FRC 4481 Team Rembrandts 2022 Build Thread

The team is busy at the shop, but I can answer this for you:

  • 40mm of Compression
  • Between ~35-45 degrees of wrap with the current configuration, I don’t have the specifics of the release angle, but it will be different depending on the distance between the shooter axle and the fender and the height from the floor (this is still in discussion based on the CAD integration and the prototype testing
  • The most recent videos the balls were filled and verified with a gage to 3.5psi, the older videos the two balls were at different pressures (unknown, one soft, one hard)
  • On Sunday we will test with the balls at different pressures

What speed are you running your feeder wheel at relative to the main flywheel?

1 Like

I’m not going to do the math on these but you could- in the bottom right hand corner of each video it says the gear ratio on the feeder and the % they are running it at as well as the % of the main flywheel. It seems like the feeder is also a Neo through various ratio’s of max planetary.


Oh good call-out, I completely missed those numbers on the video. Thanks!


Great conclusions and nice idea to feel game playing in simulator :wink:

Good luck!

1 Like


A quick update on our intake progression!

We’ll be posting our shooter videos tomorrow but those take a little longer to edit… At least I don’t want to get your bored watching a 2 minute video for 10 double shots.

I’ll be quick cutting those tomorrow including results.
We’ve been testing 5 different types of hood grip.
1 Neo vs 2 Neo
All UPPER shots


We’ve been working with the idea of adding a top roller above our eventual intake. Today they tested two different types of ways to get the CARGO down into the intake.

Sadly we couldn’t get these prototypes recorded on carpet while driving so they’re stand-still shots but still quite interesting…

Test 1 = Carwash with the non-slip drawer liner.
Seemed to work pretty well. The spacing and geometery was sub-optimal on this setup since we had to deal with what we had bolted on there. Make sure that when you’re using a CARWASH style that the flaps that spin won’t get out of the 16" frame extension :wink:

Test 2 = The expensive velcro roller.
We bought some plastic hook and loop velcro which was quite stiff, wide and hard. This type of velcro seems to not damage the CARGO that much.
We’re really worried about using velcro on our robot because it will most likely damage CARGO for worse… But after couple test runs the CARGO didn’t seem to bother it that much.

Both tests can be seen in the video below.


It started with a couple 3D prints, a few extra iterations to check what geometry would work. Both for the positioning of the spiral roller itself on the robot as well as the helix dimensions and pitch.

Whenever the CARGO fits inside an entire width of a screw it seemed to work best for us.
These were still just regular PLA prints.

They were similarly mounted as our mecanum intake so they’re easy to swap.
We’re leaning into the idea of designing both intakes and see which works best on the entire robot eventually.

The screws are being printed out of TPU currently so they don’t break as easily, are a little more grippy and can flex a little.


We added a “storage” on the kitbot plus the mecanum intake. To see what needed to be done with the drivetrain in order to intake the CARGO through the bumpers.

After narrowing down the slanted plate from DT into higher “storage” we added a couple belts to get the CARGO through the robot.

This style of “connecting” “subsystems” helped us a lot in figuring out complete dimensioning and see if we could get things to work properly. If it works as janky as this it will probably work out of sheetmetal as well…


Tomorrow we’ll post a longer update including the shooter videos and conclusions.
Our team meeting on monday evening will be completely remote and we’ll do our first real design session based on the strategy outcomes of 3DM and the prototype outcomes.

By comparing those we can update our requirements for the robot and adjust the goals we have if needed.

Thank you all!

We’ve been getting quite a lot of positive comments through DMs, on Discord, on SLACK, on Social Media which really means a lot for us. We love to be an inspiration to others and being helped by the community whenever we’re making a mistake or someone has an suggested improvement.

That’s all what Open Alliance is about and we’re proud to be part of it!
Stay tuned for more videos very soon! :heart:

If you have any questions… you know where to find us :wink:


I love that shooter prototype! Would you guys be willing to share the cad (dxf, dwg, whatever is easy for you) of those side panels? We have started testing in our shop, but need to head in a different direction and this would help is greatly!

That intake is magic. Well done!


Would adding more mecanum wheels to one half side of the intake shaft help intake cargo when 2 have made contact with the intake mechanism at the same time so they don’t get stuck in the mid opening of the bumpers?
This is great footage that’s helping out teams that have no cargo at all to be testing intake designs. We are still waiting to get our hands on one cargo to test.
Thank you for your invaluable information!

This is a good idea, but to be honest I would bet the problem solves itself once you start driving the intake around a lot more. All you have to do is turn a bit in one direction after intaking and that should end up putting one ball into the bumper opening before the other.

