Mecanum vs Treads

[CalTran]

Originally Posted by karomata

If you think that you could pull it off, a teammate and I developed a drop center tread/mechanum drivetrain. If you want to know more and maybe see some image designs, let me know.

So like Octocanum with treads then.

[karomata]

Originally Posted by CalTran

So like Octocanum with treads then.

Not quite, I will be sure to post it though.

[dtengineering]

This is all very practical advice... and I agree that for winning this years' game, likely neither tank treads nor mecanums are the optimal choice.

Not to understimate the significance of competition, but allow me to point out that your robot will retire from competition just four months from now. Okay... maybe the odd off-season event, but really, once the championship is over, every design choice you made for "winning the game" suddenly becomes redundant.

It is totally okay to use treads or mecanums or swerve or hovercraft technology just beacause you think it is awesome.

We used mecanum wheels in 2007 (it didn't work nearly as well as we'd hoped) but those wheels have kept on being awesome. People still look at the machine and ask about the wheels... allowing me to give a brief lecture on vector mechanics. Our design choice might not have accomplished its mission on the field.... but as far as inspiring science and technology discussions it is still hard at work six years later.

Sure, if you have the time and resources you could build an off-season bot (especially if you are going for the hovercraft drive), or just demonstrate mecanums and treads using VEX... but that isn't quite as cool as having it on a "real" machine.

So kudos for asking advice... you've got plenty of good advice so far in this column... but honestly, if Orville and Wilbur Wright had taken good advice they would have packed up and gone back to their bicycle shop.

Of course, Orville did darn near kill himself flying one of those things. Ignore the advice at your own peril... but feel free to ignore it!

Jason

[lcoreyl]

I had to revive this thread due to some great discussion found here. Our team has posted a whitepaper addressing a few mecanum misconceptions, and I think all of them are here in this thread: mecanum sacrifices torque and/or speed, is inherently inefficient, et al. The link is in my signature.

*while i'm about to address some points in this thread, i suggest that your responses specific to mecanum go in this thread

Some points more geared to a teams experience with mecanum:

*NOTE: I'm not advocating for mecanum this year (although we are using it... most likely) I've just decided for some reason that now after most teams have decided was a good time to start weeding out bad information.

-We don't do a good job with weight distribution or frame flex and have NEVER even considered a suspension, and our bot operates just fine (i.e. very little deviation from expectation). We even balanced on the bridge last year. (would regular wheels have been easier? sure)

-our inexperienced programmers get gyro/encoder feedback working every year without much trouble and then it reallyoptimizes the driving.

-our drivers have found robot-centric drive vs. regular about the same, and strafing when needed was very easy and intuitive. Field-centric drive is REALLY intuitive and a major upgrade. (I guess you could do a 6wd field-centric program... just never heard of it)

-While we did get 2 sets of andymark 8" (because everyone scared us about them), we never had to do any maintenance during competition (on the wheels that is)

-I've seen over and over the "straw man" argument that if you want to be a block/push defense bot, mecanum is a terrible choice. I've never seen anyone advocate that, and can't recall a team asking input for that idea. Last year driving towards while also orienting the intake towards a ball was actually a defensive technique for which mecanum could be a good choice. The "keep away" defense. Playing "get in the way" style can also have success. Our alliance member last year actually did some heavyweight blocking/pushing (although not as their main strategy) with good success. would 6wd push better? sure. Does mecanum suck at it? no.

-Cool factor IS a valid consideration since we are looking to attract mentors and sponsors