Obstacle Sensing Robot Report

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A
Project Report
ON

Obstacle Avoidance
Robot
Submitted in the partial fulfillment for the award of the degree
in

Bachelor Of Technology
IN
Electronics & Communication
Engineering

Submitted To
Submitted By
Miss. Shubhi agarwal
Chandra

Ankur

Anil
kumar gangwar
Gaurav kumar
Dharmendra
kumar
B.tech
E.C. final yr.
Department Of Electronics
Engineering
Bareilly.

Rajshree group of Institution Of Management &Technology

2014-15

TABLE OF CONTENTS
 INTRODUCTION
 PLATFORM USED
 AIM OF THE PROJECT
 BLOCK DIAGRAM
 WORKING OF THE PROJECT
 CIRCUIT DIAGRAM
 COMPONENT LIST
 CIRCUIT DESCRIPTION
 PCB LAYOUT

 STEPS FOR MAKING PCB
 PROGRAMMING
 COMPONENTS DESCRIPTION
 APPLICATIONS
 CONCLUSION
 REFERENCE

INTRODUCTION
The nature’s most spectacular creation is human brain. The
main feature of the human brain is its ability to sense the
obstacles and respond according to them. The men always want
to transplant his ability to the artificial things so that they can not
only sense the problem but also respond according to that.

In this competitive corporate world every organization wants to
improve the efficiency as well as its productivity. To improve the efficiency of
organization, automation is a preferred solution.

Robots help automate thousands of factories around the world, making
the delivery of mail, packages and materials fast and efficient. Scientists and
engineers have been experimenting with snow ploughs and even passenger cars
that can follow magnetic lines in “smart” highways. These robotic vehicles can
sense the road, obstacles and each other, eliminating traffic snarls and making our

highways safer and easier to travel. Someday we’ll simply tell our cars where to
take us and line following circuitry will help get us there safely and without effort.
Our project is Obstacle sensing robot, this project is microcontroller based
we are using a microcontroller Atmega16 Atmel Controller used for sensing the
signals and taking decisions according to that microcontroller is used for sensing
the distance according to value given by distance sensor.

PLATFORM USED
SOFTWARE REQUIREMENTS
1. Bascom for programming of Microcontroller
2. DIPTRACE for Circuit Designing
3. DIPTRACE for PCB designing

HARDWARE REQUIREMENTS
1.
MICROCONTROLLER Atmega16
2.
CRYSTAL OSCILLATOR
3.
RESISTORS
4.
CAPACITORS
5.
TRANSISTERS
6.
REGULATOR
7.
CONNECTORS
8.
DC MOTOR
9.
WHEELS
10.
BUZZER
11.
OBSTACLE SENSOR
12.
BATTERY
13.
REMOTE

14. TSOP1738 SENSOR

AIM OF THE PROJECT
Problem of moving a robot through unknown environment has attracted much
attention over past two decades. Such problems have several difficulties and
complexities that are unobserved, besides the ambiguity of how this can be
achieved since a robot may encounter obstacles of all forms that must be bypassed
in an intelligent manner

Our aim is to design a robot that finds its way in a complex route. This Robot is
going to be React on facing the obstacle. It will move in other direction as the
obstacle comes in its way robotic system capable to be navigated within its
environment through logically acting on the sensed data to avoid such obstacles.
The robot tries to locate hindering obstacles, both stationary and moveable, plans
ways to bypass these objects and, finally, acts according to the resulted plan.

BLOCK DIAGRAM
BLOCK DIAGRAM

SUPPLY
SECTION

REMOTE

MICRO
CONTROLLER
Atmega16
(DECISION MAKING)

DIGITAL VALUE
DISTANCE
SENSOR

ROBOTIC CAR

Working of the project
WORKING OF THE PROJECT
This project comprises a microcontroller. A sensor for sensing distance is
interfaced with controller, while moving if there is any obstacle arrive, it will send
an analog signal to the AVR controller which has inbuilt ADC. It convert the
analog signal to digital and transfer it to microcontroller, it will process the signal
arrive at its pin and control the DC motor movement. The DC motor runs the
wheels .The signal transfer through a remote interfaced with AVR
microcontroller .The transmitted signal receive by the receiver on robotic unit. In
this way we can make a robot that senses the obstacle.

CIRCUIT DIAGRAM

J5

J1
1
2
3

VCC

U2
LM 7805H

BATT+

1
2
3

D2

1

VCC

3

R L M T 0 3 (M )

R L M T 0 3 (M )
C 10
C EL5
1 0 M /6 3 V

2

C9
C EL5
1 0 M /6 3 V

C8
C C ER
104P F

+5V

C1
C EL5
1 0 M /6 3 V

C2 C CER

1

39P F

Y1
XTA L

C3

R1
R
1K

4
5

C C ER

39PF

12M H z
P 3 .0
P 3 .1

P 3 .7

2
3
6
7
8
9
11

U1
RST

19
18
17
16
15
14
13
12

P 1 .7
P 1 .6
P 1 .5
P 1 .4
P 1 .3
P 1 .2
P 1 .1
P 1 .0

X2
X1

J3

B A TT+

J9

D3
D2
D1
D0

1
2
3

4
3
2
1

RC2
RC1

R L M T 0 3 (M )

