LigerBots 2877 | Open Alliance Build Thread 2024

FIRST FRC Open Alliance
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Welcome to the LigerBots 2024 Open Alliance thread! We are excited to continue to be part of this great community of teams this season. We appreciate the opportunity to learn more from other teams and hope that this thread can be used as a resource for anyone looking for new ideas. If you have any questions please ask!

Overview

The LigerBots, FRC Team 2877, is composed of members from both the Newton South and Newton North High Schools in Massachusetts. We are a student-led team and have over 140 members.

We have spent the last few months training our new team members for this upcoming season.

Open Alliance

Our goal is to post bi-weekly thread updates. We will compile summaries of the day from each build team with pictures of our mechanisms and links to our online resources; and then on Mondays and Thursdays we will upload updates to the thread. We hope that this thread will show the complete picture of our design and mechanical process.

Links

Whitepapers

Distance Learning with Zoom: LigerBots Distance Learning Whitepaper
Vision Processing: LigerBots Vision Whitepaper
Camera Latency: LigerBots Camera Latency Whitepaper
Electrical Test Bench: LigerBots Electric Testbench Whitepaper
Cleanup Bot 9000: LigerBots Cleanup Bot 9000 Whitepaper

Training materials:

FIRST Robot Mechanisms: FIRST Robot Mechanisms.pptx
Drive trains/chassis: Drive trains and chassis.pptx
Robot Recipes: Robot Recipes.pptx
Intro to Robots and FIRST Strategy: FIRST Robots and Strategy.pptx
Sensors: Sensors Presentation.pptx
How Motors Work: Motors Presentation.pptx
Intro To Manufacturing and Assembly: Intro to Manufacturing
Nuts and Bolts of Nuts and Bolts: Nuts and Bolts of Nuts and Bolts Presentation
LigerBots Build Season Process: Ligerbots build season process 2021.pptx
LigerBots branding standards: LigerBots Branding Standards
LigerBots team booklet 2023: LigerBots team Booklet 2023
LigerBots Robot Flyer: LigerBots Robot Flyer 2023
Ligerbots Design Process: Ligerbots Design Process
LigerBots Sponsor benefits flyer: LigerBots supporter benefits flyer

Training Cad:

Krayon CAD: Krayon CAD
Double Jointed Arm: Double Jointed Arm
Cascade Elevator: Cascade Elevator

Past Year Cad:

2023 Robot: 2023 Cad
2022 Robot: 2022 Cad
2022 Chain in Tube Drivetrain: Chain In Tube WCD
Citrus Circuits CADathon 2021: Citrus Circuits CADathon 2021
2020 Robot: 2020 Robot Cad

Code: LigerBots - FRC Team 2877 · GitHub

2024 CAD: Onshape

Website: https://ligerbots.org/
Flicker: LigerBots FRC2877 | Flickr

Socals:

Youtube: https://www.youtube.com/c/ligerbots
Twitter(X): https://twitter.com/ligerbots
Facebook: The LigerBots | Barnstable MA
Instagram: https://www.instagram.com/ligerbots_frc2877/
TikTok: TikTok - Make Your Day

Previous OA threads:

LigerBots 2877 FRC OpenAlliance Build Thread 2023!

LigerBots FRC 2877 OpenAlliance Build Thread 2022

@Evan-G Will be leading this thread so feel free to bug him about posting updates :wink:

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This post was written by @Evan-G, but he currently does not have the perms to post multiple images so I am posting it on his behalf.

Preseason Update 11/12/23

Outreach robot update #1:

Outreach robot CAD: Outreach robot CAD

Over the summer we had weekly meetings for 3-4 hours to CAD an outreach robot that we currently have started to build in preseason.

Our robot design took a while to make and is designed for 2022’s cargo. It includes pneumatic wheels so we can drive over curbs, a turreted hooded shooter so we can aim to launch the balls to little kids, and a floor intake made up of acrylic tubes that we can cover in grip tape.

NERD:

We participated in NERD, an off-season competition this year. Nothing major broke, but we did have to replace a bracket that supported our bumpers.

Rockwell:

On November 8, we attended the Rockwell Automation Conference, an annual conference that we were invited to as an FRC team. We brought our 2023 robot and participated in mock games of Charged Up.

