What do you think they did to make it so it couldn’t be pushed easily?
What do you think they did to make it so it couldn’t be pushed easily?
I can see what you are saying. At the start of championships, everyone knew that Galileo was the field with the best robots. But the other fields had equally as good of robots. You can’t just jump to a conclusion based on who is on which field. I know there is the “Curie Curse” but everyone thought that 469 and 1114 were going to win championships last year. 67,177,and 294 pulled off an amazing victory with the odds favored against them. Galileo definitely deserved to win, but Newton gave them a run for their money in the Semi’s and Archimedes gave them a pretty good run for their money in the finals. The only reason I think that Archimedes didn’t reach the scores that Galileo did in the finals was because of the 3v2 that was happening.
I can tell you what we did. We were geared near the wheel slip limit for mecanum wheels. We used 6" mecanum wheels direct driven with 12.75:1 toughboxes. Most of the time we could push defenders out of our way without too much trouble. We had a top speed of maybe 9 fps - we bet that our HP could get us game pieces so we wouldn’t have to cross the field much. In my mind, two regional wins confirms that this was a legitimate strategy. Our weakness was not the drivetrain - it was our 2 second minibot.
EDIT: Also, the arrangment was very controllable - we were a perfect 11 for 11 hitting the double ubertube on Newton.
To the post above: it was 67, not 254 last year.
I think that the bad rep that Mecanum wheels have acquired is, in large part, due to their relative lack of experience. Mecanum drive simply has not been around for long enough for a large number of teams to really know how to “do it right.” As a result, you see a lot of teams using mecanum wheels that don’t execute well.
As always, there are outliers and exceptions…I personally know of a handful of teams that have built excellent Mecanum-drive robots, but few (if any) of the veteran teams have really experimented with Mecanum drive-trains enough to be willing to use them. I don’t believe that Mecanum-driven robots have any sort of inherent advantage that always makes them a clear choice over other types of drivetrains; rather, I see Mecanum drive as a drive type that has its own strengths and weaknesses, just like six- or eight-wheel drives or swerve-drives. Those strengths and weaknesses must be evaluated by the team when deciding what drive type to use. At the same time, I don’t see any inherent disadvantages that make Mecanum drives perpetually inferior to other types.
Mecanum wheels have their advantages and disadvantages; however, as with what has been said before: it’s not the drive-train that determines how competitive a robot is, it is the whole package: drive-team, human player, end-effector, build-quality, reliability, etc.
EDIT: I think that in 2012 there is as good of a chance of a robot with Mecanum wheels on it making the trip to Einstein as any other year (unless the game turns out to be like Lunacy…in which case…well, we won’t talk about Lunacy.)
Out of curiosity, what drive trains did make it to Einstein this year?
6 and 8WDs
As of now, mecanum has been around for 6 FRC seasons. I really doubt teams have just not figured it out yet.
And an “H” drive (51).
Still, not a lot of teams have done it well. I don’t think, either, that lack of knowhow is the culprit.
Only 12 teams out of over 2,000 made it to Einstein this year. Lots of quality teams with 6WD and 8WD didn’t make it either. A well done drivetrain of any type is just one part of a total robot / program that is required.
Good luck is also required. For example, one could argue that 148 suffered from a qualifying schedule that was too easy. They were third seed because their opponents didn’t put up enough points. Had they been first seed, the entire alliance selection on Newton would have gone down differently - but this is nothing more than a bit of bad luck.
Uhh, what? When has the championship winner ever be “pre-determined?”
Didn’t everyone think that if 1114 and 469 got together they would win last year? How well did that work out?
And wasn’t it supposed to be whoever won Newton in 2006? And wasn’t Newton being written off in 07? And wasn’t the Archimedes “super division” in 2005 supposed to create the division champion?
Given that AndyMark has been selling the wheels since 2006(?) and other teams, like 357, were making their own even before that, the book is pretty much out on how to do a mecanum drive correctly. The only really recent innovation in the drive has been the new introduction of “octocanums” and “jump drives,” which had long been contemplated but never put on the field until recently.
The bad rep that mecanums get is acquired from… physics. High end teams don’t like sacrificing ~30% of their power and a good chunk of friction.
And weight/precision machining time. Mecanums require 4 gearboxes. 6/8wd requires 2 and even 51’s H and 148’s (2010) Nonadrive only really need 3.
I think Hawiian Cadder is saying he didn’t see much of a chance of beating the eventual champions after alliance selection. We can talk about relative divisional strength all we want, but ultimately it doesn’t mean that much until we see which robots from that division actually get together. (And the first seed in Newton in 2006 did a great job preventing powerhouse alliances)
No arguing with that last point though.
Has anyone compared to the percentage of teams that use mecanum to the percentage of 6/8 wheel drive? I wish I had my scouting notes from the past few years, but I think they would be surprisingly close. Its easy to look at the top teams (111, 217, 148, 1114, 254…) and say that barely anyone uses mecanum drive, but there are a lot of average to below average teams that use mecanum drive every year.
The issue with mecanum drives at the high level of play is you are pretty much screwed against a decent defender. The idea of strafing out of the way, or dancing around a team that is actually playing smart defense (which is not what most average teams play in average qualifying matches) is just silly.
If you’re the number two scorer on the alliance, it’s not a hindrance (or if you’re not playinh capable defense), but don’t plan on being the top scorer.
Do keep in mind though, the semifinals came entirely down to the minibot coin flip in match 1, and the finals were 2v3. While 254 / 111 / 973 was undoubtedly the better alliance, it was certainly not predetermined.
It is true that defense can be tough on a mecanum robot. However, it is an exaggeration to say that mecanum is screwed against good defense.
I’ll get one of my students to upload our videos, including the ones against 973. What you will see is a mixture of two things: 1) 973 wasting a good chunk of our time playing good defense, and 2) us getting around them some of the time. This is to be expected. 973 played what I thought was the best defense of any team I watched this year - they were able to stifle not just mecanum opponents but others as well. Yes, it is true that they were not only defending our robot, but that is also to be expected.
It’s true that mecanum isn’t going to “dance around” or “drive circles around” 6WD defense. But it is not true that mecanum is helpless against defense, either. It’s also not true that 6WD is strictly better against defense in every regard. Notably, a mecanum driver can more easily fake out the defender and get them to start in the wrong direction and allow you to rather quickly get past them in the other direction. I’m not saying that works all the time, but it does work some of the time. And yes, mecanum looks pretty bad when the defense is working well and wasting 20 and 30 seconds at a time. Not denying that… I’m just saying that a defender is not able to guarantee this outcome. And do remember that good defense is also capable of wasting 20 and 30 seconds of a 6WD robot’s time.
If one wants to argue that 6WD is better against defense than mecanum, then I can agree with that. 6WD is better at hitting the defender on their side near a corner, turning them some, and pushing past, which is a higher percentage play than trying to fake them out.
I don’t think it is a liability to have one offensive mecanum robot on an alliance. It does get to be a problem when you have 2 or 3 mecanum robots and you lack a good 6WD to play defense or play some other strategy that requires pushing around. Not having those strategic options available (as 973 did when they switched over to defense after presumably playing offense all season long) is, in my opinion, the bigger downside to mecanum drive.
If I don’t miss my guess, Brendon is talking about the PVC Pirates (1058). They were able to lock the rollers of their Mechanums, basically changing them to a skid steer system, on the fly.
It was, IMHO, very impressive.
Did they post any descriptions, pictures, or CAD drawings, do you know?