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2012 drivetrain
So i was wondering what drive team did everyone's team use? And if you had to redo this year would you use the same drive train again?
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Re: 2012 drivetrain
We used 4-wheel tank drive from KOP parts this year, as we always do. If I could re-do this year, I'd probably go with an 8-wheel drop center system (something like a modified Kitbot on Steroids) to help with the turning. Our handling on carpet was so bad that we covered the treads on the wheels with duct tape.
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Re: 2012 drivetrain
I would want smaller wheels and a better method of getting over the bump. It was not that easy to get over with our 8wd 6" wheels. We sometimes got stuck and had to back up and go forward again to get over. Watching some robots just bounce and glide over was really cool (1114 comes to mind).
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I feel our 8 wheel drive train worked really well. With being a long bot, being able to only need 6 wheels on to triple balance worked great. Never had issues with going over the bump.
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We had a wide, four wheel drive robot. It worked really well, and did what it was designed to do perfectly. Looking back, having a way to go over the bump would have saved us a lot of time messing with the bridge, but it would have been kinda hard to implement in our design, since 90% of our robot base was wide open for balls to come in.
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Re: 2012 drivetrain
We had a pretty standard 6WD. Dropped center, the high-traction tread, etc. However, over the summer, we'll be making an 8WD and seeing how it compares.
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Re: 2012 drivetrain
Wide 4WD, 4CIM, 23.35:1 reduction with 12-inch pneumatics (the same type used on the team's first robot (2004). It was great at going over the bump and mechanically one of the most solid and reliable drivetrains I have worked with. For me, there is no reason to consider doing it differently if I were to do it again.
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Re: 2012 drivetrain
We had a wide-bot 4wd with articulating, non-powered wheels in the center. Normally, they remained off the ground, but were attached to the outer wheels in such a way that on the bump they would raise up, contacting the surface of the bump. The outer (drive) wheels would lower down to remain on the ground on bot sides of the bump.
It was powered by 4 CIMs in SuperShifter gearboxes. The outer wheels were 8in aluminum with roughtop and wedgetop tread, and the inner wheels were this years' KOP 4in traction wheels. |
Re: 2012 drivetrain
Kind of forgot to say this at the beggining but my team had a wide driving ten wheel tank drive with four inch plaction wheels with blue nitrile trad from mcmaster. The center six were dropped .125". If we were to replay this year i would stick with this it gave us lots of traction and we could hang multiple wheels off the bridge if needed
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Re: 2012 drivetrain
We used 6wd long orientation, with 8" pneumatics from AM, and the Super Shifter. In hindsight, The pneumatic wheels had nice traction, but were a pain because their sizes varied quite a bit. I would have preferred colsons from what I have heard of them. We had originally planned to go over the bump, but ended up not being able to due to geometry, I wish we had gone with smaller and more wheels to enable this. Also, our Supershifters had the wrong ratio for 8" wheels, so the high speed was too fast for our drivers and was thus never used, leaving us with wasted weight and a tad slow. I would have switched the gear ratios to slow everything down a couple fps or switched to a lighter and slightly faster 1-speed transmission.
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I can't tell if they have something to lifts their robot or if their sheetmetal frame is just shaped to pop them up and over. 971 and 254 have a little drop down wheel that launches them over, but I can't remember what 1114 does. Something passive would definitely be nicer. |
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Re: 2012 drivetrain
We used a 6WD drop center wide with Andymarks pneumatic wheels. We designed our drivetrain to have sufficient ground clearance to clear the bump, which we did with ease. The only time we had trouble was when our driver decided to try simultaneously running over 4 balls and crossing the bump :rolleyes: .
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Re: 2012 drivetrain
8 wheel tank with a center drop. The only thing I'd change would be adding a ski of some kind to help us go over the bump. We only made it over the bump once our twice in practice and when we did we would spend the next hour bending our bridge manipulators back into their proper position.
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Re: 2012 drivetrain
8WD, 5" Colson Performas, drop center, "long" configuration (34")
Going with an 8WD with smaller wheels and drop down skids/wheels to go over the barrier would have been a better choice for crossing, otherwise it performed well. |
Re: 2012 drivetrain
48/3193 ran with a 6WD with 8" AndyMark pneumatics (work flawlessly - great product - now offer a 6" version!), no center drop, angled frame with riveted delrin skids.
We easily cross the barrier and possess good maneuverability in both high and low gear. The lack of a center drop permits more stable shooting with no rock. |
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Re: 2012 drivetrain
6wd long, with supershifters, and a wedge integrated into the frame. If we were going to do it again, I would have gone with 8wd, smaller wheels, and drop down wheels, just so we could get over the barrier slightly quicker. It still wouldn't have made much of a difference, a couple of seconds per match at most.
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Re: 2012 drivetrain
We ran 4 8" plaction wheels with toughboxes. For another game where we drive into a steel bar like the bump we might look at different wheels, though two regional events and the championship with just one broken wheel the way we abused them isn't that bad.
We are planning to build a prototype geared drivetrain this fall, much like 25s, because the chain is what gave us the most trouble. Wetzel |
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We also did very slightly lower the pressure of the front and rear tires relative to the center, which we kept near max pressure. There is no noticeable rock on the robot at all. Here is a link to a pic of the underside of 48's robot: https://docs.google.com/open?id=0B5w...3RiTkV6SmlyVXc |
Re: 2012 drivetrain
We used an octocanum drive base this year -- 4 traction wheels and 4 articulated mecanum wheels, so we could switch between traction and mecanum drive. This was our "best of both worlds" drive train. 6 inch traction and 6 inch mecanum, but the mecanums were sped up 1.5x the traction wheels speed.
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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.
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Re: 2012 drivetrain
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. :rolleyes:. 4WD Tank, Wide Drive. |
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Re: 2012 drivetrain
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. |
Re: 2012 drivetrain
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. |
Re: 2012 drivetrain
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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. |
Re: 2012 drivetrain
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Lower pressure pneumatic tires have a lot more surface area, and have a lot more opportunity to "interlock" with the carpet fibers (think of it almost like Velcro). When this happens, the drive train will draw significant current while trying to turn, potentially even enough to trip the main 120amp breaker if other subsystems are in use at the same time. |
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The drivetrain is a 6WD using the AndyMark 8" pneumatic wheels (long configuration). |
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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. :) |
Re: 2012 drivetrain
Wide brecoflex tank treads.
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Re: 2012 drivetrain
Wide base, 6-wheel tank. AM roughtop plaction center, omni-wheel corners, back 4 wheels powered. CimPLE boxes, 2 CIMs per side.
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Re: 2012 drivetrain
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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. |
Re: 2012 drivetrain
Swerve baby swerve.
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Re: 2012 drivetrain
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Re: 2012 drivetrain
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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. |
Re: 2012 drivetrain
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. |
Re: 2012 drivetrain
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! |
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Re: 2012 drivetrain
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.
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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. |
Re: 2012 drivetrain
We used a 4 wheel mecanum drive train, which was perfect with our 4 sided pick-up system. We could get over the bumb easily with skid plates, we could balance just fine, but I really wish we would have made a wide bot.
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Re: 2012 drivetrain
Tank treads.
even though no one on the team had done it before they worked very well even though it took more time then i wanted to spend on the drive train to get them working( week 3 and still didn't have it completed) and took time away from testing our shooter. I would defiantly use them again. even with only two CIMs we couldn't be pushed around. even on the bridge the traction kept the robot from sliding down. |
Re: 2012 drivetrain
We used a 6wd WCD drivetrain, however, the center wheels were mounted on pneumatic cylinders so we could retract them to go over the bump. Overall, it didn't work that well since the middle wheels were not powered.
you never learn anything without trying. Kelly |
Re: 2012 drivetrain
Team 1325 ran a 6wd (long configuration) using custom 2 inch wide wheels powered by 4 CIM's through a single speed gearbox (all wheels powered). We loved the traction they gave us, especially in the key and on the bridge. Once we were in position, be it at the fender or defending a bridge it was near impossible to push us sideways.
The drivetrain was awesome this year, through 2 regionals it never ever failed us. |
Re: 2012 drivetrain
We had a supershifted 6 wheel WCD with 6in wheels. We relied on the bridge for crossing from one side of the field to the other. We never had any issues with this. Even if there as a ball under the bridge we had enough power in low gear to simply crush it using the weight of the bot against the bridge.
Personally, I wouldn't change anything (except for using loctite on the clevice for the piston on the shifters, it came loose once o.O). We intend to use variants of this drive train in the years to come. |
Re: 2012 drivetrain
Well, we are on the West Coast...
6 wheel WCD (our "poor team's" version), 1/8" center drop, 6" kit wheels. AM Supershifters driven by 2 CIMs each, directly driving the center wheels. (We replace the output shaft on the Supershifters with a long hex version, but leave the rest of the shifters unmodified so that we can reuse them.) The KOP wheels were the best traction on the bridge we could find. What was key for us this year is the size of the bot - 27" square. Axle separation was 10 inches, track width 26". This meant easy Barrier traversal (using our "skip-loader" arm to do a "push-up" on the Barrier to raise the front of the 'bot) and taking up a total of 17" on one end of a bridge during triple balances. This is the best driving robot we've every built - no reason to change the drive system. (Now our shooter was a different matter...) - Mr. Van Coach, Robodox |
Re: 2012 drivetrain
4 wheel 8" pneumatic drive, actuated middle 6" Colson wheel up and down... so 4/6 wheel. All wheels powered. 2 speed gearbox's (4fps/12fps).
-Nick |
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