2471 Off-season differential swerve

For fun, during the off-season, we are looking into creating a differential swerve. We think that it should be a fun machining and programming challenge and could possibly be useful in the official season if all details were planned out prior.

The module is powered by two Neos. The steering has a gear ratio of 19.5:1, which is slightly higher than what 2910 was running on their MK2 module. The module is driven by a 2.75" wheel with 1" Blue Nitrile tread, it geared to 15.75 ft/s free speed. While it is geared high I feel like it will still have quick accelerations using both Neos.

Inventor currently has the weight of the module at around 5 pounds including everything in the picture above.

The module could use Cims or mini Cims but would need either an encoder on the motors or on the wheel as the current design is using the neos built-in hall effect sensor. The module also uses the same KHK bevel gears used in 2910’s modules for the differential.

The module while it takes up a large footprint 7" by 7" from outer frame rails, it is short at only 5.2" tall. Mounted to the top of a 2 by 1 tube the module provides 1.375" of ground clearance.

This module is inspired by Aren Hill/971 and Bryce C.

As always questions and critics are welcome,
Owen Wilks
FRC 2471

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Are you planning on releasing the CAD?

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Most likely once everything is finalized.
-Owen W

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Could we have a view of the bottom of the module? It isn’t too clear how the bevel gears are packaged from the picture we have currently.

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You can’t really see the bevel gears from the bottom they are pretty hidden, but I tried to capture them the best I could.

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Where is the small bevel gear from?

It looks like an expensive watch - I like it.

How are you planning on controlling this module? Are you using an absolute encoder somewhere for rotation?

I think neo sensors are being used to close the loop

The smaller gear is from KHK or can be found on Swerve Drive Specialties(https://www.swervedrivespecialties.com/collections/mk2-module-parts/products/mk2-15t-bevel-gear)

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Thanks you, and yes there is an absolute encoder mounted directly to the wheel module, it has the three prongs sticking up and is the same one we used this year

I under stand a differential in terms of a car, but what purpose does it serve with a swerve who’s wheels are already independent?

Differential swerve allows each module to use both of its motors for driving or both for steering, or any mix in between. So if you are in a pushing match you can be using the power of 8 motors instead of 4

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What’d you render that with?

What’s supporting the bing bevel ring gears? Aren’s module had 4 sets of bevel wheels nestled between the wheel and the rings, but I don’t see anything like that on yours.

Good luck - it looks like a really strong design!

First, thank you! I have put a decent amount of time into it, the main image was rendered using Inventors built-in system.

While the system I used is similar to what Aren had, the system I am actually using was done by Bryce a while back, using the bevel gear and 84 tooth gear to trap the bearings in place when bolted together. If you look closely at the images above you should be able to see what I am talking about.

-Owen W

Could you put this in the AriMB spreadsheet? I’m curious to see the acceleration.

Also, I suggest an approach like this Another Crack at Differential Swerve to get a higher speed without changing the steering ratio. 15 FPS actually seems a bit low for all that power, but I’m no expert.

Hey Carlos,

I have never actually used the acceleration feature of AriMB’s spreadsheet, but I believe that I have put everything in correctly.


The speed I have it geared for is not much slower than an ideal 5,10,15 or 20 foot sprint, only slower by around .25 seconds at most. I also personally feel that acceleration is more important than top speed and that for our first diffswerve the slower it goes the easier it will be to control. But I know that with all the power it could defiantly be pushed harder and faster.

-Owen W

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