6 wheel swerves

Does anyone know anything about 6 wheel swerves? Has it been done?

Is it possible to do a 6 wheel drop center swerve? Where the center 2 wheels are dropped the normal 1/8 of an inch, enabling easier turning with the same swerve capabilities? Is that bad? Do you not need it to turn easier?

Any pics/vids would be great! Gonna go look at CD Media some more and see what I get.

Thanks!

[Ankit S.]

I believe 1625's 2010 robot was a 6 wheel swerve. Heres a vid: http://www.youtube.com/watch?v=U7sXWhHfULs

Wouldnt it just be easier to program the robot for turning in a "wide" orientation?

[thefro526]

Team 1625 built a 6WD swerve in 2010. It ended up playing on Einstein.

If you search through Aren Hill's recent posts, he's got some solid information and pictures out there. Or PM directly if he doesn't post in this thread.

I believe that 1625's 6WD swerve is the first and only 6WD Swerve.

Good picture in this post: http://www.chiefdelphi.com/forums/sh...7&postcount=21

[O'Sancheski]

Like everyone has stated, 1625 has done it. (I believe that they are the only ones so far.)

Here are some pics that I got from CD-Media. I'm sure that 1625 has many more on their website.

http://www.chiefdelphi.com/media/photos/35824

http://www.chiefdelphi.com/media/photos/35087

http://www.chiefdelphi.com/media/photos/35854

Also, here is a great whitepaper that 1625 published about their swerve drives throughout the teams history.

http://www.chiefdelphi.com/media/papers/2578

[Peyton Yeung]

1625 also posted this paper that references the 6 wheel drive swerve.

http://www.chiefdelphi.com/media/papers/2578

Thanks all! Just finished watching their video on youtube from 2010. Seems nice. The only real implementation I can see is extra pushing power in all directions, which is in itself useful, depending on the robot.

[Aren_Hill]

If you want to know more about that message Dillon Carey, he's the one who made the thing

[Akash Rastogi]

Originally Posted by Aren_Hill

If you want to know more about that message Dillon Carey, he's the one who made the thing

People tend to forget that 1625 isn't solely Aren Hill.

[Lil' Lavery]

Originally Posted by SuperNerd256

Thanks all! Just finished watching their video on youtube from 2010. Seems nice. The only real implementation I can see is extra pushing power in all directions, which is in itself useful, depending on the robot.

See the litany of other threads on the issue, but more wheels does not mean more "pushing power."

[thefro526]

Originally Posted by Lil' Lavery

See the litany of other threads on the issue, but more wheels does not mean more "pushing power."

This is not always true, especially with small rough-top tread wheels. I believe someone posted Data on the subject that showed a ~20% increase in Pushing Power/Tractive Force/Force of Friction when a 4" wheel was widened from 1" to 2". (For all intents and purposes, the same as adding another 1" wide wheel to the DT.)

This seems to be caused, at least in part, by the way rough-top tread interfaces with carpet.

^ What Dustin said.

[Lil' Lavery]

Originally Posted by thefro526

This is not always true, especially with small rough-top tread wheels. I believe someone posted Data on the subject that showed a ~20% increase in Pushing Power/Tractive Force/Force of Friction when a 4" wheel was widened from 1" to 2". (For all intents and purposes, the same as adding another 1" wide wheel to the DT.)

This seems to be caused, at least in part, by the way rough-top tread interfaces with carpet.

Please provide a link.

[Aren_Hill]

234 has not posted the Data online, as it is their choice. But Chris graciously sent me the info and test setup they used to determine traction differences. They compared 4",6", and 8" wheels, 1" and 2" wide. 4x2 wheels won out by a very significant margin

[thefro526]

Originally Posted by Lil' Lavery

Please provide a link.

I don't have a direct link to the data as it was given to me second hand.

If all goes well, I will have some data soon on the relation between pushing force and contact patch once we complete testing with our prototype chassis.

[JamesCH95]

Originally Posted by thefro526

This is not always true, especially with small rough-top tread wheels. I believe someone posted Data on the subject that showed a ~20% increase in Pushing Power/Tractive Force/Force of Friction when a 4" wheel was widened from 1" to 2". (For all intents and purposes, the same as adding another 1" wide wheel to the DT.)

This seems to be caused, at least in part, by the way rough-top tread interfaces with carpet.

Originally Posted by Lil' Lavery

Please provide a link.

I think that the principal is sound from a real-world physics standpoint. I think that it is very possible to see significant traction gains from wider wheels.

From my race car experience (both designing, setting up, and driving) I have learned that polymers' coefficient of friction is related to their contact pressure. A larger contact area therefore leads to a higher coefficient of friction.

They way it was explained to me is that as a polymer, i.e. roughtop or a tire tread, is pushed onto a surface small parts of the two surfaces become interlocked. As normal force between the two surfaces increases, the two surfaces interlock less and less per unit normal force. At some point the polymer/material interfaces are completely saturated and there is not much more grip to be had.