In one of the last games we managed to shear a belt on our telescoping arm that allowed it to extend and retract. (9mm HTD belt)

Mock 3 day design:

To prepare the new team members on the team for kickoff we ran a mock 3 day design where we had first years brainstorm strategies and robot designs for 2014’s aerial assist game. Each group had ~2 team veterans and a coach guiding the first years and helping them develop their ideas. At the end of it, we had a large group discussion where we looked at all of the small groups designs and strategies and gave feedback.

FLL Scrimmage:

In preparation for the FLL Newton Qualifier we hosted, we ran a scrimmage for local teams so they could practice. The teams got a chance to compete in practice matches scored by referees and also got to practice presenting their project and robot to judges for feedback in order to receive an opportunity to improve them before the competition.

FLL Qualifier:

We hosted our annual FLL qualifier event a few weeks ago on November 18th, it was a ton of fun and a good warm up for us for our big District Champs event on December 16th. At the qualifier we had 14 teams and we sent 7 to the District champs(which we are hosting). We had STEAM activities running and had our 2022 robot there for kids to interact with.

Pumpkin Smash:

The LigerBots attended the annual Newton Pumpkin Smash on November 4th at City Hall, bringing our custom built smasher. Each year team members design and build a new one from scratch. This year we designed a gravity based smasher.

The smasher (as seen above) had metal pipes on the top of it that acted as the weight as well as a surface to smash pumpkins with. As a last minute addition we added a large aluminum angle bracket to attempt to cut the pumpkins in half. The pumpkins turned out to be a lot harder than we thought they would be and the bracket ended up bending a lot. Still, it was a smashing success!

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Preseason Update 1/4/2024:

Outreach robot update #2:

We have made much progress building and manufacturing our outreach robot. So far we have the basis of the turret done, the translator, and the drivetrain.

We made the decision to not build the intake due to the cost. We will still have a way to feed the balls in through what we call the “translator”

We have started programming the outreach robot, but still have much to do.

Outreach robot code: Outreach robot code

Outreach robot CAD: Outreach robot CAD

Training:

Manufacturing (Elevator):

One of our projects is building an elevator that a team member CAD’ed to teach new team members many of the basic skills of manufacturing, showing them how to manually mark and measure with precision and how to use tools such as the drill press and bandsaw. We’ve also familiarized many new team members with the shop, showing them where to find tools and materials.

Programming:

We have covered a lot of the basics of FRC programming, from coding examples of commands and subsystems to explaining control mechanisms like PID loops and Trapezoidal Motion Profiling. Currently, we are starting to program parts of an outreach robot both as a training project and implementation of new mechanism designs such as a turret for the team. This would prepare the programming team for the upcoming build season in terms of collaboration, process, and organization.

Mechanical Design:

This year, we took a different approach to teaching mechanical design. Rather than doing CAD training, we did very little teaching in CAD software, and instead prioritized giving the students the right tools to clearly express their ideas for mechanisms. As we said throughout the training, we want to teach them how to tell a story, not how to use a pencil. Last year, people doing Mechanical Design noticed a number of people working in the shop that had many ideas for mechanisms, but didn’t want, or have time, to CAD. This year, we took an approach that will hopefully give those people a chance to get their ideas across to people who can CAD, during build season.

Electrical:

The main activity for electrical training this year has been designing and wiring up the electrical system for our outreach-specific robot that we designed over the summer.

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Elliot’s Last minute CAD post

Hi CD, I am the Lead Designer for the LigerBots this year for the robot. I also have been leading some of the CAD training for this fall. I want to quickly post some of the various CAD projects people on the team have been working on before kickoff tomorrow. If you have any questions, feel free to ask. We are committed this year to being an open team where if you ask we will answer, nothing is hidden or secret.

Our two main training projects besides the Outreach robot this past fall have been an elevator and a double-jointed arm. The arm got one and a half gearboxes assembled and the elevator got fully assembled except for the full rigging.

Arm CAD: Onshape

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Elevator CAD: Onshape

I could write way more on the elevator. If people are interested, just let me know. Fun fact: the elevator uses the same plate for all of the bearing mounts! That is 32 of the same plate!

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Video of it working:

KrayonCAD practice: Onshape

I introduced KrayonCAD to the team and have shown most of the team how to use it. We are all super excited to use it over the next few days for 3DD!

