With this project I turned a simple chineese electric quad into a self driving line following quad. To do this I used two gears, a chain and a old winshield wiper motor for the steering. I hacked the controller of the quad by sending a PWM signal on one of the wires to get throttle control. I used a ultrasonic sensor on the front for obstacle detection. I also used the three tcrt5000 line sensors. Two for line sensing and one for a steering position sensor.
To build the quad follow the following schematic.
Upload the code to the arduino and you are done. First run all the test codes to make sure everything is working correctly. Also make sure the RedBot library is installed.