Best Drive Train
 

What type of drive train do you guys think is the best in terms of speed, pushing force, agility (mobility), durability, and overall efficiency? Typically, my team uses regular Tank drive, though we did experiment with Mecanums a few years back.

Drivetrains:

Tank
Mecanum
Holonomic
Slide
Swerve
Any others?

Re: Best Drive Train
 

Where is the Jump Drive?

Re: Best Drive Train
 

Ya, the 2 big names you left off were Octocanum and Nonadrive.

Re: Best Drive Train
 

Swerve has always seemed to me like an unambiguous favorite if you have a good, light design and the resources to pull it off cleanly.

This offseason, 4464 is going to be looking at designing nonadrive/octanum, as that seems reasonably within our machining capabilities (we can do lasercut 1/4'' delrin, which ought to be sufficient for the wheel modules if they're designed properly) and offers a significant, strict increase in performance over slide drive/mecanum.

Re: Best Drive Train
 

100% of all nine-sided drive base robots have won einstein.

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I chuckled.

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Whatever works for your strategy.

Re: Best Drive Train
 

Quoted for truth. It took me a while to learn this, but in FRC, there is no universal "best" anything. Whatever works best for your team is going to give you the best results (that being said, 10 wheel nonacanumswerve drive isn't the best drivetrain).

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Some intrepid CADer should take the initiative and draw up a design of this for all of our entertainment. :P

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...and is within the resources (cost, machining, etc) for your team.

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Isn't tank drive the naming convention for the style of controls? Either way, if your using tank drive you MUST drop those center wheels. Otherwise the drive system will be useless because you wont be able to maneuver well...

Re: Best Drive Train
 

Shouldn't those factor into your strategy? ;)

NOT true at all. If your wheel base is wider than it is long... or actually, just read Chris' paper http://www.chiefdelphi.com/media/papers/1443

Re: Best Drive Train
 

Sorry my version of tank drive has been corrupted over the years due to how we ALWAYS have had 6-8 wheel drive and a long bot at that....:p forgot about the wide bots....

Re: Best Drive Train
 

On Truck Town we like tank because it works well with our transmissions that shift from low to high gear. But I would like to experiment with other drive systems and wheels, because who wouldn't want to use beast wheels like 25? :ahh: :ahh:

Re: Best Drive Train
 

But I also like mecanum, maybe not for our team, but for other younger teams. They get the versatility that they want without taking on the challenge of swerve, that some of the best, most experienced teams can't conquer. Just like 2010! *shutters* :(

Re: Best Drive Train
 

Similarly if 6wd swerve has 100% chance of making it to Einstein I'm sure 8wd swerve would win. ;)


For us on 3467 its 6wd all the way! Its simple, easy to build/maintain, provides great maneuverability/speed, and is extremely reliable. I'm sure down the road we will experiment with fancier systems but this fall we will work to refine our 6wd on a custom level that is better, lighter, and more reliable than any of our prior drive systems.

Re: Best Drive Train
 

Where is the warp drive?

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It's why next year, we're building a Triple Killough. :ahh:

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One drive train that is not thought of a lot is no drive train at all.

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I'd love to, but first, I think I need to figure out just what that means...

Nine swerve pods, each with an octacanum rocker, and an extra set of sideways omniwheels?

Re: Best Drive Train
 

Fixed it for you. ;)

Swerve is hard to beat in terms of agility if you do this. It'll par on durability and has a lot of benefits on pushing force and will get you most any speed you want, though if you're talking about shifting it's considerably harder than slapping a Super Shifter on a tank drive.

Re: Best Drive Train
 

Here is a ranking my team made:

We picked 6WD shifting WCD for our strategy, and we couldn't have been successful in our strategy without it. Not only was it maneuverable, fast, and strong, but it also cleared out a ton of extra room inside the chassis.

Re: Best Drive Train
 

I would think a drive base would be worth the extra 20pts for dumping and the slightly more adaptive strategy (hybrid climb/defense)...

