pic: 6-sided tank drive

Wouldn’t a hexagonal shape limit how close you can get to the outside walls of the field? I’d imagine if you skim the wall, you would end up being spun in some direction.

In some cases, this is good. Some bumper materials have a lot of friction, so if you get caught up on the wall, it can be a pain to get away.

I agree that tbones are very common and drivers should be prepared for them, but I don’t think I’ve ever seen a team make a mechanism specifically to break pins.

FRC 1114- drop down omni wheels

FRC 118- Drop down omni wheels

FRC 971 - Unique chassis shape

just 3 off the top of my head

I believe 1986 had a drop down omni wheel up front also.

As well as a large number of teams using lower friction bumper materials, off the top of my head I can think of 971, 67, 1678, 1717, 254, 148, 1114, and 2056.

In the 67 case I recall it was at least partially for their intake based on what my brother said.

My students have spent a chunk of their summer designing a hex chassis 8WD because of this very problem; we saw lots of t-bones, and we contributed to a fair number of them. :wink: We finished 3D printing the narrow/wide wheels this evening. I’ve been researching new bumper materials, and the mixing of materials for maximum benefit whether defending or trying to avoid pins. Great stuff!

If that’s true, then 67 is the only example of a separate mechanism being used to break defense. The drop down omnis/chassis shape are drivetrain-related mechanisms.

What? 67’s choice of bumper material may have been unrelated to the drivetrain and pinning, and driven rather by the intake, is what Andrew is trying to say. And drop-down omnis are definitely a separate mechanism.

The bumper material was primarily a function of their intake mechanism.

Drop-down omni wheels and alternate chassis shape are two attributes of a robot only present for the purpose of getting out of t-bone pins.
I guarantee 971’s chassis shape wasn’t there just to look cool.

254 switched to a sail cloth fabric for their bumpers this season just so they could get out of t-bones easier.

In a game like 2014, 2011, where defensive t-bones are prevalent and extremely effective, these mechanisms can be very important. However, there are some games, like 2012, where defense was unimportant and not prevalent.

It depends on the game, but after this year I see mechanisms like this increasing in popularity immensely.

987 had a drop down ball caster on their robot that tey would use to swing out of pins.

I didn’t drive it myself so maybe they could tell you their exact experiences with it, but I thought it was pretty neat since it was probably had the highest simplicity to benefit ratio of a secondary mechanism I’ve seen in a while.

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We copied this in 2013 and 2014.

In 2013 it worked great for us.

In 2014 we were forced to place it on our heavy side and it didn’t work as well.

Have you guys thought about the benefits of an equilateral hexagon? 2851 executed this in 2013 and it improved our offensive ability greatly. Now if only our shooter didn’t jam :stuck_out_tongue:

I’ll be pointing some team members to this thread (and to the thread where you posted that super neat looking 6 wheel setup)