Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I've almost had enough of just arguing, debate, and throwing words back and forth at each other.

I want to challenge one very, very common claim about mecanum drives - the premise that mecanum drives are significantly more maneuverable than a six wheel skid, and in particular that mecanum drives can "run circles" around their six wheel skid defenders. I've personally never seen a mecanum behave that way.

So here's your challenge. Find a video that demonstrates a mecanum drive doing just that - being defended actively by a skid steer drive and repeatedly scoring successfully by outmaneuvering the opponent.

Do not post anecdotes. Don't post stories about how your team totally dominated Whatever Regional with your mecanum drive. I'm looking specifically for video - something that we can all objectively observe and critique.

If what I think is the case is true - nothing will be found.

If the opposite of what I think is true happens - we'll have a pretty cool video to watch and use as a reference point when debating the merits and drawbacks of a drive system.

Go!

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

ive never seen a mechanum run circles around tank, i have seen some crab drives come close though.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Anecdote: We used Mechs for Overdrive ('07) and I thought we manuevered well. When thebluealliance is available, I'll search for some videos of us.

Though I have a feeling that you are looking for a 1v1 thing?

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I'm looking more or less for a 1v1 thing, but anything with a mecanum drive outmaneuvering targeted defense repeatedly would work.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Let me quickly convince Truck Town to do a mecanum this year, and you'll get your footage in a few months :p

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Look at 188 from last year, they had really good drivers that used mecanum to its fullest ability. It really is a trade off though, its nice that we all have such easy access to a simple omni-directional drive system thanks to AndyMark! Some times we look over how much easier AndyMark make it for us all. I remember the days talking thinking about either trying to build a complex Swerve Drive or underpowered pure omni drive and it was never worth it due to the manufacturing complexities. If driven right mecanum can be a better option then 6wd, all depends on your strategy and the game.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I like what you tried to do with this thread Chris. Unfortunately, it appears no one really read your post...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Here are our 2007 drive tests:
http://www.youtube.com/watch?v=v_vUYyJAkCc
http://www.youtube.com/watch?v=YbluSr2Mf5Q
http://www.youtube.com/watch?v=W0XN6iSvCXo
Here are a few more:
http://www.youtube.com/watch?v=L01Ok-6AMhM
http://www.youtube.com/watch?v=RXGbo3tQapE
http://www.youtube.com/watch?v=ZnoMhVEqx1c
http://www.youtube.com/watch?v=oamC4esbGfI
http://www.youtube.com/watch?v=KfOLERgWQrU
http://www.youtube.com/watch?v=fdS8BmQom58&NR=1
Not any competition videos but i'm pretty sure these show a mecanum robot COULD run circles around a 6wd bot.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Not good enough. I know how a mecanum works and I've seen them drive on empty fields all day long. I want to specifically see this "feature" of the drive if it's really as prominent as everyone says.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I like what you tried to do with this thread, except you decided to ask for video in the middle of an outage of The Blue Alliance. Containing your annoyance a day or so until the site was back up would be a little less one-sided.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Unfortunately all of our competition vids are on TBA which has been down for about 3 days now. If we end up assembleing out kop bot chassis, when we finish our competition chassis we could make a video seeing which one can out-maneuver the other.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Or no one can find the video he is asking for. I am personally of the opinion that no one will find a good video which consistantly shows a mec drive driving circles against a decent 6wd. They are, in my opinion, very overhyped. I have seen many many mec drives, most of them were opporated poorly (that is, like a skid-steer drive.) The few that I saw which were well driven performed pretty well, but their performance suffered under defense. (re: Elims).

It's traction deficit outweights its sideways capabilities. You can argue about effieciency loss and manuverability all day long but at the end of the day I don't want to use a drivetrain which can be pushed sideways with one hand, end of story.

Of course, others value sideways motion above traction, as a comunity we will never completely agree because, frankly, we want different things from our drivetrains.

Just remember, The best drivetrain is the one that gets you where you need to go when you need to be there. If it doesn't do that then it has failed.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

This isn't 100% what you want, Chris, but I think it's pretty close:

http://www.youtube.com/watch?v=QwlHlx-QAIQ

Watch 2337 and 2619 duke it out. 2337 had 8" mecanums and custom gear boxes. 2619 had 4 wheel tank drive with a wide bot. 2619 was the red alliance's main scoring robot and 2337 shut them down until the end game.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Dubious thread,

But to share a video from the 2010 Waterloo Finals where a mecanum drive was doing what it was supposed to:

http://www.youtube.com/watch?v=7mBxVPvyYwQ

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

@ Mr. Lim

No fair. Using 1114 in ANY comparison is like arguing Mustangs vs Camaros and then posting a video of Bumble-Bee.


