Re: Good drivetrains observed
 

sorry i had starbucks expresso beans im calm now lol

Re: Good drivetrains observed
 

THREE NINE THREE!


They used what looked like go-cart wheels you would see at the fair or something.

Re: Good drivetrains observed
 

I would have to disagree with you. Our robot this year has mecanum wheels and we played defense just as well as anyone. We were pushing 6 wheels and 4 wheels. :D The rollers on the mecanum drive system are not made of plastic; they are made of urethane. Urethane is more like rubber in that it provides traction. It also allowed us to get onto the ramp. I believe that our choice in drive train was a very good one. I don't believe that any drive trains out there are any better than the others, but it just comes down to how you play the game. If you would like more information on our drive train, you may find the info you're looking for here: http://www.chiefdelphi.com/forums/sh...ight=meca num

Re: Good drivetrains observed
 

753 had the best drivetrain that I think I've ever seen. They went with treads that were (I think) 2" wide and made of a very sticky material. It was the most robust design by far at the Sacramento competition and they had no trouble pushing us sideways towards the ramp and then sideways up the ramp.

Fortunately we got 1662 on our alliance, and they were the only team that I saw push 753 around. 1662 had 4 2" wide, 8" diameter IFI traction wheels, and they could push around whoever they wanted. Their robot was a little on the skinny and long side, though, so they hopped quite a bit while turning.

Re: Good drivetrains observed
 

I felt that 753 had too much traction and paid for it in the finals when they started tripping breakers from drawing so much current from its drivetrain. Besides that I that that robot was great and I look forward to see it at nationals.

Our robot this year uses 6 wheels that only has 4 on the gound at a time, which allows smooth turning without sacrificing any traction. I felt our robot could push almost everyone at Sac and SVR, but 1662 proved us wrong. our robot has a wedge on the back and 1662 rode on it, putting them on two wheels and they still pushed us. I felt that 1662 had the most pushing power and traction but suffered from an inability to turn smoothly.

Re: Good drivetrains observed
 

I have to say that 1114 (and likely the other triplets, though I've only seen 1114 on my field so far) has a really nice adaptation of tank tread. I always thought it would be slow and incredibly hard to turn, but somehow, they make it look easy. They do "hop" a bit, but its a lot more manuverable than I would have expected.

That said, unless we have to climb stairs or anything else strange like that, I think 1511 is in love with our current drivetrain. We have two custom center 8" traction wheels, and four AM omni wheels on all corners. The thing pivots on a dime, but much to our suprise, we were able to push around every robot at FLR!! Its also an advantage because when other teams try to push us, our driver just spins around them and shoots from somewhere else. At the risk of giving away our secrets, I really wanted to share this with other teams that might be looking for a simple option. I will admit, we NEVER thought we could be a defense bot, but after finding we could push a lot of teams, we thought much more of our drivetrain :)

Re: Good drivetrains observed
 

I like 968's gearbox. They have some pretty large gears in their, but it is a good size, pretty lightweight, and they can direct drive the wheel off of it. It is very elegant.

Re: Good drivetrains observed
 

We originally had 6 wheel drive, but we determined that the amount that we had to put the middle wheel down to work with mountainboard wheels without hopping was too much. When we fired, the balls rotating in our helix on one end and flying out of the shooter on the other made the robot rock back and forth, affecting our exit angle too much. To remedy this problem, we converted to 4 wheel drive with 2 pneumatically activated ball casters for turning. Therefore, when we do maneurverability work, we are essentially a 2 wd robot. When we have to push, we drop down on all four wheels. While the system weighs more than normal 6wd drivetrains, we have found that it is the ideal drivetrain this year, as pushing on the corners of robot does not make it rotate as easily as 6wd robots.

For gearing, we used four Dewalts, as they were much easier to make and lighter than any other solution, as well as providing 3 speeds.

Re: Good drivetrains observed
 

Video of our robot at GLR can be found here:

http://www.freebmw.net/don/FIRST_Sponsor.wmv

It's a big file... 52 Megs...

You can see that with the casters down, we are very manueverable and quick. When the casters are up, we have good power and are hard to push.

A good example is when near the end of the match, we get into position and put our casters up (watch the wood floor in our ball pick-up area), but then back down to get into better position, but 894 starts to push us. We decided to see if we could make shots while begin pushed, so we leave them down... After we escape and get back into position, and raise the casters, they can't move us very well and we make the rest of our shots.

Re: Good drivetrains observed
 

How would you do an 8 wheel drive train and have 6 wheels on the floor at all times? And doesn't that make it a little hard to turn?

Re: Good drivetrains observed
 

Our drivetrain was really solid this year; 6-wheel drive with 2-speed pneumatic shifters.
The gearboxes direct drive the back wheels, then connect to the other two wheels with seperate chains.
Head to head we can push tank treads. In fact, I don't think we lost in a head-on match once.
Unfortunately, our high center of gravity still caused a little bit of hopping when we turned, but I don't even want to think about what it would have looked like with 4-wheel drive.

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While pushing is important, there is more to every game than pushing, you know, like driveability and maneuverability. Pushing matches don't score any points really.

Re: Good drivetrains observed
 

Yes, which is why we used those extra two wheels. We could push a lot last year, but our maneuverability wasn't the greatest. 6-wheel drive adds a much greater degree of maneuverability.