Question about wheel preferences

[sanddrag]

Originally Posted by Cory

Everyone knows Truck Town is the only team that can't be pushed

Especially the 2003 one, before the ruling.

[Andrew Schreiber]

Originally Posted by sanddrag

Especially the 2003 one, before the ruling.

Gosh was that a good looking robot. They did so much research on what tread to use. I was going through one of 68's cabinets last year and found about a half dozen tread samples (12+ treads each)...

[Ankit S.]

Originally Posted by R.C.

I don't remember/see getting pushed during the comp by mecanums.

-RC

My bad then, our driver said he was doing the pushing so I believed him

[jwfoss]

Based on your team number and assumed rookie status as an overall team, I would strongly suggest staying away from mecanums for your first year of competition. There is only ~2 months to kickoff, which I don't believe is enough time to purchase, build, code, and practice with the drivebase.

My suggestion would be to build a 6wd as soon as you get the kit of parts, and start driving it. You should be able to source everything you need directly from the KOP with a few additions. A well built kitbot can out perform ~50%+ of what teams put on the field each year.

Go watch the "Kitbot on Steriods" video that team 1114 was nice enough to film and post for everyones use. If you find you would like to improve upon the KOP chassis setup, review the gearing and consider using treaded wheels, IFI/VexPro and AndyMark have lots of options available.

As a rookie, build a simple robot that you know how to maintain and fix, and really focus on your superstructure/manipulators that interact with the field and game element.

I am personally tired of the mecanum vs. 6wd debate; each have there uses, tradeoff, and advantages. This opinion is not based on my preference of traction drives vs. omni-directional drives. It is based on the resources, cost, and training that I believe are required to produce a solid rookie robot.

[Taylor]

Why would being a rookie team prevent them from using mecanum drive? In our experience (2011) we found the mecanum drive to be easier to install, more robust, and with less mechanical problems than a traditional chain-driven 2WD, 4WD, or 6WD*. Plus, canned code for mecanum can easily be found. We simply plugged in some sourced code and went at it.

With an hour or two of practice, our rookie drivers performed admirably at the CAGE Match, comparable to our "professional" regional drive team this past season.

Given, mecanum wheels are not cheap, but if any team has the resources and initiative, I say go for it.

*Of course this comes with the type of implementation. We put the wheels directly on AndyMark nanotubes, and put the kitbot chassis on top of that assembly. Aside from having to keep an eye on the axle bolts that hold the wheels in place+, we had no issues at all, we didn't have to fool with chain runs, and our drive system was in a small, compact, constrained space.

+ checking them every 3-4 matches to make sure they were tight

[Clinton Bolinger]

Originally Posted by Cory

Everyone knows Truck Town is the only team that can't be pushed

Didn't Truck have Mecanums this year?

So does this mean the Mecanum are un-moveable in the right situation?

-Clinton-

[Aren_Hill]

Originally Posted by Clinton Bolinger

Didn't Truck have Mecanums this year?

So does this mean the Mecanum are un-moveable in the right situation?

-Clinton-

Only TruckTown

[AdamHeard]

Originally Posted by Taylor

Why would being a rookie team prevent them from using mecanum drive? In our experience (2011) we found the mecanum drive to be easier to install, more robust, and with less mechanical problems than a traditional chain-driven 2WD, 4WD, or 6WD*. Plus, canned code for mecanum can easily be found. We simply plugged in some sourced code and went at it.

You can make the case for your mecanum drive being more reliable than your previous 2/4/6wd's, but not the general case that mecanums are more reliable than 6wds.

Edit: Fixed, thanks Taylor! Also TIL what FTFY actually means!

[Taylor]

Originally Posted by AdamHeard

You can make the case for your mecanum drive being more reliable than your previous 2/4/6wd's, but not the general case that mecanums are more reliable than 6wds.

FTFY.

And that's exactly what I was doing. In our experience, we found that to be true. I did not intend to make that a global statement. As with everything, your results may vary.

[thefro526]

Originally Posted by jwfoss

Go watch the "Kitbot on Steriods" video that team 1114 was nice enough to film and post for everyones use. If you find you would like to improve upon the KOP chassis setup, review the gearing and consider using treaded wheels, IFI/VexPro and AndyMark have lots of options available.

Quoted this for emphasis. Many, many teams would benefit immensely from taking the standard kit bot and tweaking it slightly. You don't even need a 2-Speed if you do it right. Just gear conservatively (~11fps or so) with some traction wheels and odds are that you'll out perform most machines at your event - especially if you always move.

[Chris is me]

Originally Posted by thefro526

Quoted this for emphasis. Many, many teams would benefit immensely from taking the standard kit bot and tweaking it slightly. You don't even need a 2-Speed if you do it right. Just gear conservatively (~11fps or so) with some traction wheels and odds are that you'll out perform most machines at your event - especially if you always move.

I'd gear a bit lower than 11 FPS for games without open fields. 8-10 FPS is better where control is desired for inexperienced teams and drivers (including my own)

[thefro526]

Originally Posted by Chris is me

I'd gear a bit lower than 11 FPS for games without open fields. 8-10 FPS is better where control is desired for inexperienced teams and drivers (including my own)

Better to be too fast than too slow and you can always slow it down in code, whereas speeding it up is a bit more of a mechanical affair. (Yes, I know, you're not using the motors in the most efficient manner, this is assuming you're not over gearing and only dialing back your speed 15-20%.)

Also, FWIW, our guys handled our 12-13FPS drive in high gear without many hiccups Chris. Maybe you should work on your driver training skills there bud. (We're still BFF's right?)

[Chris is me]

Originally Posted by thefro526

Better to be too fast than too slow and you can always slow it down in code, whereas speeding it up is a bit more of a mechanical affair. (Yes, I know, you're not using the motors in the most efficient manner, this is assuming you're not over gearing and only dialing back your speed 15-20%.)

I'm just reminiscing about the lack of precise control we had when making verrry small adjustments at the rack. You guys had a better robot so you didn't have as many small adjustments to make as we did, but we have a super long arm which makes lining up a bit of a challenge.

For the full field, we love the extra speed, but at the rack we need some work. Maybe we can adjust our controls appropriately.

[AdamHeard]

The point shifts with the amount of friction in the drive, but past 10 fps with 4 CIMs in drive as a single speed is a risky proposition. Many teams have achieved success with it, but it requires more skill to drive. Slowing down in code is a complete nonsolution and provides no more benefit than the driver just deflecting the joystick less. It doesn't add any resolution.

The lack of precision due to the higher speed is one downside, and the ability to push real well without tripping breakers becomes marginal.

In my opinion, the single most beneficial thing a rookie team can to to reach competitive success is to build a 6wd kop frame with supershifters.

Shifting completely eliminates the tradeoff of being able to push hard enough, and drive fast enough.

[thefro526]

Originally Posted by AdamHeard

The point shifts with the amount of friction in the drive, but past 10 fps with 4 CIMs in drive as a single speed is a risky proposition. Many teams have achieved success with it, but it requires more skill to drive. Slowing down in code is a complete nonsolution and provides no more benefit than the driver just deflecting the joystick less. It doesn't add any resolution.

Any time we've experimented with slowing the drive down in code we've used scaling functions and never had issues, always felt like it drove the same, just slower. Actually helped our drivers utilize mid-range speed much better, for what it's worth.