Multirotor VTOL has uncontrolled yaw, motors not spinning at same rpm

[gkashyap]

I have a multi-rotor VTOL aircraft config as shown here

New airframe doesn't fly well

@gkashyap Hi, just create a new toml file in here which contains the geometry of your vehicle. You want to specify the location of each motor with respect to the CG. It uses an xyz coordinate system where x points forward, y to the right and z points down. I haven’t looked at it for a while but I think you should scale the distances such that the longest distance is equal to 1 (not sure about this, maybe the script scales automatically and you can use any units, as long as you are consistent.) …

The aircraft is flying but there is a constant yaw to the right and there is no yaw control to the left.
4 of the 8 motors are spinning at higher rpm than the other. Here’s the log
https://logs.px4.io/plot_app?log=fac68d7d-287b-4198-896e-9a0b1cdc9c7f

@LorenzMeier @bresch @tumbili Can somebody please help?

[bresch]

The yaw controller is doing as much as it can do, but it not enough. I guess the rotors are not properly aligned or they don’t rotate in the correct direction.

[gkashyap]

@bresch thanks for the quick response.

Does this also explain the difference in motor rpm?
I will recheck the rotor directions and post the result tomorrow.

Kind regards,
Kashyap

[bresch]

@gkashyap yes, the vehicle tries to yaw, this is why four motors (spinning in the same direction) are at full speed and the four other ones (in the other direction) are at low speed.