24-04-2017, 10:33 AM
Concept of line follower work is related to light. We use here the behavior of light on the black and white surface. When light falls on a white surface it is almost completely reflected and if black surface light is completely absorbed. This light behavior is used in the construction of a robot line follower.
In this robot based arduino line follower we have used infrared transmitters and infrared receivers also called photodiodes. They are used to send and receive light. IR transmits infrared lights. When the infrared rays fall on the white surface, it reflects backwards and is captured by photodiodes that generates some changes of voltage. When IR light falls on a black surface, light is absorbed by the black surface and no rays are reflected backward, so the photodiode does not receive any light or rays.
Here in this line robot follower when the sensor detects the white surface then arduino gets 1 as input and when the meanings of the arduino black line receive 0 as input.
Explanation of the circuit
The complete line follower robot can be divided into 3 sections: sensor section, control section and controller section.
Sensor Section:
This section contains IR diodes, potentiometer, comparator (Op-Amp) and LED's. The potentiometer is used to set the reference voltage at the terminal of a comparator and IR sensors are used to detect the line and provide a voltage change at the second terminal of the comparator. The comparator then compares both voltages and generates a digital signal at the output. Here in this line follower circuit we have used two comparators for two sensors. LM 358 is used as a comparator. LM358 has incorporated two low-noise Op-Amps.
Control section:
Arduino Pro Mini is used to control the entire process of the robot line follower. The comparator outputs are connected to arduino digital pins # 2 and # 3. Arduino reads these signals and sends commands to the driver circuit to the drive line follower.
Driver section:
The driver section consists of the motor driver and two DC motors. The motor driver is used to drive the motors because the arduino does not supply enough voltage and current to the motor. So we add a motor driver circuit to get enough voltage and current for the motor. Arduino sends commands to this motor controller and then the drive motors.