pic: Team 691 Drivetrain CAD

[Garret]

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[steelerborn]

It looks really nice.

I have one question though, I only see two transmissions mounted, are these for the turning of the wheels or the module (I assume the wheels because they are cimple boxes). Just wondering on what you plan to use for the module turning.

[Tytus Gerrish]

Originally Posted by steelerborn

It looks really nice.

I have one question though, I only see two transmissions mounted, are these for the turning of the wheels or the module (I assume the wheels because they are cimple boxes). Just wondering on what you plan to use for the module turning.

it appears to be a coaxial crab drive with drive power supplied to the wheels through a shaft that rides inside the center of the crab module axis. at the top of each module you should see two sets of sprockets. the lower for steering. the upper for propulsion.

the trade off being you can rotate your modules arround and arround forever and not tangle wires, but with mechanical loss in the drive chain limits overall power put to the ground in cpmparison to motor-in module designs

[JVN]

I've said it before -- I don't think any team should spend their resources developing a Swerve drive during the competition/build season.
http://www.chiefdelphi.com/forums/sh...84&postcount=2

This is a mechanism intensive game -- there is a lot of development to be done in elevation systems, gripper systems, and minibots. Go with a reliable proven drivetrain, and you'll be MUCH happier with your robot's performance.

The performance gains you could theoretically get from going with a swerve drive will be 100% negated by the effort you'll spend developing it and getting it working, and the effort you'll have moved away from the other developments you could have been doing...

In short, I strongly believe that if you do a swerve drive your robot will be significantly worse than if you hadn't.

That said... good luck, and let us know if you need help.
-John

PS - The CAD models from the 148 2008 swerve are here:
http://www.chiefdelphi.com/media/papers/2277 Make sure you use bigger bevel gears than we did...

[Chris is me]

In addition to what John said - you made a post earlier abut how your team tried to do every objective in the game in 2010 and as a result could not reliably score. This post isn't an attempt to call your team out or anything - but if you guys haven't had a really strong season with a complex robot, maybe it's time to go for a simpler robot that can score reliably. Trust me, a simple robot that performs well on the field is much more inspiring than an engineering feat that doesn't drive.

[Tytus Gerrish]

yep. coax crab drive is the white elephant of first

[thefro526]

If your team has their hearts set on building a coaxial swerve drive for this game, you may want to look into using the team 221 modules. Using an off the shelf module with cut down on the amount of development you'll need to do significantly, just leaving you to design a frame, steering system and then working on the controls.

That being said, I'd listen to those in thread that speak against building a swerve drive during the build season - without having prototyped one in the off-season first. By the time you get the bugs worked out, your season may be over...

[Garret]

Thanks for your comments and concerns.

My team is in a better situation this year. We have more mentors, team members, a bigger build area, more money, better machining, basically better everything.
And then to add that, our sponsors are being extremely supportive this year and as a result we are making two different robots this season. One of them is a simple drive train, mecanum or 6WD (it can go between the two by changing wheels and adding the gear boxes). And the second is the swerve drive. We are also making a second robot to practice autonomous after ship. In other words we are working on both a simple and "stretch robot" this year.

I am handing the swerve modules off to sponsors tonight, and I will be handing the frame off either tomorrow or wednesday so yeah we are well on our way. And we are only directing a small amount of the team's resources to the swerve drive, basically me and some of the mentors, while the rest of the team and mentors work on manipulators. We are almost done prototyping our lift out of aluminum and are beginning to work on the grabber. Our programmers have already started planning how the code will work.
In other words we are doing pretty well right now (at least for my team).

But about the render it is old. I finished that on friday. I shall post a more up-to-date version soon.

But I appreciate all of your concern and advice.

So thanks.

[Duke461]

Good luck Garret. Make sure you give your drivers lots of practice time