Project Report on Obstacel Detector Using 7404

7/23/2019 Project Report on Obstacel Detector Using 7404

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A

Project Report on

Obstacle Detector

Submitted for the partial fulfillment of degree of

Bachelor of Technology

in Department of Electronics & Communication Engineering

Project Incharge Submitted by:

Mr. Lalit sing Rao HEMAL PATEL

09EPFEC021

Department of Electronics & CommunicationEngineering

PACIFIC INSTITUTE OF TECHNOLOGY, UDAIPUR

Rajasthan Technical University


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ACKNOWLEDGEMENT

This report would be incomplete without the mention of those who have directly or

indirectly helped us during the tenure of this project.

We would also like to express our deepest sense of gratitude towards Mr. Ashok

Kherodia, Head of the Department, Electronics and communication Engineering, Pacific

Institute of Technology and Mr.LalitSingh Rao, the Project coordinator, E.C.E

Department, Pacific Institute of Technology for their invaluable help during this project.

Their guidance has been instrumental and has proved to be of immense help at every stage of

the project.

We would like to thank our guide Mr. Deepak Vyas, Assist. Professor, Electronics

and communication Engineering,Pacific Institute of Technologyfor constantly monitoring

our progress and suggesting improvements at various stages in the project

We would like to thank all the other staff members of Electronics and

communication Engineering Department,Pacific Institute of TechnologyforCo-

operatingwith us all through the period of project.

Lastly, we would like to thank everyone who has been involved in the progress of the

project, whose contributions, have added a lot of value.


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INDEX

ABSTRACT..1

Chapter 1: Introduction......2

1.1Block Diagram....2

1.1.1 Power Supply...2

1.1.2 Inverter IC (7404)....3

1.1.3 DC motor.....3

1.1.4 Obstacle Sensor...3

Chapter 2: Embedded System...42.1 Introduction..........................4

2.2 Examples of Embedded Systems.5

2.3 Microcontrollers and Microprocessors6

2.4 Typical Microcontroller Architecture and Features.6

2.5 The UART: What it is and how it works.8

2.5.1 Synchronous Serial Transmission....8

2.5.2 Asynchronous Serial Transmission..9

Chapter3: Hardware11

3.1 Inverter (7404)....11

3.2 Voltage Regulator...13

3.3 Motor Drive14


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3.4 Motors.16

3.4.1 Definition.16

3.4.2 Dc Motor......17

3.4.3 Principle...17

3.4.4 Construction.18

3.4.5 Working of Dc Motor..19

3.4.6 Advantages and Disadvantages.......................21

3.5 Obstacle Sensor...22

3.4.1 Circuit of Obstacle Sensor...23

3.4.2 Features24

3.4.3 Applications24

Chapter 4: Infrared Technology.........................................................25

4.1 Introduction.25

4.2 Wireless Communication....25

4.3 Infrared Technology....26

4.4 IR Advantages..27

4.5 IR Disadvantages.28

4.6 Health Risks.28

4.7 Security....29

4.8 Importance of Standards......29

Chapter 5: Circuit30

5.1 Circuit Diagram...31

5.2 Circuit LevelDescription31

5.3 Working...33

5.4 Component Used.33

5.5 Hardware Testing34

Chapter 6:KEY FEATURES OF OBSTACLE AVOIDANCE ROBOT...36

6.1 Advantage...36


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6.2 Limitation...36

6.3 Problem Faced....36

6.4. Future Enhancement..36

Conclusion37

List of Figure

Figure1.1 Block Diagram..2

Figure2.1 Block diagram of Embedded System5

Figure 2.2 Basic Layout of Microcontroller.7

Figure3.1 Pin diagram of 740412

Figure 3.27805 terminal.14

Figure 3.3 Pin Diagram of L293D...15

Figure 3.4 Dc Motor17

Figure 3.5Parts of Dc motor...18

Figure 3.6 Basic Commutator.19

Figure 3.7A Simple Electric Motor...20


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Figure 3.8 DC Motor Rotation vs Polarity.21

Figure 3.9Obstacle Sensor....22

Figure 3.10 Circuit Diagram of Obstacle Sensor..24

Figure 4.1 Electromagnetic Spectrum...26

Figure 4.2 A radio frequency energy wave superimposed upon an infrared energy wave...27

Figure 5.1Circuit Diagram...30

Figure 5.2Motor driver circuits....31

Figure 5.3: Regulator circuit.32

Figure 5.4Ir sensor...32

Figure 5.5 Basic Diagram of IR sensor....33


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ABSTRACT

In robotics, obstacle avoidance is the task of satisfying some control objective subject

to non-intersection or non-collision position of constraints. Normally obstacle avoidance is

considered to be distinct from path planning in that one is usually implemented as a reactive

control which a controller will then guide a robot along.

Whenever robot senses any obstacle automatically diverts its position to left /right and

follows the path. Robot consists of two motors, which control the side pair wheels of each and

help in moving forward and backward direction. It senses the object with help of obstaclesensor. IR pair is used for detecting the obstacle.