Edit: Sorry, jumped the gun and forgot that 1114 was not mecanum drive. But the statement still stands.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

*polite cough* I think he was pointing our the quick maneuvering of the blue robot with the mecanum wheels. Not 1114 with their 8-wheel drive.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

You've got a good point... the FRC field is just too crowded for a mecanum to really open up and put its maneuverability to use repeatedly and consistantly. For years I've been hoping to see a larger field, but realize there are physical limits at the venues.

Ever since we built our mecanum, years ago, I've advocated that you don't build an omni-drive because of competitive advantages, but because of aesthetic ones. A well-driven mecanum (or other omni) is a thing of beauty that will be a joy to drive long after the competition is over.

Mind you, taking our torquey, tractiony, 8wd from last year and burning doughnuts and pushing cartloads of people down the hallway with it is kind of fun, too... but even through it was probably the superior drive train for competitive mobility it wasn't as magical as a mecanum.

Jason

"No fair. Using 1114 in ANY comparison is like arguing Mustangs vs Camaros and then posting a video of Bumble-Bee. "

Great analogy... even if they weren't specifically referring to 1114!

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The 4WD bot they're defending is way too slow. Like 8 FPS max. If you can find a mechanum driving circles around a 16 FPS 6WD with competent drivers I'd be impressed.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The too slow robot that was top seed at Ann Arbor and a first round pick at MSC and the CMP? They were geared for torque and couldn't take advantage. That said Chris spcifically asked for videos of mecanums against six wheels drives + and we didn't even score until the endgame.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

If you give us a couple of weeks we may be able to come up a video that either proves or disproves a Mecanum drive running circles around a 6 wheel drive.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The real issue is driver practice. There were several mecanum robots at kc that got out maneuvered by skid steer robots. The main difference is driver practice, in 2009 we had 3 days to drive our robot and we ran circles around everybody except crab drive, that little bit of practice helped a lot. Any Drive system needs refinement time and practice. A lot of teams including us wait till the last second to put everything together. That drive time is critical.



I think that mecanum can out maneuver a skid steer but not run circles around it.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The 2337 driver played excellent position defiense, positioning between 2619 and the bump and blocking the line to the goal. But watching the actual maneuvering, I see no maneuvers that any reasonable skid steer chassis couldn't do. The only intentional "strafe" move sideways I see is at the end when they position for the hang. The driver skill was key to this defense, not the drive base.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The bottom line for me is that I don't think the drivetrain is the deciding factor in a competition. We use Mecanum's whenever possible because we just really like to use Mecanum's. We won KC last year, were runner up at 10,000 lakes, and came within 1 point of making the semi's at Newton - on Mecanum wheels. Our weakness wasn't the drivetrain - it was our ball control.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Thank you Chris for this post!!! In theory Mecanum should be faster, but the complexity of control and their lack of precision makes them worse.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Hmmm. Not exactly what you wanted, but to show the other side, here's a video of an 8wd running circles around mecanum drive.

2010 SVR, 971 vs 675:
http://www.youtube.com/watch?v=0X27bojZ26k

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I'm looking for an offensive mecanum bot avoiding defense, not the other way around.

Also, with all due respect to 2337, they literally did not strafe the entire match. This match could have happened with a tank drive. They also played position defense rather than anything involving pushing.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Convince? ;)

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

One other item (a bit off topic). Mecanums don't like split-mu. Our practice field is made up of several chunks of carpet and a lot of duct tape. The Mecanums spin out whenever we cross the duct tape. There's a lot of tape on this year's field...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

This video is absolute abuse and a classic example of a team who has no clue how to use mecanum (which in my experience is a large majority of teams using mecanum).

I really like this thread because it just reinforces the fact that mecanums simply will not outmaneuver a "good" 6 or 8wd drivetrain. I'll take 254/968's drive against any mecanum any day.

