pic: 3928 Swerve Module
 

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Aren and Co. over on the Neutrinos have cooked up a swerve module unlike any FIRST has seen before.

"Necessity is the mother of invention" pretty much sums this up for me. They thought "How else could you make a swerve module lighter and smaller?" and this is what came of it.

I've been excited about this thing for a long time and am very pleased to see it successfully constructed. Extremely elegant design.

-Brando

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Wow. I hope you guys make it to championships so I can see this in person. Do you have any shots from other angles? I can't see where you put the drive motor, but I assume it's on the other side of the wheel?

Incredible design.

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Wow, this looks amazing! I like the belt tensioning system. A few quick questions:

• How do you drive the wheel? It is somehow coaxial, or driven by a motor that rotates with the wheel?
• What type of bearring did you use for the wheel steering?
• What diameter is the wheel?

Also, I know Aren_Hill famously said that a swerve drive should be built on the offseason and then given a year to sit before putting it on a competition robot. (I'm sorry, I can't find the quote right now.) What lead you to decide that a swerve was needed to be competitive, despite the fact your rookie team had never done one?

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Both of you look closely at the module and you will see how it is driven.

-Brando

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driven with internal motor in the center of the wheel? and what did you choose for the drive motor. looks great guys! but diet mtn dew.......really?

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Wow, it's out in the wild. I'm proud to have seen one of the original concepts and have told you that you were crazy, still think you're crazy.

Great execution, and good luck!

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I see it now...that's a CIM. WOW just..wow

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When Aren started talking about this concept, I was convinced it was a joke. That any team - let alone a rookie team - actually built a swerve drive with a CIM motor as an axle absolutely blows my mind.

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It's like one of images that's usually captioned, "When you see it...".

Holy crap this is amazing. Can't wait to see some shots from other angles.

- Sunny G.

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Until I found out there was a CIM in the middle of the wheel, I was thinking that Aren and company had somehow managed to make a single motor do both the rotation of the wheel and the rotation of the module, and was trying to figure out how that worked.

Next year, maybe...

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What is the weight of the assembled module as shown?
How do the modules attach to the chassis?
What is the maximum allowable horizontal rotation, and how do you keep the CIM motor wires safe and secure?
I'm having trouble envisioning the other side of the module. Do you have a pic handy that shows the "back"?

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What's cool is that Aren's students were the ones who really wanted to pull off the swerve. We knew Aren was crazy before he even proposed the design, but now there's a whole team of crazies! Glad it's finally out in public. I hope people finally understand the Aren Hill drillbit meme on Facebook haha.

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CD to IKE: "You cannot give credit to the same post twice."
IKE to CD: "If a 3928 can pull off a swerve module like that, then they deserve double credit."

Bravo to 3928.

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Aren,

I am usually not a very big swerve drive fan, but this is awesome!

Very inspiring!

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Ingenious and elegant! - does that banebots turn it quickly enough? We had a swerve for lunacy but turning reliably (lots more torque reqd on carpet) and quickly the next year was tough. This design is much more compact and more clever though.

Any worries about radial loading on the CIM shaft? Or is is coupled (can't see the other side)?

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Wow. That is one heck of a swerve module. Bravo to your rookies for not only wanting to take on the challenge, but also completing it in a way that is just magnificent. I expect great things from this team. They built one of the best swerve modules their rookie year. Let's see them do better next year. ;)

Great job 3928! Keep building at a little under the speed of light! (sorry but you've been disproved. :()

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Had to do a double take on this one. Love it to death. Major props for pulling it off!

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Now that's a cool idea. What's the overall reduction? Any chance we can get a side view to see the CIM motor going through the wheel assembly?

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Apparently the only thing you cannot use a CIM for is a flotation device in our eventual water game. ;)

I, too, would like to see more pictures. Or .dwf? ;) :D

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I wish our students were around to answer your questions and explain all the work they did, but unfortunately most of them are way on a band trip.

