FRC95 2022 Build Thread

Time for another Grasshoppers build thread!

Here are some important links:
Youtube
Imgur
OnShape
Open Alliance for 2022

We are beyond excited for the number of teams joining the Open Alliance. I specifically want to thank @Ty_Tremblay for leading the rowdy group of OA teams and making things official. Officialish anyway :wink:

95 did not meeting in person from March 2020 through August 2021. We have a lot of rust to knock off still, but with a handful of new students and four new FRC alumni coaches we are shaping up well. The Director of our home tech center, HACTC, has moved on to another directorship. He was a big champion of STEM and 95; seeing him go was a bit scary. Fortunately, the interim director is excellent and is providing us with all the support we need. All of our main sponsors have come back online too (phew!) after we declined to do any fundraising last year.

We have acquired a real high speed video camera for this season. After HSV analysis of power cell shooting was well-received last year we have decided to up the ante.

I want to talk briefly about something important to me in FRC: setting your own goals. If you enter an FRC season without a clear set of goals for yourself and/or your team it can be easy to lose your way or be disappointed with how the season turns out. After all, only a few teams get to win on Einstein. We have not picked our goals for this year, but in the past our list has looked like this:

  • No lost-time accidents
  • Win a judged award
  • Make eliminations at every event
    • Bonus: captain an alliance
  • Implement something new on our robot
  • Stretch: make the GDC write or amend a rule

I hope every team takes a few minutes to set goals for themselves. It has helped us tremendously.

Good luck to all teams!

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Hopping on this early I see.

(pardon the pun)

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No need to pardon good taste.

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Now that’s a beautiful goal.

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https://us.motorsport.com/f1/news/banned-tech-brabham-bt46b-fan/4808235/

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I do not recommend suction :wink:
(didn’t get us a rule anyway)

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So, one of our goals every year is ‘no lost time incidents’ meaning we want to avoid any safety issues were much more than a bandaid is needed to address the harm.

And here we have COVID.

So let us apply the engineering/lean problem- solving process to address this issue.

Define: people can get COVID from attending in-person robotics meeting.

Measure: this is tricky with safety. We could measure it in hospital costs, opportunity cost, or something else. I’m inclined to say: ‘my student’s health is priceless’ and move on.

Analyze: COVID infections spread when an infectious person exhales airborn particles that are inhaled by an uninfected person in sufficient quantity. A significant portion of transmission occurs in the pre-symptom stage of infection, peaking with the onset of symptoms. Not even regular testing is foolproof with Omicron.

Improve: improvements fall under prevention and mitigation.

Prevention methods:

  • Stay home (not an acceptable solution for many people)
  • Do not attend a meeting if you are symptomatic or have had close exposure

Mitigation Methods:

  • Get vaccinated to reduce viral load emitted and symptoms/hospitalization if you become infected
  • Wear a mask to reduce exhaled and inhaled viral loads
  • Ensure all gathering spaces are sufficiently ventilated to limit viral particle concentration
  • Clean air in gathering spaces, removing or neutralizing viral particles

Control: in order of presentation above…

  • Self-enforced
  • Self-enforced
  • Self-enforced
  • Team policy that all members be masked at all times during meetings outside of sipping water. Straws that can be used from under a mask are highly encouraged. Surgical and N/KN95 masks strongly encouraged.
  • Use a CO2 monitor as a measurement correlated to exhalant concentration and thus viral particle concentration. Ensure CO2 concentrations do not exceed 800PPM in meeting spaces (generally agreed upon threshold for ‘well ventilated’ space). We can open doors and turn on fans to improve ventilation as needed.
    Example
  • Use a HEPA + UV-C air purification unit to catch and kill viral particles. HEPA filters are fine enough to capture exhalant droplets. UV-C light is an effective neutralizer of the COVID virus.
    Example

This will be our mitigation plan for the season. So far during the pandemic the building we are meeting in has recorded no transmission instances with their HVAC settings and masking policies. With the added air purification to further reduce transmission risk I think we will be at a reasonable risk level. More importantly we will have some real numbers (CO2 concentration) to monitor that we’re doing a reasonable job of keeping our air reasonably clean.

Stay safe everyone!

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For our final preseason meeting last night we brainstormed, debated, and created our priority list for the year.

  1. Safety - No COVID transmission or lost time incidents
  2. Foster a positive team experience
  3. Lern Gud™
  4. Captain an alliance or be a first-round pick at every event we attend
  5. Win the Quality award; build out our quality plan, design the robot for service, etc.
  6. Implement a scouting system and practice it
  7. Develop something new and interesting on the robot

One of our students is turning this into a spider chart with clear action items to move towards completing each of these goals. Hopefully I can post it soon.