R L M T 0 4 (M )
R 14
R
1K

P 3 .0
P 3 .1
P 3 .2
P 3 .3
P 3 .4
P 3 .5
P 3 .7

R 15
R
1K

R 16
R
1K

R 17
R
1K
P 3 .0

R9

Q1
BD 139

Q2
BD 139

R
470E

R 10

P 3 .1

R
470E

89C 2051
VCC
VCC
R 12
R
1K

R8
R 2K2

R7
R 2K 2

C 13
C C ER
0M1

J10
VCC
RA0

RA0
VCC

R L M T 0 3 (M )
P 3 .1

1

1
2
3

P 3 .0

2
3

R 13
R
2K2

4
5
6

C CER

C 11

7

22PF

Y3
XTA L

C 12

9
10

C CER

22P F

4MH z

11
RC1

12

RC2

13
14

U4
/M C L R

RB7

R A 0 /A N 0

RB6

R A 1 /A N 1

RB5

R A 2 /A N 2

RB4

R A 3 /A N 3 /V R E F

RB3

R A 4 /T 0 C K 1

RB2

R A 5 /A N 4 /S S
OSCI

RB1
IN T /R B 0

OSCO

RC7

RC0

RC6

RC1

RC5

RC2

RC4

VCC

28

P 3 .7

27

J7

26

8
7
6
5
4
3
2
1

25
24
23
22

R2

BZ1

R
220E
BUZZER

R L M T 0 8 (M )

21
J8

18

4
3
2
1

17
16
15

D TM F_D V

VSS

GND

+5V
VCC

R L M T 0 4 (M )

VS

RC3
P IC 1 6 F 7 2

T it le

Component list

ROBRFOB

S iz e
B

D ocum ent N um ber
PCB ROBOT

D a te :

T h u rs d a y , D e c e m b e r 1 7 , 2 0 0 9

R ev
1 .1
Sheet

1

of

1

CIRCUIT DESCRIPTION :-

POWER SUPPLY SECTION:

Consists of:

1. Regulator: ----LM7805 is used to give a fixed 5v regulated supply.
2. Capacitor: -----It is again an electrolytic capacitor 10M/65v used for
filtering to give pure dc.
3. Capacitor: ----- It is a ceramic capacitor used to remove the spikes
generated when frequency is high (spikes).
So the output of supply section is 5v regulated dc.

MICROCONTROLLER

SECTION:

Requires three connections to be successfully done for it’s operation to begin.

1. +5v supply: This +5v supply is required for the controller to get start
which is provided from the power supply section. This supply is provided at
pin no. 20 of the 89c2051 controller.

2. Crystal Oscillator: A crystal oscillator of 12 MHz is connected at pin no.5,
x1 and pin no.4, x2 to generate the frequency for the 89C2051
microcontroller and 4MHz is connected at pin no.9 and pin no. 10. The
crystal oscillator works on piezoelectric effect. The clock generated is used
to determine the processing speed of the controller. Two capacitors are also
connected one end with the oscillator while the other end is connected with
the ground. As it is recommended in the book to connect two ceramic
capacitor of 20 pf—40pf to stabilize the clock generated.
3. Reset section:
It consists of an rc network consisting of 10M/35V
capacitor and one resistance of 1k. This section is used to reset the controller
connected at pin no.1 of AT89c2051 and connected at pin no.1 of PIC16F72.

PCB LAYOUT:-

STEPS FOR MAKING PCB

Prepare the layout of the circuit (positive).
 Cut the photofilm (slightly bigger) of the size of the layout.
 Place the layout in the photoprinter machine with the photofilm above it. Make
sure that the bromide (dark) side of the film is in contact with the layout.
 Switch on the machine by pressing the push button for 5 sec.
 Dip the film in the solution prepared (developer) by mixing the chemicals A &
B in equal quantities in water.
 Now clean the film by placing it in the tray containing water for 1 min.
 After this, dip the film in the fixer solution for 1 min. now the negative of the
Circuit is ready.
 Now wash it under the flowing water.
 Dry the negative in the photocure machine.
 Take the PCB board of the size of the layout and clean it with steel wool to
make the surface smooth.
 Now dip the PCB in the liquid photoresist, with the help of dip coat machine.
 Now clip the PCB next to the negative in the photo cure machine, drying for
approximate 10-12 minute.
 Now place the negative on the top of the PCB in the UV machine, set the timer
for about 2.5 minute and switch on the UV light at the top.
 Take the LPR developer in a container and rigorously move the PCB in it.

 After this, wash it with water very gently.
 Then apply LPR dye on it with the help of a dropper so that it is completely
covered by it.
 Now clamp the PCB in the etching machine that contains ferric chloride
solution for about 10 minutes.
 After etching, wash the PCB with water, wipe it a dry cloth softly.
 Finally rub the PCB with a steel wool, and the PCB is ready.