IMO the only omni-directional drive worth pursuing is a swerve or crab, which brings with it a whole different set of problems, but when properly executed can be a big advantage.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

A MASSIVE problem with mecanum drive this year, just as you could have had the issue in Breakaway last year with our mecanum bot, is the steel plates under the carpet.

Our build lead and I ran some simple vector addition, and realized that any mecanum wheel on a slight incline like the steel plates under the towers can and likely will cause 20% of the force lost on one wheel diagonally opposite to one on the incline, and transferred to the wheel on the incline. This will cause you to lose significant control of the robot, and in this case, a trip to your scoring lane can likely end up as a trip to the opponent's zone. It is very hard to right the bot after that, and can cause the rollers on the mecanum wheel to lock up.

Be wary of this.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

This entirely depends on your CG. If your CG is nice and low, the downforce on the front wheels won't change much on an incline so you'll retain manuverability. If your CG is high, the slight incline will shift more of your weight to your back wheels.

Reason number 450,000 to build with a low CG.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I think that particular driver would be able to look better regardless of which robot he was driving.

What's the fastest mecanum drive anyone has seen? They all tend to be pretty slow. WPI's 2005 drive seemed faster than anything I see now.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I am a bit confused. Chris is me what are you trying to prove? That mecanum is ineffective or not as effective as people think they may be?

I really believe it depends on the team and what they are comfortable with. 25 and 103 have used the same drive system for years 6 and 4 wheels both and every year are a force to be reckoned with. My team 272 has used mecanum now since 2007 minus 09 obviously. We absolutly love them. In reality do we use the crab function that much. No actually almost never but we have that capability and at times it has proven useful....
Our programers love it because in their minds it simplifies their code in autonomous. Whether or not that is even true if in your mind you believe it so isnt it true to you.

As many have pointed out it really comes down to the drivers and the software controlling the commands. If you are fortunate enough to have a combination of both I dont care if its 4 6 8 wheels mecanum or not you can be very dangerous.

I like mecanum well because I do. Others like 6 and 4 wheel tank drive because well they do.

I know pushing power I will give that up any day of the week for a little of the crap. I love seeing that happen. :yikes:

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I think what he is trying to announce to the public is to back up all statements. He is trying to illustrate that an idea that may seem logical in someone's mind is not always fact. Never make dogmatic statements without solid proof, such as a video.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Not sure where you're getting this - Our mecanum drive had no problem last year on either the bumps or the slight rise before the bumps. It drove beautifully.

As for "running circles" around other robots - that's not why we build mecanum drives. We build mecanum drives because they're a fairly large gain in maneuverability (extra axis of motion opens up a lot of extra possiblities when driving, *especially* in anything involving lining up) for a fairly negligible increase in complexity and a small decrease in maximum pushing force. Not every benefit in maneuverability comes directly from robot-on-robot situations, and even in those, while you might not be "running circles" around a 6wd, you certainly will have an advantage if your goal is to get past the other robot rather than push it out of the way (and even with a traction drive, pushing another robot out of the way is far from trivial and often not the best course of action).

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Until and unless the normal force on any wheel becomes small enough to cause that wheel to slip, the force reduction has no significant effect on the kinematics of the mec drive.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Which is unfortunate, because I don't think people were actually paying attention.

http://www.youtube.com/watch?v=7mBxVPvyYwQ

There's the link again, and watch the one robot with mecanum wheels play to its strengths.

Does this one video mean mecanums are definitively better or worse? No, but this mecanum drivetrain did its job in this particular match.

Count the balls scored for the winning alliance - 3 in autonomous, and 3 in teleop. I would challenge a LOT of teams to hold an alliance of 1114 and 2056 to 3 balls scored in teleop, and the little blue mecanum bot was a big reason why that happend.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I believe 1305 and 1310 had wonderful robots last year and actually used their mecanum drive to their advantage. Seriously.

However - it doesn't meet the strict definition of this thread - I don't think they proved to be better offensive robots adept at evading defenders with their mecanum drive.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I am, by no means, a fan of mecanum. I have, however, subsided with using it once in the 1 year it has been allowed during my tenure as a Team 2337 member ('09 and '10).

That said, maybe 2010 isn't a good year at which to look. Take teams that didn't have steel-solid ball control (let's face it, like 90% of teams). These teams cannot hold a ball going directly backwards (totally us in early (like until mid-April). Because most ball control mechanisms provided totally backwards force, and little side-to-side control besides friction, a strafe would be even harder than backwards movement for ball control.

