Swerve Drive CAD

[echin]

Thanks for the suggestion on the plates. I just changed the top and bottom plates and cut out almost .5 lbs total.(per module) I have been thinking about more compact cylinders, but I can't decide what to use. A final version will probably have something much smaller. I thought that I had a spacer underneath the sprocket, but looking back apparently I didn't...
The bearings are needle bearings and are mounted between two flat plates to give them a flat bearing surface. The entire caster is held on with several stop collars to prevent the caster from bending.

[Bryce2471]

Cool design concept. I have a few suggestions though, the shifting would be nice, but if you're planning on puting this in an actual frc robot, you need to watch the BOM. I believe that AM super shifters run for abou $240, and most conventional swerves are over $250, you multiply this cost by four, and you could use over half of your robot budget in the drive train.
Also, its vary important to have good encoding to run a swerve drive so you should draw the encoders, if you haven't already.

[echin]

I have a pretty much complete BOM, and 1 module comes to arround $500... Almost half of that is shifting parts or parts needed to use the shifter.
What do you mean by drawing the encoders in?

[Jefferson]

I think he's talking about the wheel rotation sensing. We use US digital magnetic encoders.

[echin]

I don't think that there are any CAD files for the encoders that I'm using, but there may be some somewhere. I do know the dimensions, and I made sure that they fit. Here's a link: http://www.digikey.com/product-searc...s=AMT102-V+KIT

[Jefferson]

Just make sure you have a controls plan for the encoders. Without absolute values, you'll either need the modules in a known position when it's turned on or have a homing routine. That is why we use analog for rotational position control whenever we can.

[Bryce2471]

The swerves my team produced this summer used two quadrature incoders from USD. Theyare not absolute, but they are very precise, and they have a built in homing tick. They work nicely, but when I put them in the CAD drawing, they almost didn't fit. That's because the swerves are compact, they only take up a 6" by 6" box.

[echin]

We used the CUI encoders on our climbing arm this year, and didn't have any problems with them except for user error. I would have used the USD encoders, but they cost almost twice as much. Both encoders should have enough space. One is mounted on the top, and the one on the bottom is farily far away from the caster.