Intake Mechanism FRC 2019

Intake Mechanism FRC 2018

Project Log

Week 7

Goal

Assemble the whole robot to bag

The rest of my team and I are working on the elevator and electronics this week as the intake, rotary mechanism, drivetrain, and hatch grabber are done. Here is the final robot with everything attached and wired.

Week 5 - 6

Goal

Design brackets to attach hatch grabber to intake and mill
Buy 2in wheels x32 (extra for multiple iterations), churros, gearbox, bearings, gears, versaplanetry 180 drive, belts, spacers
CNC plates
Cut 1/2'' shafts to length
3D print spacers
Assemble gearbox
Assemble intake

Our team was having a lot of trouble with the CNC. Meanwhile, I cut shafts and 3D printed spacers so when the CNC was working and the plates were cut and the rest of my parts came, I was ready to assemble. Here are the brackets I designed and made (using manual mill) that would be attached to the intake via 1/4'' bolts and nuts, which would then be able to connect to the hatch grabber with the same bolts and nuts. Here is also the gearbox (made a spare) and printed spacers.

We were able to get our CNC working eventually and my plates were cut and my parts arrived. I assembled the intake and the belt spacings were off... I had bought the wrong type belts (HTD instead of GT2). I bought the wright belts and once they arrived I assembled. This took some patience and learning to use tools more efficiently and fast(drills, alen keys, wrenches, press machines, etc.) I also weighed the intake after assembled, and it was pretty light: 6lb. However, with the hatch grabber on top and the rotary mechanism attached, the load for the elevator will be greater. Might have to reduce some more weight.

My mentor and I decided to test this intake with a battery connected to the motor. It works pretty well! We also attached one of my teammate's recent hatch grabber prototype to

show how it would work in-game.

Week 3 - 4

Goal

CAD intake into vertical design
Figure out belt spacing calculations and implement into CAD

I designed version3 of the intake in Onshape CAD application because that was the application I knew how to CAD in. However, our mentors are experts in Solidworks and advised us to switch to Solidworks so they could help us if we ever encountered any problems when designing. A couple of my teammates and I decided to self learn CAD from online tutorials as well as some basic principles from our mentors. In this 4th version of the intake that I CADed in Solidworks, the plates are one piece instead of having two separate ones connected to a metal tubing. This is to minimize weight since the base is now fully polycarbonate. It's also more aesthetically pleasing. It uses the same one motor system, but I learned you can't just attach belts to pulleys at any size away because belts are made in specific sizes (specifically number of teeth), unlike sprockets and chains where you can change the length of the chain by just cutting the chain. I used this website to calculate my belt spacings then implemented them into the geometry of my cad.

At the time, a couple of my teammates and mentors had finished designing our team's elevator, drivetrain, and rotary mechanism. I added some holes for mounting the intake to our rotary mechanism

Here are images of our robot with the intake attached to the rotary mechanism, which is all attached to the elevator.

Week 2

Goal

Design/Make version 3 of the intake prototype

As my mentors were helping other subteams with their prototypes, I wanted to start making a more robust intake and more representative of the final version. A mentor and I got into a discussion on whether to think of making our intake oriented in a horizontal way, which is what I wanted and how my previous prototypes were designed and built, or a vertical orientation, which my mentor wanted. My mentor said a vertical orientation would be better because the force of gravity has less effect on the ball than if it were in a vertical orientation. This factor is actually very important since our team decided we would be using a vertical lifting elevator for the intake to place the ball at high height goals. The main reason I opposed the vertical implementation was because I thought my prototypes and design would be scrapped, which I didn't want (lol very selfish at the time). So I decided to show my mentors what I actually was thinking of in a digital form. In addition, my mentor let me know that we would need the intake to be low weight for the elevator gearbox to bring the intake up and down. He recommended using pulleys and belts instead of sprockets and chains to reduce weight. Using the CAD skills in Onshape I've learned in the past, I designed the third version of the intake with more features than the previous prototype: four polycarbonate plates attached to a metal bar. I implemented one motor system with belts and pulleys. The one motor system would use a 775pro motor attached to the metal bar and would have a shaft attached to the end of the motor to place gear. This gear would touch another gear next to it, which would be attached to another shaft on the metal bar right next to it. I would then run the pulleys and belts to both of these shafts with the gears on them as well as on to the shafts with the wheels on them.

I showed it to my mentor and he liked the design and wanted me to build it to test it out as all engineers do. So I did just that. I first exported the CAD files of the plates I designed to be laser cut out of polycarbonate material like the last prototype. This iteration had 6 wheels on each side so it only needed 10 pairs of bearing holes, 6 pairs for the wheels, 2 pairs for the motor/gearbox/gear and the other shaft with gear, and two pairs for shafts that would have pulleys connecting the pulleys from the shafts with the connecting gears and the shafts with the closest wheels on their respective right and left side. Although I used belts in my CAD assembly, I stuck to sprockets and chains just for this prototype because it would be faster to build/assemble. I found a stock 1/4'' aluminum piece in our lab to use as the base. I also didn't make bearing holes on the metal piece for the shafts for the gears I was running the wheels with two drills just for this prototype. Again for the sake of prototyping and speed, I used shaft collars to hold the wheels and sprockets in place.

The spacing between each plate that I calculated was too short so it wouldn't let the ball fully into the intake. So I had to rebuild it with two inches greater distance between each plate.

When I tested it out by first throwing the ball in and then powering it with two drills(seen in the videos above), I noticed that It actually held the ball well. When my teammate and I shook it around, it didn't fall at all. And when I tested it on a floor to simulate a floor intake, it also intakes the ball very well. However, the outtake was not impressive since the ball was also touching the floor. This wouldn't be a problem anyway because we would never outtake from the floor. Although our mentor who recommended the vertical implementation wasn't at the lab that day, I still wanted to put his suggestion into practice. We put the intake onto a stool in the vertical position. And it intakes great, and outtake ok, but better than I expected. With a proper motor and gearbox, the outtake could actually be better with the vertical implementation using the same motor system and design as the horizontal design. We also came up with an idea of having the vertical intake attached to a rotary mechanism onto the elevator. This would allow us to rotate the vertical intake up and down to pick up a back and place it higher if needed. I started to really like the vertical orientation and so did the rest my time.

My teammates also were designing a mechanism to grab and place the hatch piece in this year's game. By making the intake vertical, we also found a way to put hatch grabber mechanism onto it which was amazing as we were struggling to figure out where the hatch grabber would go. It would look something like this.

Day 6 - 8

Goal

Make version 2 of the intake prototype

In this second prototype, the intake consists of two laser-cut caded plates with 4 in wheels on the intake displaced angled out attached to a wooden base. This prototype also has 8 pairs of four in wheels (8 on each side).