This means that most teams couldn't strafe while holding a ball. Thus, they probably didn't strafe! This limited them to essentially a 4 omni wheel drive, on offense anyway, and not exactly like omni, and ability to strafe to get balls, just not while possessing, and multiple other exceptions.

I'm not saying every game won't have similar situations. I don't know.
But let the record show that I am not a fan of using mecanums.

In 2337's defense (most members would go the "it's more maneuverable route"), we used our strafing to hang. Strafe into tower, line up with forwards/backwards motion. We also used it while getting shoved backwards, to turn and strafe, at the same time, getting out of the essential pin. We were pushed both because we were geared for speed, not only due to the mecanums.

As has been mentioned, in 2007 getting pushed at all (especially from the side) was a huge deal, and in 2008 there wasn't a large advantage except not having to turn if you're just doing laps. We did mecanums in 2008. I don't know the reason, but we did okay I guess. Second divisional seed at the CMP...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Last year we wanted the pushing power of 6WD but the maneuverability of mecannum so we came up with this.

The middle wheels in the video are white wheels that can slide. This was before we had out middle wheel s manufactured.
The actual wheel were 8inch diameter by 2 inch wide CNCed aluminum wheels with roughtop threads.
To be able to travel sideways the middle wheels were lifted off the ground 1/4 of an inch.

http://www.youtube.com/watch?v=s5vBpImX8Ds

and also this:

http://www.youtube.com/watch?v=LVtHI...eature=related

Meccanum is great in my opinion but it needs some semi-intelligent programming.
in 2010 we had a gyro on the robot that did 2 things:
1, to stop the robot from spinning when it was not desired. (robot kept its direction even if pushed by other robots)
2, pushing the joystick forward in mecannum mode always meant the robot travels away from the driver no matter what orientation it was in.

We also had the vision system that on demand, kept the robot pointed at the target and the driver could translate freely.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Here is video of us from the final match of the Boilermaker regional.
We used a gyro for field centric mecanum drive, watch how the robot looks like its moving with purpose, effortlessly doing what the drivers want it to do.
You can't get that kind of motion with a 6 wheel drive.

http://www.youtube.com/watch?v=v2jZz0r0wbk

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The robot in the video is completely undefended...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

When one of four wheels is lifted a half inch, one of the other three wheels is extremely likely to have its normal force reduced by a significant amount.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

16 FPS? That's a bit quick for an FRC field don't you think?

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

That's about the free speed 971 was running at in the above video.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

From the 254 website:
2010: 15.5 FPS (high gear)
2009: 15.4 FPS
2008: 18.5 FPS (high gear)
2007: 16 FPS (high gear)
2006: 16 FPS (high gear)
2005: 14 FPS (high gear)
2004: 15 FPS

So no, he probably doesn't think so ;)

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Not really. It's usually the high gear of a 2-speed transmission. The Poofs have had a top speed of somewhere in the 15fps + range for as long as I can remember. (And for as long as I can remember they've been kicking butt, so I guess it works.)

On the subject of Mecanums and out-driving 6WD's, I'm fairly confident in saying that it IS possible, but hasn't happened yet. Mr. Lim's video is a good showcase of what a Mecanum is capable of with decent drivers, but the field last year wasn't really big enough for a Mecanum to fully stretch it's legs.

It seems that many teams that pursue both Holonomic and Mecanum Drives do not invest enough time in training their drivers to fully utilize the omni-directional motion these drives are capable of. More often than not, I see many Omni-Drive robots driving EXACTLY like a skid-steer until they need to move left or right a hair. I would absolutely LOVE to get my hands on a well built Mecanum or Holonomic drive just to see what happens.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

It's worth noting that a 15 FPS free speed is faster than most drivers can handle without experience and / or practice - one of the reasons veteran teams build fast bots that are so well controlled is because of their extensive practice time.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Like everyone else I wish TBA was up to get a video, but our team's going with a holonomic drive this year partially as a result of our experience with team 263 (aftershock) at the Long Island regional last year. We seeded first at the end of the qualification rounds due to our scoring ability and won an offseason competition in October thanks to this same ability. The most effective defensive team at the regional in our eyes was 263 by far, and they shut us down for a good portion of the match each and every time we were against them. It's not exactly what you were asking for (the mecanum bot was defending, not scoring), but watching them last year left quite the impression. We'll see how holonomic drive works for us, but right now I'm feeling pretty confident in it's potential at least.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I'm not positive about this, but I heard somewhere that mec drives have never been on Einstein in FRC. I think the cons of a mec drive outweigh the cons of i well built 6wd. The biggest of these being practice time for drivers.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Considering mecanums in FRC was pioneered by (if memory serves me) team 357 in 2005, and since they've only become "popular" since their commercial introduction by AndyMark in 2007? And since in 2009 they weren't allowed, I'm not surprised.

