30304668 Pc Based Mobile Robot for Navigation

7/27/2019 30304668 Pc Based Mobile Robot for Navigation

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MINOR PROJECT REPORT

ON

PC-BASED MOBILE ROBOT FOR NAVIGATION

SUBMITTED AS A PART OF COURSE CURRICULUM FOR

DEGREE OF BACHELOR OF TECHNOLOGY

IN

ELECTRONICS & COMMUNICATION ENGINEERING

Under the guidance of: SUBMITTED BY:

M.K.Soni Ashish Goel (2206020)

(Lectt. ECE) Kanwal Singh (2206049)

Krishan Rangi(2206050)

Department of Electronics & Communication Engineering

Swami Devi Dyal Inst i tute Of Engineering & Technology

Barwala(PKL. )


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HOD : Under the guidance of :

Er.Rajnish Garg Er. M.K. Soni

HOD ECE(Deptt.) Lect. ECE(Deptt.)

ACKNOWLEDGMENT

We feel honored to have worked under the able guidance of our Lect.

Mr. M.K. Soni.

We are particularly grateful to Mr. Rajnish garg (HOD ECE) & Mr.

Amit Gupta (Sr. Lect. ECE) for there valuable advice and timely

suggestions in helping us overcome all sorts of problems.

We extend our heartiest thanks to the entire staff members who gave

suggestions during the development of the project.

Ashish Goel(2206020)

Kanwal Singh(2206049)

Krishan Rangi(2206050)


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PREFACE

Excellence is an attitude that the whole of the human race is born with.It is the environment that makes sure that whether the result of thisattitude is visible or otherwise. A well planned, properly executed &evaluated industrial training help a lot in inculcating a professionalattitude. It provides a linkage between the student and industry todevelop an awareness of industrial approach to problem solving, basedon board understanding of process & mode of operation of organization.

During this period, the student gets the real, firsthand experience forworking in the actual environment.

The quest for knowledge can never end. The deeper youdig the greater this unexplored seems to be. No man can honestly saythat he has learned this world has to offer. We cant achieve anythingworthwhile in any field only on the basis of theoretical knowledge from

books.


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ABSTRACT

It is truly said that practice makes a man perfect. But as far as

project making is concerned, it refers to combination of certain

constructive ideas building up consistent project team,

analyzing and rearranging of raw materials and resources,

finalizing the methodology and making things really work outpractically. It is definitely necessary to have strong command

over the theoretical and practical aspects of project under

consideration, as all theoretical knowledge and practical

application goes in vain if we cannt fetch desired results. Theminor project is an output of our exposure to the real and

applied world of electronics.


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The aim of this report is to briefly cover whatever has

been done during making of the minor project. The project oPc-

based mobile robot pfor navigation.

LIST OF FIGURES

S.no. FIGURE NAME PAGE no.


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1 Working prototype of the PC-Based mobile robot 2

2 Program output of mobile robot 8

3 Actual-Size, Single Side PCB for PC-Based MobileRobot For Navigation

12

4 Component Layout for the PCB 12

5 Working prototype of the PC-Based mobile robot 16

6 Power supply 16

7 Working prototype of the PC-Based mobile robot18

8 An optocoupler 20

9 Schematic diagram of opto-isolator 21

10 A simple circuit with an opto-isolator 22

11 Darlington Array 24

12 Pin Diagram of ULN 2803 25

13 Rectifier Diodes 26

14 LEDs 27

15 Carbon film resistors 28

16 Metal film resistors 29

17 Variable Resistors 30

18 Electrolytic Capacitors 32

19 Ceramic Capacitors 33


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LIST OF TABLES

20 25-pin,D-type, parallel-port male connector 35

21 Rotation of stepper motor 37

22 A picture of stepper motor 41

23 A typical low-cost webcam used with many

personal computers

44

24 A step-down transformer 46

25 Rectification of AC 47

26 26Electrolytic Capacitor 48

27 Voltage Regulator 7805 48

28 soldering iron 50

29 solder 50

S.no. TABLE NAME PAGE no.


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CONTENTS

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1 Colour codes of the Wires for 55SlM-25DAYG

Stepper Motor

6

2 Normal 4 step Sequence 7

3 Sizes of different resistors 28

4 Sizes of different resistors 29

5 Color Codes of resistor 30

6 Function of pins of 25-pin,D-type, parallel-port

male connector

35

7 Base addresses 36


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Appendix

Datasheets


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Block Diagram

motor motor

Pc with

controlling

software


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CIRCUIT DIAGRAM


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LIST OF COMPONENTS

S.no. Component Specification Quantity

Semiconductors:

1. IC1-IC8 MCT2E optocoupler 8

2. IC9 ULN2803 buffer/driver 1

3. IC10 7812 12V regulator 1

4. D1-D4 1N4001 rectifier diode 4

5. LED1 5mm light- emitting diode 1

Resistors: (all watt, 5% carbon)

6. R1 1-kilo-ohm 1

7. R2-R9 470-ohm 8

Capacitors:

8. C1 1000uF,35V electrolytic 1

9. C2 0.1uF,ceramic 1

Miscellaneous:

10. X1 230V AC primary to 15V,1A

secondary transformer

1

11. CON1 25-pin,D-type, parallel-port

male connector

1


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12. SM1,SM2 y 12V, 7.5 deg/step

stepper motor

y 8-conductor ribbon cable

(3.5 metres in length)

y Two wheels for the rightand left side of the robot

y One caster wheel for

front

y Two side brackets for

stepper motors support

y One chassis board

y One web cam or pc-

camera with USB

interface cabley nuts and bolts

y 2-pin sip connector (male

and female)

y Two 5-pin sip male

connector

y DC socket and plug

2

1

2

1

2

1

1

30

1

1

2


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INTRODUCTION

Pc - based Mobile Robot for Navigation is basically anelectric-powered, three-wheeled vehicle or robot attached with aPC camera or webcam. It can be used for navigation or as a toy.The robot can move up to a radial distance of 3.5 meters from thecomputer. For longer distance, you need a longer data cable for the

parallel port and USB hub to increase the length of the interfacecable for the camera.The purpose of this design and implementation is to motivate the

beginners. It cannot be used independently in line following,obstacle detection and pothole avoidance applications as it is notintelligent enough to take decision and control by itself. However,line following, obstacle detection and pothole detection can bedone by constantly monitoring its movement from the live scenecaptured by the PC camera. It can be controlled from the PC tomove forward, backward, right and left.The project provides an educational test bed for understanding thetransition from theory to practice, contest requirements and alsoother studies in developing advance applications, creative control,etc. The working of the circuit, control system, sensory system,software program, testing and assembly steps for the robot aredescribed in the succeeding sections. The main componentsinclude two stepper motors, a motor driver circuit, a PC with

parallel port connector and a camera (webcam).


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Circuit description

The interface-cum-driver circuit for the PC-based mobile robot isshown in Fig. 2. It works off a 12V DC Power supply.MCT2E is the most popular integrated circuit used for isolatinghigh-voltage circuits from low-voltage circuits. Used to protect the

parallel port from damage, it is an opto-coupler having an internalphototransistor and an LED. The LED glows when it receives highoutput pulse from the parallel port. The transistor conducts whenits base receives light from LED. Resistors R2 through R9 limit thein order to protect the parallel port.

IC ULN2803 is used as the driver for rotating the stepper motor. Itis basically a Darlington pair IC used for driving high-currentcircuits.The power supply circuit is shown in Fig. 3. It consists of a 230VAC to 15V AC, 1A secondary transformer, filter capacitor, bridgerectifiers and 12VDC regulator 7812 (1C10). The regulated 12VDC is connected to ULN2803 driver IC. In place of the powersupply circuit shown in Fig. 3, you can also use a 12V, 4.5Ah

battery to power the main circuit.


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Robot control operation

Two stepper Motors are used for moving and turning the robot.Stepper motors with various specification are available in themarket. Here we have used 55SIM 25DAYG unipolar steppermotors rated at 12V DC, with step angle of 7.5" per pulse. Each ofthese stepper motors has five wires for connecting to the drivercircuit. Out of the five wires, four wires emerge from coils of thestepper motors and the fifth is the centre-tapped common terminal.Correct identification and connection of these wires is importantfor successful assembly of the stepper motor.

The unipolar stepper motor has two centre-tapped coils. Theircentre-tapped terminals are joined to make one common terminal.If you have a multimeter, set it in 200-ohm range and check theresistance between these wires The resistance between thecommon terminal and the rest of the coil terminals will be around36 ohms, while the resistance between two coil terminals will bearound 72 ohms. Connect these coils to the output terminals of the

driver circuit in sequence. To help you in proper connection, thecolour codes of the wires for the 55SIM-25DAYG stepper motorare listed in Table I. Note that for the same ratings, differentmanufacturers may have their own coil specifications.

TABLE 1

Colour codes of the Wiresfor 55SlM-25DAYG

Stepper Motor

Colour IdentificationWhite CommonRed L1Blue L2Brown L3Yellow L4


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The software uses wave-drive 4- step sequence technique forrotating the motors. To run the motors, specific sequences of

pulses are given to the motor windings. Generally, there are three

types of digital signal sequence given to run the stepper motor. Buthere, we have used a 4-step sequence as shown in Table II. Theadvantage of this technique is that it consumes the least power.Only one phase is energized at a time, which assures of positionalaccuracy regardless of any winding imbalance in the motor.

TABLE 2

Normal 4 step SequenceClockwis

-eStep

#Windin-g A L1

Windin-g B L2

Windin-g C L3

Windin-g D L4

CounterClockwis

-e

1 1 0 0 0

2 0 1 0 0

3 0 0 1 04 0 0 0 1

Since the motor rotates at 7.5 deg per step, it takes a total of 48steps to complete one rotation. The higher the step angle, the fewerthe pulses needed for complete rotation of the motor. Hence if thespeed of the robot is desired, use a motor with higher step angle,and if more accurate position control is desired, you may use amotor with lower step angle.


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Direction control.:

To control the direction of motion, a combination of differentrotational directions of the two motors is used. If the left steppermotor (SM1) moves anticlockwise and the right stepper motor(SM2) moves clockwise, the robot moves in forward direction.Similarly, if SM1 moves in clockwise direction and SM2 in anti-clockwise, the robot will move in backward direction. If SM1 andSM2 move in clockwise direction, the robot will turn left. If SM1and SM2 move in anti-clockwise direction, the robot will turnright.

Speed control .:

To control the speed of the robot, timer delays are used. The valueof the delay time for the timer can be increased or decreased by theslider control provided in the software. The selected speed of therobot (1 through 999) is also displayed in the text box as shown inFig. 4.

Camera view.:

In this project, a camera is used as the visual sensor to control themovement of the robot. For live viewing of the scene through thecamera fitted on the robot, a command button is provided in thesoftware. On clicking the button, the executable file of the camerais run and the pictures can be viewed in another window. We haveused a 'Quantum Hi-Tech' camera. It has l0 level zoom for live

motion picture, special visual effects, night vision, microphone,snapshot function etc.


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Construction

Constructing this project is very simple. Just assemble the ICs andresistors on any general-purpose PCB and mount the steppermotors over any solid base with the help of suitable mechanical

parts. Put the camera on the base and fix it with the help of clam ornuts and bolts.