In this project we develop a robot such that it will be moving according to path

assigned to it if at all there is any obstacle in between then the robot stops and change its

direction. This sort of project is very much useful in the industries where the automated

supervision is required.

Hardware specification are Regulated power supply, Inverter Ic ,IR sensor, DC Motor.Software tools are Proteous and Express PCB For circuit design and layout.

This robot can be applied at the toys where children will play. ROBOT can be used for

the army application by fixing a cam to it. We can apply number of IR pairs for the safe

direction control. This project is considered to be the key link to the 3rd generation of

robotics.


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Chapter 1

Introduction

A robot obstacle detection system comprising: a robot housing which navigates with

respect to a surface; a sensor subsystem having a defined relationship with respect to the

housing and aimed at the surface for detecting the surface, the sensor subsystem including: an

optical emitter which emits a directed beam having a defined field of emission, and a photon

detector having a defined field of view which intersects the field of emission of the emitter at

a finite region; and a circuit in communication with the detector for redirecting the robot when

the surface does not occupy the region to avoid obstacles.

Obstacle sensors are nothing but the IR pair. As the transmitter part travel IR rays

from to receiver here also transmitter send the data receiver but these IR pair are places beside

each other. So whenever the obstacle sensor found an obstacle in between its way the IR rays

reflects in a certain angle.

1.1 BLOCK DIAGRAM:

Figure1.1 Block Diagram

FRONT

SENSOR

Inverter Ic

(7404)

MOTOR

DRIVER

RIGHT

MOTOR

LEFT

MOTOR


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1.1.1 POWER SUPPLY:

Power supply can be broken down into a series of blocks, each of which performs a

particular function. The transformer is 230v AC supply. Transformers work only with AC and

here we are using step down transformer because to step down high voltage AC mains to low

voltage AC (i.e.; 230v to12v). This transformer is fed into rectifier.

In bridge rectifier there are several ways of connecting diodes to make a rectifier to

convert AC to DC and it is most important and it produces full-wave with varying DC so that

we go for smoothing capacitor it smooth the DC from varying greatly to a small ripple. By

using regulator we can eliminate the ripple. In regulator to set DC output to a fixed voltage.

1.1.2 INVERTER IC (7404):

Here we are using 7404 Inverter. This is used to control all the operations of a circuit

to get the accurate result. The IC we use is of the 14 pins and consist of 6 ports.

1.1.3 DC MOTOR:

Motors are used for the movement of the robot. Here we use the dc motor as it has the

principle of the speed controlling.

1.1.4 OBSTACLE SENSOR:

The obstacle senor is used avoiding the robot from the clash to any external devices or

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.


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Chapter 2

Embedded Systems

2.1 Introduction

An embedded system is a special-purpose computer system designed to perform a

dedicated function. An embedded system performs one or few pre-defined tasks usually with

very specific requirements and often includes task-specific hardware and mechanical parts not

usually found in a general-purpose computer. Since the system is dedicated to specific tasks,design engineers can optimize it by reducing the size and cost of the product.

Physically, the embedded systems range from portable devices such as digital watches

and MP3 players to large stationary installations like traffic lights, factory controllers or the

systems controlling nuclear power plants. In terms of complexity embedded systems run with

a single microcontroller chip to very complex with multiple units, peripherals and networks

mounted inside a large chassis or enclosure.

Mobile phones or handheld computers share some elements with embedded systems,

such as the operating systems and microprocessors which power them but are not truly

embedded systems themselves because they tend to be more general purpose allowing

different applications to be loaded and peripherals to be connected.

As the embedded system is the combination of both software and hardware .Software

deals with the languages like WINAVR, C, and VB etc., and Hardware deals with Processors,

Peripherals, and Memory.

Memory: It is used to store data or address.

Peripherals: These are the external devices connected

Processor: It is an IC which is used to perform some task

Processors are classified into four types like:


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1. Micro Processor (p)

2. Micro controller (c)

3. Digital Signal Processor (DSP)

4. Application Specific Integrated Circuits (ASIC)

Figure2.1 Block diagram of Embedded System

2.2 Examples of Embedded Systems

An embedded system typically has a specialized function with programs stored on

ROM. Examples of embedded systems are chips that monitor automobile functions, including

engine controls, antilock brakes, air bags, active suspension systems, environmental systems,

security systems, and entertainment systems. Everything needed for those functions is custom

designed into specific chips. No external operating system is required.

Another example is a chip for a microwave oven. It is specifically designed to run the

front-panel controls and all the timing and electronics of the oven.

Network managers will need to manage more and more embedded systems devices,

ranging from printers to scanners, to handheld computing devices, to cell phones. All of these

Embedded

Software Hardware

o WINAVR

o C

o VB

Etc.,

o Processor

o Peripherals

o memory


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have a need to connect with other devices, either directly or through a wireless or direct-

connect network. Most will have custom operating systems or variations of existing operating

systems (e.g., Microsoft Windows CE).

It's easy to picture nearly every electronic device as having an embedded system. For

example, refrigerators, washing machines, and even coffee brewers will benefit in some way

from embedded systems. A critical feature of an embedded system is its ability to

communicate, so embedded systems support Ethernet, Bluetooth (wireless), infrared, or other

technologies.