Some KrayonCAD practice images

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My rendition of the outreach robot

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Abby Z.’s 2018 arm

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Tyler’s Robot Practice

I hope everyone has a safe kickoff in NE with the snow forecasted for Sunday. But you know what snow is a form of? WATER! watergame

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LigerBots 2877 Build Season Update #1:

Build season is finally here!!! We are kicking off our build season with 3 day design (3DD) where we break up into small groups and the first day we come up with our strategy, and the second and third we brainstorm designs.

Yesterday as a team we wrote up our Require, Desire, Aspire chart with the goal of going to worlds.

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LigerBots 2877 Build Season Update #2:

What a week it’s been, from kickoff to 3-day design to prototyping to CAD weekend. We’ve been pretty busy!

New swerve!

We got 3 new swerve modules that students assembled Friday. They had to improvise a bit because the assembly video was out of date. They also took apart our spare swerve module to update the sizes of the holes from 8-32 to 10-32 to be consistent with our new ones.

Mechanism prototyping:

Split roller shooter:

The team wanted to see how splitting the rollers for a top/bottom shooter worked to see if we could give the note variable spin without destroying it. We were somewhat successful with our first iteration (see photo below)

Our second iteration used colson wheels because all our regular wheels were in use for other prototypes and ended up shooting pretty fast(~20 f/s). As of this post we have not tested the rollers with variable speeds

Side wheel shooter:

Another of the designs we are testing is the side wheel shooter. The shooter consists of two sets of wheels on either side. The goal with this prototype was to figure out if we could give the note variable spin by varying the speeds of either side.

Here is a video of it working: https://youtube.com/shorts/3Ccw8BCgeaM?si=jt_o-QmH5Tc-9g6g

Roller intake:

We started with a large roller intake that worked really well!

After talking with the CAD team we realized that it needed to be smaller so we prototyped a new smaller one that took a while to get working well. A issue we had was the note getting stuck when the wheels were too far apart

Video of it working: https://youtu.be/RjyR0o40yIE?si=qcFI-TtKWXxXXaP1

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LigerBots 2877 Build Season Update # 3 - CAD overview

Main Robot CAD

Highlight features of our robot this year:

  • Split bumper at different heights
  • Under bumper intake
  • Pivoting shooter on angled elevator
  • Winch climber

|485.21379310344827x375.2853012273948

Intake+Center

CAD

  • Under Bumper intake
  • 1 roller of 1.375in Bane Bots wheels for kicking up the note
  • 3 polycarb rollers covered in silicon tubing
  • 1 roller of 2in flex wheels

|554x427.8113159477961

Angled Elevator

CAD

  • 4:1 reduction with 1 NEO
  • Cascading style rigging
  • Belt for first stage and rope for second
  • AM bearing blocks
  • 2x1 WCP punched tube
  • Custom CNCed gussets

Shooter

Shooter Note:
We have two designs and are going to prototype both to see which is better. Also, the CAD for the shooters are configurable to either design

General

  • 2x1 C channel on sides to act as frame
  • Versa Hubs and Blocks to act as pivot points
  • 1/8th polycarb on top and bottom for rigidity
  • NEO for pivot with overall ratio of 22.5:1
  • Feeder powered by a NEO powering 2 sets of 2in flex wheels with a 2:1 reduction and polycord to swap direction on opposite side

Side/Horizontal Shooter
  • 4 sets of two 2.875in BaneBots wheels
  • Shaft directly driven by 1 vortex motor on each side with belt between the wheels on each side
  • Wheels inside of C channel

Top/Bottom Shooter
  • Dimensions copped off 6328’s shooter then adapted to fit belts and gears we have
  • 4 sets of 3 2.875 BaneBots wheels
  • Cantilevered hex shafts, I am not 100% sure how well this is going to work but one of our coaches says to give it a try
  • 2 Vortexes with 1:2 increase

Drive Train

CAD

  • Split bumpers
    • Front is lower to push notes away and to allow for more room for the chain to get lower in the robot.
    • Back bumpers are high to allow for note to pass under
  • Rectangle in both directions
    • 23in x 27in Drive base
    • 29.25in x 27.5in Frame perimeter
  • Steel box tubes as frame rails to virtually eliminate chance of frame bending and to lower COG
  • Mk4i L2 Gearing because that is what we have
  • Neo Drive(may switch to Falcons if time allows), NEO Steer

Climber

CAD

  • Work in progress
  • 2 independent NEO’s with 15:1 reduction for each side.

If you have any questions, feel free to ask! All documents should be public but let me know if there is something that is not.

