Trying to configure a tri-motor, Y-configuration, v-tail VTOL, with two forward tilting motors and one rear lift motor. Currently I have the Airframe set to Generic Quadplane VTOL Tiltrotor and it seems to have it’s issues. Is there another airframe type that could potentially work better?
For your Y-config tri-motor VTOL, the Generic Quadplane Tiltrotor is probably the closest PX4 airframe, but yaw can be tricky—make sure your tilt angles and yaw control are properly tuned; there isn’t a built-in alternative that fits that exact layout.
Thanks, and there-in is our issue. For yaw, I get both motors tilting forward, where I’d expect either one forward/ one aft, or left forward for right yaw and right forward for left yaw.
I should mention that tilt servos are mirrored, so one is reversed. Both react properly to rotorcraft/aircraft mode change, but yaw is an issue.
Ah, that makes sense — sounds like your yaw mix is still symmetric, so both tilt servos get the same input. You’ll need to flip the sign on one servo’s yaw contribution in the mixer (or in the tilt config), so they oppose each other instead of moving together.
Mixer in the RC Tx? Or is there a way to access that in QGC?
Not on the RC Tx — mixing is done in PX4. In QGC, just tick “Rev Range” on one of the tilt servos so its yaw input is inverted. If you need finer control, the mapping is in ActuatorEffectivenessTilt.cpp.
1 Like
I’ve tried that, the result is that in rotorcraft, one up, one down, and in Aircraft mode they are reversed. As the motors are installed mirrored with the gear outboard, REV seems correct as currently, both down for aircraft, both up for rotorcraft. In Aircraft mode, only the ruddervators move as required. It only seems like rotorcraft Yaw requires tweaking.