During my bachelors I was looking for a project to put what I had learn in different courses to practice. A line follower seemed a good opportunity to buy an Arduino board and tinker with some electronics and software. These simple robots are designed so that they follow a black line over a white surface.
The design is composed of a pair of motors, an arduino board, a motor control circuit, a sensor board and a battery. The components are mounted into a wooden frame.
The electronics were done in a protoboard. The H bridge circuit allows for the motors to turn in both directions.
Additionally, a circuit for detecting whether the robot is following the track was built. Here photoresistors and UV leds work together to tell if the surface beneath them is either black or white.