This is a offseason project I worked on much earlier this year, just as a personal CAD project. I wanted to wait until I had 1 real module to post, but Kickoff is creeping up, so I’ll post that when I have one.
While I liked the very compact and Lightweight setup of the CIM in wheel, I didn’t want to deal with the wires ever again, and would rather avoid mercury on the robot (sliprings). This lead to the fun mental exercise of “if I were to make another swerve, what would it be?”
This module is the answer.
Showed this to Kevin on 2451 and he took off running and now has a fancy 2 speed version.
So when my poem said a new swerve from Aren Hill, it wasn’t kidding!
Looks great! What is it geared for? I can’t tell from the section view, but it looks like it’s cutting close on the clearance for the wheel. Do you know off hand the amount of clearance it is?
A few questions immediately pop up for me:
How is the CIM shaft so short? Isn’t it against last year’s rules to modify motors?
Where would you get the bevel gears, and how much would they cost?
What’s the weight?
From the cut-out in the other picture, I’m having a hard time figuring out how the large turning gear is mated to the grey-ish ring that acts as the weight-bearing thrust bearing for for the entire robot. It seems like all of the robot’s weight is hanging from this ring which is hanging from the gear?
A few years back I found it very difficult/impossible to find a non-Mercotac COTS slip ring that was simultaneously (a) rated for FRC current levels and (b) within single-components COTS cost limits. It is possible that you could make your own spring-loaded slip ring, but YMMV with inspectors/rules in a given season.
It is possible (now), I don’t have the link handy but they do exist. It’s for use in wind turbines so it’s actually got three wires. I’ve also found a few on various websites that are rated for 30A continuous.
R30 specifically allows wiring, mounting brackets and output shafts to be modified. That rule has been there for years, so I would assume it would stay.
It has to be the most compact and lightest swerve to date!
Professional grade designing, I looked through the entire design earlier this year and thought it was brilliant. We tried to design something totally unique but nothing we came up with was as elegant. Thanks for the inspiration!
It’s compact for sure, but I can’t figure out the bearing design.
As far as I can tell, all of the vertical loads are taken by the CIM shaft (!), and I can’t really tell what takes the horizontal loads. There’s an upper steering bearing on the CIM shaft, but the only lower bearing I can see is the white ring below the steering gear and that doesn’t have much radial contact. What am I missing?
+1. I have a swerve design exactly like this on my computer, except with a 2" colson instead of a 3.25" versawheel, ad it weighs a minimum of 5.3lbs. Still heavier than Bryce’s swerve, albeit only very slightly.
Plus, making it into a shifting version requires a lot of weight unless you don’t use a COTS shifter shaft.
EDIT: Of course, if anybody could make the design lighter it would be Aren. So it could be lighter actually.
Very nice swerve Aren. It’s cool seeing your drives. Are you using a dead axle? Is it possible to flip the cim?
Just curious, is there any way we can get our hands on the CAD files to take a closer look at the module? I know this may be a stretch but worth a shot too: If a team wanted to build this, would the spec sheet include all the parts that come together to make this?
I don’t think theoretical weights are fair to compare. If the system isn’t made and working, it doesn’t matter how light it is.
I could go design a 4 lb swerve now, no guarantee it will work or hold up. Many of the recent designs posted aren’t robust enough to survive a season (I think Aren’s here would though, as he’s fielded 5+ swerves at this point I think).