A weather station on top of a building may employ an embedded system that gathers

information from external sensors. This information can be pushed or pulled. In the push

scenario, the data is automatically sent to devices that have requested it. In the pull scenario,

users or network devices access the weather station to read the latest information.

If the weather station is connected to the Internet, it may have its own IP address and,

ideally, will provide information to anyone that accesses the IP address. In this sense, the

weather station is acting as a mini-Web server. In fact, many embedded systems are basically

Web servers on a chip. The chips contain HTTP and HTML functions, and custom

applications appropriate for the environment in which the chip will be used.

2.3Microcontrollers and Microprocessors

A microcontroller (orMCU) is a computer-on-a-chip. It is a type of microprocessor

emphasizing self-sufficiency and cost-effectiveness, in contrast to a general-purpose

microprocessor (the kind used in a PC).

A microprocessor is a programmable digital electronic component that incorporates

the functions of a central processing unit (CPU) on a single semi conducting integrated circuit(IC). The microprocessor was born by reducing the word size of the CPU from 32 bits to 4

bits, so that the transistors of its logic circuits would fit onto a single part. One or more

microprocessors typically serve as the CPU in a computer system, embedded system, or

handheld device.


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2.4Typical Microcontroller Architecture and Features

The basic internal designs of microcontrollers are pretty similar. Figure 1.2, the block

diagram of a typical microcontroller. All components are connected via an internal bus and

are all integrated on one chip. The modules are connected to the outside world via I/O pins.

Figure 2.2 Basic Layout of Microcontroller

The following list contains the modules typically found in a microcontroller. You canfind a more detailed description of these components in later sections.

Processor Core: The CPU of the controller. It contains the arithmetic logic unit, the control

unit, and the registers (stack pointer, program counter, accumulator register, register file . . .).

Memory: The memory is sometimes split into program memory and data memory. In larger

controllers, a DMA controller handles data transfers between peripheral components and the

memory.

Interrupt Controller: Interrupts are useful for interrupting the normal program flow in case

of (important) external or internal events. In conjunction with sleep modes, they help to

conserve power.

Timer/Counter: Most controllers have at least one and more likely 2-3 Timer/Counters,

which can be used to timestamp events, measure intervals, or count events. Many controllers


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also contain PWM (pulse width modulation) outputs, which can be used to drive motors or for

safe breaking (antilock brake system, ABS). Furthermore the PWM output in conjunction

with an external filter be used to realize a cheap digital/analog converter.

Digital I/O: Parallel digital I/O ports are one of the main features of microcontrollers. The

number of I/O pins varies from 3-4 to over 90, depending on the controller family and the

controller type.

Analog I/O: Apart from a few small controllers, most microcontrollers have integrated

analog/digital converters, which differ in the number of channels (2-16) and their resolution

(8-12 bits). The analog module also generally features an analog comparator. In some cases,

the microcontroller includes digital/analog converters.

2.5The UART: What it is and how it works

The Universal Asynchronous Receiver/Transmitter (UART) controller is the key

component of the serial communications subsystem of a computer. The UART takes bytes of

data and transmits the individual bits in a sequential fashion. At the destination, a second

UART re-assembles the bits into complete bytes.

Serial transmission is commonly used with modems and for non-networked

communication between computers, terminals and other devices.

There are two primary forms of serial transmission: Synchronous and Asynchronous.

Depending on the modes that are supported by the hardware, the name of the communication

sub-system will usually include A if it supports Asynchronous communications and S if it

supports Synchronous communications. Both forms are described below.

Some common acronyms are:

UART Universal Asynchronous Receiver/Transmitter

USART Universal Synchronous-Asynchronous Receiver/Transmitter


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2.5.1 Synchronous Serial Transmission

Synchronous serial transmission requires that the sender and receiver share a clock

with one another, or that the sender provide a strobe or other timing signal so that the receiver

knows when to read the next bit of the data. In most forms of serial Synchronous

communication, if there is no data available at a given instant to transmit, a fill character must

be sent instead so that data is always being transmitted. Synchronous communication is

usually more efficient because only data bits are transmitted between sender and receiver, and

synchronous communication can be more costly if extra wiring and circuits are required to

share a clock signal between the sender and receiver.

A form of Synchronous transmission is used with printers and fixed disk devices inthat the data is sent on one set of wires while a clock or strobe is sent on a different wire.

Printers and fixed disk devices are not normally serial devices because most fixed disk

interface standards send an entire word of data for each clock or strobe signal by using a

separate wire for each bit of the word. In the PC industry, these are known as Parallel devices.

The standard serial communications hardware in the PC does not support Synchronous

operations. This mode is described here for comparison purposes only.

2.5.2 Asynchronous Serial Transmission

Asynchronous transmission allows data to be transmitted without the sender having to

send a clock signal to the receiver. Instead, the sender and receiver must agree on timing

parameters in advance and special bits are added to each word which is used to synchronize

the sending and receiving units.