The actual-size, single-side PCB layout of the circuit is shown inFig. 5 and its component layout in Fig. 6.

Cut the PCB along the straight line shown in the integrated PCBlayout (Figs 5 and 6) to separate the power supply section. ThePCB layout for the power supply section is made separately sothat if you want to use a 12v battery you can remove it from theinterface-cum-driver section.


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Fig. 5. Actual-Size, Single Side PCB for PC-Based Mobile Robot For Navigation

Fig:6. Component Layout for the PCB


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Tips for assembling the robot

1.First, secure the stepper motors into the two side-brackets

2.Next, fix the wheels on the shaft of the motors. (Each of thewheel has an 8mm plastic flange with threads and a metal nutfor securing it in position).

3.Now, take the chassis or base plate. Identify its front, left, rightand rear sides. Secure the PCB and camera on the chassis plate.

4.Secure the side-brackets( left and right) on the chassis plate.

5.Insert the front castor-wheel bolt into the 10mm hole on thechassis and secure it loosely with the help of its nut. Check thechassis level. Use extra spacers over the threaded portion of

castor-wheel nut after removing the castor wheel. If the levelingappears alright, tighten the castor wheel to the chassis.

6.Now, insert the connectors of the two motors in the circuit asshown in the PCB layout diagram. Connect the 12V powersupply connector to the PCB. This completes the mechanicalassembly of your robot and external electrical connections.(Before connecting the 12V supply to the circuit, re-check the

assembly for proper and complete connections.)

7.Check directions of rotations of the two stepper motors byclicking 'Move Forward' button in the Mobile robot.exe


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program. Both the stepper motors should energies and rotate insuch direction as to move the robot forward. In case one or bothof the stepper motors rotate in reverse direction, identify theleads by referring the colour codes of the coils for the 55SIM-

25DAYG stepper motor as listed in Table I and connect themaccordingly.


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Testing procedure

1.Mount the stepper motors and camera on the base as shown inFig. 1.

2.After assembling the PCB, check the circuit connections beforeswitching on the power supply.

3.Connect the parallel-port cable (with male connector) to theparallel port female connector available on the back side of the

PC.

4. Run the software to see that the robot is running properly.


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HARDWARE DETAILS

OPTO-ISOLATOR OR OPTO-COUPLER

In electronics, an opto-isolator (oroptical isolator, optical couplingdevice, optocoupler, photocoupler, or photoMOS) is a device thatuses a short optical transmission path to transfer an electronic signal

between elements of a circuit, typically a transmitter and a receiver,while keeping them electrically isolatedsince the electrical signal isconverted to a light beam, transferred, then converted back to anelectrical signal, there is no need for electrical connection between thesource and destination circuits. Isolation between input and output israted at 7500 Volt peak for1 second for a typical component costing lessthan 1 US$ in small quantities.

The opto-isolator is simply a package that contains both an infraredlight-emitting diode (LED) and a photodetector such as a photosensitivesilicon diode, transistor Darlington pair, or silicon controlled rectifier(SCR). The wave-length responses of the two devices are tailored to be

as identical as possible to permit the highest measure of couplingpossible. Other circuitryfor example an output amplifiermay beintegrated into the package. An opto-isolator is usually thought of as asingle integrated package, but opto-isolation can also be achieved byusing separate devices.


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Digital opto-isolators change the state of their output when the inputstate changes; analog isolators produce an analog signal whichreproduces the input.

Schematic diagram of a very simple opto-isolator with an LED andphototransistor. The dashed line represents the isolation barrier, overwhich there is no electrical contact.

A common implementation is a LED and a phototransistor in a light-tight housing to exclude ambient light and without common electricalconnection, positioned so that light from the LED will impinge on the

photodetector. When an electrical signal is applied to the input of theopto-isolator, its LED lights and illuminates the photodetector,

producing a corresponding electrical signal in the output circuit. Unlike atransformerthe opto-isolator allows DC coupling and can provide anydesired degree of electrical isolation and protection from seriousovervoltage conditions in one circuit affecting the other. A highertransmission ratio can be obtained by using a Darlington instead of asimple phototransistor, at the cost of reduced noise immunity and higherdelay.

With a photodiode as the detector, the output current is proportional tothe intensity of incident light supplied by the emitter. The diode can beused in aphotovoltaic mode or aphotoconductive mode. In photovoltaicmode, the diode acts as a current source in parallel with a forward-biaseddiode. The output current and voltage are dependent on the loadimpedance and light intensity. In photoconductive mode, the diode is


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connected to a supply voltage, and the magnitude of the currentconducted is directly proportional to the intensity of light. Thisoptocoupler type is significantly faster than photo transistor type, but thetransmission ratio is very low; it is common to integrate an output

amplifier circuit into the same package.

The optical path may be air or a dielectricwaveguide. When high noiseimmunity is required an optical conductive shield can be integrated intothe optical path. The transmitting and receiving elements of an opticalisolator may be contained within a single compact module, formounting, for example, on a circuit board; in this case, the module isoften called an optoisolator oropto-isolator. The photosensor may be a

photocell,phototransistor, or an optically triggered SCRorTRIAC. Thisdevice may in turn operate a powerrelay orcontactor.

Analog optoisolators often have two independent, closely matchedoutput phototransistors, one of which is used to linearize the responseusing negative feedback.

A simple circuit with an opto-isolator. When switch S1 is closed, LED

D1 lights, which triggersphototransistorQ1, which pulls the output pinlow. This circuit, thus, acts as aNOT gate.

APPLICATIONS

Among other applications, opto-isolators can help cut down on groundloops, blockvoltage spikes, and provide electrical isolation.


