Offset X frame configs. Just changing angles, or manually setting roll/pitch factors? Digging through code, need help!

OK, in summary I have a TBS discovery and I want to do a better job of setting up its odd angle arms to work with the APM.  I feel like understand this would also be great for testing and adding new platforms like a spider Octa, hexa V, etc.

I've made pictures because I feel they can better convey information.  Basically, I've found the angles on my non-pure X frame (not 45* spacing) from the horizontal and vertical lines.  I tried do a simple edit of these values (see picture 3), but it didn't see very stable over the normal X with the same PID settings.


I also looked at how the Octa V is setup, and I'm thinking that is the best way to tackle this problem, but I don't quite understand how I might map these values out for this setup.  Who wrote the V code?  Could they share any insight?

Here is the normal X frame, and the rough Roll/Pitch factor that gets applied after the add_motor function by my calculations. 

I then looked at the Octa V and saw how it skipped the add motor function and just wrote raw roll/pitch factors.  I mapped them here to try to better understand how their placement would change my offset X.

 

So can I get away with my angle changes running add_motors, or do I need to find out what the real roll/pitch factors for this offset should be?

 

Edit: Updated pictures.

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Permalink Reply by airmamaf on November 28, 2012 at 11:45am

Based on this, I modified the code off AP_MotorsQuad.cpp (see joined file), and add in APM_Config.h

#define FRAME_ORIENTATION V_FRAME

it seems to be better for me, can someone can also test and share PID ?

Attachments:
Permalink Reply by Josh Potter on November 28, 2012 at 1:25pm

I'm running Dimitri's angle based setup currently and it's flying great.  What motors and props are you running?


Permalink Reply by airmamaf on November 29, 2012 at 2:16am

I'm running Turnigy L2210C-1200kv with Graupner 9x5 propellers

Could you give me your motor setup in AP_MotorsQuad.cpp ?

The attached Excel file explain what is the method I used.

Attachments:
Permalink Reply by Josh Potter on November 29, 2012 at 11:05am

Using Dimitir's angles, the add_motor function is coming up with pretty much the same raw values you found, so either using add_motors with angles or add_motors_raw with raw values is going to be about the same. 

I'm running stock DJI motors so I don't know how well my PID's will match up.  I'm going to do some more testing today and let you know how things are flying.   

Permalink Reply by Josh Potter on November 29, 2012 at 11:06am

Forgot to attach. 

Attachments:
Permalink Reply by Dode Maddog on January 20, 2013 at 6:15am

Josh/Dimitri/all,

I noticed this thread as I too have a Disco with an APM.

I don't know anything about code editing but have done some looking up.

If I was to use the Arduino IDE to edit the code, How do I navigate to the section of the code that I'd need to include/replace the values to/with?

I've looked at the 2.9 rc5 fw and can't see where I'd put it?

Many thanks in advance

Permalink Reply by Rick on February 1, 2013 at 1:58pm
Is the 14deg angle base in the above V-frame diagram where the FC is, or is the base at the bottom of the V formed by the motor arms?

If it is at the base of the motor arms, then the total angle for both arms is 28deg, right?

I'm playing with the V to figure out my motor spacing and total craft size.

TIA.
Permalink Reply by Josh Potter on February 2, 2013 at 7:08am

Rick,

I didn't make that design, but I believe it's from the APM to that arm. If you haven't, please see this wiki page.

http://code.google.com/p/ardupirates/wiki/motormixing

Permalink Reply by Rick on February 2, 2013 at 1:07pm
Thanks, Josh. I have seen that page.

I'm thinking that the APM is at the CG. The motors don't fit a circle like the TBS does. Specific info is scarce on the V, even checking the Mikrokopter forums.
Permalink Reply by Josh Potter on February 3, 2013 at 7:18am

Rick,

Actually thinking of your CG makes sense. Looking at the pitch/roll V frame picture I made.  Note how danni gave the full pitch force on motors 8 and 4, but greatly cut back on the roll factor.  

Permalink Reply by Jay Neeley on March 15, 2013 at 1:36pm

I think that I want to give this a try, beinging a total newbie, how to I load apmotorsquad.pp file in to my APM?

Thanks

Jay

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