Line Follower Robot45

8/4/2019 Line Follower Robot45

1/37

Mini project 2011 Line follower robot

ACKNOWLEDGEMENT

All glory and honour to god all mighty who showered his grace on us

to make this endeavor a success.

We take this oppurtunity to express our heart felt gratitude and thanks

to our principal Prof.P.V.SUGATHAN for Providing the facilities for our studies and

constant encouragement in all achievement.

We would like to express profound gratitude to our Head of the

department, Mr. RAMACHANDRAN.C, for his encouragement and for providing all

facilities fo r carrying out this project.

We also extend our heart felt gratitude towards our mini project co-

ordinator Mr.Lalji cyriac and Mr.Anoop. for their valuable guidance and help towards

the completion of the projec t and providing us with the required facilities for

completing this project .

We express our sincere thanks to all staff members of department of

electronics and communication engineering who helped us with their support. Last but

not least we would like to thank our parents and friends and friends for their support

and encouragement throughout the project.

1Dept. Of Electronics and communication Engg. College of engineering Thalassery


2/37


ABSTRACT

Line following robot is a robo car that can follow a path. The path can be visible like

a white line on the black surface (or vice-verse). As a result of this line following property it

has many applications in future and now itself.

Line following robot with pick and placement capabilities are commonly used in

manufacturing plants. These move on a specified path to pick the component from specified

location and place them on desired locations.

Basically,a line-following robot is self operating robot that detects and follows a linedrawn on the floor. The path to be taken is indicated by a white line on a black surface. The

control system used must sense the line and manoeuvre the robot to stay on course while

constantly correcting the wrong moves using feedback mechanism,thus forming a simple yet

effective closed-loop system.As a programmer you get an opportunity to teach the robot

how to follow the line thus giving it a human-like property of responding to stimuli.

The robot has two sensors installed underneath the front part of the body, and two DC

motors drive wheels moving forward.A circuit inside takes an input signal from two sensorsand controls the speed of wheels rotation. The control is done in such a way that when a

sensor senses a white line, the motor slows down or even stops. Then the difference of

rotation speed makes it possible to make turns.



3/37


CONTENTS

1.INTRODUCTION................................................................................04

2.BLOCK DIAGRAM............................................................................05

3.BLOCK DIAGRAM EXPLANATION..............................................06

4.CIRCUIT DIAGRAM..........................................................................07

5.COMPONENT STUDY.......................................................................08

6.CIRCUIT DESCRIPTION...................................................................15

7.WORKING...........................................................................................17

8.SOFTWARE SECTION.......................................................................19

9.HARDWARE SECTION.....................................................................22

10.CONSTRUCTION.............................................................................26

11.PCB LAYOUT...................................................................................27

12.COMPONENT LAYOUT..................................................................28

13.LIST OF TOOLS & EQUIPMENTS REQUIRED............................29

14.COMPENENTS REQUIRED.............................................................30

15.PRECAUTIONS..................................................................................32

16.APPLICATIONS.................................................................................33

17.LIMITATIONS....................................................................................34

18.CONCLUSION....................................................................................35

19.REFERENCE........................................................................................36

20.APPENDIX...37



4/37


1.INTRODUCTIONThe line following robot, operates as the name specifies. It is programmed to follow a

white line on a dark background and detect turns or deviations and modify the motors

appropriately.

It consist of sensors,comparators,microcontroller and motor drivers.We uses

darlington phototransistor as the sensor. The core of the robot is the AT89C51

microcontroller.Here it act as a decision making device.

It consist of two dc motors and driver ic to steer it. The differential steering system is

used to turn the robot. In this system, each back wheel has a dedicated motor while the front

wheels are free to rotate. To move in a straight line, both the motors are to be rotate at same

speed.To manage a turn a motor is to stop at correct circumstances according to sensor

output.



5/37


2.BLOCK DIAGRAM



6/37


3.BLOCK DIAGRAM EXPLANATION

Fig.1 show the block diagram of automated line following robot. It consist of mainly

four parts: two sensors,two comparators,one decision making device and two motor drivers.

The robot is built using micro controller AT89C51,motor driver L293D,operational amplifier

LM324,phototransistor and a few discrete components.In the circuit, the sensor are used to

detect the white strip on a black background. The sensor output is fed to the microcontroller,

which takes the decision and gives appropriate command to motor driver L293D so as to

move the motor accordingly

3.1 sensor: The sensor senses the light reflected from the surface and feeds the

output to the comparator. When the sensor is above the white background the light falling on

it from the source reflects to the sensor, and when the sensor is above the black background

the light from the source doesnt reflect to it. The sensor senses the reflected light to give an

output, which is fed to the comparator.

