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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Comment by DaveyWaveyBunsenBurner on March 13, 2011 at 3:43pm
If you are runnint 8 motors in a standard coaxial configuration you should be able to run it using y leads to split 4 channels into 8.

In a coax config, two motors receive exactly the same signal.
Comment by Peter Koch on March 13, 2011 at 3:56pm

@ Ike: The developmet is made with SolidWorks.

 

This was also my first thought but of the coax config I will los the Yaw effect.


3D Robotics
Comment by Chris Anderson on March 13, 2011 at 4:25pm

I think eight is supported by the ArduPirates code.

 

ACM will start with quad and tri support


Developer
Comment by Max Levine on March 13, 2011 at 5:18pm

NICE render, love SolidWorks .. You should ask Jason for 8X frame support :) There is many free out-put pins left on the APM, so may be you can use some, I guess...

When you will have it ready for a spin ??

And can you share more info on that frame ???

 

IINM  ArduPirates code use I2C ESC for OCTO frame.

 


Developer
Comment by Jani Hirvinen on March 14, 2011 at 7:10am

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.

Comment by Daniel Gru on March 14, 2011 at 7:18am

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

Comment by Darren on March 14, 2011 at 7:30am
I think Davey is right, can you not just tie the top/bottom esc's together on the signal side for simple redundancy on each arm? should just act like a normal quad, but with (a bit more horsepower) ;) then use a seperate bec for the electronics.
Comment by Darren on March 14, 2011 at 7:38am
However I do have to add, I agree with Jani too, there are much better ways coming down the pike... I also think Y'ing the two motors can get tricky due to syncing rpms two a tee. independant control allows minor differences between motor/esc's to be handled without alot of the issues that come with y cable, as well as failure of a motor for i would imagine.
Comment by Peter Koch on March 14, 2011 at 7:54am

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.

Comment by DaveyWaveyBunsenBurner on March 14, 2011 at 8:02am

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?????

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