What is an Infra Red (IR) Sensor and how it is used to distinguish between white & black color line in Line / Path follower robot

Infra Red Sensor

IR reflective sensors have one emitter (IR LED) and one receiver (Phototransistor or photo diode. If we have white surface it reflects the light and it will sensed by the receiver, similarly if we have black surface it absorbs the light and receiver can not sense light.

Photo diode has property that if IR light fall on it its electrical resistance comes down (i.e. it comes down from 150kΩ to 10kΩ if no noise present).

Use of Voltage Regulator ICs in Robotics - 7805 / 7809 / 7812

What is voltage regulator IC ?

 The 78xx (sometimes L78xx, LM78xx, MC78xx...) is a family of self-contained fixed linear voltage regulator integrated circuits. The 78xx family is commonly used in electronic circuits requiring a regulated power supply due to their ease-of-use and low cost. For ICs within the family, the xx is replaced with two digits, indicating the output voltage (for example, the 7805 has a 5 volt output, while the 7812 produces 12 volts). The 78xx line are positive voltage regulators: they produce a voltage that is positive relative to a common ground. There is a related line of 79xx devices which are complementary negative voltage regulators. 78xx and 79xx ICs can be used in combination to provide positive and negative supply voltages in the same circuit.

Practical Definition - Voltage regulator, any electrical or electronic device that maintains the voltage of a power source within acceptable limits.

Embedded C code / program for Line follower robot using AVR micro-controller ATMega 16 - IR sensor based

 Are you making a line follower robot using a AVR micro controller - ATMega 16 / ATMega 16A  programmed using AVR Studio?  Here is the code for making a simple line follower robot.

This embedded C programming language Code is based on the following design. You can modify it based on your requirements :
No. of sensors  - 2
Signal from sensors- 1 for white and 0 for black
No. of motors - 2
About motors - Both the motors are DC motors and are connected to the micro-controller through a Motor driver IC.

AVR Micro controller based Line Follower Robot using Infrared Sensor, Driver IC L293D/Relays & AVR Dev Board

Introduction:

This article presents the design and implementation of line follower robot using AVR Microcontroller. It is a machine that follows a line, either a black line on white surface or vise-versa. The path is sensed by the IR (Infra Red) sensors. The microcontroller controls two DC motors of robot to navigate through its path.

Basic Principle:

The basic principle involved in this is it captures the line position with IR sensors mounted at front end of the robot.  The block diagram of the line follower robot shows that, when the sensor senses the path, output will be 0s or 1s which are then fed to the microcontroller, and then the microcontroller decides the next move according to the program. When both the sensors are indicating low (0) then robot start moving on the black path, for white if it indicates high (1) then it moves along the path. 

Block Diagram