Line-Following Robot

• Sensors and interface

  Seven photoresistors with 1 kΩ voltage dividers into Arduino analog A8–A14 distinguished black vs. white. Four potentiometers on analog inputs served as a live interface for adjusting Speed, P, I, and D.

• Motor drive and code

  Soldered a motor shield to the Arduino and implemented motor control code to command left/right motors independently for forward/backward motion.

• Hardware iteration

  Designed and 3D printed a new chassis, added a cardboard light shield to block ambient light, and replaced the breadboard sensor array with a custom PCB that set sensor/LED height and leveled them close to the ground.

• Power integrity

  Added a 9 V battery directly to Arduino VIN and removed the VIN jumper to prevent motor-induced brownouts that reset the microcontroller.

• Calibration and tuning

  Calibrated sensors on black (≈700–820) and white (≈590–650) surfaces; tuned SPID on the track to reduce oscillations and increase speed.

1. Potentiometers

   Clockwise turns decreased readings; counterclockwise increased them due to divider polarity.

   Swap power and ground on the pot, or invert the analog mapping in code.

2. Photoresistors

   Readings were skewed by shadows/bright ambient and excessive sensor height.

   Added a cardboard light shield, added LEDs for a controlled source, and lowered sensor height a few millimeters.

3. Power

   Motors induced brownouts that reset the MCU.

   Fed Arduino VIN from a separate 9 V battery and removed the VIN jumper; runs stabilized and speed improved.

Create a robot that could quickly and accurately follow a black line. Work spanned circuit design, Arduino programming, chassis design/assembly, and hardware implementation.