FRC 4481 Team Rembrandts 2022 Build Thread

We have tried both compliant and stealth wheels indeed. We didn’t see a lot of performance difference between the compliant and the stealth wheels.

We indeed ended up switching to the orange stealths due to team aesthetics mostly. I think you’ll be fine with compliant wheels as long as you use 4 or 5 of them as a big drum.

We ended up compressing our shooter with ~40mm and with 4" stealths.

What this would mean for compliants I couldn’t give you a proper answer since we didn’t test enough with it.

What are you aiming for mostly, LOWER or UPPER?

Edit: here are the STEP files for our shooter layout if you want. Of course we’d love some pictures and videos if you guys end up running something similar! :smiley: :heart:

https://drive.google.com/drive/folders/1juw6ZIgKExxE1kzMzBxcWbVjdV6B_tlz?usp=sharing

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Looks like you’re lifting on the retract stroke of the cylinder. Don’t forget to take into account the lost area caused by the piston rod when calculating your potential lifting force.

Looks like with two 40mm pistons @ 60psi you’d be creating about 230lbs of force or so. Definitely should be enough for lifting a robot. But if you’ve got a significant sized rod on your cylinder, that force could be reduced significantly.

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We are primarily aiming for lower, but also hoping to hit upper, all from the fender.
We had a different design going, it would shoot out one side to go high and shoot out the other for low.

its a long story, but in short, we wanted to dump cargo into the low, and shoot high, but saw your prototype and decided that was much better. We borrowed your prototypes cad and made our own (although it pretty much looks the same in the end).
So heres roughly what it looks like now


This is our mockup assembly so ignore the mess lol

Also sorry for the cell phone screenshots of cad, im replying to this while stuck in traffic after our meeting

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A student on our team did a similar analysis for Power Up, but just for the Alliance scores. I really like breaking that down to individual robots.

The charts are eerily similar!! :slight_smile:

https://drive.google.com/open?id=1ji8vNdHoexAADC7dkEz_nGXyW8C8I5YW

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So far so good!!! We have tested quite a bit with our 80/20 test rig that we built and we decided to start with 6" wheels and 2" of compression. Tonight was the first night we were able to use the Falcon 500’s with your design of side panels after testing with an impact gun. The students wanted to have some fun and tested at 100%. Obviously this would never happen in a match, but is cool to see (the inner teenager in me saying that).

https://youtu.be/BvrilWUS2DI

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FRIDAY - WEEK 3

It has been a while since we posted an update… sorry about that! The last weeks most of our team members were having exams and school work.

Sunday Week 2 Testing

We’ve been testing with various different variables on a 4000 rpm PI controller.

  • CARGO with 3.0, 3.5 and 4.0 PSI.
  • Different alignments on the fender: left, right, from the middle
  • Shooting with a cargo between the bumper and the fender
  • Again smooth polycarbonate vs. ribbed rubber

You can see all the different tests on our youtube channel. (https://www.youtube.com/c/Teamrembrandts/videos)

This was the last test run we’ve done for the day:

What did we learn?

  • Shooting from the fender into the LOWER and the UPPER can be done with a 2 position hood. But when there is a CARGO in between your bumper and the fender, you might get in trouble. It can be done with a 3 position hood but we don’t like the added complexity for now. For rev1 we’re sticking with a simple 2 position pneumatic adjustable shooter.

  • We’re still liking the ribbed rubber, which seems to increase shooting consistency.

  • With 40mm of compression we see hardly any difference between the different PSI shots.

Intake Rev1 Testing & Rev2 CAD

Sadly the drivetrain wasn’t done in time due to a production mistake on our end.
We focused mainly on testing the shooter which meant we have no progression on the intake in the last week.

CAD Rev2

We’ve been working on the actuation part of the intake. It will be powered by a pneumatic cylinder.

The extending stroke will push a rack down inside a tube > retracting the intake within the frame perimeter. The intake arms have a laser cutted pinion down that rotates since the rack pushes down.

On the extending stroke there will be a spring that counterbalances the weight of the intake. This means we can use smaller bore cylinders > less air pressure/volume needed.

On the retracting stroke we make use of the weight of the intake itself. The gravity of the intake helps overcome the spring force.

See the movements in the CAD below. On the right we have a functional model of a cylinder with spring and a bag with 750 grams of weight. Approximately the weight of our intake.

Rev1 Robot Is Alive!

We got the robot up and running. Need to do a final check up tomorrow and fixate the intake at the right angle to test with intaking cargo as well.