3.2 comparator: The comparator compares the analogue inputs from sensors

with a fixed reference voltage. If this voltage is greater than thereference voltage the

comparator outputs a low voltage, and if it smaller the comparator generates a high voltage

that acts as input for decision-making device(microcontroller).

3.3 microcontroller: The micro controller is programmed to make the robot move

forward,turn right or left based on the input coming from the comparator. The outputs of the

microcontroller are fed to the motor driver.

3.4 motor driver: The current supplied by the microcontroller to drive the motor

is small. Therefore a motor driver ic is used. It provides sufficent current to drive the motor.



7/37


4.CIRCUIT DIAGRAM



8/37


5.COMPONENT STUDY

5.1 Operational amplifier

An op amp is a high-gain, direct-coupled differential linear amplifier whose response

characteristics are externally controlled by negative feedback from the output to the input.

OP amps, widely used in computers, can perform mathematical operations such as summing,

integration, and differentiation. OP amps are also used as video and audio amplifiers,

oscillators, etc. in the communication electronics. Because of their versatility op amps are

widely used in all branches of electronics both in digital and linear circuits. OP amps lend

themselves readily to IC manufacturing techniques. Improved IC manufacturing techniques,

the op amp's adaptability, and extensive use in the design of new equipment have brought the

price of IC ops amps from very high to very reasonable levels. These facts ensure a very

substantial role for the IC op amp in electronics

Fig shows the symbol for an op amp. Note that the operational amplifier has two inputs

marked (-) and (+). The minus input is the inverting input. A signal applied to the minus

terminal will be shifted in phase 180 at the output. The plus input is the non-inverting input.

A signal applied to the plus terminal will appear in the same phase at the output as at the

input. Because of the complexity of the internal circuitry of an op amp, the op amp symbol is

used exclusively in circuit diagrams.



9/37


IC LM324

LM 324 is a low power quad operational amplifier which we uses in our project ascomparator. The LM124 series consists of four independent, high gain, internally frequency

compensated operational amplifiers which were designed specifically to operate from a

single power supply over a wide range of voltages. Operation from split power supplies is

also possible and the low power supply current drain is independent of the magnitude of the

power supply voltage.

Application areas include transducer amplifiers, DC gain blocks and all the

conventional op amp circuits which now can be more easily implemented in single power

supply systems. For example, the LM124 series can be directly operated off of the standard

+5V power supply voltage which is used in digital systems and will easily provide the

required interface electronics without requiring the additional 15V power supplies.

features

Internally frequency compensated for unity gain

Large DC voltage gain 100 dB

Wide bandwidth (unity gain) 1 MHz (temperature compensated)

Wide power supply range: Single supply 3V to 32V or dual supplies 1.5V to

16V

Very low supply current drain (700 A)-essentially independent of supply voltage

Low input biasing current 45 nA (temperature compensated)

Low input offset voltage 2 mV and offset current: 5 nA

Input common-mode voltage range includes ground

Differential input voltage range equal to the power supply voltage



10/37


5.2 Phototransistor

We uses L14F1 phototransistor as the sensors in our circuit. The standard

symbol of a phototransistor, which can be regarded as a conventional transistor housed in a

case that enables its semiconductor junctions to be exposed to external light. The device is

normally used with its base open circuit, in either of the configurations shown in fig. 5.9.2,

and functions as follows.

Fig. 5.9.1Phototransistor symbol.

In practice, the collector and emitter current of the transistor are virtually identical and,

since the base is open circuit, the device is not subjected to significant negative feedback.

The sensitivity of a phototransistor is typically one hundred times greater than that of a

photodiode, but is useful maximum operating frequency (a few hundred kilohertz) is

proportionally lower than that of a photodiode by using only its base and collector terminals



11/37


and ignoring the emitter, as shown in fig.5.10.2. Phototransistors are solid-state light

detectors with internal gain that are used to provide analog or digital signals. They detect

visible, ultraviolet and near-infrared light from a variety of sources and are more

sensitive than photodiodes, semiconductor devices that require a pre-amplifier.