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y switched-mode power supplies use optocouplers for mainsisolation. As they work in an environment with much electricalnoise and with signals which are not small, optocouplers with lowtransmission ratio are preferred.

y Where electrical safety is paramount, optocouplers can totallyisolate circuitry which may be touched by humans from mainselectricity.

o Medical equipment often uses optocouplers.o One of the requirements of the MIDI (Musical Instrument

Digital Interface) standard is that input connections be opto-isolated.

y Optocouplers are used to isolate low-current control or signal

circuitry from transients generated or transmitted by power supplyand high-current control circuits. The latter are used within motorand machine control function blocks.


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DARLINGTON ARRAY (ULN 2803)

INTRODUCTION

A ULN2803 is an Integrated Circuit (IC) chip with a High Voltage/High

Current Darlington Transistor Array. It allows you to interface TTLsignals with higher voltage/current loads. In English, the chip takes low

level signals (TLL, CMOS, PMOS, NMOS - which operate at low

voltages and low currents) and acts as a relay of sorts itself, switching on

or off a higher level signal on the opposite side.

Its features are:

A TTL signal operates from 0-5V, with everything between 0.0and 0.8V considered "low" or off, and 2.2 to 5.0V being

considered "high" or on. The maximum power available on a TTL

signal depends on the type, but generally does not exceed 25mW

(~5mA @ 5V), so it is not useful for providing power to something

like a relay coil. On the output side the ULN2803 is generally rated

at 50V/500mA, so it can operate small loads directly.

Alternatively, it is frequently used to power the coil of one or morerelays, which in turn allow even higher voltages/currents to be

controlled by the low level signal. In electrical terms, the

ULN2803 uses the low level (TTL) signal to switch on/turn off the

higher voltage/current signal on the output side.


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Its features are summarized below:

Output current (single output) 500mA MAX.

High sustaining voltage output 50V MIN.

Output clamp diodes.Inputs compatible with various types of logic

PIN DIAGRAM

The ULN28

03 comes in an18

-pin IC configuration and includes eight(8) transistors.

y Pins 1-8 receive the low level signals,

y pin 9 is grounded (for the low level signal reference).

y Pin 10 is the common on the high side and would generally be

connected to the positive of the voltage you are applying to the

relay coil.

y Pins 11-18 are the outputs (Pin 1 drives Pin 18, Pin 2 drives 17,

etc.).


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DIODES

A diode is a semiconductor device which allows currentto flow through it in only one direction. A diode is

specifically made to allow current to flow through it in

only one direction.

Some ways in which the diode can be used are listed here.

A diode can be used as a rectifier that converts AC to DC for a power

supply device.

Diodes can be used to separate the signal from radio frequencies.Diodes can be used as an on/off switch that controls current.

This symbol is used to indicate a diode in a circuit diagram

Rectification / Switching / Regulation DiodeThe stripe stamped on one end of the diode

shows indicates the polarity of the diode.

The stripe shows the cathode side.

The devices shown in the picture are diodesused for rectification. They are made to handle

relatively high currents. The device on top can

handle as high as 6A, and the one below it can

safely handle up to 1A.

However, it is best used at about 70% of its

rating because this current value is a maximum rating. This diode is

typically used to protect the circuit from momentary voltage spikes.

Light Emitting Diode ( LED )

Light emitting diodes must be chosen according to how they willbe used, because there are various kinds.


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The diodes are available in severalcolors. The most common colors are redand green, but there are even blue ones.The device on the far right in the

photograph combines a red LED andgreen LED in one package. The

component lead in the middle is common to both LEDs. As for theremaing two leads, one side is for the green, the other for the redLED. When both are turned on simultaneously, it becomes orange.


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RESISTORS

The resistor's function is to reduce the flow of electric current. Thissymbol is used to indicate a resistor in a circuit diagram, known as

a schematic. Resistance value is designated in units called the "Ohm."

There are two classes of resistors; fixed resistors and the variable

resistors. They are also classified according to the material from which

they are made.

Fixed Resistors

A fixed resistor is one in which the value of its resistance cannot change.

Carbon film resistorsThis is the most general purpose, cheap resistor. Usually the tolerance of

the resistance value is 5%. Power ratings of1/8W, 1/4W and 1/2W are

frequently used. Carbon film resistors have a disadvantage; they tend to

be electrically noisy. The physical size of different resistors are as

follows.

From the top of the photograph

1/8W

1/4W

1/2W

Rough size

Rating power

(W)

Thickness

(mm)

Length

(mm)

1/8 2 3

1/4 2 6

1/2 3 9


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Metal film resistorsMetal film resistors are used when a higher tolerance (more accurate

value) is needed. They are much more accurate in value than carbon

film resistors. They have about 0.05% tolerance. They have about

0.05% tolerance. Ni-Cr (Nichrome) seems to be used for the

material of resistor. The metal film resistor is used for bridge circuits,

filter circuits, and low-noise analog signal circuits.

From the top of the photograph

1/8W (tolerance

1%)

1/4W (tolerance

1%)

1W (tolerance

5%)

2W (tolerance

5%)

Variable resistorsThere are two general ways in which variable resistors are used.

1.One is the variable resistor which value is easily changed, like the

volume adjustment of Radio.

2.The other is semi-fixed resistor that is not meant to beadjusted by

anyone but a technician. Semi-fixed resistors are used to

compensate for the inaccuracies of the resistors, and to fine-tune a

circuitThe rotation angle of the variable resistor is usually about 300 degrees.

Some variable resistors must be turned many times to use the whole

range of resistance they offer.These are called "Potentiometers" or

"Trimmer Potentiometers."

Rough size

Rating power

(W)

Thickness

(mm)

Length

(mm)

1/8 2 3

1/4 2 6

1 3.5 12

2 5 15


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In the photograph , the four

resistors at the center of the

photograph are the semi-fixed type.