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I don't want to get into technicalities because although I understand the different drives, I only have experience with tank drives (I also can't elaborate at the moment, I would be happy to do so tomorrow if you want), but I will say I have participated in many competitions, built atleast seven robots for different games, and designed for many others I didn't participate in, but I have never encountered a situation where a tank drive couldn't do the jub efficiently and easily, not even in 2010 that was a classic year for holonomic drives (IMO).

Re: Best Drive Train
 

What about fan-bots?

On a more serious note, I have seen very very very few years where a good 6 WD dropped center drive won't do well in a game. It's easy to do, a lot of people have done it, and it just frees up so much time to deal with the rest.

Re: Best Drive Train
 

Our team is really small. We have at the most 15 people. Most of the those people do not come every day and work for all the time so we had to decide to do one thing. My team chose to climb. We ended up spending close to half of our build season building a pyramid corner so that we could corner climb. With a week left we decided to scrap the idea and build a 20 point side climber. Those pictures are of our first legal climb to 20.

I know what you are talking about. In my team I was a huge advocate for not doing a climber because I thought a climber (without a drive train) was an all or nothing approach. I was really surprised and happy that this year in competition we were the 8th seed alliance captain which is the best we have ever done.

There are good things about having a really small team. This year is my freshman year. My team also does FTC where I was one of the hardest working people. Because of that I was able to be the sole operator of our robot. It for me was a great experience.

Re: Best Drive Train
 

Straight up Six Wheel Tank will work every time. If you have time/space/weight/money, adding a two speed shifter is a great way to spice up a tank drive for more versatility. Throw in some roughtop tread and #35 chain for the drive, and you can fight it out with the best of 'em. Two speeds and decent traction will let you overcome most defenders with easy. There is no reason to waste time on a swerve or other drive, though omni-wheel rockers on a 4 wheel setup are also very effective and cool. In my opinion, finish the tank early rather than spending time on a swerve and get more driving practice.

Swerve is cool and all, but it isn't necessary. There was only 1 swerve on Einstein this year. And the winning alliance was all tank. Because it works

Re: Best Drive Train
 

I felt that our Butterfly Drive Module was extremely effective this year. We could go fast with omni's (15fps) and also drop down to traction mode (which we really enjoyed playing with because of the pneumatics) to push robots, mentors, members, and pyramids (although our robot usually lost).

Last year, we were the team with the Innovative Swerve Drive Module. This was one of the lightest and most compact modules out there. Although we never got time to train our drivers with it, we tend to not recommend it to other teams with the issues we experienced with it, although we like to see what other teams innovate on existing swerve drives. Feel free to check out our CD post on our swerve drive, which has had lots of discussion.

Re: Best Drive Train
 

We like our 6-wheel tank drive that we've used in some form or another since 2010.

2010: Long Kit Bot frame. Wedgetop wheels in center. Omni-wheels in the corners. 4 Toughboxes with One CIM each powering each of the back 4 wheels.

2011: Long Kit Bot frame. Plaction roughtop wheels in center. Omni wheels in corners. 2 CIMple boxes with 2 CIMs each powering center wheels only.

2012: Wide Kit Bot frame. Plaction roughtop wheels in center. Omni wheels in corners. 2 CIMple boxes with 2 CIMs each powering back 4 wheels.

2013: 29*25 Kit Bot frame. Plaction roughtop wheels in the rear. Omni wheels in the front. 2 Kit Toughbox Minis with one CIM each powering rear wheels only. (I know there's only 4 wheels this year, but the design was inspired by our success the 6 wheel drivetrains in the past.)

Omni-wheels mean you can spin in a circle with no issues. It's about as maneuverable as you can get without a Swerve drive, Holonomic or Mecanum, with way more traction than Holonomic or Mecanum, and I'd argue Swerve as well and it blows them all away in speed and ease of building/programming.

That said, I agree that there is no one drivetrain that works every time. You might want Swerve if and when we get a maze game.

Re: Best Drive Train
 

And don't forget about 6wd swerves!

