Penalizing mecanum wheeled robots durring alliance selection.

[Lil' Lavery]

Guys, mecanum wheels were on Einstein this year.

[notmattlythgoe]

Originally Posted by magnets

The fact that no mecanum wheeled robots on Einstein has occurred means any number of these 4 things.

1. Mecanum wheels somehow prevent teams from going to Einstein
2. Teams who chose mecanum wheels also do things that prevent them from going to Einstein
3. Teams who build robots who are capable of going to Einstein do not chose mecanum wheels
4. Einstein has gotten unlucky. This is unlikely, as we've seen an incredible number of robots on Einstein since mecanum wheels first entered FIRST, and none of them have mecanum wheels.

I will rewrite my statement with more disclaimers.

From events in a specific region that I have attended since 2011 and robot that I have seen on the field, I have seen that the majority of mecanum wheeled robots make other decisions that I do not agree with. On a world wide scale, I have yet to see more than one or two mecanum wheeled teams be very successful and claim it had to do with their mecanum wheels.

Also, in the year that mecanum was most useful (IMO, 2011), 254 won with a simple 6WD, proving that you don't need mecanum. In fact, every single Einstein match ever proves that you don't need mecanum to be a very successful team. Personally, I prefer to work with a team that realizes that something like mecanum drive is not something needed to be the very best and spent more time on other parts of their robot.

This is an opinion, and only applies to robots that have only mecanum wheels on drive.

My one defense for mecanum is, when done right, they can be extremely intuitive to drive. Our 2011 robot that made it into the Curie elimination rounds was an extremely easy robot to drive, and I believe that help us succeed that year.

With that said, we have not used mecanum since, including *winning* Galileo this season.

[Gregor]

Originally Posted by Lil' Lavery

Guys, mecanum wheels were on Einstein this year.

I had no idea.

[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.

I often ask a team with a mecanum drive in the pits what their drive train allows them to do that the kit drive train cannot achieve. If the answer is a blank stare or simply "strafing" for no well thought out reason, then I am obviously going to deem their drive as a disadvantage when I see them using it to no advantage on the field. This is because there are then plenty of things that an all else equal robot with a traction drive CAN achieve that this mecanum drive robot cannot. Even the two teams mentioned above did have their limitations owed to their mecanum drive trains, but at least their mecanum gained them something (hey look, points). I'm sure there are more examples of this, but for most mecanum bots I am left thinking that the robot would be at least as effective with a traction drive.

TL;DR consider the marginal gain of your mecanum drive. If one does not exist, why bother?

[Electronica1]

I'm curious, do people move octocanum drives lower on their list/ automatic dnp in a similar fashion to mecanum drives?

[RonnieS]

When we go through our picking process, the first thing is always going to be the best robot in the category we seem.to need first will be brought up first for discussion. After that, we will look at the limitations that pick would have for our alliance and the strategy we want to play. Unfortunately, I will say I hate most mecanum bots because they almost always lack the driver experience needed to make them affective. Granted, there is always that occasional team but not often. Through my experience, I have always been able to find a better robot with some sort of traction setup. Even if that team with traction capability had not shown much, I would feel more confident for example sticking them in the corner and leaving them their for the whole match to inbound and spit out and not move. Where if I had a mecanum bot, I couldn't believe as much that they wouldn't be pushed out of position. (Examples from Arial assist; obviously will vary upon game). I am typing from my phone so excuse any errors haha.

[Karthik]

There are a lot of people dealing in absolutes here, which we should all know is dangerous. (Frankly, the only reason to issue an absolute blanket Do Not Pick rank on a team is for a demonstrated pattern of dishonest and unethical behaviour. This is an absolute that even a Jedi would get behind.)

I echo many of the thoughts said by others in this thread. Each team should be evaluated on a case by case basis, on how their design and level of demonstrated functionality would complement your own robot and your desired elimination strategy. From my own personal experiences, I would say that most mecanum robots we've competed with have not been fit to be included on a picklist. Sometimes this is because their drivetrain makes them easy to defend against or unable to defend others. Other times it's been because the robot is just not generally very good. However, this is not an absolute. In 2010 at GTR, we were very close to picking a mecanum robot (Team 188) over a team who has never lost a regional (Team 2056), and ended up winning the event with a mecanum robot as our third alliance member (Team 1547). So it's not impossible for teams to use mecanum wheels with a great degree of success, albeit the frequency seems to be much lower. As for any talk of an inherent bias against mecanum wheels that isn't precipitated by actual robot performance, this is just dumb. The only inherent bias I've seen from teams when it comes to alliance selection is a bias against inferior robots, which is exactly what the picking process is based around.

