Mecanum Rolling Chassis

Second season, 4134 going with something different.

[EricDrost]

What are your reasons for choosing mecanum?

It's Cool.

[EricH]

Originally Posted by DMike

It's Cool.

"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.

[EricDrost]

Originally Posted by EricH

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

So this ISN'T a program to inspire youth?

Good to know.

[ehfeinberg]

Originally Posted by EricH

"Cool factor" should never be the driving factor for a design choice. "Correct" answers for this would include anything related to functionality.

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.

[pfreivald]

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.

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.

[Chris is me]

Originally Posted by DMike

Why wouldn't mecanum be a reasonable choice for this game?

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.

[NotaJoke]

Originally Posted by Chris is me

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.

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.

[pfreivald]

Originally Posted by DMike

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.

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.

[Anupam Goli]

Originally Posted by DMike

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.

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!

[IndySam]

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.

[BJC]

Originally Posted by IndySam

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.

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

[pfreivald]

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.