1 Like

What rpm is the Mecanum intake roller running at? I found in 2020 that while our prototype ran great with a drill, when we ran our production one 2:1 off a Falcon (~3200 rpm) it vectored even faster.

Might want to try increasing your speed and see how it does.

1 Like

You can find the CAD files here.


Nick, it’s currently running at 3:1 off a NEO / MAXPlanetary Combo, we will be looking into increasing the speed for the final version, it’s good to hear you have had good results with it at 2:1

We’re not done with iterating though! We just ordered some extra 2"mecanum wheels to test more with it.

Like you’ve already suggested, adding more mecanums/decreasinng the gap in between the mecanums will increase the speed on the CARGO thus getting it in earlier/quicker than a CARGO with mecanums that are wider spaced.

We preferably have a touch it own it intake at all times. Preferably not something like “that will be automatically fixed later on”
That mistake has been made before on our side and eventually bites you in the end :wink:

So what do we still want to test on this mecanum intake

  • Different spaced mecanums on each side

  • Stacked mecanums without spacing

  • A 3" wheel in the middle of the shaft/intake roller

  • As @Nick_Coussens suggested we’ll be trying different intake speeds. Currently in the driving video it’s at 100% geared 3:1 on a NEO on 2"mecanums. We’ll see how 2:1 works for us!

These 4 listed things we’ll check on our new high fidelity prototypes in the end of week 2 hopefully. Then we can easily swap out these variables and test their impact in different scenarios.


Hi dear Ronny! First, I want to thank to you for your priceless experience sharing. I have a few questions about your prototype systems and game strategy.

1)I remember you talked about balls are bouncing too much so upper-hub scoring is not worth. Is this thought still valid?
2)Actually did not get it reason of using carwash, how it is contribute to cath/intake balls?
3)You have tried so many things with the cargo, are they durable? (Just wonder)
4)Can we complete the intaking process without mecanums? Is it worth to use them? (I mean the enter of indexing mechanism can be designed largely for it)
5)Is it sensible using a shooter that score to either hub? (It can be adjust by motor power, your shooter prototype videos are inspired me. Upper in auto, lower in teleop.)

Thank you for your time and have a good night :slight_smile:

Hey Zent,

Here are the answers to your questions!

  1. What do you mean with the bouncing? Bouncing in the air or bouncing on the floor?
    I think it’s still going to be interesting to see how CARGO will fly into the hub with 6 robots on the field and that it well happen sometimes that CARGO hit each other in the air and bounce out/away from the UPPER hub.

  2. The flaps spin in the same rotation as the mecanum wheels. The flaps push the ball down and since it’s non-slip drawer liner it flexes around the CARGO to form to the position of the ball. Velcro might be too stiff and push/hit the ball if it enters at a wrong angle where the non-slip drawer liner deforms to the incoming CARGO.

  3. Yeah better than we expected! We got 6 CARGO on the way from Andymark so then we can test the durability :wink:

  4. You mean creating a big enough of a gap in the bumper that you don’t need an indexing mechanism? I wouldn’t advise to go down that path since you’ll be a defense magnet. With big gaps it will get easier to be pushed around.
    But basically a gap is a gap so this reason also counts for us. We’re hoping to be tiny, quick and offensive enough to avoid the defense.

  5. Yes very much so! Going for 4" wheels with a wider drum so stacked wheels side to side and then 2x NEO on 1:1 will get you shots that can shoot in either goal. It’s all in the details on how you tune from there, hood material for backspin, software control etc. We’re aiming for scoring LOW and UPPER in AUTO depending on what the other 5 robots will be planning on doing.

Hopefully that answered all your questions, if not let me know :wink:


Week 2 - Monday

Our media & branding team has worked hard on a cool recap video of week 1. Please go check it out, give it a thumbs up and hit that subscribe button :wink: We’re currently uploading videos to YouTube straight away, it might happen that there are videos on YouTube than a post on Chief Delphi.

So if you want to be the first then hit that subscribe button and put on your notifications.

That being said… ENJOY!

Shooter Testing

We’ve been testing our shooter prototype over the weekend on various variables.
Every video down below has a whiteboard in the right corner with the right settings of the test in there.

If there is a black area with white text then that’s there to correct a mistake on the whiteboard. In the upper right corner we displayed a picture of the materials we used on the backing of the hood. If there is no picture then we just used the polycarbonate of the hood.

1 Neo Shooter vs Different Hoodmaterials

Apparently all our previous shooter videos were with only 1 neo powered… Shame on us! So we’ve spent testing for an hour with only running 1 neo and no PID or just P controller.

