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.

[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.

[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.

[Peyton Yeung]

6 6" colson wheels with a center drop in a wide orientation. I liked how it drove but would have preferred a system which takes it over the bump.

[JesseK]

There is a very basic paper that explains why a drop-center wheel (or set of wheels) is totally unnecessary for wide-drive robots at or near the max robot base dimensions.

http://www.chiefdelphi.com/media/papers/1443

Orientation is just as critical in these responses as # of wheels. .

4WD Tank, Wide Drive.

[Peyton Yeung]

Originally Posted by JesseK

There is a very basic paper that explains why a drop-center wheel (or set of wheels) is totally unnecessary for wide-drive robots at or near the max robot base dimensions.

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

[pfreivald]

Long-orientation octocanum.
9:1 reduction p80 CIMs direct driving fixed AndyMark HD 6" mecanum, in turn driving articulated 4" performance wheels with roughtop tread via gates sprockets and belting. The performance wheels were at an additional 5:1 reduction, for a total of 45:1.

We love the drive -- it's robust and (relatively) elegant, fast and maneuverable, has monstrous pushing power, and I love that it's chain-free. We're looking at doing something similar with smaller traction wheels -- perhaps 2" colsons -- in the off-season.

[IndySam]

Wide 6 wheel drive with modified AM shifters. Plenty of speed and power.

We used the KOP wheels in a live axle hex driven setup and were thrilled with their performance, especially on the bridge.

[Siri]

Originally Posted by JesseK

There is a very basic paper that explains why a drop-center wheel (or set of wheels) is totally unnecessary for wide-drive robots at or near the max robot base dimensions.

http://www.chiefdelphi.com/media/papers/1443

Orientation is just as critical in these responses as # of wheels. .

4WD Tank, Wide Drive.

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.

We went with 4-wheel swerve (fully independent drive and steering). It's a great drivetrain, but you do have to compensate for things like hanging off the bridge/even close to the edge and managing ball control while maintaining workable geometry for the Barrier. Definitely doable (we did, though all our official triple balances have been as the middle robot), but extra axles definitely have their benefit.

[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.

[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!