Robotics is a branch of science that deals with Mechanical, Electrical and Software fields. Robots are the machines that are used in our day-to-day to life to reduce men power and work accurately without any distortions. Robots can be classified into two different sections basing upon their skills as Automated and Manual.  Obstacle detector is a Automated robot which itself recognizes the obstacle in its path and moves in free direction. Robot detects the obstacle by using two IR Sensors placed in front.              The IR sensors are placed on left and right side of the robot through which continuous Infrared radiation is emitted for detection of obstacles in the path. These IR Sensors are connected to a controlling element AT89c51 µc. When a obstacle is placed in the path of robot IR beam is reflected to the sensor from the obstacle. On detecting obstacle in the path sensor sends 0 volts to µc. This 0 voltage is detected by Microcontroller which avoids the obstacle by taking left or right turn. Similarly if the sensor sends +5v to Microcontroller, the Microcontroller assumes it as clear path and makes the robot to move in straight.           Two motors namely right motor and left motor are connected to Motor driver IC (L293D). L293D is interface with Microcontroller. Microcontroller sends logic 0 & logic 1 as per the programming to driver IC which makes motors to rotate in clockwise and anticlockwise direction. Wheels attached to the motors rotate accordingly with the motor shaft causing in the moment of the robot by wheels. In front portion of the robot a free wheel is attached to move the robot easily in any direction as per the requirement.     A 12Volts DC battery is attached to the circuit. As the microcontroller and sensors requires only 5v, set of resistors and capacitors are used to supply 5v DC to them. Power Management System is not maintained in the circuit as the battery can be removed after the usage of robot. So it does not cause any loss in the power of battery.                This type of robots has multiple applications in various fields. They can be used to know the strength of the opposite army in defense system. They can be used as floor and wall cleaners. They are used in automated GPS vehicles to calculate the moment of the vehicle overhead. These robots are easy to construct and  cheaper in cost with long durability.

2. INTRODUCTION
Robot is a computer-controlled machine that is
programmed to move manipulate objects, and
accomplish work while interacting with
appropriate sensors and actuators mounted on it
for carrying out the desired operations.
In this robots Infra red pairs are used for sensing the
obstacles and IR leads are used for transmitting
and receiving infra red rays. Using infrared rays
robots will find out the obstacles present in front
of them and move right or left from their current
position and move forward.

3. Obstacle detection robots are nothing but self thinking robots which can
take decisions itself using programmed brain without any guidance from
human beings.
There are two types of robots in one type robots perform action as we give
signals remotely where as second type of robots are self thinking robots
which can detect obstacle and move forward. This project is of second
robots.

4. Graphical Block diagram:
Obstacle Avoiding Robot

5. Block diagram:

6. Interfacing circuit of Robot

7. OBSTACLESENSORS
The obstacle senor is used to avoid the robot from the clash to
any external devices (or) that is like walls, any obstacle which
comes in its way. Here we are using the IR communications .the
transmitter and the receiver parts. The transmitter produces the IR
rays and they are received by the receiver section.

8. Architecture of 8051 Microcontroller
 Features
 RAM 128bytes
 ROM 4K
 I/O 4 ports
 Timer 2
 Interrupt 6

9. Pin diagram of IC AT89C51

10. MANUFACTURE S OF MICRO
CONTROLLER
 Atmel
 Dallas Semiconductor
 Intel
 Microchip
 National Semiconductor
 Texas Instruments

11. H-BRIDGE MOTOR DRIVER
The name "H-Bridge" is derived from the actual shape of the
switching circuit which controls the motion of the motor. It is
also known as "Full Bridge". Basically there are four
switching elements in the H-Bridge as shown in the figure
below.

12. Truth Table
High Left High Right Low Left Low Right Description
On Off Off On Motor runs clockwise
Off On On Off Motor runs anti-clockwise
On On Off Off Motor stops or decelerates
Off Off On On Motor stops or decelerates

13. Logic Table of the Circuit
Direction P0.0 P0.1 P0.2 P0.3
Forward 1 0 1 0
Backward 0 1 0 1
Right 1 0 0 1
Left 0 1 1 0

14. Electrical motor
An actuator which converts electrical signal into rotation”.

15. Why only DC motor?
We all know that AC motors are normally constant speed motors. Variable speed
ac drives uses very complex circuitry because the ac motor speed is varied by
the frequency variation and is not quite easy.
Stepper motor gives calculated angle of rotation they take number of steps in
one revolution they cannot be stopped in between the step. Also they are not
constant running motors their use is limited to the area where you want
calculated steps to be taken such as printers, plotters, and other similar
applications.

16. Advantages of DC motor:-
Dc motors are widely used in industry
where wide range of variable speed is
required.
High starting torque & easy speed
variations are some of the other
characteristics of DC motors.

17. ALGORITHM
Step1: Initialization of I/O ports.
Step2: Set Direction as Forward/ Backward/ Left/ Right.
Step3: check if any obstacle is detected according to that
change the motion of Robot. If no then Robot will goes
in forward direction.
Step4: Wait for some time.
Step5: go to step 3 to repeat the process.
Step7: Wait for some time.
Step 8: End

18. FLOW CHART

19. Advantages & Disadvantages
Advantages :
 Whenever robot senses any obstacle automatically diverts its position to left or right and
follows the path without human guidance.
 The programming of the microcontroller is easy.
 It is a low cost circuit.
Disadvantages :
 It is time consuming project.
 It is use for short distance only.
 It is not recommended to keep the range very long because this would cause the ROBOT to
keep moving forward and backward as it senses any obstacle, even far away from it.
 It is not in human control

20. Applications
 Obstacle sensing robot can be applied at the toys
where small children will play.
 It can used for the army application.
 We can apply number pairs of IR pairs for the
safe direction control of the robot.
 In Mines.

21. FUTURE ASPECTS:
 We can extend this project with wireless
technology by IR (or) RF.
 This robot can be used for pick and place the
required object by giving directions to the robot
but IR pair should be replaced depending upon
the application.
 By doing extra things, it can be use in Army
application.

22. Photographs:

23. References
 BOOKS:
1.The 8051 microcontroller & Embedded
System
( Mazidi , Pearson Education ,III edition)
2.Mechatronics Principle and Applications
(Godfrey Onwobolu, Pearson Education)
3.Embedded System
( Rajkamal, Pearson Education, II edition)
4. .Introduction to Robotics
(Vikram Kapila, Pearson Education,IV Edition)

24. Website:
 http://mechatronics.poly.edu
 http://www.roboticswikipedia.com
 http://www.mecatronicswikipedia.com
 http://www.datasheets.com
 http://www.J2RScientific.com
 http://www.expresspcb.com
 http://www.kiel51.com
 http://www.8051microcontroller.com