7/23/2019 Project Report on Obstacel Detector Using 7404
1/43
1
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
7/23/2019 Project Report on Obstacel Detector Using 7404
2/43
2
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
3/43
3
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
7/23/2019 Project Report on Obstacel Detector Using 7404
4/43
4
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
7/23/2019 Project Report on Obstacel Detector Using 7404
5/43
5
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
7/23/2019 Project Report on Obstacel Detector Using 7404
6/43
6
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
7/23/2019 Project Report on Obstacel Detector Using 7404
7/43
7
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
8/43
8
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
7/23/2019 Project Report on Obstacel Detector Using 7404
9/43
9
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
10/43
10
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:
7/23/2019 Project Report on Obstacel Detector Using 7404
11/43
11
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
7/23/2019 Project Report on Obstacel Detector Using 7404
12/43
12
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
13/43
13
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
7/23/2019 Project Report on Obstacel Detector Using 7404
14/43
14
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
7/23/2019 Project Report on Obstacel Detector Using 7404
15/43
15
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.)
7/23/2019 Project Report on Obstacel Detector Using 7404
16/43
16
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
17/43
17
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
18/43
18
Pin Diagram:
Figure3.1 Pin diagram of 7404
7/23/2019 Project Report on Obstacel Detector Using 7404
19/43
19
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
http://en.wikipedia.org/wiki/Linear_regulatorhttp://en.wikipedia.org/wiki/Integrated_circuitshttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Integrated_circuitshttp://en.wikipedia.org/wiki/Linear_regulator7/23/2019 Project Report on Obstacel Detector Using 7404
20/43
20
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
7/23/2019 Project Report on Obstacel Detector Using 7404
21/43
21
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
7/23/2019 Project Report on Obstacel Detector Using 7404
22/43
22
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
http://en.wikipedia.org/wiki/Enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/AC_motorhttp://en.wikipedia.org/wiki/Synchronous_motorhttp://en.wikipedia.org/wiki/Induction_motorhttp://en.wikipedia.org/wiki/DC_motorhttp://en.wikipedia.org/wiki/Brushed_DC_electric_motorhttp://en.wikipedia.org/wiki/Brushless_DC_motorhttp://en.wikipedia.org/wiki/Electrostatic_motorhttp://en.wikipedia.org/wiki/Electrostatic_motorhttp://en.wikipedia.org/wiki/Brushless_DC_motorhttp://en.wikipedia.org/wiki/Brushed_DC_electric_motorhttp://en.wikipedia.org/wiki/DC_motorhttp://en.wikipedia.org/wiki/Induction_motorhttp://en.wikipedia.org/wiki/Synchronous_motorhttp://en.wikipedia.org/wiki/AC_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Engine7/23/2019 Project Report on Obstacel Detector Using 7404
23/43
23
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_motor7/23/2019 Project Report on Obstacel Detector Using 7404
24/43
24
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
25/43
25
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
7/23/2019 Project Report on Obstacel Detector Using 7404
26/43
26
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
27/43
27
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
7/23/2019 Project Report on Obstacel Detector Using 7404
28/43
28
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
7/23/2019 Project Report on Obstacel Detector Using 7404
29/43
29
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
7/23/2019 Project Report on Obstacel Detector Using 7404
30/43
30
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
31/43
31
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.]
7/23/2019 Project Report on Obstacel Detector Using 7404
32/43
32
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
7/23/2019 Project Report on Obstacel Detector Using 7404
33/43
33
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
7/23/2019 Project Report on Obstacel Detector Using 7404
34/43
34
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
7/23/2019 Project Report on Obstacel Detector Using 7404
35/43
35
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
7/23/2019 Project Report on Obstacel Detector Using 7404
36/43
36
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
7/23/2019 Project Report on Obstacel Detector Using 7404
37/43
37
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/Electricity7/23/2019 Project Report on Obstacel Detector Using 7404
38/43
38
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
7/23/2019 Project Report on Obstacel Detector Using 7404
39/43
39
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
7/23/2019 Project Report on Obstacel Detector Using 7404
40/43
40
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 -
7/23/2019 Project Report on Obstacel Detector Using 7404
41/43
41
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
42/43
42
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.
7/23/2019 Project Report on Obstacel Detector Using 7404
43/43
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
Top Related