Penalizing mecanum wheeled robots durring alliance selection.

Despite formerly being on 1523 (who has used mecanums since 2011) with the OP for years I agree with all your statements except for the above, where is the data to support that statement since mecanums have nothing to do with a manipulator?

Purely anecdotal. My experience supports this claim but I cannot say that there is correlation with any sort of certainty.

Correlation doesn’t necessarily imply causation here, and mecanum robots aren’t considered by us to have poor manipulators because of their wheel choice. I’m trying to say that many teams that have mecanum wheels didn’t get picked for other reasons as well, not just their wheel choice.

As for data, the robots that are near the bottom of our pick lists or on our DNP lists are more likely to have mecanum wheels than the robots near the middle or top of our pick lists. I could publish our Finger Lakes pick list from this year if you really want hard numbers, but it’s just a trend I’ve noticed. There are exceptions, and I’m reasonably sure that 1523 would be one.

We saw a lot of mecanum-powered robots at the Pine Tree district event earlier this year. Generally, mecanum robots weren’t really good at offense, but were crushing in defensive scenarios (important in an event where both teams in the finals relied on parking at the 1-goal and firing.) However, like most teams, we wanted offense over defense. Unless the mecanum bot isn’t one dimensional, we don’t really have them high up on our list.

Maybe it is a region thing, for the most part in Florida the mecanum bots do not have poor manipulators, though a lot do follow your statement about drivers not being as well versed with driving as their traditional drive counterparts. Like you said their are exceptions to every rule though your offer of data does bring up something, if possible I think it would be interesting for someone to compile data from events and see if there is a correlation between drivetrains and their ranking, and elimination selection/performance.

1065 has a SOLID robot this year, despite having mecanum wheels. We picked them during elimination matches and made it to semi-finals. :smiley:

I think Moose had a drop down traction wheel on each side this year

1065 was not pure mecanum. They had jump drive which was powerful enough to push 233’s 8WD sideways. Im shocked we where able to pick them in Orlando as the #4 seed.

Yeah, they had 2 1" diameter traction wheels bolted together on each side. As fart as I know, they only used them during pushing matches though. So when you tried to stop shots into the goal :stuck_out_tongue:

Who knows, Skystalker V2 may come equipped with 8 wheel drop center mecanum.

They where this year.

All other things being equal, we would most likely pick a non mecanum drive over a mecanum drive.

However, I think it’s important to point out that rarely are all other things equal. Like anything else, design to play the game well and be consistently contribute to the alliance in a positive manner.

Yeah, but they never touched the carpet :wink:

This year, the robot’s drivetrain didn’t matter to us nearly so much as how the robot was being driven. This was probably our biggest selection factor; I asked scouters specifically to note great or poor maneuvering (especially around defense). We even used our first pick as 2nd seed at North Carolina on a 44th seeded box bot, just because they drove very well. Likewise, plenty of drivers at champs proved that mecanum was no hinderance if utilized well.

Discriminating against robots for particular attributes should not be done if they can hold their own on the field, period. Unfortunately, teams with such attributes do have to prove themselves to overcome doubters, and even then, the tiniest of concerns might be enough for alliance captains to discredit them… it’s really unfortunate, but it happens, whether you’re a mecanum bot, rookie team, or had no intake this year :frowning: (cries in corner).

When teams were scouting our robot it seemed like they were penalizing us for having mecanums even when we told them we were using 4 cims and 4 mini cims.

8 motor mecanum isn’t bad

You have peaked my interest, was there any noticeable difference in performance in comparison to the traditional 4 motor? Specifically in terms of pushing power or resistance?

Not to call you out specifically, but you mentioned something that is frequently spread around, and not quite true. Mecanum is often touted as being good for being evasive, but due to the fact it must be geared slower (for more torque) to strafe well, they typically can’t outmaneuver a tank drive (this is especially true in the 6 CIM era). If you want an example of this, look to Ultimate Ascent;

There was a very small handful of robots able to complete 7 cycles, which was a task that required nearly no pushing, and all maneuverability. If mecanum wheels were more maneuverable, you would expect the best cyclers to be mecanum robots, but this was not the case. 118, 469, 610, 245, 868, 11, etc., were all tank drive robots.

“Pushing Power,” is a function of coefficient of friction with the floor, robot weight, and torque. Wheels sizes (widths) can influence coefficient of friction, but tread material is typically a more important factor. Wheel diameter can also affect coefficient of friction by changing the size of the flat patch you have on the carpet, but this has a pretty minor effect. Torque is a function of your gear ratios and wheel diameter together, as well as the efficiency of your transmission, but you can gear for as much toque as you want, regardless of wheel size.

TL;DR: You can push with small wheels if you want to, just be aware of the variables at play.

As a team that went with mecanum this year (as much as I did not want to) I can say that it was a factor in teams selecting us. At TVR we had teams tell us they would pick us if we switched to traction wheels. I believe we had a great bot design for the game but the mecanum just made us a bot that could get pushed all over ( esp by 2791). Needless to say we have switched them out for offseason events, Im looking forward to seeing the results.

Wait, being fed by human player doesn’t count as an intake? :wink:

Yes, if you have mecanum wheels it will lower you on my picklist. Especially for our third pick robot we try to avoid teams with mecanums because its very hard to play effective defense with mecanums. It is possible I have seen it done but most of the times these teams have a solid offensive strategy too meaning we wouldn’t want them to play defense to begin with as we need them to score.

We have picked/accepted invitations from teams with mecanums more notably this year we allied twice with 58 and once with 126 both were very effective robots on the field with mecanums. If there were identical robots to them just with tank drives I would have rather gone with the tank drive.

You might call it “penalizing” but I see it as a weakness if the other alliance can push you around as much as they please.