I plan to do what is called a "pull" to made changes to the custom code regarding custom shaped copters.
This change in code would only impacts irregular shaped quads, hexas, and octas when the pilot specifically opts to go custom versus the default (the standard X or +). You have a custom quad if the:
o aspect ratio <> 1 (length is different than width).
o rotors are non symmetric around the
- forward axis (y) going through the center of gravity (CG)
- sideways axis (x) going through the CG
- vertical axis (z) going through the CG
o has a front that is more open for a camera
o deviates from the pictures of a a + or X for the quad, hexa, or octa
o this includes ships described as spider, V, H, U, 88--88, C, etc.
o motor spin direction(s) are different than the pictures
o your CG is pushed somewhere else besides the centroid of the motors.
The advantages of going custom is that the motor factors will be tuned to the coordinate/spin system of your copter versus the coordinate/spin system of the regular copter. They will fly better. Pilots will probably not notice small deviations nor would they see significantly improved flight times. Large deviations might be noticed and provide noticeable changes in flight duration.
Please reply with the motor number (the out-pin number on the APM), coordinates of the motor, and rotation direction of each rotor. For example,
the owner of this copter would reply (motor number, x, y, CCW/CW):
o 1 (400, 200) CCW
o 2 (-250, -200) CCW
o 3 (-400, 200), CW
o 4 (250, -200 CW
[note: no need to tell us your units of measure just so long as you are consistent in measuring; say mm or inches]
Please note:
o The center of gravity of any quad spider or V is not necessarily where the bars cross. The bars typically cross behind the CG. .
o The CG is the center of the coordinates or (0,0) where x=0 and y=0
If you decide to participate by replying, the idea is that you will be able to access your custom motor factors without having to compile firmware. No promises at this point. First we see what's out there. But if you do reply, it's far more likely that your design will be implemented in the library.
If you have any questions or difficulties in doing this, let me know so I can help.
Replies
What about this?
I like the behavior of yawing if all CW motors run at full with little help of CCW motors, just because the cog of CW motors = to cog of the copter...
Now, I still don't know where to start on how to modify the code, use your excel, basically set up my toochain ( I like eclipse and use it already for my avr projects)
Could you guide me on that part?
Thanks
so something like this? though i better update the Custom Hexa CAD Excel worksheet, since someone is building one.
Widest possible "open view" ... , "the hexa-quad" ;)
Really want to try that out, and get my hands on the APM / Pixhawk toolchain....
Brilliant. With just the right proportions, coupling is zero.
I've attached a modified Custom Hexa CAD that allows more freeform designs.
Custom Hexa CAD.xlsm
And what about the "FOV" ... , could be better no?
forgot to tell you ... the worksheet is not as developed as it is for the Octa and Quad. In those, the FOV vertex is definable (as it is here), but it then attaches the tangent line to your prop circle so that the FOV can be precisely calculated.
FOV is nice. Figure out the camera and FOV of that camera. Then build the hexa to just give you that + 14 more degrees (for gimbal follow turn mode).
Correct, CM is a more precise term. But doesn't abbreviate well. CG is the same exact point, unless you plan to built a really tall ship or put rockets on it and fly it in outer space. For us lay people CG works OK. We won't bite your head off if you use it.
I may be lacking understanding of what you are trying to say or accomplish the running the CW motors full with a little help from the CCW motors in the drawing .
- Yaw will respond according to the motor factors in code, and yes, these can be changed.
- If you run the red motor high and the blue motors low to Yaw the ship CCW, as shown above, then you also create a Yaw couple to Roll (the ship would roll left)
Are you sure you don't want to build an Octa. Efficient and no issue on coupling.
Actually you are brilliant. that layout is the only one that works. so ignore what i said about coupling (so much for my quick math skills).
Reading through the post and thereafter the comments, I see that there might be something that's missed and is related to the CG of the frame.
For example I have a 500 spider quad which is loaded and unloaded with stuff frequently, i.e. gimbal for scenic stuff, no gimbal for fpv... With this in mind and that my FC positioning is probably much irregular, how would the FC handle the irregularity of the frame and a tail heavy frame with a CG that is not center in relation to the FC (tailheavy and FC almost at front)?
I understand that this is still a call for sources sought maybe, but still the question pops if we provide motor positioning for library or such purposes :) Shouldn't the motor positioning be relative to the FC for example and not CG and allow in the code for such integration?
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