Is there a reason that you used specifically a Neo for the turning motor? It seems like it just makes the module much more expensive and throws a lot of unnecessary power into the system.
I’ll hazard a guess that they didn’t want to have to go for the comparatively larger reduction of a 775pro. Additionally, it lets them get away with having 2 of the same motor (i.e. making it easier to keep spares). With the extra stage required, I wouldn’t be surprised if the 775pro version were significantly heavier.
If I were to nitpick this design, it would be really cool if the drive and turning motor shared the same pinion, so that replacements could come from the same reserve.
The main reason for using the NEO is that the higher torque, lower speed nature allows for the simple 2 stage reduction. The NEO weighs just a little more than a Bag or 775. It also makes the module look nice and symmetric. It would never be used to its full power potential in this application, but that’s ok. There really isn’t anything lost by using a over powered motor.
The Neo + Spark Max is comparable in price to a BAG + Talon SRX. If the NEO lets you get away without a VersaPlanetary then that is a big cost saver.
That totally makes sense, I was mostly just thinking that a lot of teams have SRXs, BAGs, VPs, etc, but as we move further from the release of the NEO that becomes less and less relevant
@sanddrag Thanks! Full CAD is available at the top of this thread if you want to check out the module in detail.
The large bevel gear is from Swerve Drive Specialties. It is a machined down khk SB1.5-6015.
The big steering bearing is a X-Contact thin section bearing equivalent in size to a Kaydon KA035XP0 or Silverthin SA035XPO also from Swerve Drive Specialties.
This is really a phenomenal design, thanks for posting it in so much detail! When the end result is so simple and elegant, it’s hard for the casual observer to see how much work went into it. It looks absolutely bombproof. Have you put any thought into a 2 speed version?
@s_forbes Thank you. We went through quite a few concepts and designs before making one we were happy enough with to designate as the MK2, figure out all the manufacturing for, and actually build.
I haven’t put much though into a 2-speed version, but the layout of this module with the extra drive gear stage seems much better for 2-speed then the MK1 module.
I really appreciate that you suspended your module with (what appear to be) picture framing wire for the photo shoot. Simple but thoughtful touch that made the presentation of this post even more professional. Seeing the module freestanding in the photos is really cool.
Have you done any driving testing with these yet?
I’m specifically curious on the effects of the NEO requiring zero speed before direction changes due to the limits of the spark.
FRC Blog - 2019 Motor Controllers and MXP read from post 349 on.
See their post in the 2019 motor options thread for a video of the NEO/Spark steering.
We have not done any actual driving tests yet. We just started testing yesterday with getting the steering of the module up and working. REV has sent us some firmware modifications that they expect will help with the direction change issue we are encountering at the moment. The plan is to work on this tonight.
Depending on if the game is good for swerve or not, all development work for this module will either continue or come to an abrupt halt until the post season.
I love this module, and I’m hoping that this game is good for Swerve. The NEO opens some interesting packaging options that weren’t quite doable with CIMs.
With the game being pretty swerve friendly I’m happy to say that development with this module has continued. The new Spark Max firmware has fixed the direction change issue we were seeing. We quickly threw together this chassis to get our programmers going. It’s not pretty, but it is up and running and working great.
Those modules are VERY compact. Having lots of space inside a base for things other than driving is pretty excellent!
So far the modules have proven to be very solid. We are looking forward to competing with them. Here is our robot reveal to see footage of the modules in action.
I’m happy to report that we drove off L2 of the Hab in all but maybe one match at Glacier Peak this past weekend without any damage to the swerve modules.
I’m curious about what kind of sensors were used on the drive and turn motors. I see the analog absolute encoder on the turn motor. Were you able to use that encoder as an analog sensor connected directly to the Spark Max, or was it used just to set the absolute position of the internal encoder? And for the drive motor, the integrated encoder was good enough?
You guys have really inspired me and my students to play with a swerve drive this coming offseason. If for nothing more than how fun it looks to drive.