So during the pandemic and nearing the 2020 graduation, Bosco Tech https://www.boscotech.edu/, my high school, was trying to decide how to safely host graduation for the seniors graduating that year (I was one of them). At some point one of the instructors pitched the idea of using the robot to hand diplomas to each the students as they graduated. The idea eventually made its way to me and I got to work. I did the design for the robot arm that was to hand the diplomas to the students and some of the manufacturing, my friend Lorenzo coded it (see his post here https://www.lorenzopedroza.me/gradbot), and my friend Maverick helped with manufacturing (all three of us were graduating that year).
The general idea for accomplishing this was to convert the shooting system from the 2020 FRC Robot https://alejandro-pina.com/2021/02/19/first-robotics-competition-2020/ to something that would be able to reliably move diplomas to the location of the student as they were crossing the stage. Since the shooting system was already on a turret with a wide range of motion the movement part was quite straightforward (didn’t even have to move the robot itself; just the turret). Another thing to consider was that all I had to work with were spare parts and extra materials from the shop.
I could’ve just made a static arm that attached to the turret but I thought that was too easy and would have been lame so I designed a two axis articulating arm powered by one motor which I also designed a custom reduction gear box for (all in SOLIDWORKS of course). One axis was to move the arm up and down and the other was to keep the diploma holder level while doing so. At first I made it too complicated by reversing the direction of the motor with a secondary transmission on the opposite side of the arm then connecting that to the second axis with a chain but what that did was everything but keep the diploma arm level. I took a step back and noticed that if the chain which connected to the second axis was not powered at all (essentially a four-bar mechanism) then the diploma holder would stay level (and it did). Throughout this process I was also coordinating with the principal of the school as well as others to make sure everything was going to go smoothly.
After the arm was mechanically functional Lorenzo was able to finish writing and tweaking the programming for it while I helped him with testing. During testing there were a couple scary moments where the arm motor or the turret motor would unexpectedly move at maximum speed for a second or so (could of seriously injured someone) but once we got it to do 100 back and forth motions (# of students graduating) consistently it was ready for finishing touches. We gave the robot a cap (an actual graduation cap on a foam mount) and gown (black safety bumpers) as well as some programmable LEDs that would change color based on which technology division the graduating student was in. They didn’t want a student operating the robot so Mr. Tom (the tech instructor who first pitched the idea) operated it and I sat beside him throughout the graduation to make sure the robot was handling smoothly.
The robot worked great during each student’s graduation except for one moment where it swung back violently for no reason (thankfully this was during a break period). It was a success and we are planning to do it again for the 2021 seniors’ graduation if needed. Below is the full Bosco Tech 2020 Graduation Video (skip to 45:38 for first robot action and to 1:57:11 for robot credits and a first person walkthrough of the graduation process that day). I’ve also included more pictures of the CAD and robot. Thanks For Viewing This Post!