CAD Update

Here are some screenshots on the current sub system development.

Plan For The Weekend

Final testing of Rev1 development robot.
Finalize CAD of Rev2 development robot.

Start preparing materials for the upcoming new revision.

Stay tuned!

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Oehhhhh and this product just launched!

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4481 Team Rembrandts is continuing their 2019 championship run with incredible progress demonstrating their ‘backpack’ robot and also their secondary robot for the Rapid React challenge. https://youtu.be/mZXx-_ed5EA

4481toa4-BTB-YT-Thumbnail-new

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Thanks for having us again @Tyler_Olds :smiley: Always nice to be on the show. Compliments to you and Greg for getting all the useful informative content out there. :+1:

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Week 3 Recap + Plans week 4

Hello everyone, here is another update of what progress we’ve made since week 3. This week we have been working on every subsystem and some other interesting stuff.

We will tell you about:

  • Complete assembly
  • Backpack robot
  • Scouting tool

[Week 3 Recap | Team Rembrandts Building Season 2022]

Complete assembly:
This week we finished our first prototype robot. It has every subsystem on it to complete a full cycle with two balls and we quickly saw a lot of good things happening, but also a few problems that occurred.

  • Our main problem right now is our intake. We saw that the balls don’t go inside our robot as fast as we wanted, and sometimes not at all. We tested a lot with the spirals, the mecanum wheels, different compressions or just no compression at all and just have a bouncy intake, but we haven’t found the sweet spot yet.

  • Since the unwritten rule is “touch it own it”, and we want an intake that can collect every ball in < 1 sec, we have to make some adjustments.

  • We did notice that having an intake that doesn’t bounce while collecting works better since it has constant grip on the ball and thus collects it faster.

  • One of the good things we saw is that our shooter works perfectly on the drivetrain. We tested everything correctly and the results show us exactly that.

  • When testing the shooter we wanted to shoot the balls in a way they don’t collide in mid-air. Until we came with the idea to shoot the first ball in the upper HUB and the second ball in the lower HUB. This is a really solid way of shooting.

    • This way of shooting has a shooting time of < 1 sec.
    • The accuracy is extremely high, since the balls will never collide. Not in mid-air and already inside the upper HUB.
    • The above two reasons make a 20 cargo RP very likely to achieve.
      Intake & Outtake Cycles Week 3
      Backpack robot:
      Get your seat ready for this fashion because it will blow your mind! This week we also finished our very first “backpack robot”. We can now use this for multiple things:
  • Our software department can now already start working on the driving paths for autonomous, instead of having to wait for the final version of our robot.

  • We can also use it as a general robot to show other people/teams what our robot looks like.

  • Since we have to travel all the way to amerika, we want to make our robot completely modulair, so we bring every robot part with us in our own luggage. It saves us a lot of costs and time to get our robot with us.

Scouting Tool:

This year we are also focussing more on strategy. So a few members have been busy making a scouting tool. We want to take scouting very seriously this year since we think it can make a very big difference. It is fully under development at the moment so there might be a lot of changes later on. (We took inspiration from team 5012, thanks for that:) Our current progress:

  • We will scout every match that will be played and get as much data from it as possible.
  • With that date we can clearly see a team’s performances and even progression throughout the competition.
  • With that team data we can predict if an alliance is going to win or not. This can change your strategy for that match. For example: shooting Lower HUB instead of Upper HUB to achieve the extra RP.
  • We’re also scraping data from The Blue Alliance to obtain more match data.
  • After all matches are played we can make a pick list based on the collected data with the best possible alliance combinations.

Current Goals:

The upcoming weeks we will be busy working on the assembly of the rev2 robot. We made the necessary adjustments to perform better on every subsystem. Our materials are ready for assembly and we are very curious about the new results. Testing, testing and more testing!

Credits for this post go to @Teis_Joepman
He’s a new user to CD and can only post 1 embedded item per post… I’m just copy pasting!

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This is now my favorite thing I’ve seen for this season thus far. Can you speak more to this? While I think it’s “just a matter of flywheel tuning”, I would imagine there is a lot that happened in the background to support this success.

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Yes, this was only possible because of the way our software department was able to tune the flywheel by using the Sysid tool.
When we starting shooting, quickly changing the setpoint by a push of a button showed decent results in terms of creating multiple ball paths. But, as the Sysid tool testing finished, the shooter had been tuned to a settling time of less than 0.5ms, with a way less heavy bump in velocity when a ball was shot. After coding an automatic detection of the 2nd ball hitting the flywheel, we were able to quickly change velocity and create a second ball path while shooting the two balls.
After some testing with multiple sets of velocities and speeds of shooting, a demonstration was done “with extreme differences in setpoints” which showed the robot hitting both hubs at the same time. This idea was then further investigated and shows great potential.

