Gripping a Tote

[mrnoble]

Originally Posted by IronicDeadBird

Has anyone tried omnis? The ability to pull in totes and still elevate them vertically is appealing to me. (As opposed to elevate side to side this ain't willy wonka)

did you mean mecanums? I know a bunch of teams used those to great effect last year.

[IronicDeadBird]

Originally Posted by mrnoble

did you mean mecanums? I know a bunch of teams used those to great effect last year.

People used mecanums for ball intake last year? Like an el toro a la mecanum?

[CalTran]

Originally Posted by mrnoble

did you mean mecanums? I know a bunch of teams used those to great effect last year.

Not in this case, no. Omnis where the wheel is parallel to ground and the rollers perpendicular would allow for the wheel to pull the tote in, yet allow for the rollers on the wheel to let the tote be easily pulled upwards by some other mechanism.

[mrnoble]

Originally Posted by IronicDeadBird

People used mecanums for ball intake last year? Like an el toro a la mecanum?

1619 and 1987 used them, and I remember a couple of El Toro intakes that used them.

[Mike Marandola]

Originally Posted by IronicDeadBird

People used mecanums for ball intake last year? Like an el toro a la mecanum?

Spectrum did

[mrnoble]

Originally Posted by CalTran

Not in this case, no. Omnis where the wheel is parallel to ground and the rollers perpendicular would allow for the wheel to pull the tote in, yet allow for the rollers on the wheel to let the tote be easily pulled upwards by some other mechanism.

I was thinking about counteracting gravity using the mecanums, though I see now what you were thinking. That's a cool idea...

[IronicDeadBird]

Is anyone else thinking four mecanums for intake that are then changed to pop the crate up?
Maybe this is the year we see a swerve drive utilize mecanum wheels... I'm down

[mrnoble]

Originally Posted by IronicDeadBird

Maybe this is the year we see a swerve drive utilize mecanum wheels... I'm down

MecaSwerve!!

[CalTran]

Originally Posted by mrnoble

I was thinking about counteracting gravity using the mecanums, though I see now what you were thinking. That's a cool idea...

Well I mean, I believe the intake design is that like the one on Ri3D 1.0, where the intake is always on the ground, so that the tote can't down with gravity, but can be easily sucked upwards. I suppose the advantage is that you can have the intake closer to the robot, therefore have the center of gravity of the tote stack closer to the robot center.

[Chris is me]

Originally Posted by IronicDeadBird

Has anyone tried omnis? The ability to pull in totes and still elevate them vertically is appealing to me. (As opposed to elevate side to side this ain't willy wonka)

Another way to achieve this result is to use a pneumatic cylinder to open and close your collector. This lets you use the grippiest wheels, provides some spring force for your collector, and still allows for a release.

Originally Posted by Mike Marandola

Did you install it on a wheel? If so which one? Lack of surface contact might be the problem. The BB wheels may be working better for you because they have more rubber and can compress which increases the contact area. We are using the Green Grippy tread on a claw with about 4 inches of surface contact. In my experience, even a 3 inch long piece when laid on the tote, is extremely difficult to move side to side.

We installed it on an AM Performance Wheel from 2010-2011. The tread was just a bit too big to fit inside the ridges of the wheel, so we just kind of put it on top. Our initial tests used rivets to secure the tread and we assumed the metal contact was the problem, so we switched to using a zip tie or two on the ends so that the vast majority of the green tread would contact the wheel. Same results.

We know the bins were only touching the top third of the wheel or so due to their V shaped profile, and I'm sure that's a big factor, but other wheels work better with the same limited surface contact.

Originally Posted by pfreivald

Blue BB wheels work very well for us--but they do wear quickly during prototyping. That should be less of an issue once we have limit switches, etc. in place to keep them from scrubbing so much.

Something else to consider that we're going to try today is using a mechanical slip clutch of sorts to prevent wheel wear. We're playing with using flat urethane belting for power transmission in our intake, which should slip when stalling but if properly tensioned will not.

[pfreivald]

Originally Posted by Chris is me

Something else to consider that we're going to try today is using a mechanical slip clutch of sorts to prevent wheel wear. We're playing with using flat urethane belting for power transmission in our intake, which should slip when stalling but if properly tensioned will not.

Good idea--methinks I'll have to steal it and present it to my team!

[JesseK]

Originally Posted by IronicDeadBird

Is anyone else thinking four mecanums for intake that are then changed to pop the crate up?
Maybe this is the year we see a swerve drive utilize mecanum wheels... I'm down

The totes aren't smooth, nor are they perfectly vertical on the sides - maybe some sort of spring-loaded horizontal suspension would make it work?

[MrJohnston]

Originally Posted by asid61

Colson wheels are unbeatable.
We tried that green tread above, blue nitrile, assorted wedgetop, roughtop, pneumatic, higrip, banebots orange, and delrin (we have a lot of tread and wheels).
Of those, I would rank colson as waaaay above anything else, followed by banebots, trailed by pneumatics. Everything else was iffy. We didn't have great results with the green tread, but perhaps it's not the same stuff.

Polycord also gets pretty decent grip.

I am wondering if there is a particular Colson wheel you found to be the best one? We are in the midst of proto-typing our device and are doing pretty well with the traction wheels from the Kitbot, but want to investigate other options...

[Ian Curtis]

Originally Posted by Lil' Lavery

Green banebots wheels worked the best in our limited trials, however we have concern over how quickly they wear.

Did you try the white kit wheels as well? We found the white kit wheels worked better than our green BB wheels, which was very surprising to me. I'm wondering if our test set up wasn't fair to different types of wheels.