5) Electronics and Software - Onion Cutter

The electronic parts of our final prototype consists of the Greartisan DC 12V 120RPM Gear Motor, an Arduino, and a power supply unit.  A simple servo motor could not provide enough torque for our needs, so we used a 12 volt motor with higher torque. For this motor, we decided against soldering the power wires onto it, since we want to be able to quickly disconnect the motor and stop the knife movement if something were to go wrong. Although this causes us to carefully place the wires during demonstrations, it provides safety benefits. Furthermore, the new motor came with two issues:

1. It runs on 12V of power instead of 5V like the servo, so we need to use the power supply unit and different pins on the Arduino board.
2. It does not have any positional control, so we instead had to code the motor to run at a certain speed for a certain amount of time. However, this proved to be inaccurate.

The Arduino is used to handle the programming and controls for the motor in our prototype. The full Arduino code will be provided in the appendix, but in short, we set the direction, disengage the motor, set the speed, and then wait a set amount of time before reengaging the motor brake. Then, we do a similar process in the reverse direction. For wiring the Arduino, we connect to the power source pins in order to handle 12V.

Finally, the power supply converts 110-120V AC power for a wall outlet into usable 12V DC power. We connected the wires from the wall to the power supply by following standard wiring color codes, and we connected the respective positive and negative terminals in the power supply and the Arduino for that end.