The Crab Challenge

Well, here we go again...
I'm assuming you've all submitted your Inventor award submissions already, and are probably looking for something to do with your mad CAD skillage. So I'm issuing a challenge: Design a crab drive. This is a very complex thing to do in Inventor, and I'd like to see which teams can come up with a plausible design. The "submission" shall be two renders: One of an individual module, the other of the frame with modules onboard. There won't really be a single winner, just us giving props to designs that seem possible.

Go for creativity! You could go with a traditional crab, or you could go with a coaxial. You could even think up something new!

Adding onto the theme of time limits that FIRST gives us, lets set a deadline: Two weeks, or on the 22nd. All designs should be posted by then, and then we can begin to examine the details (plus this thread will serve as a good inspiration point for teams wishing to try out a crab).

So fire up Inventor!

[Brandon Holley]

and what is the prize??

Bragging rights, and having something pre designed before the upcoming season. (yes, there's always an upcoming season, no matter when it is!)

[Crebb]

Where do we post these pictures. Want us to upload to the CD galleries and then link to it from this thread?

That sounds good, or just attach them to the thread. As long as we can get to it from here, it doesn't matter too much.

[Aren_Hill]

mines already posted from awhile ago and were using an iteration of it
3-speed shift on the fly swerve +coaxial

The point of the challenge was to have those who are interested design a new one. I also have about 3 designed, but for the sake of the challenge, I'll be designing a very very, VERY different one.

[Tom Bottiglieri]

You mean a swerve drive?

The difference between the two is negligable in relation to the contest, so design whichever you think is more fun/challenging!

[=Martin=Taylor=]

My first attempt at a crab drive was unsuccessful. The idea was to use as many off-the-shelf parts as possible to save time machining. Although I had some innovative ideas, the design was ultimately too heavy and required to many chains.



Our team basically abandoned the idea even before the season started.

However, after being inspired by 118's crab drive (they were next to us in Atlanta) I took another shot at coaxials.





Although the modules themselves look nothing like 118's, the chain-system and frame are very similar. I haven’t CAD'd the frame, so no pic...

The modules themselves are made from single pieces of U-channel, which eliminates the challenge of machining 5 bolted side-plates. By using two wheels I also eliminated the chain (which in the original design had no method of tensioning). And by eliminating the chain I made the modules much shorter.

Specs:
-5" wide
-4.5" tall (base of wheel to top of module)
-4" wheels

I'm going to machine these over summer-vacation so stay tuned for another pic!

[zander_108]

I am going to model a full version of a crab drive that i have designed.. Just not right this second

[Daniel_H]

what is a crab drive?

[zander_108]

A crab drive is a drivetrain That all of your wheels can rotate along the Z axis, as well as being able to drive normally.

see these links

http://www.chiefdelphi.com/media/search/results/40411

http://www.chiefdelphi.com/media/search/results/40412

[negfrequency]

o man its ironic you post this thread

in the preseason my team was playing around with chassis designs and one of my buddies drew up an incredible crab drive design on inventor. Id provide it but i don't have it. Maybe he'll send me a rendering.

They are difficault because you not only have to keep the systems in sync, but you also have to carry rotation to the wheels somehow, unless you have the motor mounted to the wheel in which case you have to find out how to carry wires

Well folks, the deadline is coming close. And so I figured I'd post my progress on a strange new variation on a crab drive.
Enjoy!