From personal experience, field centric mecanum drive is about a hundred times easier to learn to control than a traditional tank drive.
Which is to say that practice time for drivers is an advantage of holonomic drives, not a disadvantage.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

That being said, 357 has used Mecanum wheels since 2005 (with the exception of their swerve in 2009), 148 used them in 2006, and a handful of other teams used them prior to the AM versions. Also, traditional Holonomics have been around since at least 2002, and I don't believe one has made it to Einstein.

Whether it be field centric, or robot centric, it seems that Mecanum Drives and Holonomics are usually not as well driven as a similar Skid Steer or 6WD. Chalk this up to a harder learning curve, less driver practice, or whatever, but one has still not made it to Einstein.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

It is not the driver that chooses the drivetrain, but the drivetrain that chooses the driver.

Pick one and go with it and any good driver will be able to make it work for you.

That being said, mecanums will be easier to align with the goals because they do not have to turn. Just my two cents.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

190 also had Mecanums in 2005.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Once TBA comes back up, look at 1086 & 384 at VCU in 2007. I'm not so sure about the "drives circles around" claim, but they were very quick and agile. The drivers performed with such tenacity that any errors were quickly resolved by trying again. They were in the 13-14fps (free speed) range.

384 also used their Mecanum to play effectively during 2008 at VCU and in Atlanta. 1086 had the same drive train (and made it to Champ. elims), but 384 made it to the division finals (only to be trumped by the 1114/217/148 power house).

Which reminds me: Tumbleweed DID run circles around standard 6WD skid. However, 148 focused so well on coaxial crab design that year, we shouldn't have expected anything less.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

384 & 1086 (I believe there was also a 3rd twin) in 2007, and also 1086 in 2008 were by far some of the most well driven Mecanum Wheeled robots to ever seen an FRC competition. If any robots had a chance of out performing a 6WD they may have been able to do it, but my exact memory is a bit fuzzy and I don't know if they ever actually did, in fact, drive circles around a well driven skid steer.

Also, I believe everyone in this thread agrees that a well built Swerve, be it a Wildstang style, or a Coax has the capability to out drive a Skid Steer, and has been proven to do so. Perhaps one of the best examples of this, also from 2008 would've been Team 16. 148 did use their's quite effectively, but their small footprint also played into their ability to out drive other teams. If I remember correctly, the Team 16 Robot had a HUGE foot print (Something like 38" x 60") and still managed to out maneuverer darn near anything that got in it's way.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Our team will likely be creating a practice bot after the competition bot is done so our drivers will have time plenty of time to practice with mecanum drive before our week one competition (GSR).

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Originally Posted by wilsonmw04 View Post
16 FPS? That's a bit quick for an FRC field don't you think?


16 fps is pretty much what our team had normally, except for 2008 where we had a top speed around 22 FPS. It does seem a little high, it did back then too, but physics doesn't lie.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I get that is possible and has been done before, but I still would wonder how useful it really is. How much time each match did you spend at the top speed?(barring OverDrive)

Bah, this is a topic for another thread...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I think a 6 wheel drive train would have trouble doing this: http://www.youtube.com/watch?feature...shqAVY#t=72 s

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

That is the true definition of tenacity. Awesome.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

WOOWWW. :eek:
I've never seen this video before, I'm sure people already told him before, but that 971 driver deserves an award for awesome tactical driving! Sweet moves!

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

With TBA back up:
In the red front zone is a mecanum driving like a tank around a mecanum driving like a mecanum.
http://www.thebluealliance.net/tbatv/match/2010ok_qf1m2

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I appreciate what you tried to do with this thread, but it doesn't look like any such video really exists.

I'll give you the reasoning that 1747 chose mecanum this year though.

