Omni Wheels Vs. Mecanum Wheels

[Ginger Power]

Originally Posted by Jon Stratis

There are other drive train configurations available, like swerve, octocanum, and apparently something my students were talking about today called "butterfly"... I'm still not entirely clear on how that one works, but apparently they got it from another team at the regional. However, those are drastically more complex and difficult to do right.

A butterfly drive is an articulating drivetrain with some sort of traction wheels paired with omni wheels (very similar to octocanum). In our configuration (which we kept off our robot for weight purposes and lack of necessity for our strategy) we have a 4" omni wheel paired with a custom made 2.5" traction wheel with rough top tread. Each module is actuated by a 1 1/16" bore 1" stroke pneumatic cylinder. We have found that butterfly drives are not overly complex but I wouldn't recommend using one without experimenting with it in the off season. The team that has really made this design famous is 3928 Team Neutrino. They had a butterfly drive for Ultimate Ascent and it worked extremely well for them. They have an even better version of it on their Aerial Assist bot. I believe Aren Hill a former mentor for Neutrino current mentor for 148 Robowranglers conceived the idea and could explain it much better than I can.

Edit: Trent B beat me to it

[Electronica1]

Originally Posted by Ginger Power

They had a butterfly drive for Ultimate Ascent and it worked extremely well for them. They have an even better version of it on their Aerial Assist bot. I believe Aren Hill a former mentor for Neutrino current mentor for 148 Robowranglers conceived the idea and could explain it much better than I can.

Didn't 148 conceive and run the first butterfly drive in 2011?

[EricH]

Originally Posted by Electronica1

Didn't 148 conceive and run the first butterfly drive in 2011?

Sort of... but you're off by a year.

148 and 217 built a "nonadrive" in 2010--in fact, they collaborated on it. The butterfly was omnis and traction, and a 5th omni was mounted perpendicularly to the rest of the drivetrain (for sideways motion).


I'd actually thought about (and tried to convince my team to do) one back in the mid-2000s I want to say '06 or so, and I know a team that did a traction/traction butterfly-type setup back in '03, so they've been around a while, in concept at any rate. These days, more teams have the resources to pursue 'em, and are more willing to share designs, so they've been getting more common.

[audietron]

A favorite of ours is using traction wheels on a six wheel drop center drive. The tractions that you choose kind of varys on what you want to be doing more of. We have found that the 4 inch versawheel spike tread is really nice for good grip and still being low to the ground. The 3.25 inch diamond tread wheels are also good but wear down a bit quicker. so these are bit better for more offensive purposes.

[Electronica1]

Originally Posted by EricH

Sort of... but you're off by a year.

148 and 217 built a "nonadrive" in 2010--in fact, they collaborated on it. The butterfly was omnis and traction, and a 5th omni was mounted perpendicularly to the rest of the drivetrain (for sideways motion).

I was considering nonadrive as a different drive because of the 5th omni, they did not run the drive that everyone now calls butterfly drive until 2011.

[JVN]

Originally Posted by Electronica1

Didn't 148 conceive and run the first butterfly drive in 2011?

It is difficult to track the origins of an idea...

In the pre-season of 2010 148 build a drivetrain which combined an H-drive (5 omni wheels, 4 in "normal" configuration and 1 sideways) with 4 drop down traction wheels. We called this a Nonadrive, since it has 9 wheels and we really like the number 9.

In 2010 we ran this same configuration on our competition robot Armadillo.

In pre-season 2011 we prototyped an Octocanum drivetrain (an articulating drivetrain which switches between 4 mecanum wheels and 4 traction wheels). This is something which I believe several other teams had done in the past.

We didn't like the performance of the mecanum wheels we had at the time, and switched them out for omni-wheels as part of a new experiment. This configuration could not move sideways, but had some cool features we liked. We jokingly called it "Butterfly" drive since you could swat it aside like a butterfly when it was in omni-mode. I believe we were the first to experiment with this configuration.

In 2011 we ran this same configuration on our competition robot Raptor.

We ran an evolved configuration in 2013 on our robot Viper.

This year, we're running another cool evolution of the Nonadrive which involves 2 center Omni-Wheels, which we're calling the "Decadrive." This is on our robot Vader.

We like articulating drivetrains. We've been playing with them since pre-season 2010, and we will probably continue to play with them. We're actually starting to work on a "History of the Robowrangler Drive" which will hopefully turn into something cool for our website.