2012 drivetrain

[JesseK]

Originally Posted by Tubatroopa

We only did 6 so we could be wide and hang off the bridge.

Originally Posted by Siri

True, It's not important for turning. That doesn't means it has no use. In fact extra wheels can provide many useful benefits, especially in non-flat field years.

I agree with you both. Yet there are only marginal incentives to drop the center wheel(s) in the wide drive configuration, as can be demonstrated by running through the math in the paper. My point isn't about extra wheels, but rather the negligibility of dropping those extra wheels. I also wanted to bring up a pretty good paper showing the math/science behind what people think they saw on the field.

[SteveGarward]

Originally Posted by Alex.q

... I know 111 tipped up the front of their robot to do this, but I never saw exactly how this was done.

Correct. We had pneumatically operated 'landing gear' - two omniwheels on a plate that would push down and lift the front of the robot up. There were two sensors at the front, one on each side, so that when the front of the robot touched the barrier, the landing gear would retract so that the robot could go over smoothly*.

You can catch a quick glimpse of it in action in our reveal video at the 1 minute mark here

*As smoothly as a 120lb robot on air-filled tires can go.

[Grim Tuesday]

Wide brecoflex tank treads.

[cgmv123]

Wide base, 6-wheel tank. AM roughtop plaction center, omni-wheel corners, back 4 wheels powered. CimPLE boxes, 2 CIMs per side.

[Gray Adams]

Originally Posted by Taylor Nicholson

Our method is passive. We just angled the front and back edges of drivetrain, and riveted on strips of Teflon along the entire base to slide over the the barrier. This has allowed us to drive full speed into the barrier and get over. On 1114, we like the Dukes of Hazzard method of getting over obstacles.

The drivetrain is a 6WD using the AndyMark 8" pneumatic wheels (long configuration).

It was very smooth looking from what I could tell. I was trying to figure out if that behavior could be replicated with 3.5" wheels and some 3x1 tubing, but it looked like you need something more like 4x1, if they even sell that. I know you guys use sheet metal, but do you know what the height from the bottom to the top of the angled part is, and what angle it's at?

The bump liked to get between our 6" wheels and lift our front really high in the air, and it always behaved differently when crossing. The teflon coated skis are probably helpful, but do you have any insight into what you think is most important? I'm guessing the frame getting close to the ground helps so you slide over, but that's just a guess.

[Jefferson]

Swerve baby swerve.

Originally Posted by cgmv123

Wide base, 6-wheel tank. AM roughtop plaction center, omni-wheel corners, back 4 wheels powered. CimPLE boxes, 2 CIMs per side.

Just curious - Why not power all 6 wheels?

[DominickC]

Here's a picture of a prototype of our drivetrain. In this picture, we've got two in-house made drive wheels on each side, each being run by two CIM's. Eight colsons are being driven via polycord to power us over the barrier. In our final design, we're powering the lower four colsons on each side via a chain, and powering the upper four via a polycord linkage to the bottom four colsons. I'll try to get a picture that shows this setup tomorrow. It's actually pretty cool what our build team came up with, especially the tensioners. We ran the chains which power the four lower colsons thru a piece of PVC.

EDIT: You can sort of see the final setup in the lower right hand side of the picture, thru the hole in the side of the aluminum plate.

[avanboekel]

We had a wide base 6wd dropped center (3/32") with 6" plaction roughtop wheels. All 6 wheels are powered by 4 cims through toughboxes.

Anybody find it weird that according to the poll, there were more teams who did swerve than mecanum? At least at the regionals that I went to, this wasn't the case.

[LeelandS]

1126 was on Swerve drive. The problems that come with being a team in their first year of Swerve aside, the only major problems were had was not directly related to the Swerve. It was mostly that our robot was top heavy and the weight was poorly distributed (When we tried to drive onto the bridge, we would almost flip ourselves because our back wheels didn't have enough weight to keep the bridge down, so it would start coming up on the middle of our drive system).

That aside, the team is generally very happy with how the swerve turned out, and (apparently, I wasn't there) we were even complimented by 16 for having a swerve as good as we did for our first year!

[Siri]

Originally Posted by Jefferson

Swerve baby swerve.

Can you elaborate more on your module and frame setup, especially for getting over the barrier? I've been drooling all season since your reveal video and am still kicking myself for missing you at Champs.

Originally Posted by DominickC

Here's a picture of a prototype of our drivetrain. In this picture, we've got two in-house made drive wheels on each side, each being run by two CIM's. Eight colsons are being driven via polycord to power us over the barrier. In our final design, we're powering the lower four colsons on each side via a chain, and powering the upper four via a polycord linkage to the bottom four colsons. I'll try to get a picture that shows this setup tomorrow. It's actually pretty cool what our build team came up with, especially the tensioners. We ran the chains which power the four lower colsons thru a piece of PVC.

Whoa. Can I ask how/why you guys came up with that idea? Looks awesome!

[DominickC]

Originally Posted by Siri

Whoa. Can I ask how/why you guys came up with that idea? Looks awesome!

I'll take more pictures tomorrow that better show what I'm trying to describe. I'm not entirely sure how/why we came up with the idea. All I know is the fact that we wanted to get over the barrier as well as climb up and down the bridges. I'll find out more info tomorrow.

[Billfred]

2815 used a kitbot-derived 6WD--kit wheels and all. Our frame was a hair low for the bump, but I think that was okay in the end due to our CG. If I were doing it again, I'd be more conscious of figuring out the bump.

[cgmv123]

Originally Posted by SuperNerd256

Just curious - Why not power all 6 wheels?

Wasn't my decision. I'm assuming it was because we would have only powered the center wheels, but they would have sat there spinning and looking dumb when we tried to go up the bridge and back gave more pushing power. (Carpet vs. lexan)

[Jefferson]

Originally Posted by Siri

Can you elaborate more on your module and frame setup, especially for getting over the barrier? I've been drooling all season since your reveal video and am still kicking myself for missing you at Champs.

We had 4 modules with a CIM mounted in the module (no bevel gear) and a window motor turning. The encoder was mounted as flexibly as possible above the module.
Thinking back on the year, we probably could have gotten away with a three wheel system, but we had such luck with the four wheel swerve last year and 2010 offseason, it was hard to get away from.
We crossed the bump in both directions. Our ball pickup helped us in one direction. There were angled guides on the bottom of the box to lift that end of the robot as it contacted the bump and delrin guides mounted to the frame next to the wheels to make sure the wheels don't take the impact. On the other side, we just had the delrin guides next to the wheels.