When a word is given to the UART for Asynchronous transmissions, a bit called the

"Start Bit" is added to the beginning of each word that is to be transmitted. The Start Bit is

used to alert the receiver that a word of data is about to be sent, and to force the clock in the

receiver into synchronization with the clock in the transmitter. These two clocks must be

accurate enough to not have the frequency drift by more than 10% during the transmission of

the remaining bits in the word. (This requirement was set in the days of mechanical

teleprinters and is easily met by modern electronic equipment.)


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After the Start bit, the individual bits of the word of data are sent with the Least

Significant Bit (LSB) being sent first. Each bit in the transmission is transmitted for exactly

the same amount of time as all of the other bits, and the receiver looks at the wire at

approximately halfway through the period assigned to each bit to determine if the bit is a 1 or

a 0. For example, if it takes two seconds to send each bit, the receiver will examine the signal

to determine if it is a 1 or a 0 after one second has passed, then it will wait two seconds and

then examine the value of the next bit, and so on.

The sender does not know when the receiver has looked at the value of the bit. The

sender only knows when the clock says to begin transmitting the next bit of the word. When

the entire data word has been sent, the transmitter may add a Parity Bit that the transmitter

generates. The Parity Bit may be used by the receiver to perform simple error checking. Then

at least one Stop Bit is sent by the transmitter.

When the receiver has received all of the bits in the data word, it may check for the

Parity Bits (both sender and receiver must agree on whether a Parity Bit is to be used), and

then the receiver looks for a Stop Bit. If the Stop Bit does not appear when it is supposed to,

the UART considers the entire word to be garbled and will report a Framing Error to the host

processor when the data word is read. The usual cause of a Framing Error is that the sender

and receiver clocks were not running at the same speed, or that the signal was interrupted.

Regardless of whether the data was received correctly or not, the UART automatically

discards the Start, Parity and Stop bits. If the sender and receiver are configured identically,

these bits are not passed to the host.

If another word is ready for transmission, the Start Bit for the new word can be sent as

soon as the Stop Bit for the previous word has been sent because asynch ronous data is self-synchronizing, if there is no data to transmit, the transmission line can be idle.


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Chapter 3

Hardware

Hardware Modules:

The Hardware modules of this project:

Inverter (7404)

7805

L293D

Motors

Obstacle Sensor

3.1 Inverter (7404):7404 is a NOT gate IC.

It consists of six inverters which perform logical invert action. The output of an inverter is thecomplement of its input logic state, i.e., when input is high its output is low and vice versa.


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Pin Diagram:

Figure3.1 Pin diagram of 7404


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Pin Description:

Pin

No

Function Name

1Input/output of 1st inverter

Input1

2 Output1

3Input/output of 2nd inverter

Input2

4 Output2

5Input/output of 3rd inverter

Input3

6 Output3

7 Ground (0V) Ground

8Output/input of 4th inverter

Output4

9 Input410

Output/input of 5th inverterOutput5

11 Input5

12Output/input of 6th inverter

Output6

13 Input6

14 Supply voltage; 5V (4.75 - 5.25 V) Vcc

3.2 Voltage regulator (LM7805):

It is a self-contained fixed linear voltage regulatorIC.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, thexx 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 lines are positive voltage regulators: they produce a voltage
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that is positive relative to a common ground. Each type employs internal current limiting,

thermal shut down and safe operating area protection, making it essentially indestructible.

If adequate heat sinking is provided, they can deliver over 1A output current. Although

designed primarily as fixed voltage regulators, these devices can be used with external

components to obtain adjustable voltages and currents.

Features

Output Current up to 1A

Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V

Thermal Overload Protection

Short Circuit Protection

Output Transistor Safe Operating Area Protection

Figure 3.2 7805 terminal

3.3Motor Driver (L293D):

L293D is used as driver IC.L293d is an IC used for driving different types of motors. The PIN

diagram is shown in below figure. It contains four non-inverting drivers placed as two pairs.

Each pair may individually be enabled or disabled through ENABLE input. Each driver is

capable of sourcing or sinking 600mA of current with a peak value of 1.2A. Vs (PIN 8) is for


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motor power supply voltage input, with a minimum limit of 5V and a maximum of 36V. Vss

(PIN 16) is a logic level input voltage with a minimum rating of 5V.

To drive a motor, only a pair of drivers is necessary which may be connected with

poles of the motor directly. Signals marked as input may be driven by port PINs of any

microcontroller.

The Device is a monolithic integrated high voltage, high current four channel driver

designed to accept standard DTL or TTL logic levels and drive inductive loads (such as relays

solenoids, DC and stepping motors) and switching power transistors.

Figure 3.3 Pin Diagram of L293D

Specifications:

Symbol Parameter Value

Vs Supply voltage 36V


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Vss Logic supply voltage 36V

Vi Input voltage 7V

Ven Enable voltage 7V

Io Peak o/p current 1.2APtot Total power dissipation at TPINs=90 C 4W

TstgTj Storage and junction temperature -40 to 150 C

3.4Motor :

3.4.1 DEFINITION:

Motor is a device that creates motion, not an engine; it usually refers to either an

electrical motor or an internal combustion engine.

