Back in 2013, we built this robot. It can follow a white line on black surface. At the same time, if any obstacle is detected in its path, it can change its direction. Five LDRs(Light Dependent Resistor) with five LEDs were used to track the line and one IR sensor was used to detect any obstacle. We used wood as the chassis and mobile phone battery for power supply. Microcontroller that we used was ATmega16 from AVR.