Phototransistors feed a photocurrent output into the base of a small signal transistor. For each

illumination level, the area of the exposed collector-base junction and the DC current gain of

the transistor define the output.

Fig. 5.9.2. Phototransistor used in circuit

The base current from the incident photons is amplified by the gain of the transistor,

resulting in current gains that range from hundreds to several thousands. Response time is a

function of the capacitance of the collector-base junction and the value of the load resistance.

Photodarlingtons, a common type of phototransistor, have two stages of gain and can provide

net gains greater than 100,000. Because of their ease of use, low cost and compatibility with

transistor-transistor logic (TTL), phototransistors are often used in applications where more

than several hundred nano watts (nW) of optical power are available. Selecting

phototransistors requires an analysis of performance specifications. Collector current is the

total amount of current that flows into the collector terminal. Collector dark current is the

amount of collector current for which there is no optical input. Typically, both collector



12/37


current and collector dark current are measured in milliamps (mA). Peak wavelength, the

wavelength at which phototransistors are most responsive, is measured in nanometers (nm).

Rise time, the time that elapses when a pulse waveform increases from 10% to 90% of its

maximum value, is expressed in nanoseconds (ns). Collector-emitter breakdown voltage is

the voltage at which phototransistors conduct a specified (nondestructive) current when

biased in the normal direction without optical or electrical inputs to the base.

5.3 AT89C51 microcontroller

The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with

4Kbytes of Flash programmable and erasable read only memory (PEROM). The device

is manufactured using Atmels high-density nonvolatile memory technology and is

compatible with the industry-standard MCS-51 instruction set and pinout. The on-chip

Flash allows the program memory to be reprogrammed in-system or by a conventional

nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash

on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides

a highly-flexible and cost-effective solution to many embedded control applications.

Features

Compatible with MCS-51 Products

4K Bytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-level Program Memory Lock

128 x 8-bit Internal RAM

32 Programmable I/O Lines

Two 16-bit Timer/Counters



13/37


Six Interrupt Sources

Programmable Serial Channel

Low-power Idle and Power-down Modes

AT89C51 is the decision making device in our project. We uses port 3 of the

controller as input and the decision is fed out through port2. We uses 12 Mhz crystal

oscillator for giving clock pulse. The port 3 output is fed to motor driver and to motor to steer

the robocar.

5.4 L293D DRIVER IC

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

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

solenoids, DC and stepping motors) and switching power transistors. To simplify use as two

bridges each pair of channels is equipped with an enable input. A separate supply input is

provided for the logic, allowing operation at a lower voltage and internal clamp diodes areincluded. This device is suitable for use in switching applications at frequencies up to 5 kHz.



14/37


The L293D is assembled in a 16 lead plastic package which has 4 center pins connected

together and used for heat sinking.

5.5 DC MOTOR

An electric motor converts electrical energy intomechanical energy. A DC motor is

an electric motorthat runs ondirect current (DC) electricity.

The DC electric motorgenerates torque directly from DC power supplied to the motor by

using internal commutation, stationary permanent magnets, and rotating electrical magnets.

Like all electric motors or generators, torque is produced by the principle ofLorentz 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.

http://en.wikipedia.org/wiki/Electrical_energyhttp://en.wikipedia.org/wiki/Mechanical_energyhttp://en.wikipedia.org/wiki/Mechanical_energyhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Brushed_DC_electric_motorhttp://en.wikipedia.org/wiki/Lorentz_forcehttp://en.wikipedia.org/wiki/Lorentz_forcehttp://en.wikipedia.org/wiki/Commutator_(electric)http://en.wikipedia.org/wiki/Electrical_energyhttp://en.wikipedia.org/wiki/Mechanical_energyhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Brushed_DC_electric_motorhttp://en.wikipedia.org/wiki/Lorentz_forcehttp://en.wikipedia.org/wiki/Commutator_(electric)


15/37


6.CIRCUIT DESCRIPTION

The fig.4.1 shows the circuit of automated line following robot. When light falls onthe phototransistor(say,T1), it goes into saturation and starts conducting. When no light falls

on the phototransistor it is cut-off. A white LED (LED2) has been used to illuminate the

white path on a black background. Phototransistor T1 and T2 are used for detecting the white

path on the black background.

