Penalizing mecanum wheeled robots durring alliance selection.

[Lij2015]

Our first pick and our second pick(1533 and 2068) at Virginia had mechanum wheels as well as our number one robot on our list at Chesapeake(1629) picked us and our second pick also had mechanums(623)

I'm personally not the biggest fan of them, but at both our regionals we were the only bot on our alliance to not have mechanums, so I'd say as long as you can use them they don't affect anything haha.

[Kevin Leonard]

I've seen one exceptional implementation of Mecanum wheels in all of FRC ever- and that is Team 2052, KnightKrawler, as has already been mentioned in this thread.

I've also seen a few robots where the ability to strafe gives them a marginal benefit over a traction drive- 126 2013, 58 2012- where the ability to strafe gives them an ability they wouldn't have had otherwise.

I think all of these robots, barring perhaps 2052, would have been just as good or in some cases better with a traction drivetrain. However, it depends on the strategy and role your robot intends to play on an alliance.

If you were a cycler in 2013, a Mecanum drivetrain can be fine, sometimes even a good thing.

If you were a full-court shooter in 2013, where your entire strategy revolves around reaching a location and staying there for the match in order to score points, you should have a drivetrain that allows that.

In 2014, any robot that could get easily pushed across the field moved down the picklist, purely because that makes it more difficult for them to score. If you drove that same robot like 33, you move back up the picklist because your driving is fantastic and makes up for that to a degree.

If your robot exhibits negative qualities in a match, it will get penalized- not because it specifically has a certain mechanism on the robot, but because the robot doesn't do what needs to be done, and that could cost my team the regional.

[BBray_T1296]

Originally Posted by Kevin Leonard

If your robot exhibits negative qualities in a match, it will get penalized- not because it specifically has a certain mechanism on the robot, but because the robot doesn't do what needs to be done, and that could cost my team the regional.

Quoted for truth

[evanperryg]

Originally Posted by Max Boord

Our alliance did this at Panther Prowl last year. We could not have been more pleased with the outcome.

At crossroads this year, my team picked 2 mecanum drives (2358, 4085) as the 8th seed. These robots were very strong as defenders because they were maneuverable and tall enough to block the other alliance's shooter. It's about picking a good alliance, not good robots.

[RunawayEngineer]

Originally Posted by MARS_James

I gotta ask, why did your team say yes to 2152 in South Florida then? The competition wasn't that deep I admit but you were next up in the pick order so the difference would have been negligible.

EDIT: Also 21 your other alliance partner ran mecanum this year, did your team try to talk 2152 out of it or no?

I can't go into specifics, but there was a lot going on in regards to Alliance Selection at SFL that we (I especially) left to chance and the gamble didn't pay out in the brackets. I learned a lot and will be making adjustments for next year.

[MamaSpoldi]

Originally Posted by KrazyCarl92

In my experience, I have only competed with 2 robots that stick out in my mind as having implemented a mecanum drive in a fashion that in some way improved their overall strategic design and were executed well: Team 230 in 2010 and Team 58 in 2012. Both of these teams had creative ways to use their mecanum drives to do something that a standard tank drive could not (or at least not as simply or with the same resources). 230 used theirs to strafe sideways once atop the bumps in the field so they could engage their hooks and climb the tower, knowing they were lined up as they did so and not having to climb as far. 58 used their mecanum drive to position themselves against field elements in auto, moving along multiple axes to ensure they were in the proper location to consistently score their 10 point autonomous.

Yup. In 2010 our robot had mecanum wheels and we definitely used them to our advantage. It was a great season for us winning 1 Regional, finalist at the other, and we made it to the semi-finals at Championships.

Originally Posted by who716

I believe that it is very well known New England is where some of the heaviest defensive play occurs. watching events all over the US I noticed that in the west its offense offense offense. even in Texas the robots were made to play a purely offensive games, example 148 118, yes they play defense but there robot designs were more offensive. therefore I believe its true that mecanum wheels would be more common in those areas then up in new England.

Although I agree that New England has some of the heaviest defense, I believe it is still possible to use mecanum to your advantage. We won the WPI regional and were finalist at the Connecticut regional (both in New England) in 2010 because we used the mecanum as a specific feature... and also because we had a very sturdy and well implemented control system.

I also agree that using it just for the perceived maneuverability and without gyro stabilization and other optimized control software can be a recipe for poor performance.

[JesseK]

At least in the Capitol Region, many of the teams who did Mecanum drives 2010-2013 had magnificent and beautiful looking drive trains, followed by piecemeal and somewhat functional mechanisms. This tells me that while the Mecanum drive probably works well, the drive team probably had very little practice with using the drive train and mechanisms together. 623 was typically a good example of this, yet in 2014 they pulled it together and found a very lucrative role they could reliably fill, winning them Chesapeake.

It's tough to write off a Mecanum drive just by itself, IMO. It's far better to see how a team uses the Mecanum and how well the robot performs a role relative to other robots that perform the same role.

BTW, to me this wording is as hilarious and ironic as a license plate that says "Epic Fai" - I just may have to change wording in some of my drive train presentations:

Originally Posted by T^2

... there are a few moments when they cause noticeable forced lateral motion of an opposing robot.

