FRC Dark Matter 2643 Build Thread for 2023

Dark Matter is excited to join the #openalliance for the first time in 2023!

Team 2643 is a student-led team in Santa Teresa HS, San Jose CA since 2008. Due to covid, we had a sort of “gap year” and now most of our students are only either 1 season experienced or totally new. Despite that, we got many new students this year and we have 50+ students and 12 mentors. The highlight of our off-season was assembling a swerve drive and practicing it in our MPR. Our team has never used a swerve before, so it was an exciting experience and we are hoping to use swerve in 2023 build season.
Our team has also never used CD to document our build season (as far as I know), so, please bear with me when I post pictures, videos, descriptions, etc. about our build season because I am still pretty new to this stuff and I might forget to post. I’ll post at least once a week.

Open Alliance Discord

We are looking forward to the 2023 build season!


Pictures and a video of our swerve drive!


Also, I forgot to mention that we recently bought a CNC mill (Shapeoko Pro)! The second image shows the enclosure that we built for it (it’s not fully assembled in the picture).


DAY 1: Kickoff!!!
Here are my slides from today. Everything we did is on there! And this post has pictures from today.

Looking forward to brainstorming and sketching out robot design ideas tomorrow!

The team agreed on a match strategy. We will be specializing in the middle level (for both cones and cubes). We are not going for the top level because we decided that we do not have the resources, experience, and manpower to execute such a mechanism in a reliable and consistent manner. We figured that if we do really really good at the middle and bottom levels, then we will be an attractive alliance member for qualifier and playoff matches.

During the meeting, we brainstormed many robot designs and asked many questions about how it would work. We also talked about the different possible ways of picking up a fallen cone.

Robot designs (for arm & grabber):

In the end, everyone presented their idea and the team asked questions. The image below shows the 4 ideas that were presented (the groups had way more ideas, but they had scrapped and/or improved them).

It’s hard to read the writing, so there’s a translation here.

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Today we began the prototyping phase.
I split the Mech Team into 4 teams: Arm team, Grabber team, Swerve team, and Field Elements team.

The Arm and Grabber teams studied the different ideas from Sunday and they went into the finer details of the designs. Like trying to understand how the design mechanism will work. There was an interesting idea to use universal joint sockets for the grabber. Once we recieve them, the Grabber team will prototype with them and report their findings, hopefully in a few days.

The Swerve Team starting sketching out a belly pan for the swerve base. There are several factors to consider, such as where the superstructure (aka the Arm) will go, the material of the bellypan, and where electronics will go. Our swerve will be 30" x 30" and the electronics board will most likely be on the belly of the robot (below swerve).

The Field Element Team got started on making the platform. They made blueprints and started to label plywood for cuts. Hoping to get the platform finished by Friday, maybe sooner.

I will post pictures soon. Our media team is still in the process of organizing the team photos.

Ok it’s been a whole week since i updated… SORRY.
Basically Week 1 has been all prototyping and building field elements.

I’ll start with the Grabber.
The team decided that we wanted something lightweight and simple. It needed to be able to grab the cone/cube from either the ground or the human station, and also release the cone/cube on the peg/shelf. As I am writing this, we have gone through almost 10 design iterations. But I’ll show our 1st prototype design:

The idea here was to use a cable to open & close the claw. The claw had sticky surface for grip. The grabber team wanted to upgrade this, so they went with a slide mechanism using a rail. Here are some pics:

Basically the bike cable was squished into a hole (1st image) which would connect to a slide. The 2nd image just shows the other side of the rail, where there is a stationary post with the cable coming out. This prototype worked pretty well, however we scrapped it because we were afraid of it breaking too easily in match, and also because rails like that aren’t consistent enough for a grabber like that.

The next prototype involved a new claw design, hex shafts, and chains.

I unfortunately do not have more pictures of this exact prototype, but essentially we had 2 claws that were controlled by a motor (i.e. a drill). We drilled holes for hex bearings in wood, added hex shafts with chain sprockets and the claw, and spun the chains with the drill. Midway through the prototype, however, we realized that the two claws were not going to close and open, but rather shift left and right in the same direction.
So, we moved on to using string and springs.

The images don’t show everything here, sorry. We added string and a spring/bungee cord, where the spring kept the claws closed while the middle shaft handle opened the claws through a string. Here, the concept worked. The only drawback was that it was very hard to make it work.

We tried to upgrade the prototype, but still no luck in making it easier to evenly open/close.

At this point, we were tired of playing with this idea, so the team discussed using pneumatics. The conclusion was that pneumatics wouldn’t fit our scope because there were 2 different game pieces, and it would also require our Electrical Lead to redesign the entire electrical board.

At the end of today’s meeting, the team wanted to try out gears, which looks to be promising. It’s not finished, so I didn’t take any pictures yet. But it’s basically two 50T gears in the middle with one 10T gear on each side, and each claw is attached to the 10T gears via hex shaft. The motor would be either on one of the 50T gears, somewhere below the grabber on the arm, or two motors–one on each 50T gear.

Ok, now the Arm team.
They initially spent a lot of time doing the math and sketching on CAD and trying to understand the best dimensions, so they didn’t get a lot of building the prototype. The team decided to go with a four-bar linkage design.

This is a very rough prototype. It won’t be made out of wood and plastic, trust me. Over the course of the week, the team made changes to the spacing between the bar linkages, the length of the bars, and the angle between the axle holes.

Here is a very basic CAD model of the four-bar linkage. This just shows the 72T sprocket attachment, which we are using from vex.
I plan on CAD-ing the motor attachment and the rest of the chain sprockets throughout this week.
Meanwhile, one of our senior members is prototyping another arm design—a telescoping pole that extends from the back of the robot. He just started today.

The Swerve team.
Waiting on parts to build the frame. Meanwhile we are just using our practice bot from off-season.

Field Elements.
Finished them today!
Video of swerve getting on the platform. (sorry for the background noise)

One of our members is making a 3D printed mount for a camera. Will post pictures about that next time.

Haven’t updated in a long time, sorry about that.
Here’s our CAD model.

It’s missing the Grabber CAD, but here it is in person:

Our arm base:

It has short arms because programming is currently testing them, and I don’t want long arms to hit the ground…
The final design will have 2 falcon motors with gearboxes.

We also made a new drivestation, and it turned out awesome.

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