Programming of
Obstacle sensing robot
#INCLUDE < P16F72.INC> ; PROCESSOR SPECIFIC VARIABLE
DEFINITIONS
MAIN

MAINLOOP
L_CJNL

DISTANCE,.22,GA1

BSF

PORTC,4

GOTO

GM1

GA1:
BCF

PORTC,4
GM1:

GOTO MAINLOOP

INTRADC:
MOVF

ADRES,W

MOVWF

DISTANCE

RETURN

INCLUDE 89c2051.mc
buzzer

EQU p3.7

main:
CLR p3.0
CLR p3.1

mainloop:

JB
CLR
CLR
CLR
JMP

p1.3,la5
p3.0
p3.1
buzzer
mainloop

la5:
JNB p1.4,la1
SETBp3.0
SETBp3.1
CLR buzzer

la1:
JNB p1.5,la2
CLR p3.0
SETBp3.1
CLR buzzer
la2:
JNB p1.6,la3
SETBp3.0
CLR p3.1
CLR buzzer
la3:
CLR p3.0
CLR p3.1
SETBbuzzer

JMP mainloop

MICROCONTROLLER UNIT

MICROCONTROLLER ATmega16 (AVR Series) 8bit
Microcontroller
In our days, there have been many advancement in the field of Electronics and many
cutting edge technologies are being developed every day, but still 8 bit microcontrollers
have its own role in the digital electronics market dominated by 16-32 & 64 bit digital
devices. Although powerful microcontrollers with higher processing capabilities exist in the
market, 8bit microcontrollers still hold its value because of their easy-to-understandoperation, very much high popularity, ability to simplify a digital circuit, low cost compared
to features offered, addition of many new features in a single IC and interest of
manufacturers and consumers.
Today’s microcontrollers are much different from what it were in the initial stage, and the
number of manufacturers are much more in count than it was a decade or two ago. At
present some of the major manufacturers are Microchip (publication: PIC
microcontrollers), Atmel (publication: AVR microcontrollers), Hitachi, Phillips, Maxim,
NXP, Intel etc. Our interest is upon ATmega16. It belongs to Atmel’s AVR series
micro controller family. Let’s see the features.
PIN count: Atmega16 has got 40 pins. Two for Power (pin no.10: +5v, pin no. 11: ground),
two for oscillator (pin 12, 13), one for reset (pin 9), three for providing necessary power and
reference voltage to its internal ADC, and 32 (4×8) I/O pins.
About I/O pins: ATmega16 is capable of handling analogue inputs. Port A can be used as
either DIGITAL I/O Lines or each individual pin can be used as a single input channel to the
internal ADC of ATmega16, plus a pair of pins AREF, AVCC & GND together can make an
ADC channel.
No pins can perform and serve for two purposes (for an example: Port A pins cannot work
as a Digital I/O pin while the Internal ADC is activated) at the same time. It’s the
programmers responsibility to resolve the conflict in the circuitry and the program.
Programmers are advised to have a look to the priority tables and the internal configuration
from the datasheet.
Digital I/O pins: ATmega16 has 32 pins (4portsx8pins) configurable as Digital I/O pins.
Timers: 3 Inbuilt timer/counters, two 8 bit (timer0, timer2) and one 16 bit (timer1).
ADC: It has one successive approximation type ADC in which total 8 single channels are
selectable. They can also be used as 7 (for TQFP packages) or 2 (for DIP packages)
differential channels. Reference is selectable, either an external reference can be used or the
internal 2.56V reference can be brought into action. There external reference can be
connected to the AREF pin.
Communication Options: ATmega16 has three data transfer modules embedded in it.
They are

Two Wire Interface

USART



Serial Peripheral Interface

Atmega16 pin diagram

Analog comparator: On-chip analog comparator is available. An interrupt is assigned for
different comparison result obtained from the inputs.
External Interrupt: 3External interrupt is accepted. Interrupt sense is configurable.

Memory: It has 16 Kbytes of In-System Self-programmable Flash program memory, 1024
Bytes EEPROM, 2Kbytes Internal SRAM. Write/Erase Cycles: 10,000 Flash / 100, 000
EEPROM.
Clock: It can run at a frequency from 1 to 16 MHz. Frequency can be obtained from
external Quartz Crystal, Ceramic crystal or an R-C network. Internal calibrated RC oscillator
can also be used.
More Features: Up to 16 MIPS throughput at 16MHz. Most of the instruction executes in
a single cycle. Two cycle on-chip multiplication. 32 × 8 General Purpose Working Registers
Debug: JTAG boundary scan facilitates on chip debug.
Programming: Atmega16 can be programmed either by In-System Programming via
Serial peripheral interface or by Parallel programming. Programming via JTAG interface is
also possible. Programmer must ensure that SPI programming and JTAG are not be
disabled using fuse bits; if the programming is supposed to be done using SPI or JTAG.

COMPONENTS DESCRIPTION
Distance SENSOR:

DESCRIPTION:

The LTM-97 series are miniaturized receivers for infrared remote control systems.
It is a single unit type module which incorporates a PIN diode and a receiving
preamplifier IC. The demodulated output signal can directly be decoded by a
microprocessor. It has excellent sensitivity and reliable function even in disturbed
working environment.

Voltage Regulators

A voltage regulator is an electrical regulator 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 or DC voltages. With the exception of shunt
regulators, all voltage regulators operate by comparing the actual
output voltage to some internal fixed reference voltage. Any
difference is amplified and used to control the regulation element.
This forms a negative feedback servo control loop. If the output
voltage is too low, the regulation element is commanded to
produce a higher voltage. For some regulators if the output
voltage is too high, the regulation element is commanded to
produce a lower voltage; however, many just stop sourcing
current and depend on the current draw of whatever it is driving
to pull the voltage back down. In this way, the output voltage is
held roughly constant. The control loop must be carefully
designed to produce the desired tradeoff between stability and
speed of response.

2.4.2

LM7805 (3-Terminal Fixed Voltage Regulator)

The MC78XX/LM78XX/MC78XXA series of three terminal positive
regulators are available in the
TO-220/D-PAK package and with several fixed output voltages,
making them useful in a wide range of
applications. 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.