Collector of phototransistor T1 and T2 are connected to the inverting inputs of

operational amplifier A2 and A1. The signal voltage at the inverting input of the operational

amplifier is compared with the fixed reference voltage, which is formed by a potential

divider circuit of 5.6-kilo-ohm resistor and 10-kilo-ohm preset. This reference voltage can be

adjusted by changing the value of the 10-kilo-ohm preset.

When sensor T2 is above the black surface, it remains cut-off as the black surface

absorbs virtually all the light falling from LED2 and no light is reflected back. The voltage at

the inverting input (pin2) of operational amplifier A1 is higher than the reference voltage at

its non inverting input(pin3) and therefore the amplifier output at pin1 becomes zero.

When sensor T2 ia above the white line, the light gets reflected from the white

surface to fall on phototransistor T2. Phototransistor T2 goes into saturation and conducts.

The inverting input (pin2) of operational amplifier A1 goes below the reference voltage at its

non-inverting input (pin 3) of operational amplifier A1 and therefore output pin 1 goes high.

This way, the comparator outputs logic 0 for black surface and logic1 for white surface.

Similarly, comparator A2 compares the input voltage from phototransistor T1 with a

fixed reference voltage.

The outputs of operational amplifier A1 and A2 are fed to microcontroller AT89C51.

The AT89C51 is an 8-bit microcontroller having 4kB of flash, 128 bytes of RAM,32 I/O

lines, two 16-bit timers/counters,a five-vector two level interrupt architecture, onchip

oscillator and clock circuitary. A 12 Mhz crystal is used for providing the basic clock

frequency. All I/O pins are reset to 1 as soon as RST pin goes high. Holding RST pin for

two machine cycles while oscillator is running resets the device. Power on reset is derived



16/37


from resistor R5 and capacitor C1. Switch S2 is used for manual reset. The microcontroller,

based on the inputs from sensor T1 (say left) and sensor T2 (say right), controls the motor to

make the robot turn left, turn right or move forward.

Port pins P2.0, P2.1, P2.2 and P2.3 are connected to pins 15,10,7 and 2 of motor

driver L293D. Port pins P2.0 and P2.1 are used for controlling the right motor, while port

pins P2.2 and P2.3 are used for controlling the left motor.



17/37


7.WORKING

Fig 7.1

Fig 7.1 shows the path of line follower robot. Where L is the left sensor and R is

the right sensor.

At the start when the robot is at point A sensors T1 and T2 are above the black

surface and port pins P3.0 and P3.1 of the microcontroller recieve logic0. As a result the

robot moves forward in straight direction.

At point B, a left turn is encountered, and the left sensor comes above the white

surface, whereas the right sensor remains above the black surface. Port pin P3.0 of the

microcontroller recieves logic0 from the right sensor. As a result left motor stops and the

right motor rotates, to make robot turn left. This process continues until left sensor comes

above the black background.

Similrly, at point C, where a right turn is encountered, the same procedure for right



18/37


turn is excecuted. When both sensors are at white surface, the robot should stop. The

output of the microcontroller depends on the input recieved at its port pins P3.0 and P3.1 as

shown in table below



19/37


8.SOFTWARE SECTION

The source program for the project is written in the Assembly language and assembled using

Metalinks ASM51 assembler,which is freely available on the internat for download. It iswell commented for easy understanding and works as per the flow-chart shown in fig.8.1



20/37


8.1 program

$MOD51

ORG 0000h

LJMP MAIN

ORG 0030h

MAIN: SETB p3.0 ;input for left sensor

SETB p3.1 ;input for right sensor

AGAIN: JB p3.0,NEXT

JB p3.1,GO

CLR p2.0

SETB p2.1

CLR p2.2

SETB p2.3

SJMP AGAIN

GO: CLR p2.0

SETB p2.1

CLR p2.2

CLR p2.3

SJMP AGAIN

NEXT: JB p3.1,go1

CLR p2.0



21/37


CLR p2.1

CLR p2.2

SETB p2.3

SJMP AGAIN

GO1: CLR p2.0

CLR p2.1

CLR p2.2

CLR p2.3

SJMP AGAIN

HERE: SJMP HERE

END

The above program is of extension .ASM since it is written in assembly language. So

in order to burn this program to microcontroller using burner, we need to convert this .ASM

file to .HEX file. We should use a asm to hex converter which is a software freely available

on internet.The generated hex code is then burnt into the microcontroller unit (MCU) usingasuitable Atmel 89 series programmer such as one from Sunrom Technologiesor Frontline

Electronics. You shouldnot remove the microcontroller from the zero insertion force (ZIF)

socket until the programming is complete.