It may also refer to:

Electric motor, a machine that converts electricity into a mechanical motion

o AC motor, an electric motor that is driven by alternating current

Synchronous motor, an alternating current motor distinguished by a

rotor spinning with coils passing magnets at the same rate as the

alternating current and resulting magnetic field which drives it

Induction motor, also called a squirrel-cage motor, a type of

asynchronous alternating current motor where power is supplied to the

rotating device by means of electromagnetic induction

o DC motor, an electric motor that runs on direct current electricity

Brushed DC electric motor, an internally commutated electric motor

designed to be run from a direct current power source

Brushless DC motor, a synchronous electric motor which is powered

by direct current electricity and has an electronically controlled

commutation system, instead of a mechanical commutation system

based on brushes

o Electrostatic motor, a type of electric motor based on the attraction and

repulsion of electric charge
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o Servo motor, an electric motor that operates a servo, commonly used in

robotics.

3.4.2 DC Motor

A DC motor is an electromechanical device that converts electrical energy into

mechanical energy that can be used to do many useful works. DC motors comes in various

ratings like 6V and 12V. It has two wires or pins. When connected with power supply the

shaft rotates. You can reverse the direction of rotation by reversing the polarity of input.

Figure 3.4 Dc Motor

Motor gives power to your MCU. Means power to do physical works, for example

move your robot. So it is essential to know how to control a DC motor effectively with a

MCU. We can control a DC motor easily with microcontrollers. We can start it, stop it ormake it go either in clockwise or anti clock wise direction. We can also control its speed but it

will be covered in latter tutorial. The design of the brushed DC motor is quite simple.

Permanent magnets

Electro-magnetic windings

3.4.3Principle

When a rectangular coil carrying current is placed in a magnetic field, a torque acts on

the coil which rotates it continuously. When the coil rotates, the shaft attached to it also

rotates and thus it is able to do mechanical work.

Every DC motor has six basic parts -- axle, rotor (a.k.a., armature), stator,

commutator, field magnet(s), and brushes. In most common DC motors the external magnetic

field is produced by high-strength permanent magnets. The stator is the stationary part of the
http://en.wikipedia.org/wiki/Servo_motorhttp://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://en.wikipedia.org/wiki/Servo_motor


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motor -- this includes the motor casing, as well as two or more permanent magnet pole pieces.

The rotor (together with the axle and attached commutator) rotates with respect to the stator.

The rotor consists of windings (generally on a core), the windings being electrically

connected to the commutator. The above diagram shows a common motor layout -- with the

rotor inside the stator (field) magnets.

3.4.4 Construction:

Figure 3.5Parts of Dc motor

Parts of a DC Motor:

Armature

A D.C. motor consists of a rectangular coil made of insulated copper wire wound on a

soft iron core. This coil wound on the soft iron core forms the armature. The coil is mounted

on an axle and is placed between the cylindrical concave poles of a magnet.

Commutator

A commutator is used to reverse the direction of flow of current. Commutator is a

copper ring split into two parts C1 and C2. The split rings are insulated from each other and

mounted on the axle of the motor. The two ends of the coil are soldered to these rings. They

rotate along with the coil. Commutator rings are connected to a battery. The wires from the

battery are not connected to the rings but to the brushes which are in contact with the rings.


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Figure 3.6 Basic Commutator

Brushes:

Two small strips of carbon, known as brushes press slightly against the two split rings,

and the split rings rotate between the brushes. The carbon brushes are connected to a D.C.

source.

3.4.5 Working of a DC Motor

When the coil is powered, a magnetic field is generated around the armature. The left

side of the armature is pushed away from the left magnet and drawn towards the right causing

rotation.

Figure 3.7A Simple Electric Motor


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When the coil turns through 900, the brushes lose contact with the commutator and the current

stops flowing through the coil.

Direction of Rotation

A DC Motor has two wires. We can call them as positive terminal and negative

terminal, although these are pretty much arbitrary names (unlike a battery where these

polarities are vital and not to be mixed!). On a motor, we say that when the + wire is

connected to + terminal on a power source, and the - wire is connected to the - terminal

source on the same power source, the motor rotates clockwise (if you are looking towards the

motor shaft). If you reverse the wire polarities so that each wire is connected to the opposing

power supply terminal, then the motor rotates counter clockwise. Notice this is just anarbitrary selection and that some motor manufacturers could easily choose the opposing

convention. As long as you know what rotation you get with one polarity, you can always

connect in such a fashion that you get the direction that you want on a per polarity basis.

Figure 3.8 DC Motor Rotation vs Polarity

Facts:

DC Motor rotation has nothing to do with the voltage magnitude or the current

magnitude flowing through the motor.

DC Motor rotation does have to do with the voltage polarity and the direction of the

current flow.


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Motor Start and Stop:

Starting a motor is a very hazardous moment for the system. Since you have an

inductance whose energy storage capacity is basically empty, the motor will first act as an

inductor because current cannot change abruptly in an inductor, but the truth of the matter is

that this is one of the instances in which you will see the highest currents flowing into the

motor. Stopping the motor is not as harsh as starting. The reason why the motor stops so fast

is because as a short is applied to the motor terminals, the Back EMF is shorted. Because

Back EMF is directly proportional to speed making Back EMF = 0.

