Mecanum Drive Train

[dtengineering]

You can find lots of examples of mecanum robots on Youtube. To get started, search for "1346 mecanum" and you'll see the one we built a couple years ago.

While I would suggest that you heed the advice about not committing to a drive train until the game is announced, there is absolutely nothing wrong with preparing to build a mecanum once you know it will match your team's game strategy. The worst thing that will happen is that you will learn a lot about mecanum (and other omni-directional) drive systems.

There are a GREAT many forums here on CD discussing the benefits/disadvantages of mecanums and tips/techniques for building them.

Jason

[Sam2197]

thanks for all the help. regardless we are going to prototype a drive system sometime hopefully in the next month. i've read about how they work and everything but i guess i wont be exactly sure until i see it. and what is the best way to attach the wheels to the gearbox and what is the best gearbox to use

[EricH]

Originally Posted by Sam2197

thanks for all the help. regardless we are going to prototype a drive system sometime hopefully in the next month. i've read about how they work and everything but i guess i wont be exactly sure until i see it. and what is the best way to attach the wheels to the gearbox and what is the best gearbox to use

Sprocket and chain is the best, though some will prefer direct drive. The best gearbox is a relatively fast one; mecanums don't transfer power in the same way as a 4WD. (Hint: Toughbox, unmodified, is/can be too slow even on a 1:1 ratio to the wheel.)

[Sam2197]

so is there any gearbox that would be best. or would we need to modify any gearbox we get

[gorrilla]

you could use the banebot transmission, they are pretty fast(when directly driven to the wheel) although reliability is an
issue

[AndyB]

Try 9:1 banebots. Thats what 1675 used this year with 6" mecanums and they were pretty quick.

[Burmeister #279]

I've been discussing Mecanum with my team as well and completely agree that committing before the 4th at bare minimum is an extremely bad idea in the sense that it could just not work for the game or at the very worst GDC could outlaw it. =/

however, [as is the case with my team *currently*] not even thinking about it do parts/labor/programming needs and the fact we've never done it before is... well, just an excuse. Nobody did it before they did it ya know? that's plain logic. If anyone remembers any of 279's robots, they can see that tank drive with an occasional perpindicular omni has been used EVERY year since Jake in 2001. I think, being our 11th year, it's time to try something new, but nobody's willing to commit the resources. I'm pretty sure that even though 6w with a larger or offset middle wheel has been the driveline of champions the past few years the mentors on my team will still not consider an alternate driveline. my question to CD is who wants to help me/us do something differant assuming something doesn't develop before... say december?


Btw, this is my first post!!! so a little about myself: My name is Nick Burmeister, though most call just call me Burmeister. I'm a Second Year student on Tech Fusion - 279. I was the 2008 Driver and Student-head of building driveline.

[EricH]

Maybe you should suggest to your mentors that they come around CD sometimes and see the various ideas that get floated around. I've seen some crazy ideas, like omnitracks. (omniwheel on a tank tread) Who knows? They might have some ideas themselves.

And, of course, this is probably one of the top 3 most helpful places to a FIRSTer. #1? The FIRST website. #2? (tie) CD and The Blue Alliance (TBA).

[Burmeister #279]

Originally Posted by EricH

Maybe you should suggest to your mentors that they come around CD sometimes and see the various ideas that get floated around. I've seen some crazy ideas, like omnitracks. (omniwheel on a tank tread) Who knows? They might have some ideas themselves.

And, of course, this is probably one of the top 3 most helpful places to a FIRSTer. #1? The FIRST website. #2? (tie) CD and The Blue Alliance (TBA).

i've showed all of the students on the team the various drivetrains that are on CD and some of the mentors.

[EricH]

Originally Posted by Burmeister #279

i've showed all of the students on the team the various drivetrains that are on CD but i think that the team as a whole is relying too much on the mentors.

Show the mentors as well as the students.

[dtengineering]

Originally Posted by gorrilla

you could use the banebot transmission, they are pretty fast(when directly driven to the wheel) although reliability is an
issue

Sigh... reliability is not an issue with the CIM planetary gearbox from Banebots. At least no more so than for any other gearbox used in FRC. There was a problem with their first batch of trannies, which, unfortunately, got shipped out as part of the KoP two years ago. Banebots went to great expense and effort to fix the problem in time for competitions and has further improved their product since then. Unfortunately it is the nature of (many) people to remember the initial problem, rather than the excellent committment to service and subsequent improvements that Banebots has made. We were one of the first teams to identify a problem in the original KoP trannies, and have since taken advantage of the free upgrade that BB offered to ALL FRC teams and have been running BB trannies on our mecanum for the last two years with no issues.

In fact BB trannies, or other direct connect transmissions (where the wheel is mounted directly to the output shaft) make for, in my experience, the most reliable drivetrain as the most common point of failure... the chain or belt... is eliminated from the system. Just make sure the output shaft is supported on the outboard side of the wheel!

An additional advantage of the BB trannies is that you can order them in a wide range of gear ratios, and can convert from one ratio to another (with some limitations) if you aren't happy with the performance.

Yep. There was a problem with the Banebots trannies two years ago that was quite disruptive. But it is hardly fair to question the reliability of the current trannies given the fact that BB stood behind their product, solved the problem in short order, upgraded over 3,000 trannies for free, and has since improved them even more.

Jason

[Sam2197]

i agree with that. our rookie year we had the banebots as kop gearboxes and we loved them. our robot was pretty quick that year. we are probably ordering them again this year

[gorrilla]

Originally Posted by dtengineering

Sigh... reliability is not an issue with the CIM planetary gearbox from Banebots. At least no more so than for any other gearbox used in FRC. There was a problem with their first batch of trannies, which, unfortunately, got shipped out as part of the KoP two years ago. Banebots went to great expense and effort to fix the problem in time for competitions and has further improved their product since then. Unfortunately it is the nature of (many) people to remember the initial problem, rather than the excellent committment to service and subsequent improvements that Banebots has made. We were one of the first teams to identify a problem in the original KoP trannies, and have since taken advantage of the free upgrade that BB offered to ALL FRC teams and have been running BB trannies on our mecanum for the last two years with no issues.

In fact BB trannies, or other direct connect transmissions (where the wheel is mounted directly to the output shaft) make for, in my experience, the most reliable drivetrain as the most common point of failure... the chain or belt... is eliminated from the system. Just make sure the output shaft is supported on the outboard side of the wheel!

An additional advantage of the BB trannies is that you can order them in a wide range of gear ratios, and can convert from one ratio to another (with some limitations) if you aren't happy with the performance.

Yep. There was a problem with the Banebots trannies two years ago that was quite disruptive. But it is hardly fair to question the reliability of the current trannies given the fact that BB stood behind their product, solved the problem in short order, upgraded over 3,000 trannies for free, and has since improved them even more.

Jason

I know, but thats not all i was considering. has anyone every seen a toughbox fail?

[EricH]

Originally Posted by gorrilla

I know, but thats not all i was considering. has anyone every seen a toughbox fail?

No. However, you can't use them in their unmodified state as mecanum gearboxes and expect speed and maneuverability to be the best. I've seen that firsthand. There are modifications that can be done to improve speed. I don't know how effective those would be when used in a mecanum drive.

[Sam2197]

i agree. last year the toughboxes were really slow. reliable but slow. and i dont think you can speed the up all that much