Figure 18: Internal block Diagram

Figure 19 : Fixed Output Regulator

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

DC MOTOR
A DC motor is an electric motor that runs on direct current (DC) electricity.
Brushed
The brushed DC motor generates torque directly from DC power supplied to the
motor by using internal commutation, stationary permanent magnets, and rotating
electrical magnets.It works on the principle of Lorentz force , which states that any
current carrying conductor placed within an external magnetic field experiences a
torque or force known as Lorentz force. Advantages of a brushed DC motor
include low initial cost, high reliability, and simple control of motor speed.
Disadvantages are high maintenance and low life-span for high intensity uses.
Maintenance involves regularly replacing the brushes and springs which carry the
electric current, as well as cleaning or replacing the commutator. These
components are necessary for transferring electrical power from outside the motor
to the spinning wire windings of the rotor inside the motor.
Synchronous
Synchronous DC motors, such as the brushless DC motor and the stepper motor,
require external commutation to generate torque. They lock up if driven directly by
DC power. However, BLDC motors are more similar to a synchronous ac motor.
Brushless
Brushless DC motors use a rotating permanent magnet in the rotor, and stationary
electrical magnets on the motor housing. A motor controller converts DC to AC.
This design is simpler than that of brushed motors because it eliminates the
complication of transferring power from outside the motor to the spinning rotor.
Advantages of brushless motors include long life span, little or no maintenance,
and high efficiency. Disadvantages include high initial cost, and more complicated
motor speed controllers.

DC MOTOR:
In

any electric motor, operation is based on simple electromagnetism. A

current-carrying conductor generates a magnetic field; when this is then placed in
an external magnetic field, it will experience a force proportional to the current in
the conductor, and to the strength of the external magnetic field. As you are well
aware of from playing with magnets as a kid, opposite (North and South) polarities
attract, while like polarities (North and North, South and South) repel. The internal
configuration of a DC motor is designed to harness the magnetic interaction
between a current-carrying conductor and an external magnetic field to generate
rotational motion.

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 (and all
that BEAMers will see), the external magnetic field is produced by high-strength
permanent magnets1. The stator is the stationary part of the 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) rotate 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.
The geometry of the brushes, commutator contacts, and rotor windings are such
that when power is applied, the polarities of the energized winding and the stator
magnet(s) are misaligned, and the rotor will rotate until it is almost aligned with the
stator's field magnets. As the rotor reaches alignment, the brushes move to the next
commutator contacts, and energize the next winding. Given our example two-pole
motor, the rotation reverses the direction of current through the rotor winding,
leading to a "flip" of the rotor's magnetic field, driving it to continue rotating.
In real life, though, DC motors will always have more than two poles (three is a
very common number). In particular, this avoids "dead spots" in the commutator.
You can imagine how with our example two-pole motor, if the rotor is exactly at the
middle of its rotation (perfectly aligned with the field magnets), it will get "stuck"

there. Meanwhile, with a two-pole motor, there is a moment where the commutator
shorts out the power supply (i.e., both brushes touch both commutator contacts
simultaneously). This would be bad for the power supply, waste energy, and
damage motor components as well. Yet another disadvantage of such a simple
motor is that it would exhibit a high amount of torque "ripple" (the amount of
torque it could produce is cyclic with the position of the rotor).

Crystal Oscillator
It is often required to produce a signal whose frequency or pulse rate is very stable
and exactly known. This is important in any application where anything to do with
time or exact measurement is crucial. It is relatively simple to make an oscillator
that produces some sort of a signal, but another matter to produce one of relatively
precise frequency and stability. AM radio stations must have a carrier frequency
accurate within 10Hz of its assigned frequency, which may be from 530 to 1710
kHz. SSB radio systems used in the HF range (2-30 MHz) must be within 50 Hz of
channel frequency for acceptable voice quality, and within 10 Hz for best results.
Some digital modes used in weak signal communication may require frequency
stability of less than 1 Hz within a period of several minutes. The carrier frequency
must be known to fractions of a hertz in some cases. An ordinary quartz watch
must have an oscillator accurate to better than a few parts per million. One part per

million will result in an error of slightly less than one half second a day, which
would be about 3 minutes a year. This might not sound like much, but an error of
10 parts per million would result in an error of about a half an hour per year. A
clock such as this would need resetting about once a month, and more often if you
are the punctual type. A programmed VCR with a clock this far off could miss the
recording of part of a TV show. Narrow band SSB communications at VHF and
UHF frequencies still need 50 Hz frequency accuracy. At 440 MHz, this is slightly
more than 0.1 part per million. Ordinary L-C oscillators using conventional
inductors and capacitors can achieve typically 0.01 to 0.1 percent frequency
stability, about 100 to 1000 Hz at 1 MHz. This is OK for AM and FM broadcast
receiver applications and in other low-end analog receivers not requiring high
tuning accuracy. By careful design and component selection, and with rugged
mechanical construction, .01 to 0.001%, or even better (.0005%) stability can be
achieved. The better figures will undoubtedly employ temperature compensation
components and regulated power supplies, together with environmental control
(good ventilation and ambient temperature regulation) and “battleship” mechanical
construction. This has been done in some communications receivers used by the
military and commercial HF communication receivers built in the 1950-1965 era,
before the widespread use of digital frequency synthesis. But these receivers were
extremely expensive, large, and heavy. Many modern consumer grade AM, FM,
and shortwave receivers employing crystal controlled digital frequency synthesis
will do as well or better from a frequency stability standpoint.
An oscillator is basically an amplifier and a frequency selective feedback network
(Fig 1). When, at a particular frequency, the loop gain is unity or more, and the
total phaseshift at this frequency is zero, or some multiple of 360 degrees, the
condition for oscillation is satisfied, and the circuit will produce a periodic
waveform of this frequency. This is usually a sine wave, or square wave, but
triangles, impulses, or other waveforms can be produced. In fact, several different

waveforms often are simultaneously produced by the same circuit, at different
points. It is also possible to have several frequencies produced as well, although
this is generally undesirable.