3.4.6Advantages and Disadvantages:

Advantages:

Easy to understand design

Easy to control speed

Easy to control torque

Simple, cheap drive design

Disadvantages:

Expensive to produce

Can't reliably control at lowest speeds

Physically larger

High maintenance

Dust


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3.5 OBSTACLE SENSOR:

Figure 3.9Obstacle Sensor

This sensor is a short range obstacle detector with no dead zone. It has a reasonably

narrow detection area which can be increased using the dual version. Range can also be

increased by increasing the power to the IR LEDs or adding more IR LEDs

The photo below shows my test setup with some IR LED's (dark blue) as a light

source and two phototransistors in parallel for the receiver. This setup works like a first LDR

but with IR. It has a range of about 10-15cm (4-6 inches) with my hand as the object being

detected.

3.5.1 Circuit of obstacle sensors:

Starting from the left you can see two IR LEDs with a resistor and transistor in series.

The transistor allows the processor to turn the LEDs on or off. This is necessary to tell the

difference between the ambient IR from daylight and indoor lighting and the reflected light

from the LEDs that indicates the presence of an object.

Next we have two phototransistors in parallel with a 1M resistor in series. You could

use only one but I wanted to cover a wider area so my transistors will point in slightly

different directions. If either one detects IR it will allow more current to flow. Since

volts=current x resistance, even a small increase in current will create a reasonable increase in

voltage across the 1M resistor. Unfortunately the low input impedance of many A/D

converters will act like a small resistor in parallel with the 1M resistor and dramatically

reduce the output to the processor. This is where our BC549 transistor comes in to save the


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day. In conjunction with the 1K and 10K resistors it amplifies the signal so that the analog

input on the processor gets a nice strong signal. The BC549 is not too critical and it has hfe

of 490 when measured with a multimeter. You should probably have hfe of at least 200-300.

This has the advantage that you can flex the leds and transistors outward to cover a

large area. This is a reversing sensor to prevent him reversing into anything and as such will

cover a wide area. I will make single Led/Phototransistor sensors for front left and front right.

This will allow him to avoid crashing into obstacles when his rangefinder/object tracker is

looking elsewhere.

Note: That the phototransistors are slightly forward of the blue LEDs. This helps stop stray

light from the LEDs being detected.

Figure 3.10 Circuit Diagram of Obstacle Sensor

3.5.2 Features

Modulated IR transmitter


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Ambient light protected IR receiver

3 pin easy interface connectors

Bus powered module

Indicator LED

Up to 12 inch range for white object

Can differentiate between dark and light colors.

3.5.3 Applications

Proximity Sensor

Obstacle Detector Sensor

Line Follower Sensor Wall Follower Sensor

Chapter 4

Infrared Technology

4.1 Introduction:

As next-generation electronic information systems evolve, it is critical that all people

have access to the information available via these systems. Examples of developing and future

information systems include interactive television, touch screen-based information kiosks,

and advanced Internet programs. Infrared technology, increasingly present in mainstream

applications, holds great potential for enabling people with a variety of disabilities to access a

growing list of information resources. Already commonly used in remote control of TVs,

VCRs and CD players, infrared technology is also being used and developed for remote

control of environmental control systems, personal computers, and talking signs.

For individuals using augmentative and alternative communication (AAC) devices,

infrared or other wireless technology can provide an alternate, more portable, more

independent means of accessing computers and other electronic information systems.


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4.2 Wireless Communication:

Wireless communication, as the term implies, allows information to be exchanged

between two devices without the use of wire or cable. Information is being transmitted and

received using electromagnetic energy, also referred to as electromagnetic radiation. One ofthe most familiar sources of electromagnetic radiation is the sun; other common sources

include TV and radio signals, light bulbs and microwaves.

The electromagnetic spectrum classifies electromagnetic energy according to

frequency or wavelength (both described below). As shown in Figure 1, the electromagnetic

spectrum ranges from energy waves having extremely low frequency (ELF) to energy waves

having much higher frequency, such as x-rays.

Figure 4.1 Electromagnetic Spectrum

In Figure 8, A horizontal bar represents a range of frequencies from 10 Hertz (cycles

per second) to 10 to the 18th power Hertz. Some familiar allocated frequency bands are

labelled on the spectrum. Approximate locations are as follows. (Exponential powers of 10

are abbreviated as 10exp.)

10 Hertz: extremely low frequency or ELF.

10exp5 Hertz: AM radio.

10exp8 Hertz: FM radio.

10exp16 Hertz: Infrared (frequency range is below the visible light spectrum).

10exp16 Hertz: Visible Light.

10exp16 Hertz: Ultraviolet (frequency range is above the visible light spectrum).

10exp18 Hertz: X-rays.]


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4.3 Infrared Technology:

Infrared radiation is the region of the electromagnetic spectrum between microwaves

and visible light. In infrared communication, an LED transmits the infrared signal as bursts of

non-visible light. At the receiving end a photodiode or photoreceptor detects and captures the

light pulses, which are then processed to retrieve the information they contain.