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There is no universal best drivetrain, but if you look at complexity and cost vs experience, you CANNOT go wrong with the Kitbot on Steroids. It takes 3 hours to build, a couple more hours to wire and program, and it is a regional winning drive train. Heck, I bet there are teams that have gone to Einstein with this drive train.

Re: Best Drive Train
 

I would agree that there is no best wheel. But, I believe the universal best design concept is one like our butterfly drive, where you are able to incorporate 2 different types of wheels (we chose 1 fast omni & 1 custom wheel that provided traction) that provide features that the other one could not solely do by itself. This was a big thing that we took into consideration when scouting and selecting other teams for our alliance, as some of them had drivetrains (I believe mechanum was one) where they could easily be pushed around and couldn't hold their ground and play defense, which was fairly important in Ultimate Ascent.

Re: Best Drive Train
 

If this is the reasoning, why is it better than swerve?

Re: Best Drive Train
 

If you need help with your small team, I invite you to contact me or another 3476 member. My story:
Last year, I was a freshman, and brought CAD design to the team. We had very limited funds, tools, manpower, or space. We still build our robots out of extruded aluminum in a 2-car garage with a tabletop chopsaw and bandsaw. We built a simple robot- and won SDR with it. We had 15 students on the team, with a ~7 member "core" team. After that season, we impacted over 20,000 people and had our program grow to 22 students representing 16 different high schools and 6 homeschoolers.
We simply worked hard, and because of that we eventually got rewarded for that effort. Anyone can do that.

Re: Best Drive Train
 

1) It's WAAAY more reliable then swerve. We never once had any major issue with our butterfly drive train this year (with the exception of breaking an omni during practice because we ran over a floor power outlet. We can also lose pneumatics (such as we did in final matches #2 & #3 at North Star and we can still drive just on omni's. If we lost an encoder with the swerve drive (ie. got unplugged), which happened a few times too many last year, we couldn't drive and it took some power cables with it.
2) It's WAAAY easier to fix then swerve. To fix a butterfly module, all we had to do was to unbolt 1 bolt and we could easily change out the module ("plug-and-play" if you will). We would just have to remove 2 additional bolts to get to the actual drive train itself. Now to fix the swerve drive, we had to work in crammed quarters trying to unbolt a bolt (which wasn't fun) and to fix wiring issues.
3) It's WAAAY simpler. The mechanics behind the butterfly drive is so much simpler then the mechanics behind the swerve drive. The fabrication and assembly of the butterfly drive was much quicker than the swerve drive. We were able to machine the parts for our butterfly drive ourselves because they didn't need to have that much precision vs getting precision lazer cut parts at our sponsor for our swerve drive modules. Assembly time was MUCH faster (~2 hours to assemble 10 butterfly modules vs 9 HOURS PER swerve drive). It's worth noting that the programming behind the swerve drive is quite complex versus the simple coding required to drive the butterfly modules. It's this simplicity that makes butterfly drive more reliable and easier to fix than the swerve drive.
4) It's WAAAY lighter and smaller. Each swerve module weighed ~6 pounds vs the ~1-2 pounds per butterfly module. I can easily hold 2 butterfly modules in my hands vs 1 large swerve module. Our chassis was also 'designed' to easily accomodate the butterfly modules.

Re: Best Drive Train
 

Saves motors, time, and is incredibly easy to use. If you want a truly great swerve, you have to use 8 motors, which is a lot of the motors you have and use. An octocanum or butterfly is just as maneuverable and only uses 4 motors, but there is no pushing power to the side. Why is pushing power on the side needed? And as said, too much easier. Swerve is cool but fairly wasteful.

Back to the original post, as stated there is no perfect or best drivetrain. Discuss what is needed (maneuverability for an intricate field, or pushing power for obstacles). My personal favorite is octocanum, because it's easier to design and make and maintain. And it covers all your bases (it's two drivetrains!)

Re: Best Drive Train
 

Sounds legit. :D

Re: Best Drive Train
 

Well, that escalated quickly.

