FIRST Robotics

ZACTF Team #426

Zombie Apocalypse Counter Task Force, ZACTF

It's a play on words, as most people are becoming a Zombie slave to their cell phones, and we were doing our best to have them put away their phones and make something.  Some of that is reflected in the artwork. 

This all started on January 4th, 2020, the day of the kickoff, when the field and challenge is announced to everyone.  We visited Morris High School, in Bronx, NY, a national historic landmark, and the school that Colin Powell attended.  We met students from two of the four high schools that share the same building, after going through the metal detectors operated by 4 NYC police officers - a light compliment on a Saturday morning.  We then learned it's one of if not the lowest income school districts in the entire country, with a graduation rate between 7 and 9%.  We met with the teachers and interested students in the library, which appeared to have just been remodeled - new shelves, new tables, fresh paint, new lights, etc.  Not a single book or computer in the entire 30' x 80' room lined with shelves.  We then learned that it was finished over two years ago, and hasn't been used by any of the 4 high schools who share the building in all of that time.  

Team #426

The team is made from a wide collection of students:

And a motley collection of mentors from around the world as well:

Robot Design

Learning the Game

Kickoff day revealed the challenge - it was then up to the team to brainstorm (BRAINS!) how the robot would accomplish the different tasks set in the challenge.  We started with the dimensions of a standard chassis, then some of the basic dimensions of the field to define the size and layout of the bot.

Robot Layout

Many sketches were flying around between the team members.  As we are a rookie team, we followed the KISS rule, Keep It Simple Stupid.  We went for a conveyor system to vacuum up the balls to a hopper,  then a second to shoot them into the lower goal.

TEAM426 Robot.avi

Color Wheel

One of the next stages in the competition was rotating the color wheel in the "Trench" area.  We wanted an agile robot, that could fut under the trench, yet have a part pop up to rotate the color wheel with a sensor to check the colors as they rotated by.

Lifting Arms

At the end of the match, you can earn extra points by lifting the robot off the ground and hanging from the "generator switch arm".  We designed the arms shown above, controlled by a winch and green straps from ratchet tie downs.  Gas springs force the arms upward, when the winch is un-spooled, and once hooked over the rod, the winch is wound in lifting the robot.

Electrical Layout

With 10 motors, 10 speed controllers, switches, lights, and a big regulation battery, there was quite a bit of wiring to deal with.  We did a couple virtual layouts of the components, and did our best to keep it neat when we ran the wiring.  We also kept things modular, so that if we needed to remove a sub-section, it would disconnect easily.

Testing 1.mp4

Testing, Testing, Testing...

We commandeered one of the parking garages at Columbia University to test out the conveyor system.  This was when we realized we needed a net over the top.  

Color Wheel Test 2.mp4

Color Wheel Test

The color wheel drive needed to swing up and down to allow the bot to pass under the trench area.  We used a 4 bar mechanism with a worm gear drive to extend and retract the wheeled drive mechanism.  This way, if the color wheel drive was extended, and the bot was driven at full speed into the trench, it would not back-drive and overload the raising/lowering mechanism.  A planetary gearbox and 3" diameter compliant tires were used to rotate the color wheel.

Lifting Arms.mp4

Lifting Arm Test

Timing was getting down to the wire.  We had built the arms with one transmission, and a 1:1 belt drive, when we realized it did not have enough torque to lift the robot.  The last weekend before we had to ship the robot, Wayne, Lauren and I swapped out the 1:1 belt drive with a 4:1 #25 chain drive, which did the trick.  As we didn't have a small 15 tooth sprocket with the proper 1/2" hex hub, I downloaded the .STP file of the gear from AndyMark.com, opened it in SolidWorks, added the proper hub, and machined it from a solid chunk of aluminum in about 35 minutes from download to finished part.

Packing & Shipping to Hawaii

With three wooden crates that were discarded at work, Vinny (Nicola's dad) recombined two of them into one larger crate for the robot, and the second original crate for tools and the awesome custom cart my good friend Brett had made.  We got the crates packed up on 3/8/2020, and loaded on my trailer just before midnight.  The following morning I delivered them to Wayne's office, where they were picked up to be shipped to Hawaii.

On to the Competition!

It was cancelled due to Covid-19.  As we were flying over the Pacific.  BTW, Hawaii is overrated.   Next year...