We still wanted to edit the video and share it with you all since some teams might not be able to run 2x Neo. So here’s the results of our 1 Neo Shooter.


  • If you’re LOWER hub scoring only then 1 neo will be enough for you.
  • 1 neo is capable of reaching the UPPER hub in these videos but image there is no software control on there AND we’re running nothing else. No climber, no drivetrain, no intake. So with only 1 neo and needing it to run at 80% to score high across 2,5 minutes of robot action on the field is not a guarantee I’d like to give you. If you want to go UPPER goal then definitely go for dual neo setup.

The first couple shots are to dial it in and were done on black nitrile roughtop tread. Halfway the video we’ll be shooting with different materials.

2 Neo Shooter vs. Different Hoodmaterials

These are the shots with dual neos powered. Still no controls so just raw percentage.

Our controls department is trying to get the PID to work properly this week. During last weekend tests we ran into some CAN wire issues.

Shooter Conclusions

We’ll be proceeding on the setup outlined below. Currently the ribbed rubber looks pretty interesting but balls hit each other quite some times. So dialing in your shot to properly shoot 2 CARGO will take some time this week.

Today’s Week 1 Recap Meeting

Today we’ve had a completely remote Week 1 Recap meeting and Design Review. We’ll post a bigger update on that on Tuesday/Wednesday on the current CAD status, goals for week 2, what we’re aiming for to have done on upcoming sunday etc.

For now it’s… ZzzzZzzzZZZzzz




During week 1, we’ve been working on creating as many prototypes as possible to get a good feeling of the game elements, performance indicators and design geometry. Make sure to check out the recap video Week 1 | Team Rembrandts Building Season 2022

After finishing up the updated requirements list based on prototype performance, we’ve decided on an approach for week 2.

The new requirements for the robot were acquired by experimentation during the prototyping phase. These requirements will function as a blueprint for the first round of iteration of the robot design.


The start of designing a robot is quite abstract. By creating boxes and talking about the things you already know, we’ll create a better understanding for the entire robot.

Where will certain parts be sourced/bought? How are we doing on total motor count? How do we think the mass will be distributed? Where will we place the hanger-subsystem most likely? Are there certain demands/requirements from departments like manufacturing or controls to take into account?

Down below you will find the layout sketches of the current robot concept we’ve decided upon. The goal of these sketches and the decompositions are to create a point of reference to discuss subsystems.

Throughout time, week by week, we’ll update these decompositions and start thinking about cable management, where the connectors will be. How will we mechanically disconnect the cargo-in subsystem from the cargo-out or cargo storage? What’s the lead time on certain parts? Do we see any risks ahead? Can all the parts be easily manufactured? Aren’t there tooo much 3D printed parts? Do we have all the parts in stock that are currently outlined?

For these types of design questions from a specific point of view we use the term: DfX. DfX stands for Design for X. Where the X in DfX is a variable which can have many possible values. Manufacturability, cost, logistics, test, minimum risk. Etc!

Build Season Timeline - Entering Phase 2

As we enter Phase 2 of buildseason, we shift our focus towards iterating the chosen prototypes of week 1.

To learn more about our subsystems we’re currently designing high fidelity prototypes so we can test more and start fine tuning our design.

CAD designs will be produced to create purely functional subsystems for our “box robot” with the requirements of the subsystems (listed above) in mind.
The box robot will be the first proof of concept for the created prototypes, and will function as the first driver practice bot to start practicing as soon as possible.

Weekly Subsystem Design Reviews - Remote Monday

Throughout the entire build season, weekly design reviews will be held on Remote Monday to update the entire team on design changes and updated requirements; departments will be given the opportunity to comment, with their unique views, on the design; and to allow all members to ask questions.

The Controls Department has been working hard this year to create a process for quick prototyping by using software libraries and control boards. With the introduction of a large group of new students, the control department has set a large number of goals including path following and quick PID loop creation. During week 2, these students will be preprogramming the box robot to quickly get it up and running at the end of this week.

Plug & Play Design Philosophy

What we’ve written today leans into our flexible, plug & play design philosophy. It’s new for us to do it like this. It’s a process that will need lots of fine tuning over the next couple of seasons most likely.

Once the designs get more detailed we’ll dig a little deeper into this. For now we’d like to share some slides from our off-season that we created to train the team and start having them think in a plug & play way.



Week 2 - Wednesday

This post is going to be all about how we analyzed how many points we will need to win an event in week 1.

Prediction Methodology

During the offseason we spent time trying to figure out how you can predict scores for new games. The problem is complicated, there are a lot of variables that you can’t be sure of before you see the first matches. So the first step is: make assumptions! We decided to take a look at the historical data and see if that could help us.

