which holonomic drivetrain do YOU think is the best any why???
 

this is a poll between crab drive/swerve drive, mecanum drive, and omni drive (small wheels are perpendicular to main wheel). feel free to list any other holonomic drive u might know about or prefer.

also feel free to IM me

Re: which holonomic drivetrain do YOU think is the best any why???
 

No poll.:(

EDIT: Didn't know if you knew it wasn't there. Thanks!

Re: which holonomic drivetrain do YOU think is the best any why???
 

the poll is up now :D.... i had to post the thread before i put up the poll... sorry :(

Re: which holonomic drivetrain do YOU think is the best any why???
 

Kiwi :D

Re: which holonomic drivetrain do YOU think is the best any why???
 

why???

Re: which holonomic drivetrain do YOU think is the best any why???
 

Asking which one is best is a bit difficult because there are many factors involved like, Cost, Build Difficulty, Programming, Control, etc...

Personally, the only type of Omni-Drive I would consider is a Swerve. The upside to a swerve drive is that you have full traction, which is something that Holonomics and Mecanums lack. The downside to a swerve is that it's difficult to build and can be a pain to program and drive.

Re: which holonomic drivetrain do YOU think is the best any why???
 

well stated.... point taken :)

Re: which holonomic drivetrain do YOU think is the best any why???
 

I think that a 360 degree with all four pivots turn independently moving swerve drive is best since that's what we are driving this year.

But I have to give very high marks to the omni/twitch hybrid I saw at Philadelphia. (Sorry I've spazzed on remembering your team number/name).

Each corner was a pair of Andy-Mark Omni's bolted together so that there was a continuous set of rollers around the circumference. They were set up in a standard 4 motor drive.

Two opposite corners were mounted on Delrin pivots. The wheels could be turned 90 degrees by two small pneumatics.

Best of both worlds: tank drive with good forward / backwards grip but a little slip to allow easy turning and the ability to flip into a omni-bot for strafing and translation movements.

A very clever solution to allow omni-bot flexibility with a low center of gravity and clearing the humps.

Re: which holonomic drivetrain do YOU think is the best any why???
 

I would say it's highly dependent on the task.

There are complexities with crab/swerve that aren't present in the others - with a short build season like we have, it may be too complex to accomplish (when you consider everything else you want to accomplish). Then again, they provide more pushing power in any direction than the others - is pushing power important enough to accept the additional risks that come with the complexity of crab/swerve? Do you have the weight available for crab/swerve (as it is typically heavier than other drive systems)?

Having Mecanum wheels on the corners works great, so does having omni wheels on each of the 4 sides. But if you need to go up a ramp, an omni wheel setup like that isn't going to work, while mecanum will. And just taking the omni's at 45 degrees to the frame in the corners is basically mecanum, only with the added complexity of needing to mount everything at 45 degrees to the frame.

So before you can really get good answers, you have to define the task and the associated parameters. Each system is good, but different systems will excel at different tasks and with different parameters. One of the key challenges with building a robot for FIRST isn't identifying a single "best" system and perfecting it to use year after year. It's in identifying what the best system would be for a given task and working in a very short time period to perfect it.

Re: which holonomic drivetrain do YOU think is the best any why???
 

You're talking about 1218, I believe they won and award for their drive.

Re: which holonomic drivetrain do YOU think is the best any why???
 

Best for what?

(I don't consider swerve drive holonomic.)

Re: which holonomic drivetrain do YOU think is the best any why???
 

You took the words right out of my mouth!

Re: which holonomic drivetrain do YOU think is the best any why???
 

1) What are the requirements of the game?
2) What can you build and program in the 6 weeks?

If the drive you choose fits both, it is the best.

If I had to choose, I'd go with mecanum, because it's relatively easy to swap out the mecanums for some standard wheels and spacers. Swerve, you have to lock the modules (depending somewhat on what arrangement you have).

BTW, Kiwi Drive is 3 omni wheels arranged in a triangle.

Re: which holonomic drivetrain do YOU think is the best any why???
 

Mecanum drive has proved quit useful to us this year.

Re: which holonomic drivetrain do YOU think is the best any why???
 

Octo-canum. ;) Name inspired by "nonadrive"

Re: which holonomic drivetrain do YOU think is the best any why???
 

point taken. the question and poll was meant to see what people thought the best drive train was in GENERAL. in other words, what drivetrain is the most adaptable to any situation? no system is going to be perfect and most teams will definatly realize the need to change strategies year after year. i also didn't want to limit this discussion in any way. i left it up to responders to give a situation and then give an opinion. FIRST is so dynamic that giving one specific situation is just as bad as giving none, no?

Re: which holonomic drivetrain do YOU think is the best any why???
 

please explain. i dont know what octocanum is. also tell us why u think it is the best

Re: which holonomic drivetrain do YOU think is the best any why???
 

Octo--8.
Canum--(me)canum.

8-wheeled mecanum drive (which is actually being done this year).

The other drive referenced: Nonadrive.
Nona--9. (For one of the teams using it, Neuna is an acceptable variation.)
Drive--self-explanatory.

Omni-drive setup with 4 wheels pointing in the same direction and a drop-down center one at 90* to the rest of them. The 4 are on pods such that traction wheels can drop down for extra power in a pushing war. Used by 148 and 217 this year.

Re: which holonomic drivetrain do YOU think is the best any why???
 

It's my play name for a drive very similar to the "nonadrive" deployed by 148 this year, but with only 8 wheels and 4 of them being mecanum instead of omni. See pg.4.

