Baxter Bomb Squad 2014 ~ Nighthawk
 

We are proud to present you with this year's Baxter Bomb Squad robot: Nighthawk! Inspired by the triumphant F-117 Nighthawk stealth bomber's breathtaking visual features, our team this year put an exceptional ball-launching robot to compete in this year's game. Please visit www.baxterbombsquad.com for more information about our team!

http://youtu.be/lcsi4zBwIjc



Send me a PM if you want a higher resolution image or images of our mechanisms (the mechanisms may take a bit of time depending on if I am at the Bomb Shelter [our shop] or not).

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Holy crap!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I love it!!!

See ya at Arkansas

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

That auto.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Man you guys are always so incredible! Shout out from your cousins here in Chicago:D Hopefully we'll meet up at Nationals!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Set the bar high for a 3 ball auto

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I wish I could see what the game would look like played with six of these.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

if that was possible, what would the other 4 do in autonomous? lol

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Amazing job as always. Looking forward to seeing you at the Arkansas Regional again this year.

Can't wait to check out your bot in person!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Arkansas is sure going to be fun!!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Wow this is a game tailor-made for you guys to succeed-
Wide-open field for swerve and a game piece made for a catapult.
Incredible robot this year. I wouldn't be surprised to see you on Einstein once again.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I knew the second the game was revealed, it was literally built for your team. Turns out I was correct. I can't wait for queen city. :D

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Thanks for all the kind words everybody. We're really proud of our robot, so it's nice to hear it from y'all. ;)

If you have any questions, feel free to ask them here. We'll check in here regularly to answer what we can.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Ok, I will take you up on that. How does your shooter mechanism work? Your robot was moving so fast I could not really get a good view of it.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Beautiful machine. Your swerve seems a bit faster than usual - what speeds are you running it at?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Yeah, one of our points in the video is to kind of hide the robot internals to an extent, but I'm happy to explain a mechanism to you. At one point we used two of the legal van door motors and two Banebot 775 geared on Versa Planetary Gearboxes at 100:1. They drive sprockets that are connected to the camshaft at about a 1:2 gear ratio (I cannot remember the exact numbers here). The cams were machined out of 1/4" aluminum and slide onto a Vex Pro hex shaft that runs across the entire mechanism working as the camshaft. I have attached some images that depict the original shape of the cams as well as the mechanism as a whole on the practice robot. Of course, it being a practice robot, we have removed one set of our 3D printed spacers to shorten them down because they added a bit too much unnecessary stress to the mechanism as a whole but this is not an issue on the competition robot (which was built much better). The reason I said the original design of the cams earlier in the post was because we added one slight notch on each side that allowed the catapult to rest slightly when cocked to lessen the stress on the van door motors. We actually learned that it was possible to remove those two motors entirely (the 775s were doing all the work anyway) and the small notches prevent any possibility of back-driving. If you have any other questions relating to the details of the mechanism, feel free to ask; I'd be happy to answer them.





It's not really all that faster, actually. The only change that was made was to switch a 12 tooth sprocket out for a 16 tooth so they could fit on a 1/2" hex shaft. The gearing farther down the line was changed to compensate (gearing was changed from 9.5:1 to about 9.3:1. The only real differences lie outside the drive train itself. This year's robot was designed to have an extremely low center of gravity (about 4" off the ground) which adds to an overall better drive base. Last year's robot was designed to have a 40 lb climber stowed away underneath, which when removed meant the robot was very tippy and had poor driving performance. Our 2014 robot also has improved programming for the steering modules (finding shortcuts for rotation of the wheels to prevent full 180 degree turns unless they are necessary, etc) and the parts were machined and assembled with a much higher standard in quality than in previous years. We really tried to put emphasis on building a finished product rather than what should be a complete prototype robot (we are currently fixing what would normally be our competition robot but is now our practice bot because we built two for this purpose). Our competition robot is built with an entire robot of experience behind us, so naturally it performs much better than even we expected of it!

P.S. To answer, we run at about 12-13 FPS in reality [geared for about 16 fps, but stress is a real thing].

Thanks for the questions, I hope I answered them fully! Please do not hesitate to ask any other questions about our robot, as we would be glad to answer them. I am more keen on answering mechanical questions and I'm sure Jefferson will be on top of any questions regarding the robot's programming time permitting.

