CAD bot in 1 day stream

[cpennell20]

I am a senior mechanical engineer with 1000+ hours across several CAD software looking for a CAD skills challenge so I decide to stream on twitch and see how much of a robot I am able to CAD in 1 day for the 2024 season.

Agenda…

1:00-1:30 - game manual review
1:30 - 2:00 – research similar games from previous years
2:00 - 3:00 - design objectives and preliminary design
3:00 - 4:00 - geometric sketches
4:00 - end of day - CAD

Twitch link… Twitch

[cpennell20]

The day is up and while I wasn’t able to achieve as much as I had hoped, particularly due to the fact that the climbing sequence requires a much more complex design than anticipated, I was able to achieve all of the other objective I set. I will be posting pictures and descriptions of the result tomorrow after a good nights rest.

[cpennell20]

I present the result of this 12 hour exercise!

Specs and Functional Decomposition…

1. ~24" total height
2. 26" x 26" frame perimeter
3. ground pickup
4. human player station pickup
5. score in amp
6. Score in speaker from protected stage and against subwoofer

A breakdown of these 6 points with pictures is below…

1&2.

3. the intake was inspired by the 2017 robot from 125. It is made of two linkages that nest within each other to decrease space on the bot. It is not modeled in this cad but just as 125 did, two pistons on each side would actuate each linkage independently.
   
   

The intake can then be actuated on the base pivot if you plan to score on the amp with the use of a telescoping arm…

Or the intake be actuated fully back in the robot and this allows the game piece to be fully passed through the intake and into a position ready to be shot…

4. The shooter is actuated by two positions for close or far shooting and the game pieces are loaded into the bot by the human player in the lower position. There is a set of bearing roller rods just above the shooter that helps to guide the game piece into the ready to shoot position…
   

   

5. A telescoping arm can be used to raise the game piece out of the intake and into the amp…
   

   

6. Can shoot from close or far position…
   

   
   
   
   

Things I learned and what I would do different.

1. I was surprised at how far the game piece has to fall into the robot when loading from the human player. I would need to create more shielding to guide the game piece into the robot as I want.
2. I would replace both the intake motor and the motor that powers the orange polybelt with PLG motors. They will be lighter and smaller and I don’t anticipate needing high rpm motors for that application.
3. I would replace the hook on the telescoping arm with some sort of compliant wheel hand, powered by a plg motor. I want to actively control that game piece when driving across the field and not need to keep the intake extended. And I would design it so that it ideally would slightly shoot the game piece down into the bottom floor of the amp.
4. Think about he climber early! It is very hard to climb on the chain while also scoring a game piece. I realized after the fact that it was more complicated than initially expected and I ran out of time to think of a solution. I did leave space on the side of the robot for extension arms to climb but did not have time to CAD anything.
5. I wish I had more active control of the game piece when it is in the base of the robot ready to shoot. I have the polybelt but with how many bot collisions there will be this year at high speeds, I am concerned with the game piece jumping out the bot.

[Chase1699]

I like the integration of this design a lot with the telescoping arm and think your takeaways are really valuable. I think there’s a lot for teams to take away from this, thank you for sharing. Have you considered if you do the changes listed in 3, that if you had a climber you could possibly do the trap with the same amp component?

[cpennell20]

Yes I have, I was playing around with it in CAD today. I havnt seen any videos yet of teams attempting any sort of climb on the chain but I have some concerns. The two main challenges I identified with trying to score while climbing is first off, with a 4ft max robot height and the bottom of the opening for a game piece on the stage being just above that, it’s really only feasible to grab a game piece from the bottom and push it that way, that would only require an addition 8” roughly of robot lift off the ground to score. In my design, because the game piece hangs down, I would need to have the top of the telescope near the top of the opening which would require lifting the bot almost 2 feet off the ground which is essentially the height of the low point of the chain. A bot who’s attached to the chain near its floor with almost certainly top over. Concern number two is the distance between the chain and the wall of the stage where you score. I believe it’s just under 2 feet. This means in order to score while being on the chain, your bot will have to attach to the chain significantly on one side of the chassis or the other and basic physics tells us that the bot will swing down from the lever arm being created between its center of mass. My approach to solving this problem… possibly not rules compliant… was to make the manipulator at the top of the telescoping arm have both a downward opening hook and an activity powered wheel to hold and discard game pieces. I would fasten three 8” pistons to the chassis that points down. Actuate the pistons while the robot is sitting between the chain and stage wall. Extend the telescoping arm, which would go high enough to score the game piece, and then actuate an arm that swing over the other side of the robots perimeter with hooks on it. Then slowly lower the bot down, the hooks on the shooter side is the bot would grab onto the chain first, as the robot lowered more, then I would retract the telescoping arm, and the bottom hook on that end manipulator Would latch onto the lip of the bottom edge of the cutout on the stage. I will send screenshots of this sequence with my bot tomorrow.