I understand the following:
Quad X frame type has motors & props spinning/configured in “normal direction.”
Quad H frame type has motors & props spinning/configured in “reverse direction.”
Is there any other difference in the Ardupilot coding between these two types of frames? For instance, if I have an “X” frame but want motors & props reversed, should I just use the “H” frame type or is that going to cause issues with the code?
Or, should I use “X” type frame and toggle on “Reverse” under Mission Planner, Setup, Mandatory Hardware, Servo Output? Do these two methods accomplish the same thing?
Thank you.
I believe they are different in more ways than just motor spin direction. Because of how the arms attach to each other and the central area, the dynamics are very different.
I would highly recommend using the correct frame type and setup the motor spin directions properly without using the Reverse option in servo outputs. The whole control system is expecting certain motors to be turning in their respective directions in order to do yaw control (at least).
Thanks. That’s what I was wondering if the code for other things besides spin direction was different.
As you said, BlHeli32 is always an option for the ESC I have.
adding my anecdatum, I just confirmed this. if your frame is h, then x config will oscillate in yaw. h config is stable. its due to h-frame flexibility i think. why isnt h config default? i dunno.
I still don’t understand the logic behind H-Frame motor reversal. If the H-frame motor placement relative to its CG is exactly same as X-frame, why would yaw will be impacted?
Anyone care to explain?
IIRC it is affected by torsion coupling, physical H style frames are assumed to be slightly twisty, default motor rotation directions would cause negative coupling between yaw and frame twist, thrust imbalance caused by yaw command would cause twist vectoring thrust to counteract desired yawing. By reversing motor directions you can achieve positive coupling so frame twist assists yawing.