Quote:
Originally Posted by ksafin
1)What kind of wheels do you prefer
1a) What kind of challenge/obstacle prompts a certain wheel choice
1b) What kind of wheel would you use if you had a low budget (aka can't afford $1,000+ on swerves)
1c) How do you personally choose what size wheel you prefer?
2) What do you make your drive train out of? (Base train, custom, 80/20, etc)
3) What gearboxes do you use for your motors, and why?
3a) Do you use shifters? Why?
4) What kind of wheel setup do you choose? (4 wheels, 6 w/ 2 dropped, etc etc)
5) How much time do you normally spend building your drivetrain?
6) Do you prefer to use belt or chain? Why?
6a) What would prompt using one over another?
7) Generally, long robot, wide robot, or it depends on the game?
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1) I (as in me myself and I) prefer high grip wheels (Colsons are wonderful). Smallish wheels (4"/5"/6" wheels are preferable, so the bot has a low center of gravity.
1a) Bumps (like this year's game and 2010) are the only reason I see for larger wheels.
1b) I think any team (large budget or not) should use a standard 6 wheel drop center tank drive. As for the wheel, traction wheels (2012 KoP wheels, treaded wheels, colsons) are the best economically, and usually the best performance wise. I'd say the 2012 KoP wheels are amazing for anyone, and a definite should-use for a low-resource team.
1c) I personally choose wheels based on my team's resources and our requirements. I suggest reading 1114's paper on drivetrains and wheels (
http://www.simbotics.org/files/pdf/d...aindesign.pdf). I'm looking into Colsons, since they match my team's resources (middle) and requirements (high grip).
2) We make our drivetrain out of square steel tubing (.75" diameter, 1/16" thick wall), welded. However, steel is heavier than aluminum. It is stronger (one reason we use it), but we carefully plan out and control our weight so that our drivetrain is heavier, giving us a lower CoG, and the rest of our bot fits in the weight limit. I do not suggest this for a rookie/newer team.
3) AndyMark CIMple Boxes. I've got to say, those are some beautiful transmissions. I love them. They are small, light, cheap, come in the KoP (not in 2013), and allow for really nice driving speeds.
3a) We're yet to use shifters, however we only plan on using them when a strategy of ours requires a low gear (for example, pushing other bots up the bridge this year. No need for one in 2011).
4) For a long bot, we like the standard 6 wheel drive with the center wheel dropped 1/8", and our robots center of gravity between the middle and back wheels (better turning than directly in the center). This year we went wide, and did a 4 wheel drive. It was still pretty stable, but we designed with a really long wheelbase, which made turning a bit slow.
5) We design many different Drivetrains in the fall, so that by the time kickoff comes, and we have a general idea of what we want in a drivetrain, we'll have ideas to work off of. Designing a drivetrain shouldn't take any more than a day. If you have a smart design and know what to do, building a drive can be done easily in a few days (4-6).
6) While I hear belt is better in terms of efficiency, I personally will stick with #35 chain. I don't like designing drivetrains around the length of the belt. I'd rather be able to use chain and have it any length I want.
6a) I'd love to experiment with belt, but we've seen nothing wrong with chain, and have no reason to switch.
7) It all depends on the game. A wide bot was advantageous this year due to the bridge (and sometimes a wider ball pickup). My rule of thumb is this: If you need to fit in a specific dimension or pick something up using the wide side of the drive, go wide. Anything else, long.
I hope this helps. You should really look unto 1114's Kitbot on Steroids. It's one of the best drivetrains out there (top 95% of all drivetrains).
http://www.simbotics.org/resources/kitbot Just because it's in the kit, doesn't mean it's bad. The kitbot was designed by engineers who know FRC. The KoS was designed by the team who has beaten those engineers.