pic: 1675's REAL IRI Upgrade

[Sb28000]

Very interesting. I would imagine that the driving style was changed to tank drive rather than the typical mecanum pattern, is this correct?

[Duke461]

Originally Posted by Sb28000

Very interesting. I would imagine that the driving style was changed to tank drive rather than the typical mecanum pattern, is this correct?

Unless tank treads now have the ability to strafe, i would say no.
Not hating on 1675 or anyone, but I'm not sure why everyone's praising this as if its a new design or a radically different/improved design, in comparison to a normal tank tread drive. Unless you can somehow strafe, the wheels are now no different than a normal tank tread drive--maybe even worse because the tread is zip-tied and not against a flat surface.
However, i would love to be disproven on this.
-duke

[ratdude747]

Originally Posted by Duke461

Unless tank treads now have the ability to strafe, i would say no.
Not hating on 1675 or anyone, but I'm not sure why everyone's praising this as if its a new design or a radically different/improved design, in comparison to a normal tank tread drive. Unless you can somehow strafe, the wheels are now no different than a normal tank tread drive--maybe even worse because the tread is zip-tied and not against a flat surface.
However, i would love to be disproven on this.
-duke

no, its because a lot of people equate mecanums with dog poo. they point out things like "no bot on einstein has had mecanums" and things like that.

I consider the picture a DOWNGRADE. mecanums work if you do it right. gear them high and try to keep the weight semi-balanced.

I know there will be some angry replies to come from this from the "mecanum haters" out there.

[Chris is me]

This "upgrade" was a friendly joke / prank from the kids on 1625. They obviously removed them, despite some of us friends teasing them that it was a big improvement. 1675 responded by hiding hundreds of mecanum rollers in 1625's tools.

Originally Posted by ratdude747

they point out things like "no bot on einstein has had mecanums" and things like that.

Yeah, how dare we point out "facts" and stuff in an engineering discussion.

I think Einstein may not be the best sample for pointing out a correlation between traction drives and success, but I certainly can name far, FAR more top robots with traction drives. I certainly don't think the best teams are just too sucky at using mecanum drives to appreciate them!

[Duke461]

Originally Posted by Chris is me

This "upgrade" was a friendly joke / prank from the kids on 1625. They obviously removed them, despite some of us friends teasing them that it was a big improvement. 1675 responded by hiding hundreds of mecanum rollers in 1625's tools.



Yeah, how dare we point out "facts" and stuff in an engineering discussion.

I think Einstein may not be the best sample for pointing out a correlation between traction drives and success, but I certainly can name far, FAR more top robots with traction drives. I certainly don't think the best teams are just too sucky at using mecanum drives to appreciate them!

Facts? Chief Delphi is not a place for facts chris.
Im curious as to how many top teams have actually tried Mecanum. Because its not that the people that dont use Mecanum are the top teams, its that the top teams seldomly use mecanum.
Chris, you seem to know every team , so whats one of the best teams you saw this year ( or any year) that used mecanum? Because im pretty sure the big name teams (71, 111, 67, 148, 233) have never used mecanum.
------
In other words, regarding tank v. mecanum, correlation does NOT imply causation.

[Chris is me]

Originally Posted by Duke461

Chris, you seem to know every team , so whats one of the best teams you saw this year ( or any year) that used mecanum? Because im pretty sure the big name teams (71, 111, 67, 148, 233) have never used mecanum.

Not used mecanum in competition. That doesn't mean they've never used, tested, built a mecanum robot! It's an important distinction.

The best mecanum team this year was IMO 2826, which had an alternating drivetrain. If you go by FRC Top 25, not one team is "pure" mecanum. The best team probably to go pure mecanum was 2337, but I do think they would be just as good with a traction drive.

In other words, regarding tank v. mecanum, correlation does NOT imply causation.

Yes, that's true, but it's not worthless either. I made a thread a few months back called "Video of Mecanum Drive Running Circles Around Traction Drives" asking for some footage. I'm still looking.

[Duke461]

Originally Posted by Chris is me

Yes, that's true, but it's not worthless either. I made a thread a few months back called "Video of Mecanum Drive Running Circles Around Traction Drives" asking for some footage. I'm still looking.

Yes i remember that thread. Excellent point, sir

[ratdude747]

Originally Posted by Chris is me

Yes, that's true, but it's not worthless either. I made a thread a few months back called "Video of Mecanum Drive Running Circles Around Traction Drives" asking for some footage. I'm still looking.

well, I am lookign for a video of a tank bot crushing a mecanum bot to bits against a wall. just like the video on your wish list, you won't see it because you are looking for too big of an advantage.

the reason a lot of top teams use:

traction: they have used it for so long and thats what they are used to and have plenty of spare parts for

crab: they have plentiful human and/or capital resources or they have used crab for so long they already know the drivetrain design before the beginning of the season.

i do recall a pure mecanum system being a division finalist. curie 2008. 2171 robodogs from crown point, IN. look at some of thier footage on thebluealliance from boilermaker regional... they had that crab drive rocking... and that was under the IFI system.

octanum sounds like a good offseason project but a waste of weight and expenses... the key to mecanum is speed... gear it high (stock toughbox nano will do) and go... you can have a scale-down button if it is too quick by itself.

[Chris is me]

Originally Posted by ratdude747

well, I am lookign for a video of a tank bot crushing a mecanum bot to bits against a wall. just like the video on your wish list, you won't see it because you are looking for too big of an advantage.

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.

traction: they have used it for so long and thats what they are used to and have plenty of spare parts for

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.

octanum sounds like a good offseason project but a waste of weight and expenses... the key to mecanum is speed... gear it high (stock toughbox nano will do) and go... you can have a scale-down button if it is too quick by itself.

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...

[ratdude747]

Originally Posted by Chris is me

I can find you hours upon hours upon hours of traction wheels playing effective defense or offense around mecanum drives. 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.

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.

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.

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]

[Chris is me]

Originally Posted by ratdude747

no, i was looking for tractions so powerful they crush stuff.

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.

[NickE]

Originally Posted by Chris is me

I made a thread a few months back called "Video of Mecanum Drive Running Circles Around Traction Drives" asking for some footage. I'm still looking.

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...

Match 1 | Match 2

[ratdude747]

Originally Posted by NickE

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.

Match 1 | Match 2

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...

[Karthik]

Originally Posted by ratdude747

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...

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

[ratdude747]

Originally Posted by Karthik

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

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).