1: Ability to strafe in front of the scoring grid.
2: help avoid defensive interaction.

Reason 2 was considered to be more secondary through the design process. The students also decided on a very aggressive ratio in the Tough Box Nanos that we are using (8.45:1) giving us a calculated maximum speed of nearly 14fps. Using a ratio like that completely prevents us from serving any kind of defensive role and means our drivers must use that speed to an advantage.

With the drive train (finalized) running on day number 9 of build season we were able to put it through its paces and even with as fast as it is, the robot has proven to be very easily controllable.

I guess the real relevance to this thread is that the issue I believe you to be addressing (Mecanum will lose out to a 6 wheel when you're considering defensive interactions) is absolutely the truth, but I don't believe it to be the reason teams used for choosing them.

Sorry if I missed your point.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I see no reason why a 4wd or 6wd with wheel in the same position couldn't do the same.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

sometime this week we plan to run our 2010 robot (12-1 bane bot p80's) direct driving gen 2 8 inch mechanums from andymark. vs this years robot (4 cims into 2 stock tough-boxes with a 28 tooth sprocket on gearbox driving 24 tooth sprockets on wheels) with 6 diam tank drive with the wheels on the ends being 6 inch omnis. i am pretty sure that the tank drive is going to

A. drive circles around the mechanum
B. push the mechanum everywhere
C. burn through batteries at 3x the rate of the mechanum (we blew the 120amp break the other day :ahh:


this is with the vet driver from 2010 returning to drive the mechanum, and no driver practice on the tank.

ill post some video here.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

His name is Scott and he is a Jr. and Team Captain this year. He is just itching to get a hold of our 6 wheeler with automatic shifting. If I had to bet my pink slip against a mechum and our 6 wheeler. I would go our six wheeler any time.

Roy

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I'm really confused - it seems your team picked mecanum for the reason I am addressing, which you claim is (un)true.

More or less, I'm challenging the idea that mecanum drive's capabilities allow it to avoid defense.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

From our point of view, beating defense with a mecanum is not about avoiding the defense so much as it is about redirecting the defense. You have to accept going in that you will get hit.

If they ram you from the side, don't try to fight the ram, ride with it and circle-strafe so that the force of their robot actually ends up pushing you to where you want to go. If they come from the front, turn 90 degrees on the spot and drive a little to the side so that the brunt of their force knocks you back into a position where you face the goal (rather than shoves you backwards) and then get behind them as momentum carries them forwards.

So no, I don't believe a mecanum can run circles around a 6WD. In fact, it's likely that 6WDs will run circles round most mecanums. But I do believe that a mecanum drive can redirect impacts far more successfully than a tank can.

Also, I'd love to see a tank drive pull off the Vin Diesel maneuver coming out of the lane. A well-programmed and well-driven mecanum can turn a 180 while moving forwards and not slowing down. Tanks will either have a time drain when having to turn around or will have to be able to move the tube from one side of the bot to the other.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

This is called a J-turn or a bootleg turn, not the Vin Diesel maneuver. Also, please don't assume anything in any of his car movies is correct information... :D

It's weird to feel old and crotchety at the age of 23...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I really don't think that is true. Last year in Breakaway our team managed to keep the scores minimum against a robot with mecanum wheels eventhough we were using the wheels supplied in the kit

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

You know, I'd been looking for a technical term for that forever. "Vin Diesel maneuver" was a joke name our mentor gave it, and it kinda stuck. Thanks for giving me something less silly to call it :P

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

6wd is power and pretty good with turning mecanum can run away and turn like its goin outa style either way they make pretty good robots it all depends on the end effector that is what makes the robot a winner

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

A good defensive robot (treads, 6WD, or 8WD) should be able to push around a mecanum robot no problem. Depending on how they are set up, they MAY be faster. However, with any tank drive robot, if you want to score (atleast in this years game), you have to come onto the pegs perfectly: If your off, you have to backup and try again.

There are cases where one is better than the other. I don't feel that Mecanum could perform well enough against a good defender to account for its pushibility. But thats just an opinion.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Or turn?

(sorry this is not on the topic of the thread)

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Actually I should apologize, since my post inst really on topic. But to answer your question, many lift based scoring mechanisms need to be straight on, onto the tower, so you would have to back up and go for another pass.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

does this suffice as a J-Turn?
midway through video (were using.. you guessed it, tank drive w/6wheel drive)

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

In our experience, not at all. There's no reason an arm bot has to be perfectly straight to score.

