2017 Drive Train
 

There's obviously a lot of debate surrounding which drive trains can serve what purposes. This thread is created to centralize this discussion to provide easier access to all teams.

One of the more uncommon drive systems which still proves useful is the h-drive. This system has omnis on all corners, with a central omni to provide lateral movement. Our team has thrown around the idea of using h-drive as a less complicated mechanum system. The movement is near-identical to mechanum and debatably easier to build. This of course being in contrast to using tank drive (reliable and simple). Can we get some insight?

Re: 2017 Drive Train
 

I'm not sure how a h-drive is simpler to build. With mecanums, you simply just mount wheels on each corner. The stock AM14U3 chassis even has support for it with Toughbox Micros. Meanwhile, with a h-drive you have to add a cross member and have a whole different drive wheel and gearbox in the middle. With H-drive you can have three gearboxes (you can tie the two side wheels together), but you need at least 5 motors. Mecanum has four gearboxes but four motors needed. Both offer challenges, but a mecanum drive is a lot simpler to mount to some versa chassis quickly (or c-channel as my team uses) and get started.

Re: 2017 Drive Train
 

This year might be more of a swerve drive game than previous years. More control of the drivetrain can help place gears, and there's a wide open field for swerve to dance around defense in. It combines the advantages of omni or mecanums (and more) without giving up resistance towards defensive robots.

Too bad I'm not confident in my team's ability to do swerve properly.:(

Re: 2017 Drive Train
 

Mechanically, H-drive is harder to make because you need the center wheel, but programming-wise, assuming you're writing your code from the ground up, H-drive is a breeze compared to Mecanum.

Re: 2017 Drive Train
 

Mecanum vs. Tank?

Mecanum has an obvious mobility advantage, but how much does it really give up in traction/strength? Is it completely outclassed in strength to a tank drive system?

Re: 2017 Drive Train
 

If there was ever a game to not overthink your drivetrain and just build a really simple tank drive, this would probably be it.

Re: 2017 Drive Train
 

Agreed. Make it simple strong and compact

Re: 2017 Drive Train
 

In a pushing match, yes.

Re: 2017 Drive Train
 

Everyone should read this before building anything but a tank drive:

http://www.simbotics.org/resources/m...rain-selection

Re: 2017 Drive Train
 

Point to consider:
6-WD tank (preferably with a COTS shifter) is the fastest, easiest drivetrain to implement and program. Is a mecanum, H-drive, or swerve so much easier to line up that it outweighs the extra practice time you should have with the tank drive? Or the extra practice time with your practice bot because the tank drive is so much cheaper?

Also, a defensive tank bot is going to shove a mecanum or h-drive all over the place. Good luck scoring a gear while that's happening.

Re: 2017 Drive Train
 

Aw man, if only I were still with Texplosion, that last part is a pure gem.

Yeah, don't overthink the drivetrain. You shouldn't need a vertical adjustment for anything. And, if you are off horizontally, build it into a mechanism rather than moving the whole robot. If you are placing a gear, have a way to rotate it or move it side-to-side. If you are a shooter, have a way to rotate your shooter to keep it on target. Put your code into things like that, not into complex drive.

Re: 2017 Drive Train
 

In 3946's experience, H-drive is harder than mecanum.

In 2013 Aerial Assault we decided to do mecanum (foolishly expecting a less defensive game), and it worked as well as expected, pretty much the first time around (OK, after fixing some wheel order issues), but we had it running two weeks after we made the decision on our prototype "Woody" (which meant ordering wheels and extra gearboxes before we could finish the build) and running like a champ on the competition robot "Buzz" before bag day. We used the WPI mecanumDrive class straight up, without encoders.

In 2015 Recycle Rush, we decided to do H-drive, and never got it working correctly all the way through CMP. It was only after the 2016 season that we got it working. If you do do H-drive, do not depend on a fixed-height strafe wheel - there is no height which provides the correct amount of load. The central wheel(s) must somehow have a controlled force against the carpet, whether passively through springs or actively through pneumatics or torque actuation, or perhaps some other ways you can come up with.

Another caveat which may or may not apply to you: H-drive requires a wheel near the CoG of your chassis (or one forward and one behind). This will interfere with the "chassis opening and combine" style gatherer that is likely to be commonly used by fuelbots this year.

Re: 2017 Drive Train
 

we are actually gonna use 610s DT from Ultimate Ascent but wooden mobility for us was not a big thing for us this year we want to just be a role player and focus on the gears but still win a pushing a match

Re: 2017 Drive Train
 

For those of us who aren't familiar with it, mind providing some details about what this is?

Re: 2017 Drive Train
 

Link to picture: https://goo.gl/images/pvbwyc

6 CIM, 6 Wheel Drive, single speed. I believe it was designed around acceleration, not a very high full speed.