pic: Why aren't omni wheels like this used?

[BJC]

Another primary reason these types of Omni Wheels will not see use in FRC is due to the roller thickness. Both the original and the "improved" wheels have parts of the rollers with near zero thickness. This comes with a number of problems including that the rubber rollers preferred for traction won't support a robot's weight on near zero thickness (bumpy ride) and as the wheels wear they will very quickly become non-round (very bumpy ride.)

[Ryan_Todd]

Originally Posted by BJC

Both the original and the "improved" wheels have parts of the rollers with near zero thickness. This comes with a number of problems including that the rubber rollers preferred for traction won't support a robot's weight on near zero thickness (bumpy ride) and as the wheels wear they will very quickly become non-round (very bumpy ride.)

That's for sure! Neither of these designs could be expected to produce a perfectly smooth ride in real life, even after they were tweaked for durability and manufacturability. Even dualies can only be perfectly smooth if the wheel axle is held perfectly parallel to the ground (flat ground AND infinitely stiff robot frame), but with a good enough roller design, they can indeed usually be expected to produce a smoother ride than these two wheel designs would.

Engineering is all about trade-offs, however, and a design like these two would seem to strike a potentially useful balance between a traditional single-omni design and a dual-omni design: smoother than a single-omni, and lighter/more compact than a dual-omni. It still remains to be determined whether they could be produced at a low enough price point to compete with the current market leaders, of course!

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EDIT:
Now there's an odd idea. I was considering refining my design and printing it in pieces just to evaluate the concept, but then I remembered that many "impossible-to-make" designs are trivial when additive manufacturing is employed. What if a multi-nozzle 3D printer were employed: nylon for the structure, TPE for the rollers, and a soluble support material to maintain clearance where necessary?

[Greg Needel]

you mean like this one?