?
Hi,
I'm guessing (and it really is just that, a guess!) that the yaw issue depends on whether you have CCW/CW CW/CCW or a matching CW/CW CCW/CCW propeller arrangement on each arm. It might be worth swapping one set (either top or bottom) of motors/props along one (so front right becomes back right) in order to see if this works better?
I may well be wrong on this but, my thinking is if you have a top and bottom motore that cancels the torque effect of eachother out, then you will loose yaw effect. If they compliment, you wont?????
Hi Darren,
your configuration with the top/bottom esc's together on the signal side will work for Roll, Pitch and Throttle but not for the Yaw because you need the turning moment of the motors and with counterrotating motors you don´t have any turning moment.
Hey Jani,
good to read what you write.
I am planning on buildiung a Y6 (so 6 motors working coaxially) Will that be possible with ACM at a later point? Will it be possible to adjust the motorspeeds singally to give the bottom more speed?
Regards
Daniel
Actually ACM has full support for Tri, Quad and Hexa's already.
For coaxial setups you should have separate control for all 8 motors due lower motors needs to run with slower and optimized speed or you waste a lot of mAh's for fighting against the wind.
Using 8 PWM outputs from APM is a bit tricky due hardware issues. OUT5-6 cannot be used to Fast PWM due hardware issues on microprosessor.
I2C is also a bit tricky to use due if one I2C fais they all fail. This is due I2C bus.
We are working on UART based ESC's that are safer to use in 8+ configurations. No real ETA for those.
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