The proposed change in code would allow APM to address every custom quad copter layout (scope limited to fixed vertical rotors).  I'm asking for input before doing a pull on code to make this happen. So please speak now or ....

Your quad may be custom if:

o the front motors are spaced different than the side motors (not square).

o the aft rotors are spaced different than the front rotors.

o prop spin is reversed.

Such layouts are typically done to accommodate a wider field of view (FOV) for a FPV or video/photo camera.  Sometimes the change is made just because it looks cool.


1) Changing the aspect of the length to width of the copter changes the relative motor factors for pitch and roll.  This is not always understood and is not always addressed by custom settings for decoupled roll and pitch PIDs.

2) Making the aft width different than the front width induces coupling between yaw and roll requiring a fix by using non-unity yaw factors for two of the rotors.

Solution:  The proposed process for setting up custom quads within APM is explained in the following video.

o The CAD system is complete and attached.
o Before I write and test the code for AP_MotorsQuad.cpp, I wanted to get input as to the approach for APM.
o Documentation is drafted.
o Approach addresses nearly every quad variant motor layout (scoped to address only vertical motors; designed for greater refinement for open front quads).
o Pilots inputs requirements in CAD (free Excel workbook).  Or pilot enters the widths and length.
o Optionally, the system morphs the design until the custom quad motor layout meets the requirements.
o Pilot finalizes design.
o System:
   - determines motor factors for Roll, Pitch, and Yaw.
   - identifies the V(ariant) model number based on yaw motor factors & prop rotation direction (model 5 to 127 for standard prop spins and -5 to -127 for reverse prop spins) providing accuracy for open front quads to 1% and most open back quads to 4%.
   - tells the pilot how to address different pitch and roll motor factors.
o Pilot builds the custom copter and then enters in Mission Planner config:  Quad and the V model number.
o No changes to MP are required.
o Only one paragraph of change in APM code.


Please let me know if you have input or support doing this.

Custom Quad CAD.xlsm

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • is there a setting I'm not seeing for Y6 frame config?

    • MR60

      not sure what you mean. what setting are you seeking?  are you seeking it in MP or in code?

      or are you just wondering where in MP you can download the Y6 configuration and then check that it did so?  if the later, then look under the MP tab 'Initial Setup'

This reply was deleted.