Omni or Mecanum?

VEX Robotics Competition Discussion VRC
#1

Our team was at tsa state yesterday and we ended up doing very well, but we had one problem that kept us from winning. We were in finals match 3 and had won auton and had a cylinder full and all our big balls even though our alliance partner was dead. we were going over to block the opponents goal when their alliance partner pushed us back into a corner and we couldn’t get to our opponents goal for the rest of the match( know they weren’t pinning just making sure we couldn’t get to the goal by occasionally pushing us. Though our mecanums had served us well in maneuverability all day since we went undefeated we felt unsure weather or not to trade them out for omni wheels and sacrifice our maneuverability for more traction.

I was just wondering weather or not I should trade my mecanums out for Omni wheels?

#2

Omni Wheels aren’t going to give you more traction than Mecanum wheels.

#3

Why?:confused:

#4

I would choose omnis in nearly every scenario. Usually turning with omnis is just as fast as strafing with mecs, and omnis usually provide more speed and power

(This is just from empirical experience, I don’t have a reason why. Maybe the rollers slip? I don’t think they do just going straight though).

Switch to omni wheels unless strafing is key to your strategy.

Edit: Mecanums actually have comperable traction to omnis though. Source: https://www.youtube.com/watch?v=OCll0hrBmRc

#5

We swapped from mecanum to omni and traction wheels because we couldn’t get strafing to work well, and because omni+traction executes our worlds strategy better.

We never tested the pushing power, but the robot’s definitely more responsive and harder to push from the sides. We did notice that swapping from holonomic arcade drive was a difficult for our driver, but after a week of 30 minute driving sessions, he got back to his original performance. He’s beginning to surpass his old performance thanks to the turning speed boost.

Hopefully, hindsight bias isn’t affecting me, but even if we did get strafing to work, we would of changed anyways. It turned out we didn’t need strafing for autonomous, and strafing in driver control would only be used to align with goals(which promotes bad driving anyways), so we would have swapped wheels

#6

In my experience, the omni rollers dig into the foam tiles like cleats. So on smooth surfaces, like the bumb, traction won’t be improved. On foam surfaces, like the rest of the field, traction will be improved. Unless your robot is extremely light.

#7

I say go with omnis, they are lighter, thinner, and you can still do a lot of the things that you can do with the mecanum wheels. The only thing about mecanum wheels is that you get a lot of traction. Switch to omnis in every situation.

#8

Mecanums also do this. That’s why they tied omnis in the traction test that Owen linked.

#9

On the Subject of Omni vs Mecanum Wheels. Would a standard Mecanum driven robot be able to strafe faster than a Omni wheeled X-Drive chassis robot? Given both are on a flat surface and with the same gearing ratios.

#10

The Omni X-Drive would be faster than Mecanum in this case. This tutorial on the AURA website does a good job of explaining why.

Edit: This article compares X-drive to standard tank, but it should still make things more clear.

#11

Mecanum wheels strafe with the same gear ratio that they have driving forwards, but they go slower strafing than forwards because of friction in the rollers. So they strafe more slowly than an omni X-drive.

#12

Thanks everybody we tried out the Omnis on our robot and our driver felt like it was to difficult to master in time for worlds since he has been using mecanums all year, but we have done something that have made our drive a bit more efficient.

#13