Is there a dominant design style?

I wonder if the advances over the last several years in product availability and information sharing have resulted in major changes to the way teams design and build their drive bases and superstructures. Is WCD now dominant? Did vexpro revolutionize the sport with versaframe? Are more teams building swerve drives than ever before, thanks to products like andymark’s? I’d love to see what people think of where their own teams are, and where they think things will go.

We’ve gone to the kit chassis the past couple years…it’s really good these days. We used to build our own.

For our team, definitely. Versaplanetaries are really good, and probably dropped out weight 10+lbs in 2014 and 2015, WCP and Vex gearboxes drop our weight more compared to our old AM shifters.
CD has helped our team learn a lot more about mechanical design.
As far as swerve drive and versaframe go, I haven’t seen many teams use either, excepting this year. But the Swerve And Steer might remain popular next year, as so many teams used it this year that it’s easy to re-use.

At $325 a pop, and building two robots, we’re looking at $2k for swerve or crab just for gearboxes and wheels. Unless we were reprising Tumbleweed, this would probably blow our budget.

We’re with MrForbes above - we did our own chassis for our second and third year, but when we forgot to opt out last year, we realized just how versatile the 2014+ KoP chassis is. We opted out this year, but have ordered two AM14U2s (2015 chassis) and these are 95%+ likely to be the main part of our chassis this year. By using some Vex 1"x1" c-channel and a drill with a 3/16" bit, it is easy enough to use KoP below and VersaFrame above; that’s our most likely construction for 2016.

WCD will buy you another inch or two of track width for the same robot width, but this has not been a major consideration in our last several robot designs. If it does prove to be one, we can always rearrange the wheels and sprockets on those shafts, and even bring the “outer plate” inside of the wheel if it seems necessary to do what I’m going to call a Gulf Coast drive. (and that’s just the beginning of some of the weird things you can adapt the KoP to do.)

As far as COTS causing a style to become (or cease to be) dominant, I think that the COTS availability of omni and mecanum wheels has done more to open up the possibilities of something other than drop-center to teams with a $1k+ robot budget than anything else.

Versaplanetary gearboxes have definitely been a game changer for us, especially with the new Versaplanetery CIM adapter. It’s just so much more convenient to be able to grab a couple of stages and put them together when you figure out what ratio you need instead of stocking many many gearboxes or ordering them in the mail and waiting. They’re extremely reliable, relatively light(compared to p80s) and you can switch them out with each other as long as you keep the number of stages consistent.

We used the Versaplanetary for our 2014 drive train… That was wicked fast! Each wheel had its own CIM and gearbox :yikes:

We copy 254’s drive train style. WCD every year.

We copy 973’s mechanism style. Tube + Holes + Gussets (essentially versa-frame)

We use vex pro ball shifters in our drive train.

We use versaplanetaries for all of our mechanisms.

We expect to keep learning from the best teams in FRC.

We expect to continue to use the VexPRO product line almost exclusively.

We would not be where we are without these resources.

-Mike

We used the 2015 KoP frame last year, but adapted it to our own drivetrain (Toughbox Nanos with 6" mechanums).
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It’s worth mentioning that if you just want the KoP frame, they sell it separately from the drivetrain and it’s $209 instead of $599.** They also sell all the sheet metal, churros, and hardware separately.

http://www.andymark.com/AM14U2-p/am-2990.htm

Wow, we are on the same page, though we use WCP gearboxes half the time, and the Vex ball shifters the other half. This is really what I’m wondering, and why I posed the question. My suspicion is that these products, and the great teams whose ideas these products seek to emulate, are becoming the go-to for many teams. It sounds like the versaplanetaries also are huge for some teams (mine included), and that AndyMark has raised the kit bot to become a much better product, too. Thanks.

Sounds a lot like my team! Especially with VexPRO products. Also, VexPRO and other Vex products are great for our color scheme since their products generally come in schemes of black, dark green, and gold-ish (mainly from their gears), Aside from pretty colors, VexPRO products have been super reliable, and I’ve had no major issue yet. Like 1678, if a transmission is not a ball shifter on the WCD drive train, it’s a versaplanetary somewhere else. I think the last time we attempted a custom transmission was in 2010. From 2013 on, it’s been almost all VexPRO COTS transmissions.

Last year was an exception though, since we used mecanum drive instead of WCD, with no shifters. After competing against 1678, 254, and 118 in several playoff and finals matches, we saw that performance with a drop center 6 or 8 wheel drive in a game is just as good if not better for maneuverability than non-linear motion drives like swerve and mecanum. It’s all about driver practice. This is especially important when considering the percieved advantage of these other drive systems in the context of a game like Recycle Rush.

We also found that strafing with the mecanum was only important when lining up with the chute. Originally we only needed mecanum to do our autonomous which was supposed to grab all 3 totes while strafing along the alliance station so the robot was in between the totes and wall. That didn’t work out, so we didn’t need strafing for the majority of the game.

After seeing the championship being won by 1678 with WCD in a game thought to favor strafing motion, 701 will probably not stray from WCD again for competition, with only exceptions in the extreme.

I think what 701 should try is tube+hole+gusset design. We do this for prototypes, but our practice and final frames are welded. I was discussing with Doug about the advantages of the mechanism versatility for making changes over the competition season up to champs, and the welded frame doesn’t give as much versatility as a tube+hole+gusset frame.

see signature below WCD FTW!

While I agree with your point, I don’t think 1678’s WCD is what made them world champion caliber.

“Because they do it” shouldn’t be your rationale. Yes, all the top teams doing something is generally a indicator that it’s a smart decision. However, blindly following them without figuring out the rationale behind their decisions is a bad idea; there might be variables at play that made WCD the right choice for them but not for you.

Note how Corsetto said that 1678 is going to keep learning from the teams they’re inspired by. Copying 254 or 973 probably had some sort of analysis of their resources and what direction was best for them.

There are successful teams that do WCD, there are successful teams that do omnidirectional drives. There are successful tube and gusset teams, there are successful sheet metal teams. Which one is right is completely dependent on the resources available to your team.

Totally agree! Well put.

“Blindly following” and “not figuring out rationale” are pretty poor ways to approach the problem.

The OP is asking the right questions. You need to start by looking out, then shift your focus to looking in. In other words, “steal from the best, invent the rest”.

Start by knowing as much of the existing knowledge base as possible (steal from the best).

Then take that knowledge, apply the things that make sense for your team (resources, experience, yada yada), and tweak/customize/throw out the things that don’t (aka invent the rest).

Too many teams flip the process, spend too much time focused inward (inventing solutions to already solved problems), and don’t realize that the competition has already left them in the dust.

-Mike

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6 WD is the most common design style, I challenge the OP to find a game where swerve drive was necessary/needed.

If people are interested, 5188 put a decent amount of effort into figuring out what drive direction to pursue for 2016, and came to a conclusion of a chain-in-tube WCD. This was an attempt to balance several factors, including cost, weight, performance, maintenance time, and machine time. I’ll see if we can publish a white paper on our decision process before build season starts.

I really like this post in that it illustrates something that is hard to understand.

There are successful teams who use WCD, Sheet metal, swerve, kitbots, and every other style in-between.

The success comes not from using a particular style of drivetrain, but from building the right kind for your team. That goes for most mechanisms too.

5254 and 20 are both probably going to use shifting 6 Wheel WCD’s in 2016. 5254 will use Versaframe and gusset one together, 20 will use stock tubing and weld it together.
5254 will likely use a lot of COTS parts and gearboxes for everything and try to build something incredibly simple and then iterate on it. 20 will likely have a detailed CAD drawing of a robot we hope will be able to compete at the highest levels, then work with it until it works like expected.

Both have the potential to be successful in 2016, despite varied styles of build and materials available.

Use what’s right for your team. Do a detailed engineering analysis of what makes sense for you. Don’t be dissuaded by people who say you can’t win without this resource or that resources- they’re wrong.

Since the modern kit chassis/drivetrain is pretty good, if you use it you can spend more of your effort on figuring out the game and building great mechanisms. Great teams can win with whatever drivetrain they pick…it’s really not that important.

Also known as the pot roast rule.

In my experience, I have seen the highest correlation between robot performance and quality bumper design*.

*obviously not valid in 2015 or before 2008

We used to use the vexpro ball shifters until last year. We stopped using them, because we broke several in 2014, and ultimately went through 4-5 total in 2014. We not use the wc products ss gearboxes. We will go with an 8 wheel WCD this season, barring some very odd game. We are will likely also to chain in tube. We went through an extensive drivetrain research last season and decided WCD is the drive of the future for us.

We use vexpro versaplanetarys for everything else.