If you can’t afford the cost of 4 full modules swerve isn’t worth considering. In running 2 modules, you loose some traction due to weight being on powered wheels. Frame design also becomes extremely weird.
A well driven 6wd or kitbot can get close to the performance in swerve most years. This year is a bit of an outlier where swerve is more dominant, but I highly doubt the GDC will keep on making swerve friendly games for very long. But look at any other year and 6wd can and does compete on the same level as swerve bots.
Take a look at 525 in 2016. IIRC, tank in the front, party mode swerve in the back.
Not quite the same thing, but interesting all the same.
If you are interested in just playing with holonomic drive base a 3 wheeled kiwi is far and away the cheapest. You can do some interesting things with traction and kiwi as well .
Ok yes three wheel can work if done correctly, however, its not something most teams will be able to pull off correctly. For most games, you are making serious tradeoffs to run 3-wheel swerve that isn’t usually worth it.
If you want to fool around with an ill-advised, sub-optimal drivetrain that gives you a lot of functionality of swerve but certainly not all of it, might I suggest octocanum?
You can, for the price of four mecanum and four regular wheels, four gearboxes, a few pneumatics, and a little ingenuity, create an easy-to-build, easy-to-drive, easyish to program, omnidirectional-and-fast-when-you-need-it-but-really-pushy-with-high-torque-when-you-want-it drivetrain. It’s fun to build, fun to show off, and isn’t anywhere even close to as finicky or difficult to work with as swerve–you run mecanum geared fast to zip around the field with high maneuverability, and if you get into a pushing match (or don’t want to be pushed) you fire one solenoid to pop down your four traction wheels (which are also geared down to traction-limited pushing torque) and suddenly you’re a tank drive with amazing push and almost no ability to turn.
We ran it for several of our most successful years before swerve was really a thing. It’s significantly less elegant and less efficient than a swerve drive, but only requires four (geared down) motors and four pneumatics plumbed to the same solenoid in order to have fast omnidirectional driving and fantastic beast-mode pushing power.
[That said, I think if you want to do swerve but it’s too expensive, save the money for a year or three and do that instead. A well-executed swerve is definitely superior to a well-executed octocanum drive, though also much harder to execute well. Whatever you do, make sure you’ve nailed it in the off-season before you try it during build season.]
I feel like a lot of people sleep on the kit bot, if you are a rookie team I would highly suggest against creating and driving a swerve since it is the most complicated to create and understand (esp in terms of programming). A kitbot will serve you well and also provide a test bed for future events and years. The last thing you want is your drive to crap out mid match and stretching yourself to make a complex drive when you could invest that time into mechanisms would be to your teams detriment.
Would it be legal to make a robot with one center wheel like the one-wheel skateboard? To steer, you’d put down “hands” to drag the floor differentially…? Then all your traction would be on that one wheel.
You could also steer by leaning if you had the right shape of tire and a weight transfer mechanism.
Of course I’ve seen “ball” robots like BB8, but hard to put bumpers on that
I don’t believe there is anything illegal about it, it would certainly prove to make packaging of your mechanisms more difficult much like an h-drive would
I would chose X drive over H drive. One less motor, a lot easier to program. The main issue with X drive is that you sacrifice speed because each wheel is at 45 degrees to the primary translation directions. but if you gear it for a higher speed, it will be plenty fast.
Plus X drive seems to do better with the normal un-evenness of typical playing field surfaces and would certainly be a better choice if there is any ramps or sizable bumps on the field. H drives always seem to require a bit of tuning to give the center wheel enough contact with the ground to maintain grip and even with tuning and a sprung suspension, it is easy for that center wheel to loose contact with the floor if there is any sort of terrain.
I implore you to think about what you will do if a module breaks in competition. If you can only afford 2 modules, and you use both on your robot - you have no spares. If swerve is an absolute “must have” for you - I would invest my energy into fundraising to buy “full sets” rather than designing a 2 wheel swerve drive.
But if you want some real advice -
Swerve gets you from point A to point B a little more efficiently - but what about when you get there? For younger, less experienced teams - you’ll get more “bang for your buck” focusing on game piece acquisition, manipulation, and delivery than on moving a little more efficiently. Swerve is a last 5% sort of improvement. Focus on the first 95%.
A two-wheeled “rocker” in the middle is better than a single wheel for an H drive, because it doesn’t have any weight on it (so it’s not stealing traction) when it’s not being used.
Hey y’all, we’re definitely interested in swerve for the future seasons, here’s a picture of our current robot using a KoP drivetrain (AM14U5). Hoping we can step it up in the off-season with some cool things!
(Full disclaimer: we are aware of the many challenges that swerve presents, we thought the 1 wheel swerve was an innovative idea that could come up with some awesome movements. We have designs for a WCD, however we did not feel that the attempt to make one over the kitbot would be worth it…glad we made that decision)
Just some academic silliness that’s loosely related to the OPs question:
You can get a 1 wheel robot that has control of 3 degrees of freedom (translational XY and rotation). And that wheel doesn’t even need to pivot like swerve!
Meltybrain robots use their 1 wheel to spin very fast and a gyro to time acceleration and deceleration of their wheel such that every time they do a full revolution, they also translate a little bit.
