Re: pic: 1675's REAL IRI Upgrade
 

I can find you hours upon hours upon hours of traction wheels playing effective defense or offense around mecanum drives. There's video of some smart defense and plays by mecanum drives too, but certainly not entirely because of their wheels. If you're asking me to find a video of a bad frame being smashed to pieces by a traction drive, what does that have to do with anything? The strength of your frame isn't determined by your wheels.

I'm sure that's why some teams use traction drives, but really? Are you really trying to say that legions of good teams in FRC just make drivetrain decisions because they've never done anything differently? That's pretty awful engineering.

If you gear it high, how are you fundamentally different from a traction drive? High gearing implies traversing long distances. When you're doing that, a traction drive would certainly be able to go slightly diagonally to counteract losing strafing ability.

Now look, this was supposed to be a lighthearted thread where both sides would laugh about a prank everybody enjoyed...

Re: pic: 1675's REAL IRI Upgrade
 

no, i was looking for tractions so powerful they crush stuff. the point is that you are looking for mecanums to be that much better. I will admit that it will not do circles around traction drive. however, it can score more efficiently when scoring involves more than just pushing things.

well, why not? if it works, do it. if you look thoguh history of things, breaking from a previous design that was successful has been a flop:

intel i860- was a RISC, not a x86 CISC cpu.
intel itanium- wasn't x86,
atari 5200/atari 7800- the 2600 was good enough, so there wasn't a need to upgrade
wankel engines- radically different than existing piston designs
microsoft bob- people liked the existing windows interface, no upgrade desired


there are more, but if there is no perceived need to change, why do it?

if what you have doesn't work or you are starting new, then that is a different discussion. point is that many top teams have been good for a long time and they never had a big reason to change (from their eyes).



If you gear it high, how are you fundamentally different from a traction drive? High gearing implies traversing long distances. When you're doing that, a traction drive would certainly be able to go slightly diagonally to counteract losing strafing ability.[/quote]

Re: pic: 1675's REAL IRI Upgrade
 

Who was saying anything about crushing power?

If you really think the best teams in FIRST don't use a single minute of their 6 month long offseason to ever try a new idea, and that you are the enlightened one here, go ahead. I'd just rather we not endlessly debate in a humorous thread.

Re: pic: 1675's REAL IRI Upgrade
 

In the 2010 SVR Finals, 675 (mechanum) played defense on 971 (traction). 971 almost literally drove circles around 675 and is able to easily push through them to score. Sorry that may not have been the video you were looking for though... :P

Match 1 | Match 2

Re: pic: 1675's REAL IRI Upgrade
 

Not quite hundreds....

maybe...

(we don't even know how many we hid, so they'll never know unless they empty all their containers!)

Re: pic: 1675's REAL IRI Upgrade
 

it all comes down to implementation. a well designed traction will stomp a poorly designed mecanum.

I wish i had footage to back this up, but my team's bot this year was mecanum. we were the fastest bot that showed up to BMR. if our manipulator had worked better, we'd made eliminations (234 told us that had their alliance mate not disagreed, they would have picked us for a 3rd defense bot).

it also had no problems during the season either other than a spare practice gearbox having a defective gear from the factory (one stolen from a 2009 KOP gearbox fixed it).

whatever on this topic... people use what people use...

Re: pic: 1675's REAL IRI Upgrade
 

Your example of a noteworthy mecanum drive is one that didn't even make the elimination rounds at a 41 team event?

Re: pic: 1675's REAL IRI Upgrade
 

Holy Straw Man argument, Chris.
The "driving circles" challenge was certainly served and, to our knowledge, never met. It calls for (paraphasing) an inferior (mecanum drive) team defeating a superior (traction drive) team simply by virtue of its drive train. But then you state that only holistically inferior teams would use mecanums in competition in the first place.
As coach of our 2011 mecanum-driven bot, I noticed during practice and competition that it could perform maneuvers that a traditional (read: 4-wheel or 6-wheel, non-crab/swerve) robot could not. This maneuverability allowed us freedom of simplicity in our overall design, and the ways we implemented the mecanum drive were not evident in middle-of-the-field play - partly due to the limited access given to defending teams, partly due to the fact that we went to one event, and partly due to the fact that the only time we were actively defended, THAT ROBOT HAD MECANUM DRIVE TOO! (3487, who rode their mecanum drive all the way to St. Louis as Rookie All Stars).
Mecanum drive trains are not the optimal system for every challenge, but they do have merit. Swerve/Crab is undoubtedly better, but that arguably takes years of practice and refining to make decent. We had our mecanum drive running early Week 2 of build season, with no previous experience.
AndyMark does not make or promote sucky stuff they leave that to banebots. They've sure got a lot of iterated mecanum wheels, though.

