I’m new to VRC and everyone in my robotics club is using 4 omniwheels for this years game, Spin Up. Why not just use regular wheels if you’re not going to use a middle wheel to strafe? Aren’t you more prone to being pushed around?
Omni wheels are what allow you to move and turn without your robot wobbling and shaking like it’s possessed. Try building an all traction drive and see how it fares. Or, you could ask your teammates who are building omni drives why they chose to do so.
To add onto what Josh said, testing out how certain wheels work on different drives is excellent notebook material.
You want to look at not only all 4 wheels, but 2 and 2 combinations. That kind of thought with a data chart to back it up makes the judges very happy.
My teams couch absolutely hates omni wheels and wants us to use the old offroad looking 5" wheels, do not use the old offroad looking 5" wheels
Dont listen to my teams coach
Omni wheels are necessary for a good competitive robot
The 5" wheels could be great if your plan is to get into the Low Goal and reshoot disks. The 5" will make short work of the low goal barriers.
But this is a prime example of “brainstorm 3 ideas” where one is the 5" wheels; then test, do the metrics on the test results and then decide.
Maybe, maybe not. The 5" wheels don’t have a lot of turn resistance (so they won’t hop as much as a friction wheel) so they may turn out to be fine. I have teams that are doing mecanum wheels because of the combo of being able to translate AND going over the barrier is important to them. Omni wheels are not always the answer, but testing and looking at the actual numbers IS always the answer.
Another holonomic chassis design is an X-drive, which also uses all omni wheels. I personally find the X-drive to be better than a H-drive. Since, if the interior wheel of a H-drive is not touching the mat, the H-drive will not strafe. The VEX fields sometimes have some slight dips, which might cause the H-drive middle wheel to not touch the ground.
Aside from that, using all friction wheels might cause some issues with turning. As many people have already commented, a good combination of wheels for a tank chassis is two friction wheels at the back and two omni wheels at the front.
Another chassis design that your team could try is a six wheel chassis. So, two omni wheels in the back, two omni wheels on the front, and two friction wheels in the middle. This should make it so that it is hard for the robot to be pushed around and also turning should still be fine. If the drive train your team wants is a 4 motor drive, the wheels on each side can be connected using gears, allowing each side to be powered by 2 motors instead of 3.