They have rollers on them which allows the robot to turn easier. The rubber tires stick to the field, so when it’s time to turn you need to break that friction. The four rubber wheels will hop as it makes the turn. On the Omni the rollers make it a smooth turn. Omni is our choice for this year’s game to get the added mobility.
Thanks but if you look at the link I sent, you will see that only two omni-wheels come in the products I bought. Imagine I had a standard drive-base: would you suggest two omni-wheel at the back (where the motors are and two normal wheels at the front, or would you suggest I buy more omni-wheels.
Using two traction wheels and two omni wheels is a popular combination. You should do some experimenting by building a simple drive base, and try out four traction wheels, then try a pair of omni wheels in the front, and in the rear. Four omni wheels is popular, but in VRC, when robots are playing against each other, they can be pushed around easily. A fifth omni wheel creates the “H-drive”, which some teams use to move side-to-side more easily. Six wheels is a popular configuration, two traction wheels in the middle, omni wheels front and rear.
The choice of drive base depends on the game and the goals you’re trying to achieve. Each design has advantages/disadvantages. Even the decision of which end (front or rear) for 2 omni/2 traction is important: automobiles steer on the front, forklift trucks steer on the rear.
It will affect how the bot turns, so it depends. The center of rotation is between the traction wheels. You could try the traction wheels on the front and back and see what you like better. For this game I would think to probably put them on the front of the bot so the center of rotation is closer to the risers that you are placing. That would allow you to be more accurate with your placement.
If you are using 4 omnis there are a couple of things I would note. 4 omnis make it impossible to get “stuck” next to a wall. Sometimes kids drive close to the wall at a weird angle and then have trouble getting away from it because the center of rotation is not at the center of the bot. With 4 omnis your center of rotation is at the center of the bot… But even if you get close to the wall as you turn if you hit the wall you just slide away from it.
For programming I think it’s a little more accurate to use 2 traction wheels. That’s what students report to me, but it makes sense as it’s hard to get the rollers in the same spot every time.
You are allowed to switch. So if you do driver with 4 omnis and programming with 2 traction 2 omnis that’s fine. Just tell them at inspection…
if i were you i would get more omni wheels. i say this because you can do so much more with them. for example with traction wheels you are stuck doing a tank drive. but if you have 4-5 omni wheels you can create x drives, tank drives, H drives, and kiwi drives. 3 of the drives allow you have side ways and diagonal motion this is a huge advantage. also the traction wheels have a tendency to warp. the omni wheels allow you to spin about the center which is extremely advantageous be cause it allows you to be much more agile which is very important for this competition .
