It would certainly be possible to drive that kinematics from a Duet 3 or even a Duet 2, although a modification would need to be done in the RotaryDeltaKinematics class in RepRapFirmware to use the 3 arms just for XY movement and use the separate motor for Z movement.
What advantages do you see for such a configuration, compared to linear delta? I can see a few disadvantages:
- Rotary deltas need very high resolution in the arm positioning. This means you have to use motors with a reduction gearbox, or alternatively use belt-and-pulley reduction. A gearbox on the motor will introduce backlash, resulting in imprecise positioning.
- Rotary deltas are difficult to calibrate. Even if you get the 3 upper arm lengths identical and the 3 lower arm lengths identical, and you know their values exactly, there are 9 factors to calibrate. This is because the 3 upper bearings may not be in an exact equilateral triangle and may be at different heights, and the 3 homing switches may trigger at slightly different arm angles. We don't yet have an auto calibration mechanism for rotary deltas, and I haven't done the maths to see whether it would be practical to do based on Z probing alone.
- Rotary deltas have to use segmented kinematics because of the trigonometric calculations involved in the inverse kinematics; whereas linear deltas casn use non-segmented kinematics because the most complex operation needed is a square root.
If you do decide to go ahead with this, and you have some C++ coding ability, I can help advise you on changing the kinematics code.