Re: Best Drive Train
 

Well put. I think the "best" drivetrain is one that is KISS'ed to fit YOUR needs. Sure you could spend the whole off season developing a super advanced wheel and drivetrain, but when push comes to shove, the simplest and easiest drivetrain will *almost* always excel the more complicated drives. As I stated earlier, there are more things that can (and will) go wrong in a more complex drive.
Another thing to consider for the "best" drivetrain is size and weight. I believe that the one listed below is a bit overkill. A robot should *generally* need only 4 "modules", which reduces a lot of weight and a lot of those "hole"y robots.

Re: Best Drive Train
 

Motors this year don't really matter. Honestly my view on it is you go all the way or you stay with the basics. We like our WCD because it is the fastest or one of the fastest in machining and assembly. This gives us more time to program, iterate, and practice(even more than butterfly or octocanum). For 99.9% of teams this is going to boost their performance more the the "extra" maneuverability will.

In response to runneals your points for 1 and 2 can be wrong. I've seen 1717 win the LA regionals in 2012 running through elims on 3 modules working(they replaced for the finals). Also with a fully independent module it is quite easy to make a module replace with the removal of 3 screws. Not quite as little as your butterfly but still very little.

Re: Best Drive Train
 

So there really isn't a "Best" drive train. It really is what the team prefers, or works best with. My team has done a 4 wheel tank drive using 2 speed shifters in the long configuration. Our drive train is very sturdy, and is great at pushing other robots out of the way. We have been using our design for the past two years, and have had no complaints.:)

A drive train that I personally want to design, test, and see how well it fares compared to our current is swerve drive.

P.S. If anyone saw 4471's robot at championship, that's our twin, both teams had difficulties with playing offense, so we were a defensive robot, and were pretty good at it honestly.

Re: Best Drive Train
 

Reading the original post i cant see any indication the poster was asking about resource draw, ease of maching, development time ect ect. from what i can tell he was just asking which is best, which is why i voted swerve, a perfected (shifting) swerve drive is the best drive train in FIRST. It allows for more versatility and options then any other type of drive train

Re: Best Drive Train
 

These two are not functions of concept but rather of execution. We are also in an exactly 0 failure year, and most of the components have never failed once in 4 years. Preventive maintenance on what are very few potential failure points (swapping wheel treads, and...well, basically that. Maybe a few things that take longer to pick up the wrench than to fix) is done off-robot after a quick switch; all 4 in maybe 5 minutes. There are very few things that could go really wrong that would require serious disassembly to fix.

Work, resources and weight I agree with (though ours isn't so long), but that's not the initial selling point you mentioned, which is why I asked. Motors I'm less worried about after this year. I can't imagine what I'd use all of them for. We did fully independent swerve and a 30 point climb with a shooter and allocations for a floor pickup and still didn't manage to run through them all.

Actually there's no pushing power along any other axis, which is a huge advantage when used correctly, but I understand that's not your point.

I have never seen an omni robot exhibit actual holonomic drive--full control of orientation while translating along any vector. Is this a function of physics or of execution? I can't tell from your page how the butterfly modules are oriented. If you had a real-time sequence of translational vectors and orientation headings, could (theoretically) you move through them simultaneously at will? (If so, remind me to make you do that when I want to push you :P)

Re: Best Drive Train
 

The only addition I would make to your drive base would be the addition of a strafe wheel in the center of your robot. You had the right idea with the butterfly drive, its pretty much a Jump Drive, but in order to make better use of your omni's I would have put a strafe wheel in the middle, otherwise you would have been better off just building a multi speed gearbox. Don't get me wrong, I love your butterfly concept, in fact, our team my try it out this summer, but you need to have a strafe wheel if you have omni's.

Re: Best Drive Train
 

We had Chris come in and give a seminar at Michigan State Championships on drivetrains. His insight is pretty amazing. He actually talked about this paper, and how it really no longer applies to FIRST robots. It'll tell you if you can turn, but beyond that the physics don't really work with FIRST anymore. The paper was written when teams used metal cleats that acted very different than roughtop does now. He went into the friction characteristics of interlocking materials versus ideal ones, and talked about torsional stiffness, weight placement, etc.

