VersaSwerve Reveal Video

[VacioArconte]

Originally Posted by Chak

Wow! Can you specify which parts are custom and how those parts would be made? I want to know how close you can get to a swerve using Vexpro COTS items as much as possible.

I see 2 ma3 absolute encoders on the module rotation. Is it just to provide a second choice of mounting, or does the use of 2 encoders help the accuracy/consistency/something? The ma3 encoder from Andymark is $45 each, and I find it hard to justify $180 extra if every other swerve uses only one encoder for position.

Actually, the left encoder (the one on the BAG output) is the steering encoder, while the right encoder (the one on the drive axle) is the drive encoder. Of course, drive encoders are optional with swerve, but after living through last season without drive encoders on swerve for autonomous, we thought it was important to include it.

There are only a couple of truly custom parts - most of the parts are machined from COTS parts. While designing, we intentionally avoided any parts that would require the use of the CNC, and so the most complex tools required for construction are a mill and a lathe.

To answer your question - the U gusset holding the wheel module together is custom, and the encoder mounts as well as the encoder coupler are all 3D-printed. There is a support tube around the drive shaft machined from a McMaster-Carr part, and a support block as well. If memory serves, everything else is machined from COTS parts.

[sanddrag]

A couple of STEP files would be greatly appreciated. What version of SolidWorks were these done in? I can't open in Inventor 2016, which usually opens most SolidWorks files fine.

[VacioArconte]

Originally Posted by sanddrag

A couple of STEP files would be greatly appreciated. What version of SolidWorks were these done in? I can't open in Inventor 2016, which usually opens most SolidWorks files fine.

These were done in SolidWorks 2015, which might explain the compatibility issues. We'll try to have some STEP files up tomorrow.

Edit: STEP file is up!

[Grant Cox]

I love this module - 2468 did an awesome job with not just the design but their documentation as well.

Full build instructions, BOM etc are now available on the VEXpro "Examples & Guides" section here: http://www.vexrobotics.com/vexpro/ex...-guides#Guides

[asid61]

Very neat. I'm looking at the CAD right now, and a lot of stuff is very well incorporated. The weight seems to be around 6.7lbs after I went through and checked the weights on the motors and stuff, although I'm sure I missed a lot. ~7lbs would be a closer estimate I think.

Cool stuff:
1. Clamping bearing block for rotation
2. 8mm to hex adapter for a pulley instead of gear reduction
3. Encoder mount doubles as a spacer
4. Use of versatube for the top of the module
5. Bearing gussets for spacing out gears in module
5a. Supported by C-channel
5b. The only precise gear-thing on the whole module
6. No need for precision except on a few parts
5c. Mostly drill press and chopsaw work, and not that much of either

Some possible improvements:
1. To make it more feasible for teams without a mill/lathe (or those who want to assemble faster), a few parts screw things up: the module rotation/support tube, and the block that mounts the aforementioned to the module. Both are relatively precise parts unfortunately, and I think it would be possible to convert it to low-precision and remove them.
1a. Why the custom U-gusset instead of two right-angle gussets on each side?
2. The encoder mounts are cool, but 3D printers are expensive. It seems to be possible to replace them with simpler pieces.
3. Encoder-shaft coupler on the versaplanetary can be removed and replaced with a versaplanetary encoder. This also removes the MA3, so it doesn't cost too much extra.
4. The square slot in the tube. I think like this can just be a 1.25" diameter hole, or even 1.375" to allow for more tensioning.
5. The slot for the bearing tensioner for the belt. You already have a tensioner with a WCP cam. According to SDP-SI's belt calculator you don't need the tensioner to achieve good contact with the 18t pulley anyway; what pushed you to have it?
6. 5/16-18 taps on the bottom shaft instead of 1/4-20 (thunderhex makes the latter easy) and the hole running all the way through the 3/8" shaft on the upper shaft of the module.
7. Bronze thrust bearings instead of roller. A completely personal preference, but they only cost a few dollars more so I like the tradeoff.
8. Use of a 48t gear as a faux versahub for the timing belt pulley. I had to do this once and did not like it. There has to be a better way...

[LCJ]

Originally Posted by asid61

1a. Why the custom U-gusset instead of two right-angle gussets on each side?

The main problem with the right-angle gussets from Vex was that we didn't feel they were quite long enough for supporting the module. The U-gusset is "taller" and therefore the screws can be installed further apart and make the structure significantly more rigid. The U-gusset can still be drilled out by hand if you download the drawing from Vex and paste it onto sheet metal.

Originally Posted by asid61

3. Encoder-shaft coupler on the versaplanetary can be removed and replaced with a versaplanetary encoder. This also removes the MA3, so it doesn't cost too much extra.

We might make that change to the design in the future. The current design doesn't have the VersaPlanetary encoder because we developed the VersaSwerve system before they were released.

Originally Posted by asid61

5. The slot for the bearing tensioner for the belt. You already have a tensioner with a WCP cam. According to SDP-SI's belt calculator you don't need the tensioner to achieve good contact with the 18t pulley anyway; what pushed you to have it?

The main reason was because Vex didn't have the length of the belt that would work perfectly. The current belt is a little on the long side, and we had to account for that with the tensioner. One size shorter, and the CIM motor would have been too close to the wheel module.