Team 3607's 2013 base

Hey, here is our masterpiece so far.

A word of advice from someone who learned the hard way, casters are evil!!!

Use them on your robot cart but never use them on your robot.

Seconded. If you replace them with an omniwheel, you will be much happier with your performance.

how are they evil?

because they are independent and swivel. You will never be able to put the robot where you want it to be. there will always be play in the position of the robot from side to side and front to back.

We decided that we want it to do that.

Lack of control was what you decided on???
We did that our rookie year at my old school. Never again!

If you’ve ever tried to push a really heavy shopping cart, you may have some experience with the issue. If you’ve got some weights, load up your frame to 150lbs, put it on carpet and try pushing it around from the rear where your drive wheels are. You’ll see what we’re talking about.

The casters will not always be aligned with the direction you want to move next. They may not be aligned in the same direction as each other. The swiveling action that wilsonmw04 refers to will cause your robot to not go straight when you try to drive forward, but start to veer off to the side instead. This makes the robot very unpredictable and hard to control.

Omnis are a great solution.

This off-season we did freshmen/ team training which involved splitting the team into 2 and challenging them to build a robot to navigate a obstacle course. One team did the same set up as you, while the other did a 6 wheel tank drive. The set up similar to yours could NOT drive straight, and every time it tried to go over even the tiniest bump (about a quarter inch at most), it would veer towards a different direction. YOU WILL GET NO CONTROL!!!

yea I see what you mean.

Yea, We just pushed it and you were right. Our drive is to have 2 wheel back powered with an independent front. Will the Omnis do ok with that

Omnis will be significantly better, and would be pretty easy to retrofit on to your current chassis. If you can find a way to run some chain from the back wheels to the Omnis in the front, that will also help a lot, and won’t hurt your turning ability at all.

Just throwing in another “Our team made the same mistake” comment. Caster wheels are evil. Eventually we chucked that idea for a relatively “better” drive system.

You have a custom chassis, and a castor drivetrain. The former is a sign of experience, but the latter is not. Omni wheels would be better than castors for sure, but overall you would have been a thousand times better off with the kitbot. 6 wheel drive in general is one of the best drivetrains.

Everyone else has piled on with the “don’t use casters” so I won’t add to that. But I will say Evan is correct that if you can find a way to chain (or belt) the omniwheels you will improved performance. You will get better traction and control while keeping just as good a turning radius.

And I don’t know that I would say you would necessarily be better off with the kitbot. What you seem to be trying to do is maximize your mobility, and that is a viable strategy for this game. The the ability to spin nearly in place away from obstacles/defense can be a very good strategy. Powering your omniwheels will aid in that.

Thanks for all the help guys will discuss with my team tomorrow

I’ll just play devil’s advocate here and note that we were an alliance captain and regional Finalist the only year we ever used casters on our robot.

We did hate them though, enough that we tried replacing them with skids at Championships that year (which may be the only thing on earth worse than casters, we only won 1 match at Champs as a result of them). I’d recommend switching to omnis as others have said, they’re easy to use and became 498’s go to drive train starting in 2007. There are some situations when they provide an advantage over the 6 wheel drop method, namely when rocking is unacceptable to your design or you want your robot to turn about one of its ends rather than its center.