X8 frame config on PX4

PX4 Autopilot
1

HI,

I am building a X8 frame using a MindPX flight controller, which runs PX4 stack.

In QGC i select Octorotor coaxial - Generic 10" Octo coaxial geometry;

PX4Airframe.jpg2112×1434 199 KB

However there is no motor map numbering on the picture. I checked px4 motor mapping document and i can see motor numbering for Quad X/+, Hex X/+ and Octrotor X/+, but Octorotor coaxial seems missing there.
http://dev.px4.io/airframes-motor-map.html

I made a numbering as below, is it correct?

Thanks.

2

Its all defined here:
https://github.com/PX4/Firmware/blob/master/src/modules/systemlib/mixer/multi_tables.py

So I guess if you use octo_x:

octa_x = [
    [  22.5, CW],
    [-157.5, CW],
    [  67.5, CCW],
    [ 157.5, CCW],
    [ -22.5, CCW],
    [-112.5, CCW],
    [ -67.5, CW],
    [ 112.5, CW],
]

The numbers are degrees relative to the forward direction (positive degrees in clockwise direction).

3

Bart,

Thanks for the direction.

I am using coaxial frame (octo_cox), so according to the code, the numbering should be like this:

I will test flight it tomorrow!

4

The figure you made is not correct.

5

Bart,

Sry but I don’t get you. In multi_tables.py,

X8
octa_cox = [
[ 45, CCW],
[ -45, CW],
[-135, CCW],
[ 135, CW],
[ -45, CCW],
[ 45, CW],
[ 135, CCW],
[-135, CW],
]

So according to this the picture i made should be correct?

Below is the same pic as above, just slight adjust on style.

The X8 frame now looks like this. It is a 350mm frame, pretty small.

octo_coax.jpg960×1280 129 KB

I did not fly it yet, just tested by holding it with my hands. The pitch/yaw/roll feels OK.

Will do more testing when have time.

Thanks.

6

I’m sorry, I confused octo_x and octo_cox. You should be fine, good luck flying :wink:

7

No problem Bart. Thank you for the help.

It’s really a happy flying!

8

Hi,

Does the OCTO COX COPTER setup provide a better flight performance than X Quadcopter . Can it survive if any of the motors fail during flight. What about the battery efficiency