Our students have played around with a swerve in the off-season, so they knew more about one than most rookie teams. We were fortunate enough to get a set of incredibly bright kids who are capable of such feats after only having a few months of experience.

-About six pounds
- If you look, you'll see a plate above the turning gear. We attached that to our bellypan.
- If I'm not mistaken, the plan was for about 360 degrees with a bit of overlap (so that there isn't a dead spot) (Aren might swoop in and correct me on this one).

We at least talked them down from swerve AND a turret. :P

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:yikes: :eek: :yikes: :eek: :yikes: Woah!

Is that just th plate mounted to the CIM that is visible or is that actually the front of the CIM?

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that's the front of the CIM, I'll have some more photos up in CD-media sometime soon.

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Exactly what I thought of after I realized the CIM was inside :P

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If it is indeed 360 degrees, it would most interesting to see how they route and/or suspend the CIM power lines.

Also, I don't see a steering angle sensor. Is it hiding in plain sight?

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The CIM wires are ran up the polycarb in the picture then have some inline spade connectors (for if they go haywire) attaching them to the wires stuck on the encoder mount that is above the module.

The steering encoder (ma3 from usdigital) is mounted above the center of the module on the polycarb hoop into a 3d printed adapter, the body of it is held on another lexan bracket that reaches from the side of the frame over the top of the module.

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A CIM as a bearing, just a beautiful and awesome idea and design.

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Please tell me you're going to mass-produce this and sell them! This is probably the best/smallest swerve out there! Any videos?

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So what goes in between the CIM and the colson? And did the colson come with that big of a bore or did you have to bore it out you're self's?

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In between the Colson and the CIM there are 12x r3 bearings (6 on each side) running on a 4140 HT steel sleeve that is over the CIM, some grooves in this sleeve retain the wheel laterally.

that sleeve is what i got to use a 2.5" drill bit on

here are more pictures:
http://www.chiefdelphi.com/media/photos/37675?
http://www.chiefdelphi.com/media/photos/37674
http://www.chiefdelphi.com/media/photos/37673

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For reference: https://www.facebook.com/photo.php?f...type=3&theater


:D

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That swerve is all kinds of awesome. Great work 3928.

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This is the kind of thing that my math and spanish spirals are filled with! who needs education when you haave First?
i thought about this once, but rejected it as insane. props to you for making it happen

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This is amazing. That is all I have to say.

Sad thing is I just started thinking on how to improve on what I have seen recently in crabs and swerves.

I now have to think harder. :D

Challenge Accepted.

- Andrew

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How are the stress loads of robot movement transferred between the wheel and frame? What kinds of stress testing has this module undergone? Finally, is it possible for extreme heat from CIM abuse to transfer through the steel/aluminum and warp the plastic beaings over the course of a competition?

Am I the only one who really likes the tensioner that mounts directly to the rotatable CIM? The overall concept seems a bit high risk/reward to me, but the little things that make it more compact are the real genius of the design IMO.

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I don't think they come any compacter than this. BUT, I want to see it run a whole season before I go out trying to replicate it. While it is small, how small is "too small"? Aside from this rare occasion when the OP says they need that tight of a space for a swerve, I don't see this being put into any real use unless they prove this season that it not only works great, but is advantageous to the user.

Nonetheless, I still want one.

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How does the smallness of a solution coorelate to the usefulness of it? When this whole competition is about how much function you can fit in a give size and weight constraint every bit counts. They are using the same axial bearing set up as 16, a team who has IMO perfected swerve drivetrains in FIRST. They are also using an axle for the wheel that is effectively 2.5" diameter. Much larger than the majority of teams. Additionally this isn't Arens first foray into swerve drivetrains.

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I am working on it.

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I've got CAD of somewhere around 5 earlier derivations of this concept, and this one, but I don't usually post it publicly.

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CAD is not a birth right. While some teams graciously post their designs in various formats and states of completion, that is totally their own choice. By no means is anyone required to post their design.