Figure 9 depicts an infrared energy wave and a radio energy wave, and illustrates the

two different energy wavelengths. As is expected based on the electromagnetic spectrum, the

infrared wave is higher frequency and therefore shorter wavelength than the radio wave.

Conversely, the radio wave is lower frequency and therefore longer wavelength than the

infrared wave.

Figure 4.2 A radio frequency energy wave superimposed upon an infrared energy wave

The above illustrates the inverse relationship between frequency and wavelength. The

infrared energy wave completes nearly 5 and a half cycles in the time that the radio frequency

wave completes 2 cycles. ]

Infrared technology is highlighted because of its increasing presence in mainstream

applications, its current and potential usage in disability-related applications, and itsadvantages over other forms of wireless communication.

Some common applications of infrared technology are listed below.

1. Augmentative communication devices

2. Car locking systems

3. Computers, Headphones


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4. Emergency response systems

5. Environmental control systems

6. Home security systems

4.4 IR Advantages:

1. Low power requirements: therefore ideal for laptops, telephones, personal digital

assistants.

2. Low circuitry costs: $2-$5 for the entire coding/decoding circuitry.

3. Simple circuitry: no special or proprietary hardware is required, can be incorporated

into the integrated circuit of a product

4. Higher security: directionality of the beam helps ensure that data isn't leaked or spilledto nearby devices as it's transmitted

5. Few international regulatory constraints: IrDA (Infrared Data Association) functional

devices will ideally be usable by international travellers, no matter where they may be

6. High noise immunity: not as likely to have interference from signals from other

devices

4.5 IR Disadvantages:

1. Line of sight: transmitters and receivers must be almost directly aligned (i.e. able to

see each other) to communicate

2. Blocked by common materials: people, walls, plants, etc. can block transmission

3. Short range: performance drops off with longer distances

4. Light, weather sensitive: direct sunlight, rain, fog, dust, pollution can affect

transmission

5. Speed: data rate transmission is lower than typical wired transmission

4.6 Health Risks:

Any time electric current travels through a wire, the air, or runs an appliance, it

produces an electromagnetic field. It is important to remember that electromagnetic fields are

found everywhere that electricity is in use. While researchers have not established an ironclad


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link between the exposure to electromagnetic fields and ailments such as leukemia, the

circumstantial evidence concerns many people.

In scientific terms, human body can act as an antenna, as it has a higher conductivity

for electricity than air. Therefore, when conditions are right human body may have

experienced a small "tingle" of electric current from a poorly grounded electric appliance. As

long as these currents are very small there isn't much danger from electric fields, except for

potential shocks. , Human body also has permeability almost equal to air, thus allowing a

magnetic field to easily enter the body. Unfortunately body cannot detect the presence of a

strong magnetic field, which could potentially do much more harm.

In terms of wireless technology, there are no confirmed health risks or scientific dangersfrom infrared or radio frequency, with two known exceptions:

1. Point-to-point lasers which can cause burns or blindness.

2. Prolonged microwave exposure which has been linked to cancer and leukaemia.

Therefore, most health concerns related to electromagnetic fields are due to electricity in

day-to-day use, such as computer monitors and TVs. These dangers, if any, are already in the

home and work place, and the addition of wireless technology should not be seen as an

exceptional risk. The strength of the electromagnetic field (EMF) decreases as the square of

the distance from the field source.

4.7 Security:

Electromagnetic frequencies currently have little legal status for protection and as

such, can be freely intercepted by motivated individuals. As presented earlier in the

advantages and disadvantages of infrared versus radio frequency transmission, what might be

considered an advantage to one method for transmission could turn out to be a disadvantage

for security? For example, because infrared is line-of-sight it has less transmission range but

is also more difficult to intercept when compared to radio frequency. Radio frequency can


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penetrate walls, making it much easier to transmit a message, but also more susceptible to

tapping.

A possible solution to security issues will likely be some form of data encryption.

Data encryption standards (DES) are also being quickly developed for the exchange of

information over the Internet, and many of these same DES will be applied to wireless

technology.

4.8 Importance of Standards:

Several of the wireless devices demonstrated during the presentation have benefited to

some degree from standardization. For example, a universal IR remote was once priced at

roughly $100.00.The X10 devices that were demonstrated in the presentation not only rely on

but have benefited from the 60 HZ AC standard which applies to most of North America. As

a result these devices are now numerous and inexpensive. One final example demonstrating

the importance of standards is the relationship of augmentative alternative communication

(AAC) devices to the General Input Device Emulating Interface (GIDEI) standard. Any AAC

device programmed to use the GIDEI protocol can access any PC or Macintosh running the

DOS, Windows, or Macintosh version of Serial Keys.

Chapter 5

CIRCUIT

5.1CIRCUIT DIAGRAM


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Figure 5.1 Circuit Diagram

5.2 CIRCUIT LEVEL DESCRIPTION:

Basically the circuit consists of the following blocks:

Power Supply

Sensors

Inverter 7404

Driver

Motors

Let us take the overview of each block one by one.

.

