The main sensors used in this project are light dependant resistors (LDR). The resistance of LDR decreases when it comes in contact with light. This characteristic of LDR is used in the comparator circuit in order to give signal to the microcontroller (AT89C51) for controlling the motors through the driver IC (L293D). In this robot, two rear wheels are responsible for moving the robot forward and turning it right or left. For providing the support to the robot on the front side, a caster wheel is used. The connections around the micro controller are standard in most of 8051 based projects, they are the crystal resonator along with the two decoupling capacitors and the debouncing circuit attached to the reset pin. Using the L293D motor driver, makes controlling a motor simple. It totally isolates the TTL logic inputs from the high current outputs. Each couple of channels of L293D can be enabled and disabled using Enable pins. When disabled, a channel provides very high impedance (resistance) to the motor, exactly as if the motor wasn't connected to the driver IC at all. In conclusion, we can say that the robot can be compared to a “moth” that has affinity towards light and moves in its direction.

Below is the working video of the project :

PROJECT REPORT