-John Taylor Novak

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Wow. Hands down the most effective robot I've seen thus far.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Normal speed. JT driving like a maniac. Sad no one has mentioned our double BFLs. ;)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

great looking robot! love the swerve...your team is the best around that does it!

question about the intake...how does the wheeled shaft interface with the lexan "arms"? looks like the shaft goes into a metal plate, that is in turn attached to the lexan. chain or similar running down to the robot to the motor? any close up pictures available?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

There is a 550 inside the beater bar. So all we have running up the arms are the motor leads.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Wow. Best one robot I've seen so far. Awesome work

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Awesome, awesome, awesome!

We "borrowed" from your 2008 ball pick-up design and it proved to be most effective at the pre-bag scrimmage. Thanks for the inspiration!

Have a great year and see you in St. Louis!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

My only regret this season is I wont be able to see this robot in person. Another great robot by the Baxter Bomb Squad. I have seen all your robots in person since 2002, this one definitely beats all of them when it comes to efficiency and effectiveness.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

You can meet it in person if you make it to Nationals:p

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Nationals? What's that?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

It's a fun American party.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Thanks for watching! I'll try to explain my best on how the beater bar mechanism works. As stated before, we use a BaneBot 550 motor that is actually mounted inside the bar itself for protection, ease of design, lowered machining times, weight, and overall cleanliness. I have attached some pictures of our CAD model below that provide a visual representation on how we fit the motor in the beater bar and how we interface the drive shaft of the motor with the bar. We machined round inserts that fit into the bar and are screwed in from the outside with flat head screws that have a hole in the center with clearance for a key so they can slip on the output shaft of the stock 25.91:1 BaneBot gearbox (it may be a different gear ratio, but I'd have to look at it to make sure). The motor/gearbox combination is attached to the poly-carbonate strips by two 1/8" stainless steel plates that capture the motor and a small aluminum block that both holds the assembly together and attaches it to the poly-carbonate frame component. The other end of the beater bar is simply held on by a small machined part that fits into a ball bearing on one end and interfaces with the Lexan on the other end via two screws. For purposes of illustration, I made the beater bar transparent even though it uses our Baxter blue livery in the real world.



-John Taylor Novak

P.S: Unfortunately, I don't think I am able to give CAD models until the season is over due to the nature of the competition, but I'm more than happy to provide pictures of the models for a rough reference to the overall idea. :)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Wow, that's quite a cool concept! The last time I've been this excited is when I found out how your swerve drive works:D Innovative ideas as always!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

That 3 ball autonomous mode is awesome! I hope my team gets to our goal of a 2 ball autonomous before our week 1 competition

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Nice to see this thing finally public. Hopefully I'll be able to stick my head inside and talk swerve with you guys at CMP this year.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

wow, now this will make Arkansas regional even more interesting! Can't wait to watch yall drive circles around us and most of the other robots again!:p It really looks great, yall did a really good job this season. How did I know that yall would do a catapult? Gut feeling I guess?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

This Bomb Squad machine looks to be one of your most competitive yet. Thanks again for the inspiration on the intake, FRC558 is running a polycarbonate armed, motor in roller, intake as well this year.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Nice to see another cam based catapult! We came up with a different solution to back driving that you may be interested in: The final 30 degrees of our cam profile is circular, so there is no reaction torque from the catapult springs. Once the cam follower gets to the circular part of the cam, there is no chance of back driving.



As a side note, we built a small cam driven catapult last year for a non FRC project, and experimented with a notch in the cam to prevent back driving. It worked, but we found there to be a large current spike when the motor was trying to get the follower out of the notch.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The reliability and repeatability of the cam driven catapult was the deciding factor for us.

We had a similar profile you describe, just not as long on the flat. Hitting that small window right before the roll over was tough. We also like the idea of being mechanically locked in there.

We do get a pretty significant current spike coming out of the notch. I watched our practice bit spike over 60A the other night. It took us several rounds to get the slope flat enough come back out to reliably fire.

Btw, y'all's robot looks very nice again this year. Good luck out there.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Please do. Nothing I like more than to geek out over swerve drive for a while.
:D

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

JT was mentioning you guys had some issues with Command Based robot stuff last year, care to elaborate?

