pic: 2015 Off-season Single Speed Coaxial Swerve Chassis

Off-season single speed coaxial swerve chassis design done by former student, current mentor, Nick Coussens.
See forum thread for more information and link to the CAD for this design and CAD for our 2014 and 2015 swerve designs.

Is there a hidden electronics pan, or was it just not CADed? The design is certainly interesting.

There is a polycarbonate panel in the center for electronics, though it has not been populated in the CAD model.

I always love seeing the swerve designs your team comes up with

Can you show a closer view of module?
and discuss what metrics you (Nick) are going after?

Love PWNAGE swerves. an also always like the bevel edge bumpers.

Why did you go with a 775 on the VersaPlanetary for module rotation? What ratios are on it/speeds can this achieve?

Can you post a link to the CAD? I can’t find any links in the forum thread. Or at least give more in-depth directions to finding the link if one exists.

The steering gearbox is a Vex Planetary with 100:1, then through a 40 tooth (this design and 36 tooth for the 2015 unit) into a 72 tooth which the wheel is attached to. 48 RPM steering speed at peak power for a 550 motor.

We have used 5XX series motors on both our 2014 and 2015 swerve drives for steering. I’m not sure why Nick used a 775, we have never had an issue with the 5XX series motor for steering. I am guessing it is because we had Nick setup our Versaplanetary gearbox in Solidworks with “Configurations” and he picked a different configuration.

To discuss configurations a little more. When designing the robot we can insert a Vex Versaplanetary gearbox into Solidworks and change it to any possible configuration. This is a tab that allows you to reconfigure an assembly automatically, once you’ve spent the time adding in all possible parts. You can hide ,surpress, change items in the assembly so that it “reconfigures” the assembly. We currently can change between single and double stage reduction. We can change between the Bag motor, RS550 and RS775 motors. We can change the output shaft options between the .375" hex, .500" hex, .500" round, and 8mm keyed CIM shaft. We can also change to a dual motor option. This all occurs with a click of a button on the same gearbox assembly. So there is no deleting and reinserting a new custom setup. There is no creating a custom assembly each time we need to insert a VersaPlaentary gearbox into the robot design. We should create a video sometime to show how to do this for the First community.

Kevin is correct, I put a large lexan sheet in center to mount electronics to as well as some smaller panels in those open side areas. I put the motor controllers in those side areas as they would be close to the swerve modules there. I chose not to spend time populating all the electronics in as that is always so dependent on the game as far as space availability and felt my time was better spent working on something else.

As Kevin mentioned, we as a team have one single assembly for every VP combo. I was working on this project on my personal computer rather than the Genesis Automation/team servers so when I tried changing the configurations I was having issues. I decided to just leave it as is since editing the VP in real life is very straightforward and could easily be changed to a BAG or 550.

I have some decent renders that show things pretty well, so I’ll see if I can get those up here.

Here are a couple renders that show things a bit better.

Feel free to ask any questions. Keep in mind that there were/are still things I would want to improve on this design, I just found a stopping point and had some other projects I wanted to hit before the new season begins.

Sorry for the large images.

Very nice swerve module, it is nicely packaged. I am really impressed that the motors are stationary in this design. I feel ignorant, but what separates a swerve drive from a coaxial swerve? What size wheel are you using and what are the drive gear ratios? Are all the gears stock? How much does the module weigh?

Also, can you explain how the bearing surface works between the wheel module and the rest of the drive module?

Are you guys willing to share your configurable VersaPlanetary assembly? If you’re OK with it, I’d love to add it to the parts library I’ve been working on for my team and the FRC community.

Looking at the other renderings you posted (here and here), I have to complement you on such a spiffy design. You guys sure do a good job of removing excess material.

What is the part number on the large bearing used for the pivoting axis of the module?

That’s the practical point of coaxial - the motor cases are stationary relative to the chassis. Coaxial swerve means that at some point, the steering bearings and the drive axle bearings have the same axis. The far more common configuration is similar to this, where the drive axle goes through the steering bearing.

Also, the wheels look to be 4" diameter, based on a 2.5" diameter CIM.

To add to this, the purpose of going coaxial is usually to prevent wires from being tangled; in a non-coaxial swerve, the motor turns with the module, so a 360* turn would be a full twist of the wires.

That’s cool, I never thought about using configurations that way. I found configurations while exploring Solidworks, but I could never figure out how it could be useful. Would changing configurations change the weight on Solidworks too? Also, would you be able to reconfigure the gearbox after it’s been mated to the robot?
+1 to sharing the file and/or a video making it.

After reading this, I just had to try it for myself. Here are my results. It has the new Versaplanetary encoder stage, but I decided not to include the motor choices in my version. It made more sense for me to separate the motors, which are bought separately. I would still want to see how you guys did it, and compare it with my own methods. It’ll be interesting to see how the “experts” did it compared to my googled knowledge.