2024:Hang

1/6/24

Discussed and prototyped on CAD a spring gate hook

1/7/24

• Prototyped two different types of hooks
• Tested both, worked well in holding on the chain and preventing slipping

1/13/2024

We started the meeting today by taking inspiration from our 2022 design for the hang mechanism. Upon further research, we decided to modify the original design to better suit our needs for this years game. We started by deciding to try a different way to prevent the arm from moving. We used a Ratchet and Pawl mechanism in 2022 and ended up having lots of problems with it, so we are going to try a worm gear this year (we will start a prototype for this once the one we ordered comes in). We also took inspiration from PRi3D of the North's 2024 robot reveal video. The hang mechanism that they used had the hook inside of the arm instead of placed on top, which would help reduce weight and will (hopefully) have less problems. We decided to stick with the hook that we tested during prototyping. 

We then worked on calculations of the hang mechanism. Based on the height of the drive base and the range that we wanted to be able to hang on the chain from (when the chain is 36" from the ground or lower), we decided that the arms should be 36.5" tall, the side that our hook will stick out on will be 2" long, and side perpendicular to that will be 1.5" long. We also spent some time discussing with the game piece group to see if the hang mechanism would get in the way of the intake/shooter. Both hooks will be completely independent from each other. In 2022 we had them connected and it was extremely hard to access anything if it broke, so we decided against connecting them. We then began working on the CAD for the arms. 

1/14/2024

We ultimately decided to go with a Ratchet and Pawl design for the hang mechanism. Because we have more experience with it, we can improve the design and try to fix problems that we ran into before instead of trying to design something completely new. One group took the Ratchet and Pawl design from 2022 and shortened the axel length for it. Additionally, we decided that having smaller teeth on the ratchet would allow for us to be more precise and have less distance to pull the pawl. We will continue modifying the design as we see fit. 

The second group for hang worked on more calculations and working on the arm design with the constant force spring. We started by calculating the force that would be on the rollers on each side of the interior arm. Each roller needs to be able to hold 18.75 lbf. Additionally, we came to the conclusion that having a 1/8" thick arm would be much stronger than a 1/16" thick arm. The dimensions of the external arm are 2" x 2" and the internal arm is 1" x 1". Since we will be using the robot frequently and pushing it as much as possible, we wanted to make the arm design extremely robust so it doesn't bend or break. We designed the spring bracket for the constant force spring and designed the bearing blocks for the 1" tube and decided to use a 1/4" bearing. 

The hang sub team decided to put the hang mechanism on plates on top of the drive base. This will allow electrical space underneath our design and will also allow us to adjust the design depending on where the center of gravity in our robot is. We want to make sure our robot does not tip when we pull up onto the chain, and we don't want to tip when scoring in the Trap, so having a bit of wiggle room with the location of the hang mechanism was important for us. 

1/18/2024

• Added bearing block holes to hook

• Discussed and created CAD design for ratchet strap attachment to hook

1/20/2024

• Attached new ratchet strap clamp to the hook assembly

• Decided we're driving each arm with 1 NEO, for 2 NEOs total
• Using 1 electric solenoid per each arm (to control the pawl), 2 electric solenoids total
• Changed one of our bearing block designs to minimize the number of smaller bearing blocks we have to make
• We decided to make one big bearing block instead of cutting two smaller ones
• Started analyzing gear ratios
• Decided to use the same ratchet strap on this robot as 2022 
• Started designing the spool that the ratchet goes around