Written by @ElliotS
Edited by @Evan-G

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I worry a bit that the bumper configuration in the CAD might not pass inspection. See R408 in the manual, and this thread for a discussion of a similar idea.

The TL;DR to my understanding is that you have to maintain the cross section in Figure 8.6 in the manual all the way around. The solution is either to bridge the two sections with an angled piece of bumper like this 1114 example, or keep the bumpers at the same height all the way around and use side skirts to keep notes out of your drive base. We’re going with the latter option.

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You’re going to want to check out the Q&A on bumpers. The 1114 example is legal (except the cut out, as they cannot have openings this year). So is one side being higher than the other 3 for example, as long as they are all within the 7.5" height limit and are constructed properly.

These two specifically will answer your bumper concerns.

To the rest of the the bumper questions already asked:

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My worry was at the transition point, the cross section where the two bumper sections meet in this CAD is not consistent with Figure 8.6 in the manual. I am aware that the 1114 example is legal, I brought it up as a potential solution.

Maybe I’m wrong on this, my experience is limited to single piece bumpers at one height all the way around. In fact, I think Q97 might be the best argument for the legality of this design.

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I think you’re interpreting this more rigidly than meant. The bumpers need to be constructed in that x-sec manner for any vertical cross section; which is a theoretical plane. It doesn’t mean bumper must be continuously at the same height.

Those we links to the official Q&A which says this is fine. There are also numerous CD threads on this as well.

For example here’s what we’re doing this year. The one bumper (back) will be at the 7.5" max height for the under the bumper intake. The other 3 will be lower to make sure a note doesn’t go underneath the bot. We construct 4 separate side bumpers every year. Ours are reversible in color so we don’t have to change them out.

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Have you guys been impacted by the strike? Have you been able to meet in person in any capacity? When Melrose teachers were preparing to strike last year, we were at risk of getting locked out of shop mid-build until it was resolved.

(Newton teachers are striking, for the unaware, and the school district hasn’t been open in ~2 weeks.)

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Justin, thanks for the concern. We have also received support directly from a couple of local teams and NEFIRST. We are grateful for the continued support of the FIRST community.

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Today, we did some Intake testing and we are very happy with the results! I will write more about that in a follow up post.
We also did some shooter comparisons between our two shooter concepts, and we will publish that data soon.

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LigerBots 2877 Build Season Update # 4 Shooter comparison:

Top-bottom shooter vs. Side wheel shooter: Shooter Testing (Top-bottom & Side-way)

  • For our design, the top-bottom shooter has a faster shooting speed at lower RPM

    • The top-bottom shooter have a 2:1 motor to wheel gearing ratio while the side wheel shooter have a 1:1 ratio
    • The top-bottom shooter can make the 17ft shot while the side wheel shooter can’t

  • The top-bottom shooter is more consistent

    • The top-bottom shooter have more contact surface with the note
    • The note’s vertical stiffness worn out slower than its horizontal endurance (Top-bottom shots worn out note and new note the same while side wheel shots the new note higher than it shots the worn out note)
    • The side wheel shooter is more sensitive angle change, which could be the result of the speed limitation from its 1:1 motor to wheels ratio

  • We found in order for the note to go in we need to:

    • When to the right of speaker, counterclockwise spin
    • When to the left of speaker, clockwise spin
    • When clockwise spin to the right, the note could spin across the inner hood and comes out (video)

Note: We had to tune the feedforward constants differently for the left and right side, which means the friction is different (about 10%).

Podium shot:

Amp zone shot:

17ft shot:

Written By: @YYml
Edited By: @Evan-G @ElliotS @prensing

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Here is a picture of the robot from today. We are working on a post about the intake that should be done by the end of the week.
For more photos of our build season, we post a ton on our flicker: LigerBots FRC2877 | Flickr

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Robot teaser video now on YouTube!

Full robot reveal video coming soon.
When the CAN bus is not acting up…

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Congrats on your performance last weekend at the BSU event! It was great to see you guys do so well - I imagine you have had some real challenges early in this build season to overcome, so it was definitely nice to see. Your auto was very effective!

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We are all super excited for this weekend! Here is a quick timelapse of us rebuilding the elevator with upgraded brackets and cross bars.

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Note passing fun with 4909 at Robo Boston.

Flicker

[Album] RoboBoston, 9/29/24
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