My post was more joking than anything, though. You should evaluate each drive within your strategy for each particular game. Each style of drive, wheel type, and variation will give you different advantages and disadvantages, and you need to see which of them are going to work best in your particular strategy.

Re: which holonomic drivetrain do YOU think is the best any why???
 

If you can pull off a field-centric, independent swerve drive, it's an amazing experience. It has a slight lag over mecanum wheels (the pods need a small amount of time to spin into position), but it's extremely agile, maneuverable, and depending on your choice of wheels and gearing, can out-push nearly anything.

But to do this, you'll need strong mechanical design, CNC manufacturing and software development resources, as well as a lot more time to develop and debug when compared to simple skid-steer 6WD. It will also take a big bite into your budget - both weight-wise and financial. And with the added quantity of components in the system comes the added chance that something will break.

Re: which holonomic drivetrain do YOU think is the best any why???
 

I love a well put together Mecanum system, but the fact of the matter is that nothing on this list can touch a simple, elegant 6WD (8WD this year) with a drop center. Just ask 1114, I haven't seen them deviate from this strategy for a great many years.

A crab can match it if done properly, but I bet a poorly rookie team could build a solid 6WD much more easily (in fact I know they can, just look at 2056's rookie robot http://www.chiefdelphi.com/media/photos/28599).

But if it is purely omnidirectional motion you are looking for, Mechanum is pure holonomic, and easy to build/maintain.

Re: which holonomic drivetrain do YOU think is the best any why???
 

Did you happen to see this picture posted during build season?

http://www.chiefdelphi.com/forums/sh...highlight=1708

Re: which holonomic drivetrain do YOU think is the best any why???
 

wow thats nice :O... do you have any follow up pics? or maybe some pics of the setup working during practice/testing?

Re: which holonomic drivetrain do YOU think is the best any why???
 

Not only did I see it, I was working in the pit right next to theirs during the DC regional. Unfortunately, 1708 had major issues all weekend, and never got to really show what their design could do at full potential. :(

Re: which holonomic drivetrain do YOU think is the best any why???
 

http://www.youtube.com/watch?v=cHJJQ0zNNOM


This

Re: which holonomic drivetrain do YOU think is the best any why???
 

Nonadrive, obviously. If you don't count that, I'm going to say 6wheelswervedrive takes the cake.

Re: which holonomic drivetrain do YOU think is the best any why???
 

Mecanum is pretty simple to build and program yet still produces good results. This made it the drive train of choice for many teams this year, including 1138.

However resources and difficulty aside, swerve definitely wins in speed and mobility as proven by 1717's amazing robot. :D

Re: which holonomic drivetrain do YOU think is the best any why???
 

I was more amazed by their hanging mechanism... Kinda looked like a machine gun sticking out of the robot

Re: which holonomic drivetrain do YOU think is the best any why???
 

After getting a tour through 217's practice bot tonight I am incredibly impressed by the Nonadrive.

Re: which holonomic drivetrain do YOU think is the best any why???
 

Given my druthers with all other constraints aside I'd go for 4-wheel, fully independent, continuous-turn swerve almost every time. a well-executed swerve beats most other pretty readily as far as widest applicability and best performance across the board. That said, there are other constraints, though they affect different teams and games in different ways.

Cost: A well-done pivot drive is almost always more expensive than mecanum or omni. In fact, if anyone's succeeded with a cheaper version, I'd love to talk. Pivot usually (though not always) requires milling, and of course more motors. After pivot, mecanum is usually more expensive than omnis, just by virtue of the wheels themselves.

Building/Wiring Difficulty: Everything's as difficult as you make it. That said, it's a lot "easier" to make a pivot drive complicated than an omni drive. That's not to say many teams don't make creative and effective omni, mecanum and other holonomic drives as well. However, from fabrication to wiring to programming, pivot drive is a tall order. I've never heard of a team with a successful pivot that didn't start examining the possibility in pre-season (then again, this is helpful for almost any type of success).

Programming: A pivot drive is certainly more complicated than a just simple tank, but how far you go with it is really up to you. We currently have crab, spin, x- and y-biased snake, x- and y-biased auto, and x- and y-biased tank (all with arbitrary fronts) at various levels of development. Depending on the game, a decent crab and/or snake can be more than enough to facilitate successful driving.

Traction: A good pivot works wonders here. Mecanum lacks in the area, as do omnis wherever they're used. (If you use omni front wheels and traction backs, you're pretty easy to push up front.) Perpendicular/angled wheels suffer here too, as you're effectively sliding the wheels' projection not along your movement vector.

Another novel idea: Last year, my team went with a 6wd wide configuration with a 7th deployable wheel in the back lowed to lift up the back 4 wheels. On the regolith, this allowed us to break more easily (transverse coefficient was greater than inline), spin quickly, and if we were lucky, move sideways. Of course, this all depends on the friction coefficients and their ratios, but suffice to say there are other options--notwithstanding nthdrive.

But if we're talking truly versatile, I've got one word: walking! ;)

Re: which holonomic drivetrain do YOU think is the best any why???
 

Personally, I like mecanum, because you don't have the weird angling issues that you get with using omni-wheels, and it's pretty much plug-and-play with a standard 4wd with 4 gearboxes from a hardware standpoint.

Even though swerve drive is probably the best drivetrain, You need to ask yourself: Is this doable with our timeframe, our experience level, and our resources? If not, you need to think about alternatives.