Historical data is available, we have about 30 years worth, so at least there is plenty to cherry pick from. But the reality is that games aren’t what they used to be, and that isn’t just me being nostalgic for games I never even played, it’s also a fact that games have evolved over time. Some notable revolutions in this evolution are double trouble and triple play, all of a sudden you don’t even have the same amount of robots working towards objectives, and every year you see an evolution in the game so it is important to decide which games are still relevant to the modern game.

After a lot of debate and research we decided to start in what is often called the sports game era (2010 - 2014). A decision was made and we started scouring the blue alliance for game data, and almost immediately we ran into trouble: 2010, 2011 and 2012 often only have the match results but not the detailed results, so unfortunately they aren’t useful to us. Easy call: we’re no longer considering these games as modern FRC (in my head there are now two ages of FRC: the Data Glory Days… and the Dark Ages). Another cut had to be made for 2020, great game, great data sets, only played consistently in week 1, and had its last events played in week 3.

So we’ve narrowed it down to 2013-2019, still 7 games, so not bad, plenty of data to go from. I still had some scripting which downloads data from the blue alliance, calculates OPR (explained better than I could, by people that are smarter than me in a lot of places like: The Math Behind OPR — An Introduction – The Blue Alliance Blog) and put it in an excel spreadsheet, we ran that for those years, not only for the match results but also for individual scoring objectives. After taking a look at the data we had another epiphany: not all scoring is the same, some games score linearly (the same action repeats for the same score: think scoring cargo in 2019) and some games score stepped (the same action doesn’t always score the same points, think gears in 2017). As great as some of the stepped games are, they aren’t very useful for predicting future score development, so unfortunately they bite the dust as well: so long 2014 and 2017. We had two other dropouts for other reasons: 2015 had to go for only playing on a half field without any chance of defense and 2018 because its scoring mechanic is not at all dependent on the quality of robots (in theory an alliance robot could score way fewer cubes in one match than another alliance in another match and still score insane amounts more).

And then there were three: only 2013’s Ultimate Ascent, 2016’s Stronghold and 2019’s Destination: Deep Space. We went to work with that data, in the following three charts you can see the OPR progression from week 1 through the championships for each of these games broken down into percentiles, from the lowest scoring robots in the 0-10% percentage group to the highest scoring teams in the 90-100% percentage groups.

These graphs tell us a lot about the scoring progression. Basically, every week teams get better in every quality group, except for week 7 when the bottom 60% outperforms the bottom 60% percent of week 8. This is not too hard to explain: the district championships happen in week 7.

Scores increase every week, by relatively the same amount. So if we can predict any point that is on this scale or might correlate to this scale we can predict the scores during every week! So we set to work on coming up with what a single top 1% robot could score in a single match by the end of the season, and then use those predicted scores to normalize the three years in the analysis. The predicted scores in general are based on autonomous, maximum expected cycles completed, their points values, and the value of the end game. Since we’re trying to predict how to win events we only used the top 10% for the graph below:

Not bad of a curve fit right? All three games progress relatively similarly, so we decided our assumptions were at the very least reasonable. So based on this we decided to say the following: you have to score 60% of the ultimate match to win events in Week 1, the average of the three games is about 55% but we chose 60% to be on the safe side.

Rapid React Prediction

So if we need 60% of the perfect match, what do we think the perfect game is going to be? We discussed this a lot, checked out other opinions, and concluded about the following.

Auto TAXI 2
Auto CARGO Points 20
Teleop CARGO Points 40
HANGAR Points 12,5
Perfect Match Top Tier 74,5
Week 1 Top Tier 44.7

You might notice that 12.5 points is not something you can score in reality, after all you get 10 points for the high rung and 15 for the traversal. This is because we don’t really know if the traversal is worth it, yes 15 points is a lot, but you shouldn’t compare it to not climbing at all, but to climbing from the high rung to the traversal rung. It would take a while, time that you could also be scoring cargo in the upper hub. If you can’t do the climb in less time than you can do 1.5 cycles it’s not worth it (at least not in the playoffs). Still, some games at a high level might be worth it, and again better to score higher than we need than to go below so we settled on half of the time you make the climb, half of the time you don’t.

Scoring Plan

And then we’ve got to the ultimate question, how do we get the 44.7 points we project to need? Without trying to emulate a terrible soap opera, we’re going to have to leave you on a cliffhanger for that one. As of now we’re finishing up the story on the cycle analysis which is valuable input for what you have to be able to do to score x amount of points, when that is fully written down it will be released in this blog as well.


What a crazy analyze :smiley: Congrats for this.

1 Like