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Dear CD,

Make a velc… err… hook-tape intake.

Love,
The Grasshoppers

PS: we’re still digesting the game and preparing a cogent analysis.

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2022 Game Piece being revealed

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Here is an outline of how different teams’ robots may progress through build season. No one comes out week 1 with 100% capability, so planning how your capabilities will grow through the season helps establish milestones and focus priorities.

We typically land somewhere between a mid-tier team and an elite team in terms of performance. You will see our schedule with some super-reach goals falls between mid-tier and elite.

I want to stress again: set some reasonable goals for your team. It’s HARD to get everything working well and have practice time. Down-scoping for early week events is a great thing.

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Some intake options got tested tonight. Velcro is sticky, rubber not so much, ripstop noylon bumper fabric is quite slick against tennis ball fuzz.

We didn’t get our KoP yet, so just an oversized tennis ball for now.

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Let’s talk drivetrains!

In the past it was easy to say “sprint distance from A to B, optimize!” and this won’t be the case for 2022. There won’t be reliable loading from a human station, cargo on the ground will be scattered all over the place, and robots will be going everywhere to get what they can.

So, we took a step back from our 2spd auto-shifting formula and revisited our drivetrain selection. We also considered goal #5 (win quality award, make things more reliable) in this decision. We had some discussions on the pros and cons of different drivetrain choices, modeled some situations in the ILITE drivetrain simulator and settled on a 6-NEO, 6WD, single-speed/single-reduction drivetrain geard for ~13ft/s. It did a good job covering the wide range of driving situations we thing we’ll see while also eliminating the complexity of a 2spd transmission. We have had transmission failures of various sorts in the past and would like to avoid them this year.

ILITE drivetrain sim

https://i.imgur.com/XUibPTY.png (out of date)

We’re using a basic sheetmetal chassis construction with wheel modules that can be removed as whole units or assembled in-place.

#35 chain runs, pretty normal, with 4x2in hex-hub Colson wheels.

I love this chain generator featurescript: Accurate chain generator FS! — Onshape

We left, for now, provisions to move the transmissions to either end of the robot in case we need to manipulate the CG, but it’s most likely we won’t need to do that. We will probably be biasing weight towards one end of the robot for a slight advantage in climbing geometry.

Overall we’re running a little narrower than normal to help get through traffic and relieve climbing alignment/fitting next to other robot concerns.

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Parabolas.

Great for basic shot options. Sometimes hard to accurately define in CAD. Well, an OnShape user made a nice demonstration on how to make them.

Drawing a Parabola — Onshape

This is a GIF of the process.

Edit: pew pew

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Finally got game pieces! The generic versions of Cargo on Amazon match the real things quite closely. With eyes closed no one could tell them apart.

We tested shooting and collecting with HSV. We varied pressure and compression in shooting, and direction/speed of incoming cargo for collecting. Both were driven 1:1 via CIM (easiest thing to rig up). There are a LOT of subtle details. Watch carefully and see what you can figure out!

Shooter used 4in colson wheels
Collector used 3in compliant wheels and KoP dual-lock strips

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HSV uses a LOT of light. We have 100W LED lamps that we focus tightly on what we’re recording.

And we still have a vintage gutted cordless drill to use for speed-controlling prototype mechanisms like these.

From a drill that @Andy_A bought in 2004ish.

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Any particular theory or experience behind starting at 3" compliant? My default is 2", and I don’t think we have any 3’s in the shop, just a couple 4’s that require hubs…

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We had a bunch of them, and they enable the intake packaging we’re looking at. I like that they have a rigid plastic hub to be driven with. I’ve had 2in wheels strip out, kind of a lot.

They come in Grasshopper Green™ like the 2in wheels, so that’s a plus.

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We worked on CAD modeling and shooter/collector testing. Here are some of the real-height shooter tests. Videos with 5x cargo are inflated from (1) basically flat to (5) really stiff, overinflated. Wheels are 4x2 colsons, running from a CIM 1:1 with about 1.5in compression. We are generally quite happy with the results. In some we feed 2x quickly, sometimes too quickly. This shooter has no flywheel mass at the moment.

https://youtube.com/shorts/XbHRu5tx1PY

https://youtube.com/shorts/sDYIYgPB5Wk

https://youtube.com/shorts/7FZtAYeJ2Ao

https://youtube.com/shorts/I9emhM8NUJk

https://youtube.com/shorts/x962RyVElrg

https://youtube.com/shorts/ivVW0NPlO0w

https://youtube.com/shorts/uGbFMf4pm0g

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I love these videos, I think that shooter design will be very solid. Have you done any testing with a flywheel with more mass than colsons to account for the loss in inertia?

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