EXTRA KNOWLEDGE
Sensing Unit:
Sensing unit consists of RF sensors whenever this sensor receive RF signal
they pass information in the form of high or low to the controller. Whenever
a key is pressed in a distant RF transmitter that key is sensed by the sensor
and further inform controller about the key pressed and further action can be
performed.

Radio frequency Receiver

Transmitter

Radio frequency (RF) is a frequency or rate of oscillation within the range of
about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current
electrical signals used to produce and detect radio waves. Since most of this range
is beyond the vibration rate that most mechanical systems can respond to, RF
usually refers to oscillations in electrical circuits.

Special properties of RF electrical signals
Electrical currents that oscillate at RF have special properties not shared by direct
current signals. One such property is the ease with which they can ionize air to
create a conductive path through air. This property is exploited by 'high frequency'
units used in electric arc welding, although strictly speaking these machines do not
typically employ frequencies within the HF band. Another special property is an
electromagnetic force that drives the RF current to the surface of conductors,
known as the skin effect. Another property is the ability to appear to flow through
paths that contain insulating material, like the dielectric insulator of a capacitor.
The degree of effect of these properties depends on the frequency of the signals.

Frequencies
Name

Symbol Frequenc Wavelengt
y
h

Extremel
y low
ELF
frequenc
y

3–30 Hz

Super
low
SLF
frequenc
y

1,000–
30–300 Hz
10,000 km

Ultra low
frequenc ULF
y
Very low
frequenc VLF
y
Low
frequenc LF
y
Medium
frequenc MF
y

300–
3000 Hz

3–30 kHz

30–
300 kHz

300–
3000 kHz

Applications

Directly audible when
10,000–
converted to sound,
100,000 km communication with
submarines

100–
1,000 km

Directly audible when
converted to sound, AC
power grids (50–60 Hz)
Directly audible when
converted to sound,
communication with
mines

Directly audible when
converted to sound
10–100 km
(below ca. 20 kHz; or
ultrasound otherwise)
1–10 km

100–
1000 m

AM broadcasting,
navigational beacons,
lowFER
Navigational beacons,
AM broadcasting,
maritime and aviation
communication

High
frequenc HF
y

3–30 MHz 10–100 m

Shortwave, amateur
radio, citizens' band
radio, skywave
propagation

Very high VHF

30–

FM broadcasting,

1–10 m

frequenc
y

Ultra
high
UHF
frequenc
y

Super
high
SHF
frequenc
y

Extremel
y high
EHF
frequenc
y

amateur radio,
broadcast television,
aviation, GPR, MRI

300 MHz

300–
3000 MHz

Broadcast television,
amateur radio, mobile
telephones, cordless
telephones, wireless
10–100 cm
networking, remote
keyless entry for
automobiles,
microwave ovens, GPR

3–30 GHz 1–10 cm

30–
300 GHz

1–10 mm

FEATURES
* Wide operating voltage range (VCC=1.5~5.0V)
* Low standby current
* Auto power off function for TX2B
* Few external components are needed

Wireless networking,
satellite links,
microwave links,
satellite television, door
openers
Microwave data links,
radio astronomy,
remote sensing,
advanced weapons
systems, advanced
security scanning

CAPACITOR
A capacitor or condenser is a passive electronic component consisting of a pair of
conductors separated by a dielectric (insulator). When a potential difference
(voltage) exists across the conductors, an electric field is present in the dielectric.
This field stores energy and produces a mechanical force between the conductors.
The effect is greatest when there is a narrow separation between large areas of
conductor; hence capacitor conductors are often called plates.
An ideal capacitor is characterized by a single constant value, capacitance, which
is measured in farads. This is the ratio of the electric charge on each conductor to
the potential difference between them. In practice, the dielectric between the plates
passes a small amount of leakage current. The conductors and leads introduce an
equivalent series resistance and the dielectric has an electric field strength limit
resulting in a breakdown voltage.
Capacitors are widely used in electronic circuits to block the flow of direct current
while allowing alternating current to pass, to filter out interference, to smooth the
output of power supplies, and for many other purposes. They are used in resonant
circuits in radio frequency equipment to select particular frequencies from a signal
with many frequencies.

Theory of operation
Main article: Capacitance

Charge separation in a parallel-plate capacitor causes an internal electric field. A
dielectric (orange) reduces the field and increases the capacitance.