[Monochron]

Originally Posted by Karthik

There are a lot of people dealing in absolutes here, which we should all know is dangerous. (Frankly, the only reason to issue an absolute blanket Do Not Pick rank on a team is for a demonstrated pattern of dishonest and unethical behaviour. This is an absolute that even a Jedi would get behind.)

I echo many of the thoughts said by others in this thread. Each team should be evaluated on a case by case basis, on how their design and level of demonstrated functionality would complement your own robot and your desired elimination strategy. From my own personal experiences, I would say that most mecanum robots we've competed with have not been fit to be included on a picklist. Sometimes this is because their drivetrain makes them easy to defend against or unable to defend others. Other times it's been because the robot is just not generally very good. However, this is not an absolute. In 2010 at GTR, we were very close to picking a mecanum robot (Team 188) over a team who has never lost a regional (Team 2056), and ended up winning the event with a mecanum robot as our third alliance member (Team 1547). So it's not impossible for teams to use mecanum wheels with a great degree of success, albeit the frequency seems to be much lower. As for any talk of an inherent bias against mecanum wheels that isn't precipitated by actual robot performance, this is just dumb. The only inherent bias I've seen from teams when it comes to alliance selection is a bias against inferior robots, which is exactly what the picking process is based around.

Super duper ditto.

[/thread]

[Rangel(kf7fdb)]

Originally Posted by Electronica1

I'm curious, do people move octocanum drives lower on their list/ automatic dnp in a similar fashion to mecanum drives?

I think we would actually move octoncanums higher on the list with of course overall performance of the robot taken fully. That drive definetely isn't that simple and takes a lot of effort and machining. More often than not, if a team can do a good octocanum, the rest of their bot is probably pretty solid. Of course this is just speculation and I do not have any statistics to back this up.

[Jonathan Ryan]

Team 145 has made it to the finals at FLR and TVR respectively the last two years with mecanum wheels.

I think the driver has a lot to do with it also. If the mecanums help you avoid getting pushed or pinned then they are an advantage.

[Citrus Dad]

In our experience the teams that are able to execute highly maneuverable drive trains build swerve drives, so we don't see top-end mecanum drive trains. So we're left choosing our second robot and the mecanum drives haven't been as well executed as the available tank drives for the specific roles we're looking for.

[Botsup]

Friends don't let friends drive mecanum. Enough said...

[EricH]

My take on this is simple. A well-executed mecanum, including driver practice, is not something to overlook/automatically DNP. A poorly-executed mecanum is something to be aware of in terms of "we don't want to pick them unless they offer some other benefit", same as any other poorly-executed drivetrain.

Therefore, drivetrain shouldn't matter, the execution of that drivetrain's capabilities on the field should.


Unfortunately, many mecanum teams haven't figured out how to build and operate that drivetrain properly yet. Therein lies the perception problem. There are teams out there that are more consistently successful with a mecanum drivetrain than with a tank drive. They are a minority...

[PayneTrain]

I don't think it's much of a stretch to say that while you can't say the mecanum as a drive system is dead on arrival, it seems to be invariably used by teams who are "in too deep" and would have more than likely struck gold with a 6-wheel tank instead of mining for limestone.

One time mecanum user, first time caller: never again. There were some minor maintenance kerfuffles at Alamo this year with an experimental drive train* but it pales in comparison to the constant retooling of the mecanum wheels and code to get the dadgum thing to drive 4 years ago. Finalist trophy, tell the haters to buzz off and whatever, not worth.

15 years later and we're finding plenty of fun ways to retool the 6WD in new and exciting ways to tailor our team. If you want to drive a mecanum, your call. You want to change drive train design on your team from the ground up annually or bi-annually? Ok.

If it a) goes out and executes a valid strategy and b) an alliance captain sees your valid strategy meshing well with theirs, then there's no reason to not do it.

The fact still remains that seeing a well-executed strategy being driven on 4 mecanum wheels isn't something that comes up too often in the history of FRC, and smart people in FRC love their FRC history. If you want to do a case study on wildly successful mecanum drives, go check out the fantasy section of the library because it's as wild a tale as Dean Kamen in a tux (well, not that wild).

*(but Wil, why did your team run an experimental drive train at an official FRC regional? GREAT QUESTION!)

[who716]

in my own personal opinion as the driver and alliance selector, I avoid mecanum wheeled robots all together. I don't see the use for them. They are too easy to block and push around. and with no real advantage, I don't see our team using them any where in the near or distant future.
we were the number one seed at an event this year and the pick list was given to me with a tie for my first pick, I went over to both teams discussed examined there robot ext. and when it came to picking the main reason I picked the team I did was they had hi grips while the other had mecanums.
it turned out that in the next event they had swapped there wheels out for hi-grips and were able to play more aggressively on the field. just my opinion.