[Sam_Mills]

Originally Posted by DanBrowne
Tanks shouldn't get t-boned because they can't get out of it.

Originally Posted by T^2

Yes, they can.

Source? We all know there are little tricks like deployable omnis or ball casters, choice of bumper fabric, etc., but if it was as simple as "yes they can," then RUSH would not have won MSC this year.

*Yes, there are methods of escaping a pin faster than others, but "yes they can," implies that T-bones are no more an issue for tank drives that other drive systems.*

*Edit: Rudeness + accuracy

[Chris is me]

Originally Posted by Sam_Mills

Source? We all know there are little tricks like deployable omnis or ball casters, choice of bumper fabric, etc., but if it was as simple as "yes they can," then RUSH would not have won MSC this year.

If you were going to site "spin out of it," or "a good driver can get out of it no problem," then you should go on TBA and watch some high level play.

I am reasonably confident that 1678 probably knows a thing or two about handling defense... He isn't saying that T-bones are easily beatable, he's saying it is physically possible for a tank drive robot to escape a T-bone pin. This happens all the time, just not quickly or reliably enough to satisfy many teams.

[AdamHeard]

Originally Posted by Sam_Mills

If you were going to site "spin out of it," or "a good driver can get out of it no problem," then you should go on TBA and watch some high level play.

I'm pretty sure they got to see some high level in play after back to back Einstein appearances as the #1 seed.

[Sam_Mills]

Originally Posted by AdamHeard

I'm pretty sure they got to see some high level in play after back to back Einstein appearances as the #1 seed.

There was no indication on the information visible in the post that he(she?) had been a part of 1678. I am very aware of how highly they perform, so I am actually pretty surprised that he/she would simplify friction pins as "yes, you can drive out of them."

When you consider that they play on the same field as 254 and 971, this comment is even more surprising, because if it was as easy as driving out of them, then 254 would not bother with their extensive testing of bumper materials, and 971(unless it is for envelope reasons) would not bother with an octagonal drivetrain. At some level you must know you cant just drive out of them either, as you too are updating your 2014 robot with a different bumper shape.

In the bulk of situations, the premise is wrong, regardless of who says it or what team they are from.

Edit: Although I will admit, my comment was unnecessarily rude. I am sure I am not the only one who gets tired of misinformation on CD.

[Kevin Sheridan]

Originally Posted by Sam_Mills

There was no indication on the information visible in the post that he(she?) had been a part of 1678. I am very aware of how highly they perform, so I am actually pretty surprised that he/she would simplify friction pins as "yes, you can drive out of them."

When you consider that they play on the same field as 254 and 971, this comment is even more surprising, because if it was as easy as driving out of them, then 254 would not bother with their extensive testing of bumper materials, and 971(unless it is for envelope reasons) would not bother with an octagonal drivetrain. At some level you must know you cant just drive out of them either, as you too are updating your 2014 robot with a different bumper shape.

In the bulk of situations, the premise is wrong, regardless of who says it or what team they are from.

Edit: Although I will admit, my comment was unnecessarily rude. I am sure I am not the only one who gets tired of misinformation on CD.

With our new bumpers we can literally just drive straight out of a t-bone. No special maneuvers necessary. We did extensive tests using 971's practice bot, which is t-bone machine (Austin used that robot to t-bone our robot with the old bumpers until the batteries died), and we were able to escape t-bones in under 5 seconds every time.

[Sam_Mills]

Originally Posted by Kevin Sheridan

With our new bumpers we can literally just drive straight out of a t-bone. No special maneuvers necessary. We did extensive tests using 971's practice bot, which is t-bone machine (Austin used that robot to t-bone our robot with the old bumpers until the batteries died), and we were able to escape t-bones in under 5 seconds every time.

Was this using the sailcloth covers? I bought some to do some testing with but have yet to get the chance to actually try it.

[Kevin Sheridan]

Originally Posted by Sam_Mills

Was this using the sailcloth covers? I bought some to do some testing with but have yet to get the chance to actually try it.

Yes. We also had new pool noodles that were significantly harder than our old ones. A "downside" is that is also became really hard to play defense with the new bumpers. Our driver could no longer rely on friction pins and had to learn how to stay in front of robots better since it became really easy for other robots to "slide" past the bumpers.

[T^2]

Originally Posted by Sam_Mills

When you consider that they play on the same field as 254 and 971, this comment is even more surprising, because if it was as easy as driving out of them, then 254 would not bother with their extensive testing of bumper materials, and 971(unless it is for envelope reasons) would not bother with an octagonal drivetrain. At some level you must know you cant just drive out of them either, as you too are updating your 2014 robot with a different bumper shape.

Tank drives such as 254's, 971's, or 1678's can get out of pins precisely due to clever use of bumper shape and material selection. One may even go so far as to say, as others in this thread have done, that the ease-of-use of such drivetrains allows teams to funnel more resources into other aspects of the robot, such as the aforementioned bumpers. Then again, even though I was part of team 1678 for the past two years, I didn't see a single one of our division qualification matches, so what do I know?