-Brando

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Aren, Could I get the sizes of those gears/pullys?

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I must say, after a day of just staring at this, I think I'm in love. Aren, every design your involved in always amazes me

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Team 3928,
All I really have to say on the subject, is this Module rivals all of the gearboxes and transmissions, on the subject of cool engineering. Between mechanical systems such as those from Pink, Cheesy Poofs, Simbotics, ect... this Insanity ranks high on my list of FIRST Cool.

I do find something this, radical, to be something of a physics mystery to me. When Midwest is over, I am sure all of us would be delighted to hear how these modules (is there an offical name for them?) held up to the rigors of competition! What compromises were made? What are the downsides and advantages? What worked with flying colors and what failed in the heat of the moment? Now of course a your Design Synopsis would be a grand feat amongst us all, and again, it is your choice to share what you want. For kids to have accomplished something so... FIRST... it is their glory and their pride to keep.

Hope to meet you at St. Louis!
Petrie

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They're 3mm GT2 belts, 24T to 40T (and my favorite part of this entire module is the tensioner)

Then 20DP gears, one cut from SDP stock, the other lasered.
16T to 80T

for a total reduction of 8.3:1 (which after watching the first two weeks is a bit quick, but I don't have money to buy new pulleys and tweak it, darn)

Its a 5"x1.25" Colson wheel, and the steering is geared at ~100rpm from the BB395, haven't had any torque issues with that, the response is quite nice.

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Unless I'm mistaken, (which happens a lot in FIRST --we learn this way right?) could you use a friction drive to the wheel and ditch the second reduction? I only thought of it because of the minibot gearing-up, gearing-down and final ratio power loss. Or would a friction drive could prove too unreliable in pushing matches?

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Friction drive worked on minibots because it was such a low torque application, you would need to provide substantial normal force and need a much harder tread material in order to transfer the CIM torque to the wheel through friction, essentially making everything really inefficient.

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This a clever little module.

If I recall FRC 141 Wo-Bots did a CIM in the wheel swerve drive last season. It was based on a larger wheel, but it was equally awesome.

Of particular note was that their design used only timing belts and was nearly silent while moving...it was kind of ominous when you were near it on the practice field. :D

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I don't often post on CD, but when I do it's on threads where the engineering genius blows my mind. :eek:

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cool!

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Do you have pictures of that?

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I also Saw this beautiful design, all anodized and powder coated, it turned me on, yes, I am attracted to good engineering, to bad I didn't get any good pics.
I wish 141 would post either their cad or a close up of the module.

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i don't have a cad drawing or a picture of it, but i will try and get one for you guys to see.

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This would make me, and much of chiefdelphi, very happy!
That design was really a work of art! Too bad we weren't able to win that semi finals match with you guys last year, you are really a great team!

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Does anyone have video of this bot in action?

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Going to be rare due to GDC ruling about the robot's tactics. Keep looking. Swerves are fun to watch, even when only practicing. It's like being envious of Gene Kelly or Fred Astaire. Maybe I'd like to dance like that, but only two chances of that - very slim and none.

This is a match that has 3928 with a superstructure on top. It's mostly of the other alliance, but there is a coopertition bridge attempt at the end. Uncertain about the outcome 'cause they were still rockin' when the video cuts off.

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Its not at competition, but here is video of the swerve in our shop.

http://www.youtube.com/watch?v=bgRVg...ature=youtu.be

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:ahh: Now I'm even more impressed. That looks like a drivetrain that is well built, and can easily beat any 6 wheel drive, without even using the regular swerve mode.

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Very, very slick. An awesome piece of engineering!

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I just posted video of FRC Team 3928 Neutrino first match EVER!
You can see their swerve in action.

http://www.youtube.com/watch?v=Yx0zv4H21MQ

And Match 16 is here:

http://www.youtube.com/watch?v=xiytvLHfR3c

To the Neutrinos:
I have several of your matches in HD video.
Someone can contact me or Carrie and I can eMail them to you.