To go back to the OP - it is pretty funny. As is the payback.

Re: pic: 1675's REAL IRI Upgrade
 

JVN disagrees with your statement. (And he says 148 hates mecanum).

I don't know what other teams do, but we don't look at drive systems first. We look at game strategy. We don't look at 6wd vs 8wd vs swerve vs mecanum vs slide vs nonadrive, we look at if the ability to translate sideways is a significant advantage, then factor that into our weighted decision matrix (the larger the advantage, the higher drive systems incorporating that will get more ranking points).

For us, the ability to train drivers to use a 6/8wd well has always led us to find the sideways translation to not be significantly helpful, except in the two years we convinced ourselves it was an advantages and built a swerve (and regretted it both times... One year we hated it so much we replaced the swerve pods with fixed wheels after the first competition)

Re: pic: 1675's REAL IRI Upgrade
 

because the other half of the robot (read: manipulator and minibot) wasn't up to par. in fact, it really didn't work at all.

version 2 of the arm and minibot/launcher improved things in st. louis, but communication issues between myself and the head programmer led to code issues, the drivers didn't have enough practice with the final system, and a catastrophic failure ended it.

it proves that although a good drivetrain is good, it isn't everything.

Trust me, my years on 1747 taught me that equally well. In 2010, we could "glide" over bumps, push robots away from towers before they could hang, and some rowdy drivers of ours (not endorsing this) even disabled my current team's (2783) drivetrain in one match and flipped a rookie in another (anybody at buckeye regional that year knows about it). however, the kicker broke beyond repair, the vacuum didn't work, the roller to replace the vacuum was destroyed in the kicker failure, and the hanging device never worked. only this time, at boilermaker regional, we were picked by the 1st seed alliance (with 1501 and 1018) but lost in the semi finals in a close battle. by the way, it was a 2 speed traction drive (front traction, rear omni duals).

Re: pic: 1675's REAL IRI Upgrade
 

525

Re: pic: 1675's REAL IRI Upgrade
 

I haven't found any recently.....hmm, remind to hide random swerve modules or something in your pit sometime

Re: pic: 1675's REAL IRI Upgrade
 

I think Ratdude actually shows an advantage of tank over mecanum. One of the reasons I want my team to use the same strong 6/8 wheel tank drive (or something similar) is that we can always play defense if we need to. Obviously, we always go into the year thinking we are going to be one of the best scorers at our events, things don't always go to plan and you need to adjust. Things break mid match or your scoring isn't quite as good as you expected, so you may be better served playing defense in some matches. This year at the Championship and IRI we played defense around half of the matches (depending on matchups), and got picked at both events because of our ability to play defense. I think there is no way we would have gotten picked if we had a mecanum drive. I don't recall seeing any mecanum drive play better than just 'ok' defense as they are just too easy to push around.

Re: pic: 1675's REAL IRI Upgrade
 

I didnt make any statement about Mecanum, i only asked if any big name teams used mecanums, and implied mecanums IN competition. I am still correct that 148 did not use mecanums in competition, right?
I guess i understand how one might interpret my statement as they havent bothered to try; that was not the intent. Rather, i was just curious for historical information.
-duke
P.S. There's really no point in arguing this guys; if this was battlebots, sure, argue away. But in a competition where there are many other aspects besides drivetrains that critically define your success, no.

P.P.S. You guys may disagree completely with me, and i'm not looking to make this an argument; however, i believe 100% that 254, 111, and 973 still would have won it all if they all had Mecanum drive trains.

Re: pic: 1675's REAL IRI Upgrade
 

I see your point, but i think mecanum can play defense. I really don't know how to explain it, at least in writing. if i had to verbally explain it to someone in person, i probably could. But, mecanum can play just as good defense, and avoid being pushed around at the same time. At BMR, 292 was scoring a solid 4-8 tubes every match, and we (461, with mecanum) played defense against them in their last Qualification match. We still lost because we didnt have that great of an outing offensively that match, but 461 kept them to i believe two tubes the whole match. again, i would probably have to write an essay to explain how/why, but i really dont feel like it, nor do i really feel like pursuing this argument :rolleyes: