Quote:
Originally Posted by Lil' Lavery
FIRST Champions:
2005:
330- 6WD, higher traction center wheel (possibly dropped)
67- Swerve
503- 2WD w/ omnis (correct me if I'm wrong)
2006:
296- 2WD w/ casters
217- 6WD, lowered center wheel
522- Treads
2007:
190- 6WD, lowered center
987- 6WD, lowered center
177- 6WD, lowered center
2008:
1114- 6WD, lowered center wheel
217- 6WD, lowered center wheel
148- Swerve drive
correct me if any are incorrect
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No corrections to be made, but I WOULD like to point out that taking the fact that there are more 6WD drive, etc. teams on this list as proof that it is a better way to drive and that there is no benefit to more exotic types is somewhat suspect logic and silly generalization.
The reason I say this is that lets say that in the data for 2005, there are what, 800 or 900 robots? Sure, hypothetically. But lets say there were 30 robots with crab drive built that season. Well, in that case, one could say that swerve drive is over-represented, and that obviously, building a swerve drive will afford you a better chance of doing well and getting in the finals, because while only 30 teams had swerve drives, one of them made it (1/30 odds) while then there were probably around 200 robots with 6WD, only two of them made it (1/100 odds.) I'm not saying this data doesn't have ANY merit, but come on guys, lets be responsible in our generalizations. In order to use this kind of analysis, you'd want to make it more statistically valid by either opening it up to all the regional and championship division winners of a particular year.
I've designed three drive trains in my tenure in FIRST, 1 4WD tank with omni (6-motor), 1 crab drive (4 pods, 2x2 chained together), and this year's 6WD with AM Supershifters. I have also given a presentation on drivetrains with Bill Beatty.
But what I would recommend to ANY team is that you shouldn't say "OH THIS DRIVETRAIN IS THE BEST 6WD 4EVAR" and be done with it. You really need to take some time and think about your design requirements--what you want the robot to be able to do, and then build a drivetrain to those capabilities.
The other thing you need to consider very closely (and this is echoed in the ANSI#25 vs. ANSI#35 debate) is your manufacturing and designing capability.
If you are a team that works in a garage with a hacksaw and a couple power drills, you are simply not going to be able to build a lot of really exotic drive systems without outside help. The reason is that many of these systems require tight tolerances (if you want to build your own gear reductions effectively) and if you are off by even a minuscule fraction, you can bind the whole thing up. If you have the capability to do this kind of stuff and build exotic systems, I actually very much encourage you to do so as long as you feel it is in line with what you want to do with your robot.
In terms of DESIGNING capability, if your team has lots of experience building drivetrains, have at it, do what you want. If you are a rookie team, I might encourage taking it easy for perhaps the first year and going with a simpler drivetrain and focusing on manipulator design and also programming. You can do a lot of amazing feats programming even a simple skid-steer robot. But once you have been in the community for a season, even a single regional, you will start to see all the stuff that has been done and is being done--you'll be more familiar with the "state of the art" and be that much more experienced, and ready to go for the next year. Then build something you think will be neat like a swerve or a linkage drive (woo Winnovation!) in the off-season, make sure it works like a charm, and then implement it on your season robot. This way, if you don't get it to work in the off-season, you can still just build the robot with the kit-drive or something else that you KNOW will work. I encourage this methodology for veteran teams too! Plus, you can have a second, better iteration of the design for the season with all of the bugs corrected.
Finally, whatever drivetrain you build or choose to build, learn it inside and out. Learn EVERYTHING about it, how it feels when you drive it, etc. Build SENSORS into the design. Try to do some modeling (mathematical, or build a little replica out of wood, or even a little Vex robot) so that you know how it can move and you can think about how you will control it.
Autonomous driving is only going to get more important guys, lets not kid ourselves.
So I guess, I can sum up my comments as follows:
1.) There is not necessarily a BEST year-after-year drivetrain.
2.) Decide on your drivetrain including your robot goals, manufacturing capabilities, and design experience as parts of the equation.
3.) It is awesome to be innovative and unique (I LOVE INNOVATIVE AND UNIQUE) but please do it in a safe fashion so that what hits the field isn't a janky prototype but a second-iteration. This will help your team, all other teams, the spectators, etc.
4.) If you're a rookie, you need to take a GOOD LONG LOOK at your capabilities, and it
may be wiser to take it slow and learn the ropes, and build something phenomenal in the next season.
5.) Whatever you do, think about the design carefully and take controls into the deepest consideration.