Mecanum Rolling Chassis
 

Second season, 4134 going with something different.

Re: Mecanum Rolling Chassis
 

What are your reasons for choosing mecanum?

Re: Mecanum Rolling Chassis
 

It's Cool.

Re: Mecanum Rolling Chassis
 

Did you make those wheels? They don't look like either Andymark or Vexpro Mecanum wheels.

Love the paint scheme :D The white rollers are a nice touch.

Re: Mecanum Rolling Chassis
 

"Cool factor" should never be the driving factor for a design choice. "Correct" answers for this would include anything related to functionality. I would use the increased maneuverability, myself.

You could also use "Inspiration" as a reason, but that's also low on the reason priority list.

Re: Mecanum Rolling Chassis
 

Beautiful. Love the color scheme. Hope mecanum works out for you.

Re: Mecanum Rolling Chassis
 

So this ISN'T a program to inspire youth?

Good to know.

Re: Mecanum Rolling Chassis
 

What other reason do you need? As long as you didn't choose it because you think it gives some competitive advantage, it's fine in my books.

Maybe this team isn't looking at becoming 1114 just yet, and they just want to have fun building a robot and learn something. It's not always about the competition with every team.

Re: Mecanum Rolling Chassis
 

The positive aspects of mecanum are surely well known as well the negatives. Cool is quite often used for design inspiration. Harley Earl would certainly agree as well as many other great designers. The cool in the design attracts attention and gives us the opportunity to explain the building process and FIRST. It's a solid design, form-function-finish.

Re: Mecanum Rolling Chassis
 

Coolness is a perfectly good design factor depending on your teams priorities. If your team wants to build something they want to build, and work on inspiring people with something that they are interested in, then coolness is a big factor in the design. However, if you just want to go out there and win, coolness isn't such a large factor in the design process.

Take this year for example, my team decided to pursue a top rung climber even though it is a big stretch for my team. We decided to go after this idea and not just be a run-of-the-mill shooter because we were excited about it. We might not succeed, and it might not be the best way to win, but hey, we will have a lot of fun building it on the way.

Although I agree that coolness shouldn't be the main design factor, different teams have different priorities, and thus hold the coolness factor to different levels of importance.

Re: Mecanum Rolling Chassis
 

In terms of inspiring sponsors to give us piles of money we may or may not deserve, mecanum wheels have well more than paid for themselves -- especially when you can explain both the benefits and the drawbacks.

99.9999%-ish of the population has never seen an omnidirectional drive, and are impressed with the very notion. They're even more impressed when the students on the team can articulately explain why they're not always the best choice for a situation.

Thus, cool-factor should not be poo-pooed, even if the demonized and well-hated mecanum drive is, in your mind, a poor choice for any given game.

Re: Mecanum Rolling Chassis
 

Why wouldn't mecanum be a reasonable choice for this game? Maneuverability would seem to be a benefit as well as the direct drive. The court is a flat surface with vertical obstacles. We have tested a 6 inch set of wheels on many surfaces including asphalt roads, light gravel, wood, tile, rug, compact dirt and more. The wheels handled it all, they were very durable. The side load from pushing seems acceptable, front and rear a bit less. With some good programming and driving, this should be a good system. It might even roll straight up the tower.

Re: Mecanum Rolling Chassis
 

Because you have a WIDE OPEN field, and relatively few zones to protect you from defense. There's no tight corners to navigate around, and the main game task really benefits from resistance to pushing that mecanums just can't give you.

Re: Mecanum Rolling Chassis
 

I'd be worried about defense -- which I think will be huge this year -- and mecanum wheels, while not as bad as many would like to think, do suffer against most conventional drives when it comes to pushing matches.

Pyramid protection helps, but doesn't eliminate, the disadvantage -- and I think it can be argued that near your alliance pyramid the mecanum drive might very well have the advantage.

Overall, as a person who personally really loves mecanum as an easy-to-implement and comparatively cheap omnidirectional drive system, I'd say that pure mecanum is at a disadvantage this year (for exactly the same reason that disk pickup is really nice but not required)... But it's not crap.

Re: Mecanum Rolling Chassis
 

I wish our chassis looked that good! Serious props, especially for a second year team. I think the subject of mecanum drive has been beaten to death, so I'm just going to sit back and admire that beautiful frame!

Re: Mecanum Rolling Chassis
 

A lot of teams are allured by the whole "manoeuvrability" aspect of mecanum, but in reality it isn't that cut and dry. What you gain with a third axis you lose in traction and power. Since the omnidirectional motion of meccanums is produced by vector summation, you'll always have some sort of power loss in whatever direction you go in. Combine that with the low coefficient of friction, your robot may be able to go sideways, but you won't be going fast, and your drivetrain will not have much power, which is never an ideal combination. A 6 wheel skid drive is proven to be far superior in every category, especially since the traction makes up for the lack of sideways movement. But, let's not turn this into a meccanum bashing thread again, shall we? ;)

The main important reason for your choice was because you thought it would be cool and would be a neat learning experience, and that's all that really should matter when it comes down to it. I also like the paint job on this drivetrain, it definitely looks neat!

Re: Mecanum Rolling Chassis
 

Don't let the haters get to you. They just can't compliment anyone on a nicely built chassis if there are mecanum wheels, on it.

You obviously put a lot of time and effort into this. Congrats on a job well done, especially for a second year team.

Re: Mecanum Rolling Chassis
 

This-- it really does look classy. Just make sure to get a lot of driver training so you can use it to it's fullest potential come competition.

Best of Luck!
Regards, Bryan

Re: Mecanum Rolling Chassis
 

The biggest advantage of mecanum drive is something I never hear mentioned on CD: your robot drives exactly as a 1st person shooter.

