Traction Wheel Problems

Hello, I’ve come to ask about a problem that my team and I have been having with traction wheels–whenever we make a drivetrain with all traction wheels, the robot turns with a violent jittering, almost as if the wheels were being dragged on the mat parallel to the axle instead of rotating. We haven’t had to deal with this because of our access to omni wheels, but the robotics team just gained a lot of new members and we are all out of omnis… is there a way to fix that shuddering that occurs with traction wheels?

Not really, that’s kinda just gonna happen with traction wheels only. I would suggest splitting traction/omni wheels front and back among your teams, as swing turns (what happens when you turn with half-and-half wheels), while annoying, are better than what you’re currently experiencing.

This will result in the turning center being in the middle of the chassis, in line with the traction wheels, instead of the center of all 4 wheels, but the robot will turn better.

Your other option is what a lot of FRC teams do, and what (i think?) is a default option in the Kit Of Parts, which is a drop center. This would require 6 wheels total, three on each side, and the center ones slightly lower than the others(significant enough to account for variation due to tile height, probably like 1/4" idk). When turning, this results in the turning center being on the two center wheels, as much less weight is distributed on the other wheels. This is a bad solution in VEX, and given that you have this parts availability issue in the first place I do not reccomend it. It’s going to be really hard to mount properly without custom lexan parts, and it’s going to make dealing with the rest of the design much more painful, but it would work.

My primary suggestion is to share the wheels between teams, but if that doesn’t work, you could try the drop center idea.

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Last season we did the half-and-half wheels, and it worked well enough for us… I’ll probably just go digging through some crates looking for 2 omni wheels. I appreciate the response!