A simple demonstration of a parallel-plate capacitor
A capacitor consists of two conductors separated by a non-conductive region.The
non-conductive substance is called the dielectric medium, although this may also
mean a vacuum or a semiconductor depletion region chemically identical to the
conductors. A capacitor is assumed to be self-contained and isolated, with no net
electric charge and no influence from an external electric field. The conductors
thus contain equal and opposite charges on their facing surfaces, and the dielectric

contains an electric field. The capacitor is a reasonably general model for electric
fields within electric circuits.
An ideal capacitor is wholly characterized by a constant capacitance C, defined as
the ratio of charge ±Q on each conductor to the voltage V between them

Sometimes charge buildup affects the mechanics of the capacitor, causing the
capacitance to vary. In this case, capacitance is defined in terms of incremental
changes:

In SI units, a capacitance of one farad means that one coulomb of charge on each
conductor causes a voltage of one volt across the device.
Energy storage
Work must be done by an external influence to move charge between the
conductors in a capacitor. When the external influence is removed, the charge
separation persists and energy is stored in the electric field. If charge is later
allowed to return to its equilibrium position, the energy is released. The work done
in establishing the electric field, and hence the amount of energy stored, is given
by:

RESISTOR

Resistors are used to limit the value of current in a circuit. Resistors offer
opposition to the flow of current. They are expressed in ohms for which the symbol
is ‘’. Resistors are broadly classified as
(1)

Fixed Resistors

(2)

Variable Resistors

Fixed Resistors :

The most common of low wattage, fixed type resistors is the molded-carbon
composition resistor. The resistive material is of carbon clay composition. The
leads are made of tinned copper. Resistors of this type are readily available in value
ranging from few ohms to about 20M, having a tolerance range of 5 to 20%.
They are quite inexpensive. The relative size of all fixed resistors changes with the
wattage rating.
Another variety of carbon composition resistors is the metalized type.
It is made by deposition a homogeneous film of pure carbon over a glass, ceramic
or other insulating core. This type of film-resistor is sometimes called the precision
type, since it can be obtained with an accuracy of 1%.

Lead

Colour Coding

Fixed Resistor

Tinned Copper Material

Molded Carbon Clay Composition

A Wire Wound Resistor :

It uses a length of resistance wire, such as nichrome. This wire is wounded on to a
round hollow porcelain core. The ends of the winding are attached to these metal
pieces inserted in the core. Tinned copper wire leads are attached to these metal
pieces. This assembly is coated with an enamel coating powdered glass. This
coating is very smooth and gives mechanical protection to winding. Commonly
available wire wound resistors have resistance values ranging from 1 to 100K,
and wattage rating up to about 200W.

Coding Of Resistor :

Some resistors are large enough in size to have their resistance printed on the
body. However there are some resistors that are too small in size to have numbers
printed on them. Therefore, a system of colour coding is used to indicate their
values. For fixed, moulded composition resistor four colour bands are printed on
one end of the outer casing. The colour bands are always read left to right from the
end that has the bands closest to it. The first and second band represents the first
and second significant digits, of the resistance value. The third band is for the
number of zeros that follow the second digit. In case the third band is gold or
silver, it represents a multiplying factor of 0.1to 0.01. The fourth band represents
the manufacture’s
tolerance. 0
0 black
1 brown

black

0 black

0 black

1 brown

1 brown

1 brown

2 red

2 red

2 red COLOUR CHART
2 red
RESISTOR
3 orange

3 orange

3 orange

3 orange

4 yellow

4 yellow

4 yellow

4 yellow

5 green

5 green

5 green
6 blue

6 blue

6 blue

6 blue

7 purple

7 purple

7 purple

7 purple

8 silver

8 silver

8 silver

8 silver

9 white

9 white

9 white

9 white

5 green

For example, if a resistor has a colour band sequence: yellow, violet, orange and
gold

Then its range will be—

Yellow=4, violet=7, orange=10³,

gold=±5% =47KΏ ±5% =2.35KΏ

Most resistors have 4 bands:


The first band gives the first digit.



The second band gives the second digit.



The third band indicates the number of zeros.



The fourth band is used to show the tolerance (precision) of the resistor.

This resistor has red (2), violet (7), yellow (4 zeros) and gold bands.
So its value is 270000 = 270 k .

The standard colour code cannot show values of less than 10 . To show these
small values two special colours are used for the third band: gold, which means
× 0.1 and silver which means × 0.01. The first and second bands represent the
digits as normal.

For example:
red, violet, gold bands represent 27 × 0.1 = 2.7
blue, green, silver bands represent 56 × 0.01 = 0.56

The fourth band of the colour code shows the tolerance of a resistor. Tolerance is
the precision of the resistor and it is given as a percentage. For example a 390
resistor with a tolerance of ±10% will have a value within 10% of 390 , between
390 - 39 = 351 and 390 + 39 = 429 (39 is 10% of 390).

A special colour code is used for the fourth band tolerance:
silver ±10%, gold ±5%, red ±2%, brown ±1%.
If no fourth band is shown the tolerance is ±20%.

VARIABLE RESISTOR:
In electronic circuits, sometimes it becomes necessary to adjust the values of
currents and voltages. For n example it is often desired to change the volume of
sound, the brightness of a television picture etc. Such adjustments can be done by
using variable resistors.

Although the variable resistors are usually called rheostats in other
applications, the smaller variable resistors commonly used in electronic
circuits are called potentiometers.

TRANSISTORS

A transistor is an active device. It consists of two PN junctions formed by
sandwiching either p-type or n-type semiconductor between a pair of opposite
types.

There are two types of transistor:
1. n-p-n transistor
2. p-n-p transistor

An n-p-n transistor is composed of two n-type semiconductors separated by a
thin section of p-type. However a p-n-p type semiconductor is formed by two psections separated by a thin section of n-type.

