Locked Omnis help


#1


so I tried my hand at locked omnis but I found that they seem to push out the a bit too much which cause the middle omnis to be slightly larger than the the ones on the front and back resulting in the robot rocking slightly and causing the wheels to sometimes spin freely

Is there any special technique for installing the screws or any way to solve this?

I am using 8-32 half inch screws and have attached a picture
IMG_20181011_142628.jpg


#2

Doesnt look like its lifting the wheels too much, have you tried it on an actual field tile? The foam should comensate for the slight variance


#3

I’ll test it out on the foam tiles tomorrow although it could still pose an issue on the platforms


#4

Huh. Never actually seen locking omnis before. Whats the purpose of doing that? Does it just make for a nice, gripping, wheel?


#5

If somehow the wheels do not contact the foam to your liking, you might want to try using shorter screws that do not push the rollers outwards as much, making the wheel closer to 4"


#6

There’s an easier way. Take the tire off a standard 4" wheel, wrap the wheel in a rubber band and put the tire back on. When I tried it a few cough years ago, it increased the diameter of the 4" wheel enough that it was slightly larger in diameter than the omni wheels.


#7

It’s supposed to allow for a non push wheel while keeping the same diameter as omnis-although this was stated in the video-which makes it ironic that the screws increase the omni’s diameter


#8

I guess if you use 5-64 half inch screws it would push out less if it’s that much of a problem


#9

We did this on our first robot this year and have been doing it since then, we believe that the screws pushing out the rubber is an advantage, as the rubber from the rollers extruding out more than normal 4" ominous, give the traction whee more traction thus it’s less likely to be pushed. This has been competition tested and didn’t budge even with an 8m pushbot going at it.


#10

I’ll try chaining the middle wheel to one of the other wheels and that should probably help a lot

wasn’t able to test on foam tiles today because class had to do something


#11

alright, sounds like a good idea. We may do this now, although we don’t have a 6 wheel drive


#12

Wait, if you only have a 4 wheel drive what dies it matter? Everything will be connecting the same across your 4 points of contact, right?


#13

probably means they’ll switch to six wheels


#14

yeah, we’re putting on 2 more in the middle.


#15

I used 6-32 motor screws for my locked omniwheels. They are thinner but still work


#16

locked omnis-
use 3/8 inch screws and push them into the corner of each green mini wheel
push them in slightly but then screw it in fully with a screwdriver
also make sure that you use the correct size screw (3/8) or it will come out easily
if you have further questions or want a full tutorial…

we have a youtube tutorial on locked omnis

Youtube Channel: 90F Fantomex