Hello, I’m Brent, I am a senior member of FRC team 4564, the lead programmer and been competing in FRC since 2016. Orange Chaos(4564) is the northernmost team in the NEFIRST district and will be attending the SE Mass and Pine Tree events this year. We are a pretty young team with 2 seniors, 4 juniors, 2 sophomores, and around 10 freshmen and eighth-graders.
Preseason Goals
Our goal this year is to be an alliance captain with a shot of winning every event we attend.
First Meetings
The way we start our season is first an unofficial kickoff at our own shop watching a stream that we invite local teams to. We didn’t do much discussion beyond buying some 6-inch pneumatic wheels to ensure that we could have them available.
Sunday, we had a potluck with family and sponsors then jumped into a quick rule overview. After that, we jumped into a game discussion. We thought that climbing is essential and at least rotation control is desirable early with the position control being easy to follow up with at a second event. We thought that the game would end up with the optimum alliance being a trench cycler, mid cycler/D and a frontcourt that may also play D but focus on picking up overflow and scoring.
Looking something like that. With that, we thought that the best designs were either a small bot that ran trench fast with a large floor intake to transition into frontcourt if a better trench runner was available or a more dedicated sniper that lined up on the Wheel of Fortune(Control Panel) that used a variable hood to be able to shoot from other locations on the field. We decide to start to prototype the sniper because we believed it to have both a higher score ceiling and cool factor. The rest of the meeting was ensuring we wanted to stick with pneumatic wheels, talking auto, and discussing climber options. The decision was made that if we planned to shoot from the WOF(control panel) we would not be small enough to go under the trench as it would only benefit auto(which an 8 ball auto is probably close to or beyond our limit) and flexing into frontcourt if we are really outscoring the opposing alliance and causing overflow which is a win-more situation. It kinda feels bad to realize that there is an optimal robot for the role you choose then the one you are building but as we are already doing everything, not overreaching is a big concern for us. As for climber we see some way to increase leveling chance to be important but haven’t decided on anything to prototype. [
After that meeting, we were really excited and jumped into prototyping. The programming subteam worked with the V3 color sensor while the mechanical subteam made a test flywheel powered by 2 miniCIMs to test the viability of the sniper. https://photos.app.goo.gl/KwXcrt8NdwUnUfEw9 I think we proved that it was at least viable.
We’ll make sure to include more pictures and descriptions of our prototypes when we update tonight. We’ll include our hooded shooter prototype, the 4” mecanum wheel intake, and the plywood drivetrain we created to choose the correct amount of center drop for 8x 6” WCP pneumatic wheels.
We would really appreciate your suggestion on the drop. Also any experience with the centipede tire shape. Curious how they change with different pressures since it looks like they would get less square with higher pressure. Main reason for that questions is whether you can reduce scrub with higher pressure in the center wheels. We will not be able to test ours for a couple of weeks due to backorders.
The (hopefully) final drivetrain rails are being machined this afternoon based on our findings, so we’ll be able to comment on the prototype today and true drivetrain shortly.
More dimensions will be included in the larger post, but tires with pressure above ~30PSI will have a noticeable crest, and changing the pressures does change scrub characteristics. We settled on 3/16” drop with 8 wheels to minimize rocking.
We started off the day with a design meeting where the CAD subteam presented their current design ideas.
The drivetrain is 4564’s standard CIT setup (12T #35 chain sprockets inside of 3” x 1.5” x 0.125” tubing) with 8x 6” WCP pneumatic wheels and a 3x NEO shifting gearbox with estimated free speeds of 16.9 FPS and 8.2 FPS. While the pneumatic wheels are harder to ‘get right’ than Colson or other traction wheels, we want the ability to speed over the boundary rails without the worry of shock loading on the drivetrain. The speeds were also chosen based on driver preference and short/long sprint distances.
The intake system would be 4” mecanum wheels with a central omni wheel feeding into the linear serializer. A simple idea that draws a lot of inspiration from 971’s 2016 robot.
The power cell storage system would be a series of urethane round belts and compliant wheels to hold 5 balls. Nothing too concrete, as this system would need to be extensively tested due to how much the dodgeballs like to stick and jam.
The flywheel shooter will be a two-position hooded shooter with a 6” VexPro Traction wheel as the shooting surface. A 6” wheel allows for longer contact time and faster linear speeds at the cost of some extra space, which we think will work with our ideal packaging.
The climber was discussed and the current plan is to have two elevators that each deliver a hook that are connected via seatbelt strapping to the final elevator stages. Individually driving each elevator would allow us to swing the robot and shift the CG as climb easily on an angled bar. The disadvantage of this setup is that it would likely require a dedicated operator with two joysticks to control and is more complex than a single hook.
Plans to simplify aligning our long-short was also discussed.
Prototypes and Productions!
A quick picture of the 3x NEO drive gearboxes. This is the result of a collaboration between 4564 and 6329 to use the internals of a WCP DS gearbox with 3 NEOs. By changing the input gear to 48T and remachining the plates, 3 NEOs will fit snuggly into a 2-stage shifting gearbox.
To test out the dimensions for our frame we decided to lay out the bearing holes on some plywood and attach the wheels. A ~130lb student sitting on the frame showed us that a 3/16” drop with our 8WD setup (9” distance between center wheels, 6.75” from center wheels to end wheels) would need a very centered CoG if we did not want the end wheels to scrub excessively on the carpet. From this testing, we decided on a 0.200” drop.
After the meeting, the programming team continued to test the color sensor v3, setup our 2020 git repo, look for driver cameras better suited to look down the field at the inner port, and create a test bench for Neos that sadly involved taking apart the drivetrain of our 2019 summer bot.
We’ll have an update for our Thursday and Saturday meeting soon!