The two resistors on the left are thetrimmer potentiometers.This

symbol is used to represent

variable resistor in circuit diagram

Resistor colour code

Example 1

(Brown=1),(Black=0),(Orange=3)

10 x 103 = 10k ohm

Tolerance(Gold) = 5%

Example 2

(Yellow=4),(Violet=7),(Black=0),(Red=2

)

470 x 102 = 47k ohm

Tolerance(Brown) = 1%

Colour Value Multiplier Tolerance

Black 0 0 -

Brown 1 1 1

Red 2 2 2

Orange 3 3 0.05

Yellow 4 4 -

Green 5 5 0.5

Blue 6 6 0.25

Violet 7 7 0.1

Gray 8 8 -

White 9 9 -

Gold - -1 5

Silver - -2 10

None - - 20


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CAPACITORS

The capacitor's function is to store electricity, or electrical energy. Thecapacitor also functions as a filter, passing alternating current (AC), and

blocking direct current (DC).

This symbol is used to indicate a capacitor in a circuit diagram.

The capacitor is constructed with two electrode plates facing eachother,

but separated by an insulator. When DC voltage is applied to the

capacitor, an electric charge is stored on each electrode. While the

capacitor is charging up, current flows. The current will stop flowingwhen the capacitor has fully charged.

The value of a capacitor (the capacitance), is designated in units called

the Farad ( F ). The capacitance of a capacitor is generally very small, so

units such as the microfarad ( 10-6F ), nanofarad ( 10-9F ), and picofarad

(10-12F ) are used.

Sometimes, a three-digit code is used to indicate the value of a capacitor.

For example, when the code is [103], it indicates 10 x 103, or10,000pF

= 10 nanofarad( nF ) = 0.01 microfarad( F ).

BREAKDOWN VOLTAGE

When using a capacitor, you must pay attention to the maximum voltage

which can be used. This is the "breakdown voltage." The breakdownvoltage is the voltage that when exceeded will cause the dielectric

(insulator) inside the capacitor to break down and conduct. When this

happens, the failure can be catastrophic.


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The types of capacitors used in our project are:

Electrolytic Capacitors (Electrochemical type capacitors)

Aluminum is used for the electrodes by using a thin oxidizationmembrane.

Large values of capacitance can be obtained in comparison withthe size of the capacitor, because the dielectric used is very thin.

The most important characteristic of electrolytic capacitors is thatthey have polarity. They have a positive and a negativeelectrode.[Polarised]

If the capacitor is subjected to voltage exceeding its workingvoltage, or if it is connected with incorrect polarity, it may burst.

Generally, in the circuit diagram, the positive

side is indicated by a "+" (plus) symbol.

Electrolytic capacitors range in value from

about 1F to thousands of F. Mainly this

type of capacitor is used as a ripple filter in a

power supply circuit, or as a filter to bypass

low frequency signals, etc.

From the left to right:

1F (50V) [diameter 5 mm, high 12 mm]





Ceramic Capacitors

Ceramic capacitors are constructed with materials such as titanium

acid barium used as the dielectric. Internally, these capacitors are not

constructed as a coil, so they can be used in high frequency


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applications. Typically, they are used in circuits which bypass high

frequency signals to ground.

These capacitors have the shape of a disk. Their capacitance is

comparatively small.

The capacitor on the left is a 100pF capacitor with a

diameter of about 3 mm.

The capacitoronthe rightside is printed with 103, so

10 x 103pFbecomes 0.01 F. The diameter of the disk

is about 6 mm.

Ceramic capacitors have no polarity. Ceramic capacitors should not be

used for analog circuits, because they can distort the signal.


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25-pin,D-type, parallel-port male connector

The parallel port is a 25 pin connector on your computer that iscommonly known as the printer port, LPT1 or LPT2. This port is nice

because it is relatively easy to manipulate it with software and the data

is transmitted using standard TTL 0 5V signals. Another pro to using

this port is there is no need for additional hardware to put the signal

back together so that it can be loaded into the microcontroller.

To utilize the parallel interface we would need 8 pins for the data

transmission, 1 pin is an IRQ which signals that the data is ready and

clocks it through, 1 pin to signal whether the data transmission was an

address or actual data because we are employing multiple

microcontrollers, and 1 pin to send a signal back to the PC telling it that

the current task has been accomplished and it is ready for the next

instruction.

Now just to transmit data we need 11 pins and 2 pins are power and

ground, so that only leaves 3 pins on port A to control our motor, which

is enough for now, but cuts down on capability for future expansion.

This is a pin out diagram of the 25-pin,D-type, parallel-port maleconnector.


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The following table lists the function of each pin in the 25-pin,D-type,

parallel-port male connector as they pertain to a printer connection.

The most useful part is the direction of signal flow for our application,

as well as knowing whether the bit is inverted or not.


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This next table lists the base addresses for the status, control and data

registers of LPT1 and LPT2.


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Stepper motor

A stepper motor (orstep motor) is a brushless, synchronous electric motor thatcan divide a full rotation into a large number of steps. The motor's position can becontrolled precisely, without any feedback mechanism. Stepper motors are similarto switched reluctance motors (which are very large stepping motors with areduced pole count, and generally are closed-loop commutated.)

Fundamentals of Operation

Stepper motors operate differently from DC brush motors, which rotatewhen voltage is appliedto their terminals. Stepper motors, on theotherhand, effectively have multiple "toothed" electromagnets arrangedaround a central gear-shaped piece of iron. The electromagnets are

energized by an external control circuit, such as a microcontroller.

