Drivetrains in Ultimate Ascent

[protoserge]

Mecanum wheels are pretty awesome. They have their place, and for our strategy, this was not the year for them. Logo Motion, on the other hand, was fantastic with them.

I'm curious how VexPro Mecanums are... I might get some this summer and create a 12-CIM Mecbot

[ice.berg]

Originally Posted by stinglikeabee

I'm curious how VexPro Mecanums are... I might get some this summer and create a 12-CIM Mecbot

We are running the Vex mecanums and have been very pleased with the results so far. The weight advantage over the AM mec. wheels is HUUUGE. Only problem is you can not replace any of the parts on the vex unlike the AM wheels. Overall though I think it is a great product!

[JVN]

Originally Posted by ice.berg

We are running the Vex mecanums and have been very pleased with the results so far. The weight advantage over the AM mec. wheels is HUUUGE. Only problem is you can not replace any of the parts on the vex unlike the AM wheels. Overall though I think it is a great product!

We now sell mecanum roller kits for those teams who wish to swap out used rollers:
http://www.vexrobotics.com/vexpro/wh...um-wheels.html

Are there any other parts you wanted to be able to replace? I think everything else is pretty modular.

-John

[ice.berg]

Originally Posted by JVN

We now sell mecanum roller kits for those teams who wish to swap out used rollers:
http://www.vexrobotics.com/vexpro/wh...um-wheels.html

Are there any other parts you wanted to be able to replace? I think everything else is pretty modular.

-John

John, This is exactly what we wanted, nice and cheap to be able to replace the rollers like on the AM versions. Your team at vex has put out some great products and a see a bright future for you guys. Keep it up!

[Nemo]

We're running VersaWheels with Vex single speed / single stage gearboxes. Gearbox is chained to the wheels (32:16). That gives us a theoretical speed of 8.7 ft/s, which is the slowest we've geared since I started.

We decided that we had enough on our plates without doing anything fancy on the drive. With the chain reduction, we were able to to keep gearing it slower until we could spin the tires.

VersaWheels + single stage is just about as simple, cheap, and as light as it gets. We like it.

[ehfeinberg]

449 is running AM mecanums directly driven off of Toughbox Minis. Our entire robot doesn't have a spec of chains or belts.

[Anupam Goli]

1648 is using a wide 4wd with the nice Vexpro traction wheels and custom black roughtop tread. I love these wheels, they have so much traction that we ended up pulling carpet fibers out of our wheels. The traction was too much for our old carpet (talk about burnin' rubber)! We're also using the Toughbox mini's with a custom ratio (can't remember off the top of my head) with some sprocket work (15T on gearboxes, 22T on wheels) to get ~9 fps using JVN's calculator.

[PayneTrain]

We'll see if the build lead for 422 comes out of the woodwork for this discussion, but I'll give you the spiel that you'll probably hear if you stop by the pit:

The drive train is quite the venture for 422, being the first non direct kit or kit-modified drive train system in years. There are a lot of things that were learned ("Hey, maybe we should be a little more gentle when welding" or "Hey, maybe our bearing blocks shouldn't be 1/12 of the robot weight") It's a 6WD "West Coast Inspired" drive system with 6-inch AndyMark performance Wheels lovingly covered in Blue Nitrile, feeding into a full VEXpro system of sprocket, chain, the single reduction gearbox, and 2 CIMs and 1 mini CIM on each side.

The numbers you're probably looking for:
15.17 fps, operating at 90% system efficiency on a total gear reduction of 8.25:1, creating what he calls a "friction limited system," a term I can't remember because I haven't slept in 30 hours. I think the idea is that as long as 422 initiates the contact, the other team is probably in for a bad time.

Now obviously a 6 motor drive train is not a battery's best friend (our new battery chargers are!), but 422 can rev up their shooter while driving (taking shots while moving isn't an ideal situation strategically or mechanically). I imagine the team will learn a lot this year, as they already have in building it. The drive team is just itching for Week 3 to come so they can pull it out of the bag and drive it around some more.

I didn't put a hand on a tool for this, that's just the readout they gave me to make the video.

[F22Rapture]

Originally Posted by PayneTrain

The numbers you're probably looking for:
15.17 fps, operating at 90% system efficiency on a total gear reduction of 8.25:1, creating what he calls a "friction limited system," a term I can't remember because I haven't slept in 30 hours. I think the idea is that as long as 422 initiates the contact, the other team is probably in for a bad time.

The term "friction-limited" refers to the fact that the wheels will slip before the motors will stall, due to the amount of torque available.

[pfreivald]

We're using VexPro mecanums direct driven off of toughbox minis, with drop-down, geared-down 2" Colsons for anticipated pushing matches.

[nerdherdmember]

Originally Posted by PayneTrain

We'll see if the build lead for 422 comes out of the woodwork for this discussion
…
I think the idea is that as long as 422 initiates the contact, the other team is probably in for a bad time.

As build lead and drive coach for Team 422, I can confirm that if we initiate the contact, a bad time is assured.

[AllenGregoryIV]

Originally Posted by Nemo

We're running VersaWheels with Vex single speed / single stage gearboxes. Gearbox is chained to the wheels (32:16). That gives us a theoretical speed of 8.7 ft/s, which is the slowest we've geared since I started.

We decided that we had enough on our plates without doing anything fancy on the drive. With the chain reduction, we were able to to keep gearing it slower until we could spin the tires.

VersaWheels + single stage is just about as simple, cheap, and as light as it gets. We like it.

We're using 8 VersaWheels + 1:5.33 single stage + 15/26 chain reduction. All of this on the VEXPro Chassis. So far it has been one of the best drive trains I have worked with in FRC. It's cheap and works well.

[Grim Tuesday]

4 CIMs in 3 stage VEX Pro ball shifters. We might switch to 3 CIMS in 1 stage gearboxes after our first event, based on how well these work.

The more interesting thing is a completely custom tread drive system. See video for some footage of it driving. The tread is a Brecoflex conveyor with the drive cog run by chain from the gearboxes. Two 3/16 side plates hold each drive module together; the idlers are made from round delron stock and the last one can move to tension the tread.

Why treads this year? It is part of our team credo never to lose a pushing match, even with Trucktown (we were on an alliance with them last year, we never got a chance to test their mettle unfortunately). Speed is reasonably good and they are quite stable.