Transistor has two pn junctions one junction is forward biased and other is
reversed biased. The forward junction has a low resistance path whereas a reverse
biased junction has a high resistance path.
The weak signal is introduced in the low resistance circuit and output is
taken from the high resistance circuit. Therefore a transistor transfers a signal from
a low resistance to high resistance.
Transistor has three sections of doped semiconductors. The section on one
side is emitter and section on the opposite side is collector. The middle section is
base.

Emitter : The section on one side that supplies charge carriers is called emitter.
The emitter is always forward biased w.r.t. base.

Collector : The section on the other side that collects the charge is called collector.
The collector is always reversed biased.

Base : The middle section which forms two pn-junctions between the emitter and
collector is called base.

A transistor raises the strength of a weak signal and thus acts as an amplifier.
The weak signal is applied between emitter-base junction and output is taken
across the load Rc connected in the collector circuit. The collector current flowing
through a high load resistance Rc produces a large voltage across it. Thus a weak
signal applied in the input appears in the amplified form in the collector circuit.

Switch
A pressure sensor or switch measures pressure. Pressure is usually expressed in
terms of force per unit area. A pressure sensor usually acts as a transducer; it
generates a signal as a function of the pressure imposed.

Pressure sensors can be classified in term of pressure ranges they measure,
temperature ranges of operation, and most importantly the type of pressure they
measure. In terms of pressure type, pressure sensors can be divided into five
categories:
1) Absolute pressure sensor
This sensor measures the pressure relative to perfect vaccum pressure.
2) Gauge pressure sensor
This sensor is used in different applications because it can be calibrated to
measure the pressure relative to a given atmospheric pressure at a given location.
3)Vaccum pressure sensor
This sensor is used to measure pressure less than the atmospheric pressure at a
given location.
4) Differential pressure sensor
This sensor measures the difference between two or more pressures introduced as
inputs to the sensing unit.
5) Sealed pressure sensor
This sensor is the same as the gauge pressure sensor except that it is previously
calibrated by manufacturers to measure pressure relative to sea level pressure.

Fig: Operation of pressure switch
1.10.1 Pressure Sensing Technology
There are two basic categories of analog pressure sensors:
(i) Force collector types - These types of electronic pressure sensors generally use
a force collector (such a diaphragm, piston, bourdon tube, or bellows) to measure
strain (or deflection) due to applied force (pressure) over an area.
(ii) Other types - These types of electronic pressure sensors use other properties
(such as density) to infer pressure of a gas, or liquid.
Here we’ll discuss only about Force collector type of pressure sensors. Force
collecting pressure sensors are of following types:
Piezoresistive Strain GaugeUses the piezoresistive effect of bonded or formed strain gauges to detect strain
due to applied pressure. Generally, the strain gauges are connected to form a wheat
stone bridge circuit to maximize the output of the sensor. This is the most
commonly

employed

measurement.

sensing

technology

for

general

purpose

pressure

Capacitive - Uses a diaphragm and pressure cavity to create a variable capacitor to
detect strain due to applied pressure. Common technologies use metal, ceramic,
and silicon diaphragms. Generally, these technologies are most applied to low
pressures (Absolute, Differential and Gauge)
Electromagnetic - Measures the displacement of a diaphragm by means of
changes in inductance (reluctance), LVDT, Hall Effect, or by eddy current
principal.
Piezoelectric - Uses the piezoelectric effect in certain materials such as quartz to
measure the strain upon the sensing mechanism due to pressure. This technology is
commonly employed for the measurement of highly dynamic pressures.
Optical - Uses the physical change of an optical fiber to detect strain due to
applied pressure.
Potentiometric - Uses the motion of a wiper along a resistive mechanism to detect
the strain caused by applied pressure.

WHEEL

A wheel is a circular component that is intended to rotate on an axial bearing. The
wheel is one of the main components of the wheel and axle which is one of the six
simple machines. Wheels, in conjunction with axles, allow heavy objects to be
moved easily facilitating movement or transportation while supporting a load, or
performing labor in machines. Wheels are also used for other purposes, such as a
ship's wheel, steering wheel, potter's wheel and flywheel.

Common examples are found in transport applications. A wheel greatly reduces
friction by facilitating motion by rolling together with the use of axles. In order for

wheels to rotate, a moment needs to be applied to the wheel about its axis, either
by way of gravity, or by the application of another external force or torque.

CONNECTORS

Connectors are basically used for interface between two. Here we use
connectors for having interface between PCB and 8051 Microprocessor Kit.
There are two types of connectors they are male and female. The one, which
is with pins inside, is female and other is male.
These connectors are having bus wires with them for connection.
For high frequency operation the average circumference of a coaxial cable must be
limited to about one wavelength, in order to reduce multimodal propagation and

eliminate erratic reflection coefficients, power losses, and signal distortion. The
standardization of coaxial connectors during World War II was mandatory for
microwave operation to maintain a low reflection coefficient or a low voltage
standing wave ratio.
Seven types of microwave coaxial connectors are as follows:
1.APC-3.5
2.APC-7
3.BNC
4.SMA
5.SMC
6.TNC
7.Type N

