Sound activated line tracking robot

The project objective is to design and build an autonomous, line following robot capable of following a track marked on a white surface separated with black lines. The robot is activated by a sound activated switch. The robot is based on the PIC 16F877A manufactured by Microchip. The microcontroller receives inputs from 3 pairs of infrared sensors; mainly the infrared emitter (OP 165 - manufactured by Optec) and the infrared phototransistor (OP505 - manufactured by Optec), which are directed by an op-amp (LM324N - manufactured by ST Microelectronics). From these inputs it would be determined if the robot should move forward or the direction that the robot should turn. Forward motion is provided by a pair of stepper motor driving the rear wheels, which are driven from a pair of current driver IC's (ULN2003 - manufactured by Texas Instrument), controlled from the microcontroller. In order for the robot to turn, one wheel is stopped while the opposite wheel continues to turn. The robot will continue moving forward until one of the sensors spots a black surface and forcing one motor to move to either left or right direction.