Steps for installation

Install ASM51 to computer-Type the program in notepad or similar editors-save the

program as .ASM in the same folder where ASM51 installed-Open ASM51.EXE from the

folder and type name of saved file-Then two files which have extensions .HEX and .LST

generated.



22/37


9.HARDWARE SECTION

PCB DESIGN & FABRICATION

9.1 PCB DESIGN

Designing of PCB is a major step in the production of PCB is a major. It forms a distinct

factor in electronic performance and reliability. The productivity of a PCB, its assembly and

service ability also depends on the design.

The designing of a PCB consists of designing of the layout followed by the preparation of the

artwork. The layout should include all the relevant aspects in details of the PCB design while

the art work preparation brings it to the form required for the production process. The layout

can be designed with the help of anyone of the standard layout edition software such as

Eagle, Orcad or Edwin XP. Hence a concept, clearly defining all the details of the circuits

and partly of the equipment, is a prerequisite and the actual layout can start. Depending on

the accuracy required, the artwork might be produced a 1:1 or 2:1 even 4:1 scale. It is best

prepared on a 1:1 scale.

You need to generate a positive (copper black) UV translucent art work film. You

will never get a good board without good art work, so it is important to get the best possible

quality at this stage. The most important thing is to get a clear sharp image with a very solid

opaque black. Art work is done using ORCAD software. It is absolutely essential that your

PCB software prints holes in the middle of pads, which will act as centre marks when

drilling. It is virtually impossible to accurately hand-drill boards without these holes. If you

are looking to buy PCB software at any cost level and want to do hand-protyping of boards

before production, check that this facility is available when defining pad and line shapes, theminimum size recommended (through-linking holes) for reliable result is 50 mil, assuming

0.8mm drill size; 1 mil=(l/1000)th of an inch. You can go smaller drill sizes, but through

linking will be harder. 65 mil round or square pads for normal components.

ICs, with 0.8 mm hole, will allow a 12.5mil, down to 10mil if you really need to. Center-to-

centre spacing of 12.5 mil tracks should be 25 mil-slightly less may be possible if your

printer can manage it. Take care to preserve the correct diagonal track-track spacing on



23/37


mitered corners; grid is 25 mil and track width 12.5mil. The art work must be printed such

that the printed side is in contact with PCB surface when exposing, to avoid blurred edges. In

practice, this means that if you design the board as seen from the component side, the bottom

(solder side) layer should be printed the 'correct' way round, and top side of the double-sided

board must be printed mirrored

9.2 ETCHING

Ferric chloride etchant is a messy stuff, but easily available and cheaper than most

alternatives. It attacks any metal including stainless steel. So when setting up a PCB etching

area, use a plastic or ceramic sink, with plastic fitting and screws wherever possible, and seal

any metal screws with silicon. Copper water pipes may be splashed or dripped-on, so sleeveor cover them in plastic; heat-shrink sieving is great if you are installing new pipes. Fume

extraction is not normally required, although a cover over the tank or tray when not in use is

a

good idea. You should always use the hex hydrate type of ferric chloride, which should be

dissolved in warm water until saturation. Adding a teaspoon of table salt helps to make the

etchant clearer for easier inspection. Avoid anhydrous ferric chloride. It creates a lot of heat

when dissolved. So always add the powder very slowly to water; do not add water to the

powder, and use gloves and safety glasses. The solution made from anhydrous ferric chloride

doesn't etch at all, so you need to add a small amount of hydrochloric acid and leave it for a

day or two. Always take extreme care to avoid splashing when dissolving either type of ferric

chloride, acid tends to clump together and you often get big chunks coming out of the

container and splashing into the solution. It can damage eyes and permanently stain clothing.

If you are making PCBs in a professional environment where time is money you should get a

heated bubble-etch tank. With fresh hot ferric chloride, the PCB will etch in well under 5

mins. Fast etching produces better edge-quality and consistent line widths. If you aren't using

a bubble tank, you need to agitate frequently to ensure even etching. Warm the etchant by

putting the etching tray inside a larger tray filled with boiling water.



