pic: 148 Follower Wheel Assembly

[Brandon Holley]

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

[BenB]

..

[=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

[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

[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?

[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.

[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?

[Jonathan Norris]

Originally Posted by JVN

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

John that sounds like a lot of work for you... we all know Karthik isn't allowed to design anything that would actually go on a robot!

[Chris Fultz]

Originally Posted by JVN

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

Do you want to forge a partnership with CollinChris?

It's a family business. Right now we have no products, we just intend to steal good ideas from Chief Delphi posts and set up shop. Right now we are producing a cool wheel follower assembly that it appears you have copied... (our lawers will be contacting you for the patent infringement)

[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...

[martin417]

Originally Posted by corpralchee

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...

This what we are doing. Not because of the slipping issue, but for "smoothness" of rotation. The large Vex omnis have two sets of rollers, offset to the sides for a smooth roll. The small ones would tend to go bumpity-bump as it transitions between the rollers. We thought the smoothness would be better for the encoders.

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

Why gear at all? ours is a direct drive set-up.

[JVN]

Wow, maybe this was NOT worthy of showing off. Sounds like almost every team in FIRST has something "identical" or better back in their shop. Color me corrected.

-John

PS - Of course I was joking about starting my own company and selling these.