Universal/Standard Drive Base

Soon team 2228 will be undertaking the task of reviewing all current drive bases to see the pros and cons of each and in the end come up with “the perfect” drive base so that we can speed up the design process of future years by having a pre-agreed upon drive base, that we feel can accomplish what we’ll need for in any FIRST game. My question to everyone is are any other teams doing, thinking of doing or have done this in the past? If so do you have any advice on the matter? And also what is your opinion on whether this is a good move or not?

Personally, I don’t really think that it is possible…

For instance (even though this was my first year in FRC), I know that many of the drivetrains we saw used in Breakaway would not be a good fit for lunacy, and vice versa.

Specifically, lets look at swerve drive. All the pictures I’ve seen of swerve drive from games that are not Breakaway, have very low ground clearance, like 221’s drive (not sure what year this was though):

If a team wanted to use that in Breakaway, they would need to use the tunnels, but a drive like that also doesn’t leave a lot of room for a kicker, or lifting mechanism. Thus, you make the robot bigger, which means it has to go over the bumps. But that frame won’t let you go over the bumps, so you have to raise your ground clearance, a la team 2108:

If you’ll use the handy-dandy search feature, you’ll see that it’s been tried, and fallen flat each time.

That being said, let me know if you make any real progress and I’ll jump on board.

Please keep in mind that you will have to post your design on a CD like forum in order to use any design created outside of the build season. Good luck I look forward to considering your new design for our teams robot this coming season.

Since each game is different, the robot to play each game has to meet different requirements, so it’s not real likely that there is such a thing as a universal drive base. If there were, it would probably not be optimized for any game.

How about coming up with half a dozen designs that are not quite finished, but can accommodate different game requirements? You can use past games for ideas for this. Of course, the real game next year will not be satisfied by any designs you come up with before then…says Mr. Murphy

Is this true? I’ve seen multiple designs based on concepts thought of during the off season this year that weren’t posted on CD.

If parts are specifically designed during the off season it has to be posted. Concepts/unfinished parts are legal to keep to yourself if you modify them during the build season

<R34> Parts custom-made for FIRST and provided to FRC teams in the Kit Of Parts for previous FRC competitions (e.g. 2006 FRC transmissions, custom-made motor couplers, custom sensor strips, FRC CMUcam II modules, etc.) may be used if the part is still functionally equivalent to the original condition and:
A. The part is now generally available as a COTS item from an accessible source, or
B. All information required to fabricate the part (e.g. complete drawings, materials list, Gerber Files where appropriate, etc.) is openly available, such that any team could fabricate the part (or have it fabricated for them).
Otherwise, such parts are prohibited from use in the 2010 competition.

Emphisis mine.

Also, be aware that the rules may change for next year … but as of right now, no final designs can be created prior to kickoff.

Team RUSH (frc27) has used the same universal chassis concept since 2008.

The team has agreed that in order to work as efficiently as possible we will use the same standard chassis design and adapt the rest of the robot to work around it.

In my opinion, many of the most successful teams deploy similar strategies…though I don’t know if they actually have an edict stating that they won’t bother reviewing other ways to design or build their chassis like we do.

Our base chassis is a simple 6wd. It has no features or options other than wheel size and transmission style.

The idea of having a “standard” drive train you use year after year does have its benefits - you already have a rolling practice robot on day 1, you can get any needed parts for the drive train early and get a basic robot built quickly to start adding manipulators, and everyone knows exactly how it works.

But it also has some con’s. As others have said, it probably won’t be the “best” drive train for any given year - jack of all trades, master of none. But there’s another huge con that you’ll be depriving yourselves and future students of: The ability to design, build, and test a new drive train every year. Where’s the fun in building the same thing every year? How much do you learn the third time you’ve built the same drive train?

We go in every year knowing the options for a drive train: 4 wheel, 6 wheel, omni, mecanum, crab, casters and traction wheels, something crazy. Over the past 4 years, we’ve done 6 wheel’s twice, 4 wheels once, and mecanum once. And every year we have a valuable discussion with the students about what drive system to use, what the pro’s and cons are, etc. Then the students get to work out the specifics of the design and build it. Yeah, it may take a little longer… but it’s a valuable process.

I think that the teams who use the 6WD found it relatively easy to carry their dropped centers into the 8WD scheme. I think it’s definitely possible to create a very basic layout, but don’t let that stymie you from any possibilities in the build season.