To make the motor shaft turn, first one electromagnet is given power,which makes the gear's teeth magnetically attracted to theelectromagnet's teeth. When the gear's teeth are thus aligned to the firstelectromagnet, they are slightly offset from the next electromagnet. Sowhen the next electromagnet is turned on and the first is turned off, the

gear rotates slightly to align with the next one, and from there theprocess is repeated. Each of those slight rotations is called a "step," withan integer number of steps making a full rotation. In that way, the motorcan be turned by precise angle.


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Stepper motor characteristics

1. Stepper motors are constant power devices.

2. As motor speed increases, torque decreases.

3. The torque curve may be extended by using current limiting driversand increasing the driving voltage.

4. Steppers exhibit more vibration than other motor types, as the discretestep tends to snap the rotor from one position to another.

5. This vibration can become very bad at some speeds and can cause themotor to lose torque.

6. The effect can be mitigated by accelerating quickly through theproblem speeds range, physically damping the system, or using a micro-stepping driver.

7. Motors with a greater number of phases also exhibit smootheroperation than those with fewer phases.

Types

There are three main types of stepper motor.

1.Permanent Magnet Stepper2.Hybrid Synchronous Stepper


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3.Variable Reluctance Stepper

Permanent magnet motors use a permanent magnet (PM) in the rotor andoperate on the attraction or repulsion between the rotor PM and the

stator electromagnets. Variable reluctance (VR) motors have a plain ironrotor and operate based on the principle of that minimum reluctanceoccurs with minimum gap, hence the rotor points are attracted towardthe stator magnet poles. Hybrid stepper motors are named because theyuse use a combination of PM and VR techniques to achieve maximum

power in a small package size.

Two-phase stepper motors

There are two basic winding arrangements for the electromagnetic coilsin a two phase stepper motor: bipolar and unipolar.

Unipolar motors

A unipolar stepper motor has two windings per phase, one for eachdirection of magnetic field. Since in this arrangement a magnetic polecan be reversed without switching the direction of current, thecommutation circuit can be made very simple (eg. a single transistor) foreach winding. Typically, given a phase, one end of each winding ismade common: giving three leads per phase and six leads for a typicaltwo phase motor. Often, these two phase commons are internally joined,so the motor has only five leads.

A microcontrolleror stepper motor controller can be used to activate thedrive transistors in the right order, and this ease of operation makesunipolar motors popular with hobbyists; they are probably the cheapest

way to get precise angular movements.


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Unipolar stepper motor coils

A quick way to determine if the stepper motor is working is to shortcircuit every two pairs and try turning the shaft, whenever a higher thannormal resistance is felt, it indicates that the circuit to the particularwinding is closed and that the phase is working.

Bipolar motor

Bipolar motors have a single winding per phase. The current in awinding needs to be reversed in order to reverse a magnetic pole, so the

driving circuit must be more complicated, typically with an H-bridgearrangement. There are two leads per phase, none are common.

Static friction effects using an H-bridge have been observed with certaindrive topologies.

Because windings are better utilised, they are more powerful than aunipolar motor of the same weight

Stepper motor

A step motor can be viewed as a synchronous AC motor with thenumber of poles (on both rotor and stator) increased, taking care thatthey have no common denominator. Additionally, soft magnetic materialwith many teeth on the rotor and stator cheaply multiplies the number of

poles (reluctance motor). Modern steppers are of hybrid design, havingboth permanent magnets and soft iron cores

.


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To achieve full rated torque, the coils in a stepper motor must reach theirfull rated current during each step. Winding inductance and reverse EMFgenerated by a moving rotor tend to resist changes in drive current, sothat as the motor speeds up, less and less time is spent at full current --

thus reducing motor torque. As speeds further increase, the current willnot reach the rated value, and eventually the motor will cease to producetorque.

Pull-in torque

This is the measure of the torque produced by a stepper motor when it isoperated without an acceleration state. At low speeds the stepper motorcan synchronise itself with an applied step frequency, and this Pull-Intorque must overcome friction and inertia.

Pull-out torque

The stepper motor pull-out torque is measured by accelerating the motorto the desired speed and then increasing the torque loading until themotor stalls or "pulls out of synchronism" with the step frequency. Thismeasurement is taken across a wide range of speeds and the results are

used to generate the stepper motor's dynamic performance curve. Asnoted below this curve is affected by drive voltage, drive current andcurrent switching techniques. It is normally recommended to use a safetyfactor of between 50% and 100% when comparing your desired torqueoutput to the published "pull-Out" torque performance curve of a stepmotor.

Detent torque

Synchronous electric motors using permanent magnets have a remnantposition holding torque (called detent torque, and sometimes included inthe specifications) when not driven electrically. Soft iron reluctancecores do not exhibit this behavior.


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Stepper motor ratings and specifications

Stepper motors nameplates typically give only the winding current andoccasionally the voltage and winding resistance. The rated voltage will

produce the rated winding current at DC: but this is mostly ameaningless rating, as all modern drivers are current limiting and thedrive voltages greatly exceed the motor rated voltage.

A stepper's low speed torque will vary directly with current. Howquickly the torque falls off at faster speeds depends on the windinginductance and the drive circuitry it is attached to, especially the drivingvoltage.

Steppers should be sized according to published torque curve, which isspecified by the manufacturer at particular drive voltages and/or usingtheir own drive circuitry. It is not guaranteed that you will achieve thesame performance given different drive circuitry, so the pair should bechosen with great care.

Applications

Computer-controlled stepper motors are one of the most versatile forms

ofpositioning systems. They are typically digitally controlled as part ofan open loop system, and are simpler and more rugged than closed loopservo systems.

Industrial applications are in high speed pick and place equipment andmulti-axis machine CNC machines often directly driving lead screws or

ballscrews. In the field of lasers and optics they are frequently used inprecision positioning equipment such as linear actuators, linear stages,

rotation stages, goniometers, and mirror mounts. Other uses are inpackaging machinery, and positioning of valve pilot stages for fluidcontrol systems.