I'd post some video, but I kind of want to save it...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I know, old thread, but does anything in this video qualify? It's 2052's mecanum showcase video. http://www.youtube.com/watch?v=Ogy65hEPIXk

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I'm really curious on what gear ratio they were using. It looks moderately quick, and it was able to push around other robots pretty easily.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Those are side steps and jukes sprinkled with some spins that simply do what a 6WD could do in the same situations. While I do agree it's better than average Mecanum driving, I don't know that I'd call it 'running circles' around 6WD.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I don't think the point of the thread was to find a video of mecanums literally driving circles around a 6wd. I think the point was to have video evidence that mecanums can be comparable/and maybe even better in some ways to 6wd, which I think the video did show.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

What I don't get is why you'd ever want to run circles around anyone. One circle sure, but multiple? Sort of kidding, but not really. What is it that we're actually looking to show?

They're not untouchable for sure, but they are maneuverable. Are they, as the OP asked, "significantly more maneuverable than a six wheel skid"? It depends on the six wheel skid. This guy's obviously a good driver, possibly with some unique control scheme. It's clear they've illustrated that mecanum can hold its own.

Have they illustrated that mecanum is comparable to 6wd in general, possibly better in some ways (in terms of specific performance)? Up for debate. I suspect what this is is an example of mecanum being driven as well some of the better 6wds...so now the playing field is more level. Until they're pitted head to head with one of them, it's hard to tell. (Of course, they've probably done this, if someone wants to check match video.)


The short course for those looking to decide, all else equal? The one you drive strategically better.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

This showcases 2 of about 5 robots I know of that I though Mecanums were used really really well.

The 573 robot that year was really clever and its "kicker" was more like a paddle wheel that cleared zones very well. The Mecanums were frequently used to dig into corners well. 2337 robot that year was a great re-director and hanger. It would also play some amazingly good defense for a mec.

I would actually say 2337 in 2008 and 2011 also used mecs fairly well. but I think you could find videos of those robots being defended or boxed out just as often as you would find amazing offense.

126 had a pretty good run with them this year. They were really good in Archimedes beating 868 (wiht a lot of help) in 1 match. This video is likely the closest to "driving circles aroudn teh defender":
http://www.thebluealliance.com/match/2013arc_qm51
126 is the little blue bumper bot, and a tall black red bot (I think 846?) repeatedly tries to defend with very little success. They have at least 4 altercations that match with the Defense slowing them down just a tiny bit. I don't know that "I" would credit mecs to this maneuverability, but I am pretty sure 126 would give them some credit. The mecs also seem to be good for lining up to the tower and to the feeder station.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Having competed against 126 in Boston, they were one of the quickest robots this year. They did not use the mecanum strafing capabilities too often but their driver had the ability to use it when necessary. I would not give the mecs 100% of the credit for this maneuverability but I would at least give them some.

Irrelevant, but the tall defender was 701, 846 was the short yellow bot on that alliance.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

KnightKrawler used 2 AndyMark Nano Tube 20's with hex shafts in the stock 12.75:1 ratio. One CIM per wheel and each wheel driven directly from the gearbox. Since we need a drive motor per wheel, we used this as an opportunity to leave out chain. The wheels are AndyMark 8" HD mecanums that come with side rollers which we do think help to smooth out the movement of the robot as it transitions between mecanum rollers.

Nate
2052 KnightKrawler Mentor

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I made the thread specifically looking for videos demonstrating that mecanum's additional mobility and agility make the drive more adept at handling defense than a 6WD. This was a common claim on CD when I made the thread.

I've gotta go now, I'll post my thoughts on a few good mecanum bots I've seen when I get back. Just wanted to clarify the intent of the thread.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

LOL...unfortunately it is true

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Our team has used 6 wheel drivetrain for the past 3 years and has been extremely happy with the results. Last year we pretty much perfected it for our purposes. This year the drivetrain all came together and I think we're going to be using it for the forseeable future. Our driver was EXCELLENT, so we had very few problems lining up to take shots, and we usually were able to hit 3 cycles on a bad match. Something I can tell you right now is that I really didn't see any mecanums utilize their maneuverability well enough to offset the disadvantages of us being able to
a. Either push right through them
or
b. Hit them on our way back and forth from the stations and screw up their shot occasionally.
Another robot for reference is 79, team KRUSH at the DC regional. They simply owned defenses trying to stop them, and they used a 6 wheel drivetrain. They juked, they used spin moves, they were able to outmaneuver pretty much every form of defense that was tried to be played on them.