  • Sunny

We have pretty much used the same design the past 2 seasons albeit with improvements on manufacturability and maintenance each year and really even the 2 seasons before; however with different materials. It is awfully hard to argue against a well designed 6/8wd drivetrain particularly when taking into account time to manufacture/design/program. I am a firm believer in sticking with the basic skid steer drivetrain unless there is some never before seen drastic change next year.

THere is a lot to be said for having a general idea of the drive walking into the season and just being able to churn one out in the first week or so and devote all of your time towards perfecting a manipulator.

I don’t know about that…some would say that 254 has done ok since standardizing their drivetrain in 2004.

I, and anyone who knows anything about the Cheesy Poofs, would have to agree with this. While this year they may have had 8 wheels instead of the usual 6 typical of the “West-Coast Drive,” there’s nothing radically different from year to year from what I have seen.

While the chassis doesn’t necessarily make or break a robot, I think there’s something to be said about using a somewhat simpler design that’s perhaps weaker in comparison to other designs, and instead using those resources, i.e. manpower and time, to focus on other challenges.

I agree with your final conclusion that time can be spent elsewhere but NOT on the reasoning. A good drive train is critical to having a successful season. It will make or break your season.

When doing your research for this SDB please consider multiple options rather than just copying 254. For example, weight the benefits and costs of sheet metal, fiberglass, wood, steel, welded tube, etc. Weight the benefits and costs of cantilevered wheels. Shifting vs One Speed. 6wd, 8wd, 10wd, 14wd. Also, share your research. Publish a white paper on why you chose one method over the other.

It was my interpretation that this would be a larger effort than a single team, and thus that it was similar to the “open source” bases that have been tried in the past.

Simply standardizing a style of drive base inside of a team is relatively simple and effective, and if that’s the direction this is going, good luck and I hope the results for your team are as potent as others.

Instead of a single “universal/standard drive base” for all occasions, why not develop your own “drive base system” - along the lines of the Ansy Mark “C-Base” chassis in the KoP but better? The kit frame can be configured for long or wide chassis, 4WD or 6WD, different wheel size & type, etc. Regardless of the final configuration, it uses standardized frame rails & mounting hardware, motor mounts, axles, chain tensioning, etc.

We have been developing our own drive base “system” over the past few years. It doesn’t look anything like the kit chassis, but it includes components that accomplish the same basic functions - and more. It has “standardized” structural elements, structural element fasteners, axles, gearbox mounts, chain tensioners & idlers, etc. It can be adapted for wide or long, various wheel arrangements (size & quantity), different ground clearance, “U” or rectangle (as viewed from above), etc. In the fall, we design and prototype improvemed components. After kickoff, we figure out what configuration we need for the game, lay out the detailed plan, and design new components if needed. It still requires some thought and takes time to build. However, it is faster than starting from scratch and frees up brain cells to concentrate on the manipulator. The parts are all based on proven concepts, and we have a lot more flexibility than we would with the kit chassis. We are usually cutting chips by the end of the first week and driving by the third week - long before the manipulator is done. So far, none of the components have been identical from year to year, but the improvements are becoming more “evolutionary” than they are “revolutionary”.

There is nothing particularly special or ingenious about our “system”. It is the product of our teams experience and efforts, and it works for us. Over time, I think most teams develop their own approach to the various bits of drive base hardware. I encourage you to approach your drive base design as a collection of “universal/standard components” that can be mixed, matched, and modified as needed, rather than a “universal/standard” assembly.

You have nothing to lose and lots to gain from this endeavor. The fact that more than one person has said that it cannot be done is good reason to try. You may find that they are right but you will still be better prepared for next season after an in-depth study of different drive systems.
Considering different materials is a great idea. As a robot inspector I savor every non Al frame!

Although we have used extremely similar drivebases each of the past seven years, we don’t go into the build season restricting ourselves to just one style. Although the style of manufacture will probably stay the same (because that is what we can build easily), the drivetrain design could change drastically.

For example, in 2009, we spent weeks deliberating on whether to build a long or wide robot. Eventually, we decided on long not because it was what we had done before, but because we believed it allowed us to optimize our superstructure. In retrospect, that may have not been the right decision, but that is a debate for another day.

True, but the claim was that any design work done in the off season has to be posted.

You’ve gotta inspect in Wisconsin then. :slight_smile: