This is certainly a "boutique" configuration, only useful for a limited set of design requirements. I'll leave out the "articulated" version except to say that I'd be more comfortable articulating all three holonomic wheels rather than just the omni. If I did articulated, I might also consider doing some sort of PTO manipulator with the omni wheel to optimize motor use. Here are some of the design requirements this would meet:
- You require being able to drive in ay direction, even if it means giving up traction. This either means that you think defense wil be light, or that you will be fast enough to get around it.
- You would rather have only three drive systems (otherwise you'd do mecanum or octanum).
- You require a rectangular chassis, either because of your technical limitations, or because of constraints imposed by the game and/or your game strategy.
Recycle Rush is probably the only FRC game so far where teams were likely to meet enough of these criteria to want to do this. The large rectangular game pieces and the lack of interaction with opposing robots could easily meet two of these requirements.
If you do decide to build a robot to this design, the inverse kinematics are the same as for kiwi, except that the angle for the two wheels not on a coordinate axis are 45 degrees rather than 30/60. Ideally, you'd want to have the center of gravity along the axis of the omni wheel, trailing the axes of the mecanum wheels internally by 45 degrees, and the same distance from each wheel's contact patch. For this, we can adjust the inverse kinematics from
Ether's kiwi paper, adjusting an angle, and letting the omni be wheel 1.
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Originally Posted by Ether's Kiwi inverse kinematics, adjusted for meckiwi (italics)
X j, Y j, & Z j are the 3 joystick axes - forward = Yc = -Yj
- strafe right = Xc = Xj
- rotate clockwise = rw = Zj
- wheel1 = Xj + Zj
- wheel2 = -0.707 Xj + 0.707 Yj + Zj
- wheel3 = -0.707 Xj - 0.707 Yj + Zj
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