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Commercially, stepper motors are used in floppy disk drives, flatbedscanners, computer printers, plotters, slot machines, and many moredevices.


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Webcam

A typical low-cost webcam used with many personal computers

A webcam is a video capture device connected to a computer or

computer network, often using a USB port or, if connected to a network,ethernet orWi-Fi.

Their most popular use is for video telephony, permitting a computertoact as a videophone orvideo conferencing station. This can be used inmessenger programs such as Windows Live Messenger, Skype andYahoo messenger services. Other popular uses, which include therecording of video files or even still-images, are accessible via numeroussoftware programs, applications and devices.

They are well known for their low manufacturing costs and flexibility.Some, for example those used as online traffic cameras, are expensive,rugged professional-grade hardware.

With video interpreting, sign language interpreters work remotely withlive video and audio feeds, typically at a relay call centre, so that theinterpreter can see the deaf or mute party, and converse with the hearing

party at the same time, and vice versa. Much like telephone interpreting,video interpreting can be used for situations in which no on-siteinterpreters are available. However, video interpreting cannot be usedfor situations in which all parties are speaking via telephone alone.

Webcams are also employed for security purposes. Software is availableto allow PC-connected cameras to watch for movement and sound,


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recording both when they are detected; these recordings can then besaved to the computer, e-mailed or uploaded to the Internet. In one well-

publicized case. a computer e-mailed out images as the burglar stole it,allowing the owner to give police a clear picture of the burglar's face

even after the computer had been stolen.

Webcams typically include a lens , an image sensor, and supportingcircuitry.

Webcams typically include a lens, an image sensor, and some supportelectronics. Various lenses are available, the most common being a

plastic lens that can be screwed in and out to set the camera's focus.

Fixed focus lenses, which have no provision for adjustment, are alsoavailable. As a camera system's depth of field is greater for small imagerformats and is greater for lenses with a large f/number (small aperture),the systems used in webcams have sufficiently large depth of field thatthe use of a fixed focus lens does not impact image sharpness much.Image sensors can be CMOS or CCD, the former being dominant forlow-cost cameras, but CCD cameras do not necessarily outperformCMOS-based cameras in the low cost price range. Most consumer

webcams are capable of providing VGA-resolution video at a frame rateof 30 frames per second. Many newer devices can produce video inmulti-megapixel resolutions, and a few can run at high frame rates suchas the PlayStation Eye, which can produce 320240 video at 120 frames

per second.


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POWER SUPPLY

The term power supply is more commonly abbreviated to PSU

To provide a useable low voltage the PSU needs to do a number ofthings:-

y Reduce the Mains AC (Alternating current) voltage to a lowerlevel.

y Convert this lower voltage from AC to DC (Direct current)y Regulate the DC output to compensate for varying load (current

demand)y Provide protection against excessive input/output voltages

Reduction of AC Mains

This is achieved by using a device known as a Transformer, anelectromagnetic device consisting of an ferrous iron core which has alarge number of turns of wire wound around it, known as the PrimaryWinding. The ends of these turns of wire being connected to the input

voltage (in this case Mains AC).

A second number of turns of

wire are wound around the Primary Winding, this set being known asthe Secondary Winding.

The difference between the number of turns provides us with a way ofreducing (in our case) a high AC voltage to a lower one.


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Conversion of AC to DC

To convert our now low AC voltage to DC we use a Rectifier Diodeconnected to the Secondary Winding.

This is a silicon diode, only allows current to flow in one direction)

As our low AC voltage will be working at a frequency of 50Hz (MainsAC frequency) it is desirable to reduce the inherent hum on this to alower level.

This is achieved by a technique known as Smoothing (Ironing out thebumps in the AC).

A simple way to reduce the hum is to use Full Wave Rectification.

Regulation of Output Voltage

In a simple PSU the easiest way to provide regulation to compensate forvarying load conditions is to use a pair of relatively high value

Electrolytic Capacitors.

Their values in this case being in the region of 470uF to 2000uF .


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One of these capacitors is connected across the DC output of the rectifierdiode(s) or bridge, this capacitor also providing an extra degree ofsmoothing the output waveform.

The second capacitor is connected via a low value, medium to highwattage resistor, which assists in limiting the current demand.

Voltage Regulator

Regulator, usually having three legs, converts varying input voltage andproduces a constant regulated output voltage. They are available in avariety of outputs.

The most common part numbers start with the numbers 78 or 79 andfinish with two digits indicating the output voltage. The number 78represents positive voltage. The 78XX series of voltage regulators aredesigned for positive input.The LM78XX series typically has the ability to drive current up to 1A.The component has three legs: Input leg which can hold up to 36VDCCommon leg (GND) and an output leg with the regulator's voltage. Formaximum voltage regulation, adding a capacitor in parallel between thecommon leg and the output is usually recommended.


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PCB ETCHING

Etching is the process where the excess copper is removed to leave theindividual tracks or traces as they are sometimes called.

Many different chemical solutions can be used to etch circuit boards.Ranging from slow controlled speed etches used for surface preparationto the faster etches used for etching the tracks. Copper etching isnormally exothermic. Almost all etching solutions liberate toxiccorrosive fumes, extraction is highly recommended. All etchants arecorrosive and toxic, mainly due to the high metal content.

Ferric Chloride

It is an old favorite chemical very good at staining fingers, clothing, etcbrown. Etch rate can be very high but is dependant on solutionmovement over the surface of the board and temperature. At 70C usingSpray etching, 1oz copper is removed in a little under a minute, normaletching temperature is more likely to be 45C.

