Generally the line follower robot is based on microcontrollers. Here we describe a line follower robot without a microcontroller for those who are not familiar with microcontrollers. It establishes the bases to build your own robot based on behavior (simulated). The robot uses interfaces for the sensors to make the behavior of the robot as versatile as possible. Two light detectors are mounted on the front of the robot. In addition, a route is provided for the robot to follow, either a black track (using black tape) on a white floor or a white track on a black floor.
Fig. 1 shows the circuit of the line follower robot. It comprises two reflective optical sensors TCRT5000L (IC1 and IC2), inverter 74LS04 (IC3), motor controller L293D (IC4), regulator 7805 (IC5) and some discrete components.
The TCRT5000L optical sensors are used as line tracking robot sensors. The TCRT5000L reflective sensor includes an infrared emitter and a photo-transistor in a lead package. The sensor and its internal details are shown in Fig. 2.
When an object enters the detection area, the emitted IR light is reflected from the object to the phototransistor. So the amount of light energy that reaches the detector increases. This change in light or photo-current energy is used as the input signal to activate the motors of the line follower robot.
The collector current of the phototransistor also depends on the distance of the reflector surface of the object from the sensor. The intensity of the reflected signal returning to the detector depends on the surface on which the robot moves. The white surface reflects the maximum infrared signal, while the black surface absorbs the maximum infrared signal.