When robot is placed on the fixed path, it follows the path by detecting the line. The robot direction of motion depends on the two sensors outputs. When the two sensors are on the line of path, robot moves forward. If the left sensor moves away from the line, robot moves towards right. Similarly, if right sensor moves away from the path, robot moves towards its left. Whenever robot moves away from its path it is detected by the IR sensor.
Do you know about How Remote Controlled Spy Robot Circuit Works?
IR sensor consists of IR transmitter and IR receiver on a board. When the vehicle is moving on a black line, IR rays are continuously absorbed by the black surface and there is no reflected ray making output high. Whenever, the robot moves out to the white surface, it starts reflecting the IR rays and making the output low. Thus depending on the output of IR sensor microcontroller indicates the motors to change their direction.
Components in the circuit:
- ATmega8 microcontroller
- Motor driver IC (L293D)
- Resistors-R1 to R4.
- IR transmitters – IR TX1,IR TX2
- IR Receivers -IR RX1,IR RX2
How to Design a Line Following Robot?
The circuit consists of Atmega8 microcontroller, IR transmitters, IR Receivers, motor driver, Motors.
ATmega8 microcontroller is a AVR family microcontroller. It is an 8 bit microcontroller with 23 programmable pins. This has many peripheral features like programmable USART, two 8-bit timer/counter, one 16-bit timer/counter, three PWM channels, 10bit resolution six channel analog to digital counter, analog comparator etc. It has 8KB flash memory, 512 bytes of EEPROM and 1KB SRAM.
The DC motors of the robot are connected to the controller using a motor driver IC. As the output of the controller is maximum 5v, it cannot drive the motors. So, to amplify this voltage motor driver, IC is used. L293D can amplify up to 36v.The driver IC has 16 pins. 2, 7, 10, 15 are input pins and are connected to the PD0-PD3 pins of microcontroller.16 pin is connected to 12v.This voltage drives the motors. 8th pin is connected to 5v. This is required for internal operations of the IC.
The two IR sensors are connected to PB0 and PB1 pins of the microcontroller. The IR transmitter and IR receiver are connected as shown in the circuit diagram.
Arrange the chassis and connect the two wheels of the robotic vehicle to the motors which are in turn connected to the microcontroller.
For more detail: Line Follower Robot using Microcontroller