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You mention mid-air collisions and possibly shooting 1 high and 1 low. Did you run into that problem a lot? I see video of a bunch of shots in posts 63 and 75 but very few mid air collisions. Do you have more footage of the dangers of shooting the balls too fast? Were the mid-air collisions reduced if you waited a little longer between shots? Was the collision usually from the balls actually hitting each other before the hub or from the 1st bouncing off of the hub?

Is this just a strategy for matches that points aren’t super close? If so why not just do both lower?

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Thanks for the insight! Looking forward to seeing this beast run cycles on a field.

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(Repost because of bad video link)

Shooting the balls directly after each other often causes one to fall out or to be misdirected by the second ball. We don’t have many video’s of this. But you can see the effect of 2 balls colliding in this link:

Creating a different ball path for the second ball reduces this problem as they land side by side:

Waiting longer between shots reduces this danger by a lot, as you don’t need to worry about collision. But, as our requirement says both balls within 1 sec, we didn’t pursue this.
We instead decided that we wanted to use the concept of shooting one ball in the upper HUB and one in the lower HUB, as the first version, and try to tune the 2 ball paths so that it is consistent later. We haven’t been able to do this yet. When we finetune it into 2 consistent ball paths, we might switch back to 2 balls in upper HUB.

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I love your concept of switching between the two shots in hopes for reducing bounce outs. I’m curious as to the mechanism you are using to change between these two shots in such a short time. Do you have a hood angle adjustment you are making as well as a change in flywheel speed?

We make changes in the flywheel velocity, with the help of Sysid

Thank you! I am really quite surprised that you are angle to hit both shots without changing a hood angle. Fantastic work!

1 Like

Thank you for all the information your team has posted! Our team has taken great inspiration from your robot!

Here is our throughput testing
https://youtube.com/shorts/MDsPWLaPkEo?feature=share

And after some changes to our polycarbonate “walls” https://youtu.be/C0vx6ZWyUGo

Thanks again!

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Sorry for the radio silence… We had a little miss communication in the team on who would post the update and they both they the other did it :wink:

So here’s some late updates!

Week 4 Climber Update

ASSEMBLY & TESTS PNEUMATIC CLIMBER

First of all, we started with the assembly of the second revision of the pneumatic climber. The main thing we wanted to test was how the climber would behave with the flexing polycarbonate and the new hinge design. After the climber was assembled, we mounted it on the robot and put it to the test. These are the main things we noticed during the tests:

  • The polycarb hinge does prevent the sideways bending in the hinge point, but still flexes which is what we want. The flex in the hinge can be seen in the pictures below.

  • We designed two different 3D printed mounting blocks for the hook, one that could hinge and one that could not. We haven’t been able to test the hinging one properly, but as the robot is just barely off the ground, the hinging hook will probably make the robot touch the ground.

  • The screws and that mount the climber to the drivetrain are hard to reach, so taking into consideration the modular design we want to achieve, we want to look into rivet nuts for easier mounting.

MOTOR DRIVEN CLIMBER

While we were busy with the assembly and tests of the pneumatic climber, a new version was already being designed. This design was based on a motor driven telescopic climber that was already designed in the off-season and was based on a west coast products climber. We also implemented a brake system based on the one 2910 used in 2021. The climber will use constant force springs to deploy and a NEO with a REV gearbox to retract. We will start with a 1:25 gear ratio as a moderate start and increase speed if needed. We went for two stages to make the system as compact as possible. The spacers for the hook are made out of TPU with various wall thicknesses, we will test which amount of flex works the best. Another thing that has been designed is a clamp to attach the climber to the shooter for extra strength.

There are a few reasons why we wanted to also design and manufacture a motor driven climber next to the pneumatic one:

  • First of all, the weight, the pneumatic climber would shift the CoM up by 15cm.
  • Usage of less space, extra air tanks aren’t needed for the motor driven climber. The overall size of the system itself will also be smaller.

There are also some disadvantages, for example that the motor driven climber will not be able to climber after T=0.

NEXT STEPS

The next steps will be to assemble the motor driven climber and to do more tests with both versions of the climber. After the tests, one design can be chosen with which we want to continue. Then we can make some final perfections on the design and send it to production after this week.