And, I'll absolutely come over and geek out. :)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

We also have Polycarb arms and inserted the motors inside the acquisition tube. I was wondering if anyone else would do this. See ya at QCR!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I wouldn't say we had issues, but we definitely didn't use commands this year. They overcomplicated the small tasks and made the more complicated tasks very difficult. Especially where we needed more time resolution than whatever cycle the commands were on. The compile time for that many objects was hard to stomach also.

Our 2013 code is up here if you want to see how we inplemented commands:
https://github.com/FRCTeam16/TMW2013

I guess we are using commands one place this year, dashboard buttons. We have two or three things we need to do infrequently enough that don't need to be accidentally pressed on the joystick. Commands make that very easy.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Yeah, the Lexan arms may look floppy and less "industrial" than rigid ones, but there's good reason we've had essentially this in 2008, 2010, 2012, and 2014. I'm beginning to see a pattern...

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Interestingly, I felt similarly when I tried to use CPP for commands last year. Since switching to Java I found Command base was fairly simple and it meant a good chunk of our code was much cleaner than comparable other methods. I know it has allowed us to iterate our code far faster. I'll have to dig into this code and take a look at your new code at CMP this year.

Of course, my day job is primarily ruby/javascript code so that could explain why CPP felt less intuitive.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Could you provide some details about your swerve drive design? Such as wheel size, steering gearing, drive gearing, slip rings, or coaxial.
Our team did independent swerve drive for the first time this year.
Thanks in advance.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Just make sure the catapult is disabled before you stick your head in...that thing really scares me!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I'll avoid standing on it while it's loaded too. ;)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I have pictures. JT better stay clear of safety judges.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Our swerve drive uses slip rings mounted at the top and we use 6" AndyMark performance wheels. I have some CAD models of our 2013 drive train if you'd like to see. Our output gear ratio is about 9.5:1 on the drive and for steering we use AM 9015s geared down using Versaplanetaries from VexPro (I'll have to figure out the gearing of that when I go to the shop later today). Here are some pictures of the model for a more visual approach. If you have any other questions, please don't hesitate to ask. Just send me a PM asking for the gear ratios for the steering and I'll try to get them to you as quickly as possible.



-John Taylor Novak

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Does your pickup mechanism have to pick up and pass on the ground, or can you accept a pass directly from another robot by pulling the arm up and running the rollers in?

It appears there are a couple of bars on your shooter that stick up, but they seem to flex when the ball enters the robot in the video. Would those bars or the intake dimensions prevent you from taking a bumper to bumper pass?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

We are able to actuate those bars (or "fingers" as we call them) with cylinders deep within the center of the robot to both shoot a truss shot and pass/receive out of the front of the robot with the pickup mechanism up. In the event of a catastrophic failure of the catapult (if it somehow happens), we are able to perfectly score one pointers in both the front and side of the low goal with ease.

-John Taylor Novak

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

If the ball is above the bumper, we shouldn't have an issue accepting it directly from another robot.

Like JTN said, those "fingers" rotate down as the ball is pulled in, so they won't get in the way. The intake is narrower than the ball, so it would need some pushing from the passing robot and pulling in with our beater bar to make it work. The details probably lie in how well the robots mate up.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Not sure what language y'all use. If it's C++, feel free to steal from here:
https://github.com/FRCTeam16/Macys2014
We have several robots on that GitHub site, but this one is probably the cleanest for swerve drive code.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Thanks. Good to know. I think there may be a pretty big benefit to not letting that ball hit the ground with the level of defense that may be present, particularly during elims. Hopefully, we'll get a chance to test it out next weekend. See you in Searcy!

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Could you talk more about the slip ring design? I was surprised to learn you guys were using that over a coaxial setup. What benefits does it give you? And how does it work?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The slipring allows power to be given to the CIM while still allowing the wires to spin. So basically the module does spin like a coaxial module without all the space.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

And without the power losses associated with bevel gears.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I didn't really want to start a new thread for one match video, but here is our 2014 robot in action this weekend! We still have some improvements to make before Queen City. (The balls were much more inflated than we expected at the competition, causing a bit of trouble in auto, but all should be worked out very soon)

http://youtu.be/F3zLJZjHv_s

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

So that was fun to watch, but I can't figure out why the defenders never so much as bumped you while you shot? I would've thought they'd be clobbering you???

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I have been mesmerized by 16's swerve drive since 2012 when I first saw it. Can I take a look at the CAD, too?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Is that the same model you guys used in Nighthawk? And where can I find it, is it in Andy Mark? Im a big fan of your work, greetings from team Roult 4403 :)

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Team 16 makes their own swerve modules, though some of the parts are COTS items available for purchase through FRC parts retailers.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The model shown is our 2014 model. The CAD models for the 2014 season will be available following the World Championship upon request. Unfortunately, our swerve modules cannot be purchased from any vendor such as AndyMark as they were designed and manufactured by our team. They are the result of 8 years of development and much frustration. The part shown is only half of the equation however, as the modules must be programmed.

-John Taylor Novak

Do you mind providing a picture/ explanation of the thrust bearing system?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The maximum speed with this gearing configuration should be about 14 fps right? Is that Nighthawks's speed?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Your team has been kind enough to share the design of your swerve and describe how it works when I have visited in your pits. When thinking about it, I have always been unsure about a manufacturing aspects of your design.

How do you get alignment of the "tower" to the wheel support structure? How do you assure center to center alignment? and then how do you assure perpendicularity of the tower to its mating piece at the bottom. Is it just a matter of being very careful with conventional tooling, do you somehow machine it as one assembly or is there some other hidden trick you can reveal?

I would think this would be particularly important, doubly so because of your integral, custom bearing assembly.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The only thrust bearing system is machined in the plate that houses the integral part of the swerve module, so that is what I will assume you are asking for. The thrust bearing is machined into two opposing plates and smashed together by the screws that also happen to hold it together. Here is a picture to show the inside of what it looks like:



(I circled the two channels for the ball bearings. Also, that sprocket is NOT floating, it is being held up by a piece of delrin that cannot be seen in the part section view.)
The two black plates sandwich the BBs between them and act as the thrust bearing.

I felt the need to add pictures of the plates themselves. The smaller round one is hidden just above the blue 3D printed part that is an unmentioned experiment for this year.





The maximum calculated speed is close to 14 fps, but the real speed due to outside forces such as friction is closer to 12-13 fps.

The method of attaching the "tower" as named above to the plate itself is actually much simpler than you might think. The thrust bearing actually is what holds the module and sandwiches the mounting plate between it and a couple of machined pieces of delrin on top. The piece is just a small aluminum block machined into an angled bracket that is also what compresses the thrust bearing and holds the entire assembly together. All of these parts are machined with CNC mills (some manual mill work is added but nothing major) to ensure all the parts will fit together very tightly and accurately, providing the perfect 90 degree angle between the module and the plate. The image below has the small plates (only one is visible) highlighted in red and the 3" tube highlighted in green for ease of visibility. More images of the overall assembly can be shown if needed to get a full perspective but until then I don't feel the need to clog up others' bandwidth too much with all these pictures!



If you have any other questions just let me know!

-John Taylor Novak

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Thank you for such a complete response regarding information on your swerve module design and manufacture.

We tried swerve a few years ago and while we eventually got it to mostly work, it co-opted some of the time that perhaps we should of spent on other subsystems. We haven't completely given up on it, but it certainly isn't a favored approach right now.

As implied in the thread above, the software and control part of this takes work as well.

There is a kind of elegance to pieces of your design that I admire.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I'm curious about the slip ring. Can you share the manufacturer and part number?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I can send (and have sent) a private message to anyone wondering what the slip ring model is.

-John Taylor Novak

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Hello JTN. i am Tristan Shepard (aka Skippy), I am a student and am part of our pit crew with (kyEOT) or (Engineers of Tomorrow team 2783). we had talked to your pit crew and some of your mentors ate the Queen City Regional, we talked to you all about how you made your swerve. They said if we wanted the CAD we just had to contacted you all. we used the wild swerve from andymark but saw a lot that could be improved on it. I was wondering if our team could get the CAD for your swerve module that your team used. Thanks. Skippy

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Why did you use 6 inch wheels over 4 inch ones? As far as I can tell, I think that 4 inch wheels would make the entire assembly smaller and lighter while needing less gear reduction. Any reason why I'm wrong?

How are the grooves for the thrust bearing cut?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I was wondering about that same thing. I've always been a fan of small wheels, especially when designing a swerve drive.
I have couple more questions too:
1. What's that pneumatic cylinder doing in your CAD render!? It really caught me off guard.
2. What is the experimental 3D printed part below your thrust bearing?

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

As the wheels do not have encoders, this could have some issues with going straight for moderately long distances. I think that the pneumatic cylinder and the notches in the blue piece might be an experimental solution. I'm sure someone on the team can answer this more accurately.

After playing around with some math and CAD, I realized that smaller wheels mean smaller reductions, which either means that the intermediary shaft has to get closer to the CIM, or the sprocket on the wheel has to get bigger and closer to the ground. I think that a 24/60 gear reduction with a 16/40 chain run will fit, but just barely. (EDIT: 24/64 and 16/38 fits better). The smaller wheel also reduces the space for the thrust bearing, but I think I can get it, or a thinner solution, to fit. These issues might be fixable by a first stage belt like 192 has recently used, but I have no experience with these.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

Could you clarify where this cylinder is? I can't seem to find it in any of the CAD screenshots that have been posted.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

I had the chance this past weekend to see their swerve pods in-person, including the experimental one with the 3D printed blue plate. I'd like to thank the members of Team 16 for answering all my questions with patience.

In the picture posted, the piston is located under the black mounting plate, and adjacent to the blue one (its the grey cylindrical object in the cad). From what they told me, it was designed to test out and eliminate the twitching that the modules may have when trying to drive in a straight line. Because the control system tries to compensate the drift, and then over-corrects the action, the piston would lock in to the appropriate groove when needed and make sure the robot drives in a straight line.

They did mention that they would have to do some more testing with the current design since the motor was able to overcome the piston lock fairly easily.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

In some ways that sound like a cool solution, and thinking outside the box. But it also sounds like they're fixing a software problem with hardware.
Regardless of my mixed feelings about this. I'd be very interested to hear if it helped or not.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

We have found 6" wheels to be more suitable because they have more tread touching the carpet (realistically) and therefore more traction in most scenarios. The grooves were cut using a simple ball end mill... pretty easy to figure out if you ask me.

The pneumatic cylinder was used (as described above) to lock the wheels in place only during wheel calibration autonomous to avoid the need to use any sort of software to keep the wheels straight and move in a straight line. It is much easier to just not supply power to the rotating modules and let them remain physically straight than run a control loop to correct it, slowing us down and removing accuracy. We didn't implement this or further develop it because of the lack of any need in this game. The 3D printed part contains the grooves that the cylinder shaft deploys into.

This is entirely wrong. We didn't even USE it this year and there was no problem with control. I'm not sure why you would think a team that has been using swerve for a decade wouldn't know how to go in a straight line, all that is necessary to achieve that is to push forward on the throttle.. As stated before, the main purpose was to ensure consistent calibration (which we only do about once per competition) and to make going in straight lines in autonomous easier due to the lack of reliance on a gyro that it would produce.

-John Taylor Novak

P.S. As of now the CAD models have not yet been released to the public but I can supply images of the model instead.

Re: Baxter Bomb Squad 2014 ~ Nighthawk
 

The Inherent problem with the gearboxes we can afford (weight as well as price) is backlash. The resolution and control should be sufficient to hold a precise position but mopping up deadband is very difficult. Some attempts include raising the gain to the point of oscillation to average out the slop. This small amount of error hasn't been noticeable for driving in teleop but can cause significant drift when driving across the field autonomously.

The cylinder was intended to improve two issues.
1. We currently calibrate the wheel positions by rotating them all straight and running a task to save the voltage from the encoders as the reference values. These are saved to a file and used as the offset from then on. The cylinders would allow more precise mechanical positioning for that.
2. We would use them to ensure home position at the start of the match. notches around the perimeter of the bearing plate could allow accurate re-positioning at 45 deg or 90 deg or other intervals.

The cylinders are not intended to force the module to a position. when extended, the module software would oscillate at low energy around the setpoint until the cylinder is seated in the detent. This would be detected by a cylinder mounted limit switch on each wheel.

Obviously this was not required for autonomous success this year. We are always trying to mop up limitations of the hardware and software for the next time precision is needed.