For instance - a major mistake our team has made twice is to directly center the weight in a 6 wheel drivetrain over the center wheel (2011, 2013) on a semi-tall bot. The result is a robot whose center of gravity constantly shifts. That creates a really ugly chatter through turns even with a very stiff frame. It also doesn't like driving straight because the weight shifts when you accelerate then shift forward again when you hit the brakes. It was really eye-opening, and explained why our driver spent the majority of the year driving with only two wheels on the floor :D

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I think when 148 does this they actually gear both wheels to be the same speed, so they can set front to traction and rear to omni, or vice versa. This allows them to move their center of rotation so they can slide around easier. Watching them drift around the pyramid was really cool, and I had multiple kids ask me how they did that. I wish JVN's blog was still up so I could show them more.

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not really much point when you are going to strafe much slower than your forward speed. They probably prefer saving the weight and complexity of adding the omni. It's actually very different then a multi speed gearbox. When they push down their outer for wheels it is impossible to turn them which is very helpful for auton, playing defense, and getting through defense.

Re: Best Drive Train
 

Definitely 1625's lobster drive from 2011. That's my favorite.

Re: Best Drive Train
 

Obviously there is no "Best" drive train. There is only best for you.

We went with what we dubbed the "Chicken Drive". It is a 6wd tank drive with super shifters. What made it distinctive was redundant chains. We actually busted a drive chain in Newton qualifiers but kept running. Using pneumatic shifters was also very useful. We saw people at regionals trying to shift with servos and that meant they had to basically come to a full stop to do so.

Re: Best Drive Train
 

Definitely not the best drivetrain but a very very good one is this year's KOP Belt Drivetrain. We decided to go with it this year to spend more time on our different mechanisms. It took roughly 2-3 hours to put together and after we assembled it we never had to worry about it again. The built in belt tensioners worked great and once tightened we never had any problems with the drivetrain itself. Being able to not worry about the drivetrain at competition was a luxury we never had before. I would also like to point out just how robust it was. We could go head to head with some of the best drivetrains in frc. Fast, enough traction to not get pushed around, and very robust. Thank you Andymark!

Re: Best Drive Train
 

We are big fans of swerve as a drive-train well suited to a wide variety of FRC situations. The ability to vector drive force in any desired direction is particularly valuable. So is the independence between chassis orientation and direction of movement. Some moves are shown in the attached link:

http://www.youtube.com/watch?v=Pej5pkFvFdY

Swerve does "cost" more. We use 4 drive and 4 steering motors and the overall weight of four pivot modules is 31.6 lb (includes all motors). Also, there is a significant investment in driver training. Despite this cost, we find that the benefits that this versitile drive-train provides to us in competition makes it worthwhile.

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Given infinite time, money, motor selection, programming ability, manufacturing ability, and driver practice time...swerve.

The more of those assumptions you relax, the more attractive plain old tank drive starts looking.

Re: Best Drive Train
 

I would say the best drive train is this:

http://www.chiefdelphi.com/forums/sh...shed%2C+around

I mean, look at that-- robust, light, simple...

Re: Best Drive Train
 

Don't forget about the fact it can travel over 100 fp/s ;)

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Re: Best Drive Train
 

Thanks. I see you doing some cool driving in what amounts to crab and 1983 doing some pretty awesome spins, but I don't see anyone obviously taking advantage of full holonomic movement. Maybe I just can't pick out the level of control from match video--do you have like a practice demo or something?

Re: Best Drive Train
 

I don't think we have a demo video put together showcasing the movement. I do have an onboard camera view though, which makes it more obvious when we are and aren't turning. If you skip to about 0:53 you'll see the robot both turning to point towards the goal and lining up with the feeder station by backing up in a weird direction. This is the same match as before, by the way.

http://www.youtube.com/watch?v=bD57jowaBwM

Re: Best Drive Train
 

Ask your driver wether he/she'd want to drive and practice with it.
Ask your programmers wether they'd be willing to program it.
Ask your scouts wether they blacklist drivetrains like that ;)
Not necessarily in that order. This goes with a drivebase ranking system.