Best Drivetrain options

[Abhishek R]

Originally Posted by JorgeReyes

What about a 4wd with the rear wheels being traction wheels and the front ones being omnis

IIRC, 1625 Winnovation used this system in 2014 (and I think in previous year(s) as well). It was one of my favorite robots; the spins were amazing, yet they still had all the versatility to be able to play effective defense as well as escape it.

Here's a video of them on Einstein. If you can't see the numbers, they are the primary scorer on the red alliance. https://www.youtube.com/watch?v=xWPjs8zn9FI

[mrnoble]

We have reconfigured a couple off season projects to the needs of this game for testing, and here's what we know:

• mecanum 6" does really well over the bump, surprisingly so.
• 6" Colson in front, omni in back does great too. we think it drives a bit like street racing, so its currently "drift drive" for us, though "mullet drive" is gaining.
• we cant decide between the two yet, so we are building both and running them through drive practice. we will let the drivers and coach decide.

I'm sure swerve is awesome. Next year, we will make that our off-season project. We have no experience with "H" style slide, so it's off the table too.

Hope that info is helpful.

[GeeTwo]

Originally Posted by Ether

Or both (octocanum). Or neither (H slide).

H drive isn't holonomic? Sure, it's anisotropic, but it can go forward-reverse, left-right, spin, and any combination I can think of.

[Ether]

Originally Posted by GeeTwo

H drive isn't holonomic?

Not if the front and rear wheels are chained together on each side.

[Shu]

Originally Posted by JorgeReyes

What about a 4wd with the rear wheels being traction wheels and the front ones being omnis

How about the reverse with omnis in the rear and traction wheels in the front? Is there any advantage for one over the other?

We converted an old kitbot over the weekend to this configuration. It seemed to pivot about the front inside wheel. We had several team members drive it and they didn't appear to have any issues controlling it.

[IronicDeadBird]

Going to have to go ahead and say strafing is a must but if you can't strafe you should at least make a chariot design with casters...

[pfreivald]

"Must"s are exceedingly rare in FRC competitions.

[IronicDeadBird]

Originally Posted by pfreivald

"Must"s are exceedingly rare in FRC competitions.

Yeah I should have phrased myself better. Depending upon level of your team and comfort if you have the ability to do omni-directional movement then it is very valuable. Not to say that the arguments against omni-directional are non existent.

[GeeTwo]

Originally Posted by Ether

Not if the front and rear wheels are chained together on each side.

How do you define holonomic? I was going off the wikipedia page, admittedly far from authoritative, but it reads:

A robot is holonomic if the controllable degrees of freedom are equal to the total degrees of freedom.

I will add that I never liked this definition - it does not require that those degrees of freedom all have at least orthogonal components. It also considers mecanum and killough not to be holonomic until you add the mechanism or software library to map three inputs to four outputs.