Mecanum or 6WD

[TEE]

Originally Posted by Paul Copioli

All,

...
2008 - 6WD skid using 4 CIM motors with shifting
2009 - 6WD skid using 2 CIM motors no shifting
2010 - Nonadrive using 5 CIM motors no shifting

This year we have decided to use 6WD skid once again. Given all of our constraints we want to put our innovation into other parts of the robot(s). I can see arguments for the other drive systems, but for us we are going with 6WD this year.

Paul

Quick question (I hope you read it...):

For your 6WD in '08, were the center wheels dropped, and if so, how much?

[spiffyspleen]

Our team is going with mecanum because it is obviously superior to 6wd in every way. There is really no debate

[Josh Fox]

Originally Posted by spiffyspleen

Our team is going with mecanum because it is obviously superior to 6wd in every way. There is really no debate

As with all decisions made in the engineering world, there are pros and cons of everything. I'm not trying to say mecanum isn't great, but if you open your mind up a bit you just might learn something.

[Andrew Schreiber]

Originally Posted by spiffyspleen

Our team is going with mecanum because it is obviously superior to 6wd in every way. There is really no debate

Remind me to just cite you as a source for anything I need in the future since you seem to have no problem making stuff up and presenting it as facts.

Dangit Jim, we are engineers not politicians.

[BrendanB]

Originally Posted by spiffyspleen

Our team is going with mecanum because it is obviously superior to 6wd in every way. There is really no debate

As long as you have built both systems and worked with them extensively, then good for your team for making a decision, but in engineering there is always pros and cons because nothing is perfect.

We will have fun pushing you around if we ever meet!

[pfreivald]

I think he forgot his [kidding][/kidding] tags!

[evoluti1]

In the end, our team is going with 6WD. The choice came down to this: A 6WD has two advantages over mecanum:

It is faster. We used mecanum in 2010, and noticed that as we accelerated, we lost power from the slipping of the rollers; however, to me, this didn't seem like a significant loss.

Secondly, it gets better traction. (I was talking with someone from 330 at one of the regionals, and they had put a mecanum drive bot in a pushing match with the 6WD. Mecanum lost consistently, even with the same gearing).

The Mecanum Drive has one advantage: its ability to drive sideways.

Here's the rub: Driving sideways would be a solution to the problem of scoring accurately, reliably and quickly. We could also solve that problem by having the driver practice with the alternative drive option. We decided on 6WD, and our plan is to give him weeks of practice on tank after ship and before regionals with the kit bot.

[EricH]

Originally Posted by evoluti1

Secondly, it gets better traction. (I was talking with someone from 330 at one of the regionals, and they had put a mecanum drive bot in a pushing match with the 6WD. Mecanum lost consistently, even with the same gearing).

IIRC, it was a 4WD (2003 drill motor drivetrain). Same principle, though. We also put those two through the block/get around block routine. Mecanum still lost! Because mecanum lost both pushing and block evasion, the 6WD stayed on our competition robot. Results of that were good; this was in 2005.

If 330 ever saw that mecanum would be an advantage, they could do it. The mecanum that lost to the tank drive systems had two years of development behind it. Knowledge doesn't disappear very well...

[Charmander]

The debate between Mecanum and 6WD is very subjective to the game itself. However each team analyzes and decides on which drive system is "better" for the suited game differs from team to team. According to the poll, 6WD is favored this year. THAT is a fact.

[karomata]

this isn't a very defensive game, so i don't think you need to worry about traction and pushing power. no other robot will play heavy defense.

[Enigma's puzzle]

Originally Posted by karomata

this isn't a very defensive game, so i don't think you need to worry about traction and pushing power. no other robot will play heavy defense.

That sir is where you are wrong, this game is a very defensive game. The robot that cannot pick up a tube, either by design or failure of strategy and prototyping, or breaking is not going to spend 2 minutes letting you put tubes on the rack. There will be defense. Every robot on that field can drive faster than you can strafe (presumably unless I am missing a strategy to move slow and relentlessly), and I expect to see a 6wd will be able to bulldoze (of course not at ramming speed) through a robot that is trying to block their path, especially if the robot isn't on tractioned wheels.

As long as the robots are allowed to contact each other, traction will be important.

Its not that hard to find a way to slow down another robot, and pinning is not the only way to slow down or stop another robot from scoring. ask all the robots that sat in front of a goal last year, or all the robots that are going to turn sideways and mirror your attempts to pass them. I think I would be able to teach my alliance partners to play pestering defense in under 30 seconds.