Overview

This project aimed to build a line-following robot that uses a Pi camera to track different colored tapes. Initially, a grey-scale program was used for testing to ensure the car could decide based on reading color values. After the car successfully was able to change directions based on when it read the tape, the Raspberry Pi was switched to read HSV colors from the tape and only look for HSV values in a specific range. Once the Pi could detect specific colors,  PID controls were implemented to change the motor speed as the camera read the error from the mean value of the tape. By fine-tuning the K values, the car completed a complicated track. However, the Pi faced calibration issues with the lighting and was inconsistent with the difficult track. Therefore, the final track attempted was the simplest for consistency with reading the HSV values and PID controls.

Challenges

• When initially designing the car, one concern was the motor wire placement, as the motors needed to be below the car for the camera to be at the correct height. Therefore, a gap was created in the car to allow the wires to go through the car and be connected to the motor drive

• When initially testing the PID controls, there were instances where the PID value was negative when correcting to one side. To resolve this issue, the absolute value of the error was taken, and manual turning values were put in the code so the motors would turn in the correct direction.

• Another issue with the PID controls was when the PID value would be less than the minimum motor PWM values when the camera was on the tape. To resolve this, the PWM was set to a constant value if the car was going straight, and the PID value was less than 35, the minimum PWM value.