anarchy-for-her

A PiTank project, inspired by HanYangZhao's Cannon Robot build; repository can be found here.

Made during the 2021-2022 school year for Bayview Robotics while we got an FTC team started up :D

Materials

Fueled by:

• Waterbottle (to act as the fuel chamber)
• PVC Pipe + T-connector (Home Depot)
  • The other workaround is to get the person with a 3d printer to make a rifled barrel :D
• Sparklighter (for the combustion with fuel)
• Duct tape (no explanation needed)
• Epoxy
• AXE's Anarchy for Her Body Spray | Dark Temptation Body Spray
• The old VEX V4 kits our school has (for chassis)
• VEX 393 motors + motor controllers (4)
• at least one fire extinguisher
• Amazon Prime
• Raspberry Pi 3B
• PiSugar Battery Pack
• the materials that come in an Arduino starter kit
• Fred's 3D printer
• Servos
• Wires
• Solenoids (not being used?)
• Stepper Motor stuff

Process

We had to majorly revamp the entire process. Pretty much none of us knew how to do anything, and the project was already 7 years old so the code was all outdated and most of the hardware listed wasn't available for purchase.

Differences

1. RIP arduino
2. Since we needed to run this in the school, we needed to find a workaround to getting the Pi connected to the wifi (static ip would not work)
   • Configure Bluetooth on the Pi

Issue Documentation

Here are a few issues that we ran into:

Getting funds for this project

• Robotics is incredibly expensive. The school being out of funds for 2 years also didn't help, so we applied to a grant to buy parts for both this project and for future club use :D

Sparklighter issues

• Not sparking

  • Make sure the wires are not crossed so the current doesn't jump
• Residue on the conductors

  • Scrape it off with a knife/clean it with rubbing alcohol

Figuring out how motors and servos work

• There's an ungodly amount of trial and error involved here, but the main takeaway was to simply test code to see if it worked.
• Motors and servos receive signals, or a PWM value, as instruction. PWM is pulse width modulation, meaning it will pulse a signal with a certain frequency to relay instruction. After sitting down with the VEX motors for 4 excruciating hours, I found that the PWM values it took were from between 6-22 by running a loop with PWM output from 1-100 and observing the behavior (direction, speeds).
• To reverse the direction of the motor without writing in another motor object reverse the polarity of the controller connectors

The cannon barrel/chamber popping off during the combustion

• This just means that the AXE:oxygen ratio was perfect. Concluded that AXE can be used as butane.
• Also figured out that using epoxy over duct tape might've been a better idea

Condensation/concentration of the AXE preventing sparking

• Chopstick + paper towel :D
• On a more serious note, the environment/temperature of the room where you're firing plays a huge role. As Canadians we're at a clear disadvantage
• As suggested, adding some sort of ventilation would work, probably a fan

PYNPUT

• DO NOT NAME PYTHON SCRIPTS THE SAME NAMES AS PACKAGES
• THIS TOOK ME 2 HOURS TO FIGURE OUT AND IT WAS ONLY THROUGH A REDDIT COMMENT
• 
• IM SEETHING WITH PURE UNFILTERED RAGE

Making tank do the wasd funny

• So unfortunately, it's needlessly more complex to try using pynput or the python keyboard library to track the time used to hold down the keys because the Pi doesn't recognize your machine's keyboard as its own

Tank Media

a video