Examples of wide-based robots using traction and omni wheels

[thefro526]

Check out this video of 1918 in 2010: http://www.youtube.com/watch?v=YGTwp...eature=related

Some of their other videos show them using standard 2008-ish Kit wheels on the end instead of Omnis. I'd contact someone on their team and see if they're willing to share their experiences with you.

Originally Posted by thefro526

Check out this video of 1918 in 2010: http://www.youtube.com/watch?v=YGTwp...eature=related

Some of their other videos show them using standard 2008-ish Kit wheels on the end instead of Omnis. I'd contact someone on their team and see if they're willing to share their experiences with you.

Thanks a bunch!

[Tom Line]

Originally Posted by Akash Rastogi

This is probably wrong actually. If you have a wide base robot, and you're powering all wheels, you should have 0 issues with wheel scrub while turning.

Not true. In fact, we went through a design change already because with a well balanced wide robot with pneumatic wheels at the corners inflated to max pressure, the robot had a very hard time turning.

[Donut]

My team used a wide robot with kit wheels in the front and omni-wheels in the back for the 2008 season, after doing this in a long configuration had worked out well the year before. In the end I think the robot ended up turning too well as we only had one or two students who could actually drive the thing and it still fish-tailed or spun out on occasion during matches (we were also geared for 13 fps which didn't help matters). Since then we've gone back to the long configuration with omnis every year since because it gives us good turning without going overkill like the wide base did with it.

I found a video of ours with some of our practice driving, skip ahead to about 1 minute in to see the robot actually driving around:
http://www.youtube.com/watch?v=7ZRYY...nCcI2E3HOLmYKZ

I'm sure the blue alliance has some match footage as well but that will probably be far away shots of the field.

When people say "turn too well" when referring to omnis, what exactly do you mean by that? Do they turn more than the controlled angle? If there were other options to ease in turning, would you suggest omnis over them, or no? If no, then what "them" would you suggest? We are hoping on using 4" wheels for our robot.

Thanks!

[EricH]

I think the post right above yours answered your question...

Originally Posted by Donut

My team used a wide robot with kit wheels in the front and omni-wheels in the back for the 2008 season, after doing this in a long configuration had worked out well the year before. In the end I think the robot ended up turning too well as we only had one or two students who could actually drive the thing and it still fish-tailed or spun out on occasion during matches [...]
I found a video of ours with some of our practice driving, skip ahead to about 1 minute in to see the robot actually driving around:
http://www.youtube.com/watch?v=7ZRYY...nCcI2E3HOLmYKZ

Originally Posted by EricH

I think the post right above yours answered your question...

Oh. I didn't see the part about spinning our of control. Thanks!

[PayneTrain]

Note when I say "traction wheels," I'm not talking about the kitwheels. i'm talking about aluminum-cut, 2 inch wide IFI roughtop wheels. The definitive stock traction wheel (We used to make some killer custom traction wheels until 2008).

Those things invented wheel scrub.

Originally Posted by PayneTrain

Note when I say "traction wheels," I'm not talking about the kitwheels. i'm talking about aluminum-cut, 2 inch wide IFI roughtop wheels. The definitive stock traction wheel (We used to make some killer custom traction wheels until 2008).

Those things invented wheel scrub.

We're using Andymark Plaction wheels, not the kitwheels.

[PayneTrain]

Originally Posted by SuperNerd256

We're using Andymark Plaction wheels, not the kitwheels.

Wedge or rough?

Originally Posted by PayneTrain

Wedge or rough?

Roughtop all the way.

[Garrett.d.w]

Have you guys thought of a six wheel drive wide base? I modified a kitbot at the start of the season to do this (1/8th in drop on the center wheel). I haven't gotten to drive it extensively, but it seems to work.

As for four wheel drive. We have successfully gone two traction wheels in the back (or wherever most of your weight is), and omnis in the front. I can't find a vid anywhere, but those at bunnybot 2010 can attest to the fact that it was quite strong and fast (we were able to tow a goal that was made out of rough plywood on uneven carpet and win a few pushing matches). It was also very easy to drive (we managed to deliver coffee without spilling it ).

If you don't want to modify your bot to try it out, you can build spacers that allow you to put two omnis on one hub, allowing you to simulate a full width wheel.

Originally Posted by Garrett.d.w

Have you guys thought of a six wheel drive wide base? I modified a kitbot at the start of the season to do this (1/8th in drop on the center wheel). I haven't gotten to drive it extensively, but it seems to work.

As for four wheel drive. We have successfully gone two traction wheels in the back (or wherever most of your weight is), and omnis in the front. I can't find a vid anywhere, but those at bunnybot 2010 can attest to the fact that it was quite strong and fast (we were able to tow a goal that was made out of rough plywood on uneven carpet and win a few pushing matches).

If you don't want to modify your bot to try it out, you can build spacers that allow you to put two omnis on one hub, allowing you to simulate a full width wheel.

We thought of doing a 6WD drop center, but that would make us even less stable than we are now.

[Mk.32]

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

2012 KOP Wide base, completely stock and it turns perfectly.
Though with another 80 or so lbs of weight it might get a bit tricky.
Omins in the front or back will help for sure, we ran them with our 2011 robot and that was LONG 4 wheel drive.

http://www.youtube.com/watch?feature...&v=3RnBf0_tKAg

[Garrett.d.w]

Originally Posted by SuperNerd256

We thought of doing a 6WD drop center, but that would make us even less stable than we are now.

With a very small drop, it is very stable (the kop drop is huge, 1/8 is about a fifth of the kop drop). Fully loaded and on carpet, the drop is barely noticeable. It also helps that we are using small wheels. Four wheel drive will always have an up on stability.

I'll post a "drivers review" about it when we start practicing next week.