pic: 148 Follower Wheel Assembly

[=Martin=Taylor=]

Originally Posted by NoahTheBoa

Here is a relevant Q&A on the subject
http://forums.usfirst.org/showthread.php?t=10919

Well... one could argue that the friction in the side-ways direction from this device COULD be used to stop the robot from sliding sideways...

But it would be one anal inspector to call you for that

[artdutra04]

Originally Posted by Greg Needel

I like the fact that black gear is an ABS rapid prototype. Want to clue the world into the right pitch for interfacing with a vex gear?

I'm about 95% sure it's 24 diametric pitch.

Edit: Yup, they're 24 DP.

[Brandon Holley]

wow JVN this looks VERYYYY familiar....ours looks almost identical...

[NoahTheBoa]

Originally Posted by Hachiban VIII

Well... one could argue that the friction in the side-ways direction from this device COULD be used to stop the robot from sliding sideways...

But it would be one anal inspector to call you for that

I think that since it's an omni wheel the sideways friction won't be enough to slow a 120 lbs+ robot.

[DonRotolo]

Very nice! But why such a big green gear? I'd have used a smaller gear and a similar green gear on the encoder. I am curious.

Also, I think we'll be stealing the idea! (kinda sorta) Thank you!

Don

[NoahTheBoa]

Originally Posted by Don Rotolo

Very nice! But why such a big green gear? I'd have used a smaller gear and a similar green gear on the encoder. I am curious.

It looks to me like it's a 1:1 ratio. Would make programming a bit easier without the extra math to account for the gear ratio.

[JVN]

Originally Posted by Raul

Humm - how much bigger than the green gear is that omni wheel? The reason I ask is because on the carpet, the wheel may sink in enough to allow the gear to grab some carpet fibers.

Also, is it just pivoting off the robot frame from that empty set of holes, and thus using gravity to keep it in contact with the floor?

It's 1/8" bigger radially. It should be okay, if there are problems during testing I'll tweak things a bit. We plan to spring load it down. Spring tension, TBD. Surgical tubing, of course.

Originally Posted by Joe Ross

We were planning to do the same thing, but with all vex components, including the new encoders. Hadn't gotten to it yet.

The electrical engineers on our team say I have an "encoder mental block" where I refuse to model them into the final design. I had a heck of a time cramming them into Tumbleweed last year. This year we knocked em out almost immediately so they'll keep their mouths shut.

Originally Posted by AdamHeard

Soo.... will Vexlabs be selling these?

How much would you pay for one? I'm starting my own company KarthikJohn.

Originally Posted by AdamHeard

We had a similar plan, and were thinking if gravity wasn't sufficient, a rubber band to add a slight amount of tension would be easy enough.

I think with some down-force this should get pretty good grip on the regolith.

Originally Posted by artdutra04

I'm about 95% sure it's 24 diametric pitch.

Edit: Yup, they're 24 DP.

Yes, 24DP. We just modded the VEX 60t Gear Model to make the coupler piece. Works pretty well.

The side plates are laser cut ABS, 1/8" thick (cut on our small 12x24" laser, not the big one that does the sheet-metal.) The coupler is 3D printed ABS on our Dimension SST. I feel pretty darn spoiled.

Probably could have gone with a smaller package, but we've got plenty of room in the drivetrain to mount it. Like Raul said, if the 60t gear catches some carpet we may change it. I'm not real concerned. *Shrug* This was done quickly and the design group moved onto other things.

-John

[Andrew Bates]

Why not use the larger omni wheel? It would get the wheel away from the gear more. Also the larger omni probably has a less likely chance of slipping...

[Travis Hoffman]

Originally Posted by JVN

The electrical engineers on our team say I have an "encoder mental block" where I refuse to model them into the final design. I had a heck of a time cramming them into Tumbleweed last year. This year we knocked em out almost immediately so they'll keep their mouths shut.

"Knocked out"....the encoder models or the EE's?

[JVN]

Originally Posted by Travis Hoffman

"Knocked out"....the encoder models or the EE's?

This year the encoder models... but thanks for a good 2010 plan.

[AdamHeard]

Originally Posted by JVN

How much would you pay for one? I'm starting my own company KarthikJohn.

-John

Not counting the cost of the encoder, I'd say $25-30 probably.

Originally Posted by AdamHeard

Not counting the cost of the encoder, I'd say $25-30 probably.

Ditto on this. With encoder, depends on the accuracy/type of the encoder.

[Jared Russell]

Looks strikingly similar to something we're making...

[Taylor]

Originally Posted by JVN

How much would you pay for one? I'm starting my own company KarthikJohn.

Where would you put this company? Halfway between Toronto and Greenville is...I dunno...Kokomo?

[Kingofl337]

With a few modifications you could use the US Digital encoders that come in the kit.