Are locked omnis still viable?

Hi,

I found a couple threads on the matter, but all were a couple years old. My question is, are locked Omni wheels still viable on a 6 motor drive? I have never actual seen anyone using them so is there some drawback I don’t know about, or is it just not necessary.

In tipping point, I feel it could be quite useful to not have to worry about being pushed around and an x drive is not viable this year. What are the communities thoughts on locked omnis?

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I don’t see why it will not work with 6 motor drive.

I might be biased, but this is definitely one of my fav TP matches :stuck_out_tongue:
Anyway, you can take a look and compare the effectiveness.

8059a was using locked omni (red top left corner) and 169a was using wedges (red bottom left).

Both methods are effective against pushing.

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locked omnis are always viable if you want more consistent turning or want to resist pushing from the side.

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They are definitely still viable but people are just finding other ways to achieve the same thing. For example the 169 traction wheel, the vex traction wheels, gears rapped in foam and rubber bands, flex wheels, and more. All of them act a little different and give different properties.

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Is using locked omnis better than using vex traction wheels? Does it turn better, better traction, or what’s the pros and cons? Also, is there a better alternative?

Omni wheels can often have better traction than traction wheels, at least in the forwards and backwards directions. 4" omnis are larger than their tractions though, which means that you need to lock them.

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Despite what the name suggests, omni wheel actually have more traction than what traction wheel has. However, whether to use them or not also depends on some other factors

4in wheel - The stock 4” traction wheel sold by vex has an OD smaller than the omni wheel. When placed in the middle, it will not touch the ground and therefore can’t act as a center wheel. Using locked omni works great for center wheel however. However, another alternative is to wrap the 4” traction tire around a 30T sprocket - typically called a 169 traction.
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Despite having less traction than locked omni, it has the added benefit of having a larger OD than omni wheels. With a 6 wheel drive, having a center wheel with larger OD will “drop center” the drive. This can improve turning speed of the drive. When only 4 wheels (half the drive) is in contact with the ground due to the larger center wheel, the wheelbase length is effectively halved while the wheelbase width stay the same, reducing the turning scrub and therefore increasing the turn speed. However, there probably won’t be a difference if the robot is heavy enough that all 6 wheels can contact the ground due to the wheels sinking into the tiles.
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3.25in wheel - I don’t think the omni is easily lockable as the rollers are smaller (may still be possible using 6-32 screws). Usually i just see teams do traction wheels in the center as the OD is close enough that it touches the ground.

2.75” wheel - Not many teams actually use 2.75” wheels for their drivetrains, but I’ll suppose that they are similar to 4”wheels - lockable, can 169 traction by using a smaller sprocket to wrap the 2.75” traction wheel with.

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Locked 3.25" wheels are possible with the use of 6-32 screws. They are a bit harder to make than locked 4" omnis since the screws don’t fit as nicely. The rollers also have a chance to pop out due to the added stress not able to be handled by the small rods which hold each roller in. However, last season my team was able to use them to much success, only having a single roller pop out in the very last competition of the season (One of our sister teams was not as lucky however)

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You can actually use the 2.75 traction wheel with 2.75 omnis. 4 inch wheels are the only ones you can’t.

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