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Finally set a module on the scale, 6.53lbs as pictured in the first post

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Sorry to revive an old thread but any plans on making this a 2-speed Aren?

-Nick

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I know how i'd do it, but that doesn't mean it EVER needs to happen, so no

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Aren,
This swerve module truly is a thing of beauty. I love how compact you were able to make it. The design work is top-notch. I'm glad you brought it down to TX so I could play with it this summer.

That said...

...having watched these two matches I haven't actually seen the swerve in action. Did you ever run into a match situation where you NEEDED to go sideways? There weren't any maneuvers in either of those videos that couldn't be accomplished by a skid-steer drivetrain. ;)

Beautiful swerve, probably not needed.

Love,
John

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Oh i'm fully aware, we kinda lost most of our practice time to rebuilding the robot the GDC didn't like, whole host of issues, but still a fair amount of fun.

You're aware of my feelings on this subject, I seem to have gotten some Texas on me

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To add, for those who don't know Aren personally, we very rarely -if ever- used the swerve to its full potential during match play.

We had very little driver practice due to undergoing a "second build season" to revamp elements of our robot instead of spending pre-regional time with driver practice.

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Maybe the GDC likes dogs instead of cats, Aren.

Also, the most important part of this photo is the can of Mountain Dew in the background.

-Nick

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Has your team been practicing with the drive since the end of the season? Any plans to stick with this going forward or will you play it by ear based on next year's game? A drive team with an entire off-season's worth of driver practice with a swerve drive would be a force to be reckoned with.

This drive gets my vote for coolest drive of the 2012 season, blew my mind when I saw it on here.

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It's even cooler in person, especially when you get to hear how it was made. Legend!

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Hopefully another Neutrino can pipe in with more accurate answers (I've been away while Uni was out of session), but most driver practice has come from demos and the like, not too much in the way of drills. We're planning on going to Cow-Town, so driver practice should be in the plans for preparation, but nothing to the extent that you might be thinking/hoping.

Nothing can be for-sure until the game comes out, but I think we're going to try going much simpler with our drive so we can put more effort/time (and money!) into other aspects.

And thank you! Two of our students devoted their entire build season to creating it, so I'll make sure they get the praise :)

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Looking forward to seeing this beauty up close at Cow-Town. After our new members see Bombsquad in action and then look at your modules I'm sure they'll be asking why we haven't done swerve since 2010. I hope they give you a great pit location to account for all the visitors we'll be sending over.

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:ahh: Why did I not realize this until now?? Cowtown is not, by any means, coming soon enough now.

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Kudos to our awesome team of swerve mod builders! Got to hold it the other day and it's pretty cool what they came up with... Weather or not we'll stick with the same design this year is to be seen.

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Wow. What a CIM placement! :ahh:

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How do connect the steering gear to the mounting plate? I assume there is some thin bearing in between, but how did you retain it vertically? This is for sure one of the coolest things I've ever seen.

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What bearings did you use around the CIMs? Are they roller bearings or ball bearings? Also, do you have a sleeve around the CIM, or are the bearings riding on the CIM?

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Between the steering gear and the mounting plate there are two .25" diameter semi circle grooves (one in each plate) with .25" diameter delrin balls running in them, essentially forming a "deep groove" thrust bearing that can also handle axial load. (This was borrowed from team 16 who has perfected this bearing and graciously answered all of my questions regarding it)

The bearing is then kept from coming apart by a set of white delrin sliders that go up over the mounting plate from the steering gear and retain it.

Around the CIM exists a ~.090" thick 4340 alloy steel sleeve (we went pretty hard as it was round 1 of this bearing concept). Riding on the sleeve are 12 r3 ball bearings (6 on each side) each riding on a 10-32 bolt.
The bearings also have a groove in the steel sleeve that is deeper than the outer race of the bearing providing an thrust surface to retain the wheel in the middle of the module.