When up to 5% of HCL is added, it increases etch rate, helps to stopstaining, and reduces the risk of the solution sludging. Ferric especiallywith extra HCL makes a very good stainless steel etchant.

The basic etching reaction takes place in 3 stages. First the ferric ionoxidizes copper to cuprous chloride, which is then further oxidized tocupric chloride.

1.FeCl3 + Cu > FeCl2 + CuCl2. FeCl3 + CuCl > FeCl2 + CuCl2

As the cupric chloride builds up at further reaction takes place,

3.CuCl2 + Cu > 2CuCl


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The etch rate quickly falls off after about 17oz/gallon (100g/l of copperhas been etched for a typical solution containing 5.3lb/gallon (530g/l) offerric chloride.


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SOLDERING

Soldering is a process in which two or more metal items are joinedtogether by melting and flowing a filler metal into the joint, the filler

metal having a relatively low melting point. Soft soldering ischaracterized by the melting point of the filler metal, which is below400 C (800 F). The filler metal used in the process is called solder.

In a soldering process, heat is applied to the parts to be joined, causingthe solder to melt and be drawn into the joint by capillary action and to

bond to the materials to be joined by wetting action. After the metalcools, the resulting joints are not as strong as the base metal, but have

adequate strength, electrical conductivity, and water-tightness for manyuses. Soldering is an ancient technique mentioned in the Bible and thereis evidence that it was employed up to 5000 years ago in Mesopotamia.

The only tools that are essential to solder are a soldering iron and somesolder. There are, however, lots of soldering accessories available

soldering iron solder


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The software

The software program for the user interface to control the robot(Mobile robot.exe) is designed in Visual Basic 5.0. The core fileused by software is 'inpout32.dll,' which can be downloaded from'www.logix4u.net' for free. The .dll file uses a kernel-mode driver.Therefore this software works as good with NT-based WindowsOS as with Win XP and Win 2000. A separate program module forthe inpout32.dll is used along with the main program of the mobilerobot For details about the .dll file, visit 'www.logix4u net'.The software uses timer controls to produce delay in between the

counting sequence that controls the speed of the stepper motors.The value of timer delay can be increased or decreased with thehelp of timers defined in the source code. Data port (D0 throughD7) of parallel port LPT1 with base address of 0x0378 is used toconnect the PC to the motors. The base address is defined in thesource Program.Install the webcam/camera driver software in your system and

ensure that the camera executable file is located under 'C' drive.

Here, for Quantum Hi-Tech camera, the executable file is'amcap.exe.'Run the Mobile robot.exe program. On clicking the 'View Picture'

button the program will get connected to *re executable file of thewebcam and run automatically. If you have any other webcam,change the path and filename in the source code and make theexecutable file of the same for running the application. Currentdate and time and present status of the buttons pressed (moveforward and backward and turn right and left) are also displayed onthe screen at software runtime.


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The relevant program for the Pc-BASED MOBILE ROBOTFOR NAVIGATION is shown below:

Private Sub Commandl _Click ( )

Unload Me

End sub

Private Sub Command2 _C1ick ( )

Label4.caption = Turn Left

Timerl . Interval = sliderl . Value

Timerl.Enabled = True

Timer2.Enabled = False



End sub

Private Sub Command3 _Click ( )

Label4.caption = Move Forward

Timer2.Interval = slider1. Value

Timerl.Enabled = False

Timer2.Enabled = True


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Timer3.Enab1ed = False


End sub

Private Sub Command4_ Click ( )

Label4.caption = Move Backward

Timer3 . Interval = slider1. Value

Timer1.Enabled= False



Timer4.Enabled = FaIse

End sub


Label4.caption = Turn Right

Timer4 . Interval = slider1. Value


Timer2.Enabled = Fa1se




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End sub


Label4.caption = Robot is Stopped





End sub


Dim aks as Integer

aks = S h e l l ( "C:\WINDOW \Amcap.exe, vbMaximizedFocus )

End sub


frmAbout . Show

End Sub

Private Sub Sliderl_ Click ( )

Timerl. Interval = Sliderl . Value

Timer2. Interval = Sliderl . Value


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Text1.Text = 1000 - Sliderl . value

End Sub

Private Sub Sliderl _scroll ( )

Timerl. Interval = Sliderl . Value




End Sub

Private sub Timerl _Timer ( )

Static a As integer

b = 2 ^ a

Out &H378, 17 * b

a = a + 1

If a > 3 Then

a = 0

End if


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End Sub

Private sub Timer2 _Timer ( )

Static a As integer

b = 2 ^ a

If b = 1 Then

Out &H378 , 24

ElseIf b = 2 Then

Out &H378 , 36

ElseIf b = 4 Then

Out &H378 , 66

ElseIf b = 8 Then

Out &H378 , 129

End If

a = a + 1

If a > 3 Then

a = 0

End if

End Sub


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Static a As integer

b = 2 ^ a

If b = 8 Then

Out &H378 , 24

ElseIf b = 4 Then

Out &H378 , 36

ElseIf b = 2 Then

Out &H378 , 66

ElseIf b = 1 Then

Out &H378 , 129

End If

a = a + 1

If a > 3 Then

a = 0

End if

End Sub



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Static a As integer

b = 2 ^ ( 3-a )

Out &H378, 17 * b

a = a + 1

If a > 3 Then

a = 0

End if

End Sub


Label9.caption = Times

Label13.caption = Dates

End sub


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PROBLEMS FACED

. Non availability of IC data sheets

. Burning of components

. Burning of PCB tracks

. Voltage fluctuations

. Fault in PCB layouts

. Non availability of capacitors & Resistors of exact values

. Improper functioning of web camera.


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REFRENCES

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Documents

30304668 Pc Based Mobile Robot for Navigation