Inverter ic (7404)

This is the most important block of the system. 7404 is the decision making logical device

which is operated on the principal of inversion of the input chip.

Motor Driver Circuit


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The motor driver circuit consists of a driver IC L293D and two motors. The

connections are shown as in figure 4.1.5. One of the two supplies is for IC and other is to

provide sufficient current for motor rotation. The pins 2, 7 and 10,15 are the inputs of motor

from the microcontroller. The outputs of the IC are taken from pins 3, 6, 11, 14. These pins

are used to control the rotation of the motors according to the commands from

microcontroller.

Fig5.2: Motor driver circuits

The enable pins, the pins 1 and 9 are also connected to the microcontroller 89s52. This

enables and disables the driver IC according to the commands from the microcontroller.

Voltage Regulator:

A voltage regulator is an electricalregulator designed to automatically maintain a

constant voltage level. It may use an electromechanical mechanism, or passive or active

electronic components. Depending on the design, it may be used to regulate one or more AC

orDC voltages. There are two types of regulator are

Positive Voltage Series (78XX) and

Negative Voltage Series (79XX)

78XX:78 indicate the positive series and XXindicates the voltage rating. Suppose

7805 produces the maximum 5V.05indicates the regulator output is 5V.79XX:78 indicate

the negative series and XXindicates the voltage rating. Suppose 7905 produces the

maximum -5V.05indicates the regulator output is -5V.These regulators consists the three

pins they are
http://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Mechanism_%28technology%29http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Mechanism_%28technology%29http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Electricity


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Pin1: It is used for input pin.

Pin2: This is ground pin for regulator

Pin3: It is used for output pin. Through this pin we get the output.

Fig 5.3: Regulator circuit

Sensor Circuit

The sensors used in this project are three IR Receiver Transmitter LEDs. The

connections are shown as follows. As the receiver a photo diode is used, produce a zero

voltage level when it receives the signal.

Figure 5.4 Ir sensor

To microcontroller


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Figure 5.5 Basic Diagram of IR sensor

5.3 Working

After finishing the assembling work, connect the 9V battery via battery snap. Then, see whathappens. The robot will automatically start traveling on the unstructured path without hittingany objects.

When the left IR module senses any obstacles on its way, it will turn righttill it stops sensing.Similarly, it will turn leftwhen the right IR module senses obstacles. If both the sensors sensean obstacle, then the robot willstop moving.

5.4COMPONENTS USED:

1) RESISTORS:

2) CAPACITOR:

VALUE

QUANTITY

150

ohm

1

510 k 1

VALUE

QUANTITY

10 uF 4


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3) ICs:

4) MISCELLANEOUS:

5.5 HARDWARETESTING:-

1.Continuity test:-

First of all we checked the PCB that all the tracks are as per the design of PCB and

showing continuity with the help of multimeter and PCB layout.

2. Short circuit test:-

Then we checked the PCB for any unwanted short circuits with the help of multimeter

and PCB layout.

VALUE QUANTITY

7404, L293D 1

7805 2

LM324N 2

COMPONENT QUANTITY

6V ,200 RPM DC

MOTOR

2

Red LED 2IR LED 2

White LED 2

9V DC BATTERY 1

Potentiometer -


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3. Soldering:-

In the next step, we soldered the required components. And then checked that there are

no any unwanted shorts occurred due to soldering without putting IC's and keeping power

supply off.

4. Power supply test:-

In the next step, we put power supply on and checked whether required voltage is

appearing at the required voltage is appearing at the required points i.e.+Vcc and GND at the

respective points. We took care of not connecting IC's in the circuit while performing this

test.


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Chapter 6

KEY FEATURES OF OBSTACLE AVOIDANCE ROBOT

6.1. ADVANTAGES Collision control.

It Provides Safe Navigation.

This is the basic of all robot and has a Wide scope of extensions

6.2. LIMITATIONS

The performance of this robot mainly depends on the sensors and number of sensors.

The IR sensor used here is of commercial application so it may easily undergointerference.

6.3. PROBLEMS FACED

Although the concept & design of the project seemed perfect, there were some

problems faced while actual implementation:

The arrangement of sensor: The arrangement of sensor should be in such a way that the

receiver detects the reflected signal from obstacle and it should not pick the transmitted

signal.

6.4. FUTURE ENHANCEMENTS

Adding a Camera: If the current project is interfaced with a camera (e.g. a Webcam)

robot can be driven beyond line-of-sight & range becomes practically unlimited as

networks have a very large range.

Use as a fire fighting robot: By adding temperature sensor, water tank and making

some changes in programming we can use this robot as fire fighting robot.

We can extend this project with wireless technology by IR (or) RF (or) ZIGBEE.

We can use the DTMF receiver by using the mobile phone.

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.


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Conclusion

The mini project is obstacle detection and the avoidance robot

Using all the above adaptive control processes which are able to traverse a given route

autonomously negotiating difficult obstacles while protecting it from collisions.

Our ROBOT successfully implements line tracking and range detection and obstacle

avoidance.

Hence it can be further used in Automobiles and industrial automation

Project Report on Obstacel Detector Using 7404

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