Intuitive driver control freaking matters, and if anyone can present the math to prove otherwise, I'm all ears. :)

Re: Mecanum Rolling Chassis
 

This is more what I was looking for, along with the later post. Just saying "it's cool" is like will.i.am saying the 2011 game was "dope" at Kickoff--there are a number of possible meanings. (For example, someone just saw mecanums and said "Oooh, I want some!" is one potential meaning.)

A little more content like this, however--the attention attractor for non-FIRSTers, the testing done so far, and other similar things--and the meaning is clear: you've looked at the alternatives and decided this is the one.

Out of curiosity... is a matching shooter going on top? You've got 4 weeks to perfect that, and a driving base to work with. Or is there something else up your sleeves?

Re: Mecanum Rolling Chassis
 

Ditto! Looks like you guys put in a lot of work for this.

How well are the Modulox gearboxes working out for you? The integration is pretty neat!

Again, great start to what I'm sure will be a solid robot. Keep us posted!

Re: Mecanum Rolling Chassis
 

Looks great, I can't wait to see what you put on top of it.

Mecanum Haters Gonna Hate™

Re: Mecanum Rolling Chassis
 

Just posted a whitepaper addressing my disagreement with much of this. The link is in my signature.

+1 irony

This part I can fully agree with you on!:D

Re: Mecanum Rolling Chassis
 

The Modulox has worked out very well. everything is Aluminum except the bearings and output shaft. We have discovered that chassis construction is very important to the success of the Mecanum drive. Both frames we have built were very rigid, square and durable. All of our cut dimensions are +- .010 and all of our bends are +-.030. All rivet locations were pre drilled and require very little modification for assembly. There are 125 3/16 blind rivets holding 9 parts together. With the CIMS the chassis weighs in at 43 lbs.

Re: Mecanum Rolling Chassis
 

For the pushing match argument against mecanums, how often are you in a straight pushing match during a match? The situation most people describe in making this argument is a six wheel tank drive bot pushing a helpless mecanum drive bot halfway across the field. Any mecanum bot that I've helped build might be pushed some, but with the right driver it would spin away from the pusher and be back down the field in no time.

Re: Mecanum Rolling Chassis
 

Perhaps there is a way to utilize both the mobility of a mec drive and the tenacity of a tank-style drive. Hmm.

Edit: Where are my manors? This is a beautiful chassis, and with the right know how (either mechanical or tactical) could be exactly what a winning alliance needs.

Re: Mecanum Rolling Chassis
 

Not often, but when it counts... (Really, the relative inefficiency inherent to mecanums is what ruled it out for me this year; we favored straight-line speed without using so many of the high-powered motors.)

But frankly, you could put square wheels on this thing and it'd still look boss. I look forward to seeing the whole thing!

Re: Mecanum Rolling Chassis
 

Great job team! That robot looks sick! also, for mecanums, I agree with PVCPirate, not just because we were on the same team. A good mecanum driver can always avoid pushing match with a tank drive and usually will just drive around it.

Re: Mecanum Rolling Chassis
 

Completely true. What a mecanum driver can't realistically do is initiate a pushing match :) Sure you can effectively annoy a 6-wheel drive robot, but you can't really move them much.

We used Mecanums in 2011 (good) and 2012 (not so good on the bridge) and this year we're trying a 6-wheel WCD, certainly pros and cons to both as has been addressed many times over.

Re: Mecanum Rolling Chassis
 

Still waiting for video of a mecanum drive doing that here... Post if you've got it!

That said, IndySam is absolutely right, that is a gorgeous chassis and I shouldn't have derailed the conversation into yet another debate about mecanum drives. Good luck!

Re: Mecanum Rolling Chassis
 

inefficient at what?

Re: Mecanum Rolling Chassis
 

Reread Wing's post:

Re: Mecanum Rolling Chassis
 

I couldn't tell if you were re-iterating what Wing said.

I disagree that power is "wasted", or speed is sacrificed for mecanum.

We have just posted a whitepaper addressing this (see my signature).

Sorry to the OP for contributing to hi-jacking this thread!! I really like the look of your bot and will be interested to see the rest, and hear how the modulox goes!!

If anyone disagrees with our paper, let's discuss it here

Re: Mecanum Rolling Chassis
 

What a beautiful drive! That is a wonderful paint job.

As for hating on mecanums, the mudslinging will probably never end. I will not hate on any drive. I will say that my team has done mecanums for the past 3 years, with an award winning omni drive my first year. In 2012, we could drive up the bridge sideways and forwards. We pushed other robots up those bridges, multiple times. And yes, the 2 times when we were engaged in a direct pushing match, we weren’t quite as strong as the six wheel robot. But instead of engaging, we used maneuverability to go around them.

There are different strengths and weakness's to every drive. Success is found by playing in a way which uses the strengths of the drive, and minimizes the weakness's, so that you are playing to your greatest ability.

Re: Mecanum Rolling Chassis
 

Really attractive chassis all around! I wish ours was as pretty :)

As for the whole Mecanum pushing thing, I think that's highly overstated. This isn't a game of tug-of-war. Good programming of the controls makes a tremendous difference in the drive-ability of the robot. We are using a single joystick to drive the robot like a car and a second joystick to provide "strafing" controls. With good acceleration/deceleration curves added to avoid "jerky" movement of the robot along with dead zones in a few places to avoid twitchy and finicky driving, it's working out great. As our robot will be reasonably light for FRC (under 100 lbs at the worst with bumpers/battery, etc.) we plan on playing up speed and maneuverability a great deal. Mecanum facilitates that when done properly.

-Mike