Even last year there were problems. If you were balancing with another robot that had mecanums, you always had to push them up. And if you went too far towards the mecanum's side, the probability of a balance just went down since there was no way the mecanums were going to be able to push a 120+lb. 'bot up the bridge.

I think that it all comes down to practice. If the team using mecanums has little to no practice, the team is usually very ineffective since they can't utilize the crab function correctly. On the other hand, a team that has had significant practice with mecanums should be able to match up well against a 6 wheel drivetrain. I think that it is, more or less, like this.

Well-practiced Mecanum <= Well-practiced 6 Wheel Drivetrain
Well-practiced Mecanum >= Good 6 Wheel Drivetrain
Little-practiced Mecanum < Good 6 Wheel Drivetrain

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I will have to disagree with this post. Last year we were one of the fastest robots at balancing both single and double with mecanum. WE were the ones that pushed robots up the bridge. I'm sure you had a bad experience playing with bad mecanums at your regionals but you can't generalize that all mecanum are this way. Here's a video of us lining up, lowering the bridge, and balancing all in around 4 seconds.
http://www.youtube.com/watch?v=fWYN5xVIyzw&t=11m1s

With Mecanum at our last competition we were hitting 5 cycles with heavy defense and 7 without.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

We have liked mecanum for several years because of the ease of lining up with field elements -- like the feeder slot. (We won a regional in 2010 and didn't this year, but despite that I can say without hesitation that this is the best robot we've built so far. That said, we did use octocanum, not straight mecanum, but we rarely dropped the traction wheels at FLR or Buckeye.)

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I believe you're looking for something like this:
http://www.youtube.com/watch?v=Ogy65hEPIXk
2052 used mecanums better than I have ever seen

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Good call, they use mecanums extremely well. Unfortunately it has already been said on the previous page.

See the previous page for discussion about it.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

At a recent meeting we had our robot from this years game with a 6 wheel drive and the mechanum bot out.The kids driving the mechanum couldnt get around the 6 wheel bot enough or by anymeans run circles around it. also if our six wheel cought the mechanum and started pushing it it was all over. so in the end mechanum is manuverable but its not great

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

[/quote]
Well-practiced Mecanum <= Well-practiced 6 Wheel Drivetrain
Well-practiced Mecanum >= Good 6 Wheel Drivetrain
Little-practiced Mecanum < Good 6 Wheel Drivetrain[/quote]

this is just abouat the best thing i have read...good drivers and practice make a great difference

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

(I'll post videos later, I'm not able to get to them now)

I was a driver for 1259 this year, and we used 4 wheel mecanum. Although I still feel we would have been a better robot with tank drive, we used the mecanum as well as we could. In Wisconsin I was able to outmaneuver some of the opposing alliances (with tank drive) with a combination of strafing and spinning to get to the pyramid so we could start our 3 level climb.

Would I have been able to do that with tank? Probably...chances are with tank we wouldn't get into situations where we had to really try hard to outmaneuver other robots. But the mecanum allowed us to move in dimensions that tank robots couldn't, and in the small, cramped side lanes on either side of the field near the pyramids, I think that additional degree of freedom helped a little bit.

A quick aside--this has befuddled our programmers for some time now. Our robot strafes almost perfectly on smooth floors, like tile, or the traditional wooden gym floors. Yet, on the field at both Wisconsin and Duluth, strafing was slow, and required a lot of manual adjustment on my end to do well. Trying to strafe with just one joystick meant turning while moving in one direction. It was our first year doing mecanum, so if anyone's able to point us in the right direction, that'd be swell. We thought it was the individual spindles on the wheels slipping, but I've seen other robots use 6" mecanum wheels from andymark no problem.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

FIRST fields ain't level. Also, carpet != wood/tile you'll get drastically different performance characteristics.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

How can you reasonably expect anyone to take your response seriously when you didn't care to take theirs seriously?

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

To be fair, mecanums have a really really good installation effort / cool factor ratio.