Buzzer

It is an electronic signaling device which produces buzzing sound. It is commonly
used in automobiles, phone alarm systems and household appliances. Buzzers

work in the same manner as an alarm works. They are generally equipped with
sensors or switches connected to a control unit and the control unit illuminates a
light on the appropriate button or control panel, and sound a warning in the form of
a continuous or intermittent buzzing or beeping sound.
The word "buzzer" comes from the rasping noise that buzzers made when they
were electromechanical devices, operated from stepped-down AC line voltage at
50 or 60 cycles.
Typical uses of buzzers and beepers include alarms, timers and confirmation of
user input such as a mouse click or keystroke.
2.9.1Types of Buzzers
The different types of buzzers are electric buzzers, electronic
buzzers, mechanical buzzers, electromechanical, magnetic
buzzers, piezoelectric buzzers and piezo buzzers.
(i) Electric buzzers –
A basic model of electric buzzer usually consists of simple circuit
components such as resistors, a capacitor and 555 timer IC or an
integrated circuit with a range of timer and multi-vibrator
functions. It works through small bits of electricity vibrating
together which causes sound.
(ii) Electronic buzzers –
An electronic buzzer comprises an acoustic vibrator comprised of
a circular metal plate having its entire periphery rigidly secured to
a support, and a piezoelectric element adhered to one face of the

metal plate. A driving circuit applies electric driving signals to the
vibrator to vibrationally drive it at a 1/N multiple of its natural
frequency, where N is an integer, so that the vibrator emits an
audible buzzing sound. The metal plate is preferably mounted to
undergo vibration in a natural vibration mode having only one
nodal circle. The drive circuit includes an inductor connected in a
closed loop with the vibrator, which functions as a capacitor, and
the circuit applies signals at a selectively variable frequency to
the closed loop to accordingly vary the inductance of the inductor
to thereby vary the period of oscillation of the acoustic vibrator
and the resultant frequency of the buzzing sound.
(iii) Mechanical BuzzerA joy buzzer is an example of a purely mechanical buzzer.

(iv) Piezo Buzzers/ Piezoelectric Buzzers –

A piezo buzzer is made from two conductors that are separated by
Piezo crystals. When a voltage is applied to these crystals, they
push on one conductor and pull on the other. The result of this
push and pull is a sound wave. These buzzers can be used for
many things, like signaling when a period of time is up or making
a sound when a particular button has been pushed. The process

can also be reversed to use as a guitar pickup. When a sound
wave is passed, they create an electric signal that is passed on to
an audio amplifier.
Piezo buzzers are small electronic devices that emit sounds when driven by low
voltages and currents. They are also called piezoelectric buzzers. They usually
have two electrodes and a diaphragm. The diaphragm is made from a metal plate
and piezoelectric material such as a ceramic plate.
(v) Magnetic Buzzers –

Magnetic buzzers are magnetic audible signal devices with built-in oscillating
circuits. The construction combines an oscillation circuit unit with a detection coil,
a drive coil and a magnetic transducer. Transistors, resistors, diodes and other small
devices act as circuit devices for driving sound generators. With the application of
voltage, current flows to the drive coil on primary side and to the detection coil on
the secondary side. The amplification circuit, including the transistor and the
feedback circuit, causes vibration. The oscillation current excites the coil and the
unit generates an AC magnetic field corresponding to an oscillation frequency. This
AC magnetic field magnetizes the yoke comprising the magnetic circuit. The
oscillation from the intermittent magnetization prompts the vibration diaphragm to
vibrate up and down, generating buzzer sounds through the resonator.
In this project, a magnetic buzzer has been used.
2.9.2 Circuit of buzzer –

2.9.3 Role of buzzer in this project
Buzzer in this system gives the beep when car moves inside cutting the infrared
light. Basically it generates the signal to indicate that car has entered in the parking
space.

FUTURE APPLICATIONS:
 Robots help automate thousands of factories around the
world.

 Robot makes the delivery of mail, packages and materials
fast and efficient.

 Scientists and engineers have been experimenting with snow
ploughs and even passenger cars that can follow magnetic
lines in “smart” highways. These robotic vehicles can sense
the road, obstacles and each other, eliminating traffic snarls
and making our highways safer and easier to travel.
Someday we will simply tell our cars where to take us and
line following circuitry will help get us there safely and
without effort

Conclusion

In the concluding remarks we would like to say that as our Obstacle sensing robot
successfully follow the path, still it needs some modification. Some modifications
are needed to make it smarter so that it can work more efficiently. To make it fast
and furious, more sensitive sensors are needed. Also vision-based robotic system
can be developed so that it can obtain the images of obstacles and can change path.
To make it more industry oriented fast sensors are required. Control can be
improved by using stepper motors.

BIBLIOGRAPHY


ELECTRONIC DEVICES AND CIRCUIT THEORY BY ROBERT L.
BOYLSTEAD AND LOUIS NASHELSKY



“Embedded System using 8051“ (E-book)
Lalit Kumar goel and Gaurav Sharma from Meerut



OP-AMPS AND LINEAR INTEGRATED CIRCUITS BY RAMAKANT A.
GAYAKWAD
DIGITAL DESIGN BY M.MORRIS MANO





A COURSE IN ELECTRICAL END ELECTRONIC MEASUREMENTS
AND INSTRUMENTATION BY A.K.SAWHNEY
SOME OF THE FOLLOWING WEB SITES WERE ACCESSED










www.alldatasheets.com
www.datasheetcatalog.com
www.electroniccircuitschematic.com
www.epanaroma.com
www.yahoo.com
www.google.com
www.scielectronics.com
www.parallax.com
www.parallaxinc.com

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