24/37


9.3 DRILLING

If you have fiber glass (FR4) board, you must use tungsten carbide drill bits. Fiber glass eats

normal high-speed steel (HSS) bits very rapidly, although HSS drills are alright for older

larger sizes (> 2mm). Carbide drill bits are available as straight-shank or thick-shank. In

straight shank, the hole bit is the diameter of the hole, and in thick shank, a standard size

(typically about 3.5 mm) shank tapers down to the hole size. The straight-shank drills are

usually preferred because they break less easily and are usually cheaper. The longer thin

section provides more flexibility. Small drills for PCB use usually come with either a set of

collets of various sizes or a three-jaw chuck. Sometimes the 3-jaw chuck is an optional extra

and is worth getting for the time it saves on changing collets. For accuracy, however, 3-jaw

chucks are not brilliant, and small drill sizes below 1 mm quickly formed grooves in the

jaws, preventing good grip. Below 1 mm, you should use collets, and buy a few extra of the

smallest ones; keeping one collet per drill size as using a larger drill in a collet will open it

out and it no longer grips smaller drills well. You need a good strong light on the board when

drilling, to ensure accuracy. A dichroic halogen lamp, under run at 9V to reduce brightness,

can be mounted on a microphone gooseneck for easy positioning. It can be useful to raise the

working surface above 15 cm above the normal desk height for more comfortable viewing.

Dust extraction is nice, but not essential. and occasional blow does the trick! A foot-pedal

control to switch the drill 'off and 'on' is very convenient, especially when frequently

changing bits. Avoid hole sizes less than 0.8 mm unless you really need them. When making

two identical boards, drill them both together to save time. To do this, carefully drill a 0.8

mm whole in the pad near each corner of each of the two boards, getting the center as

accurately as possible. For larger boards, drill a hole near the centre of each side as well. Lay

the boards on the top of each other and insert a 0.8 mm track pin in two opposite corners,

using the pins as pegs to line the PCBs up. Squeeze or hammer the pins into boards, and then

into the remaining holes. The two PCBs are now nailed together accurately and can be

drilled together.

9.4 SOLDERING



25/37


Soldering is a process in which two or more metal items are joined together by melting and

flowing a filler metal into the joint, the filler metal having a relatively low melting point. Soft

soldering is characterized by the melting point of the filler metal, which is below 400 C

(752 F). The filler metal used in the process is called solder.

Soldering is distinguished frombrazing by use of a lower melting-temperature filler metal.

The filler metals are typically alloys that have melting temperatures below 350C. It is

distinguished from welding by the base metals not being melted during the joining process

which may or may not include the addition of a filler metal.[2] In a soldering process, heat is

applied to the parts to be joined, causing the 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 metal cools, the resulting joints are not as strong as the base metal, but have

adequate strength, electrical conductivity, and water-tightness for many uses.

9.41 Solders:

Soldering filler materials are available in many different alloys for differing applications. In

electronics assembly, the eutectic alloy of 63% tin and 37% lead (or 60/40, which is almost

identical in performance to the eutectic) has been the alloy of choice. Other alloys are used

for plumbing, mechanical assembly, and other applications.

An eutectic formulation has several advantages for soldering; chief among these is the

coincidence of the liquidus andsolidus temperatures, i.e. the absence of a plastic phase. This

allows for quicker wetting as the solder heats up, and quicker setup as the solder cools. A

non-eutectic formulation must remain still as the temperature drops through the liquidus and

solidus temperatures. Any differential movement during the plastic phase may result incracks, giving an unreliable joint. Additionally, a eutectic formulation has the lowest possible

melting point, which minimizes heat stress on electronic components during soldering. Other

common solders include low-temperature formulations (often containingbismuth), which are

often used to join previously-soldered assemblies without un-soldering earlier connections,

and high-temperature formulations (usually containing silver) which are used for high-

temperature operation or for first assembly of items which must not become unsoldered

during subsequent operations.

http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Solderhttp://en.wikipedia.org/wiki/Brazinghttp://en.wikipedia.org/wiki/Brazinghttp://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Soldering#cite_note-indiumcorporation-1http://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Wettinghttp://en.wikipedia.org/wiki/Alloyhttp://en.wikipedia.org/wiki/Eutectichttp://en.wikipedia.org/wiki/Liquidushttp://en.wikipedia.org/wiki/Solidus_(chemistry)http://en.wikipedia.org/wiki/Solidus_(chemistry)http://en.wikipedia.org/wiki/Bismuthhttp://en.wikipedia.org/wiki/Silverhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Solderhttp://en.wikipedia.org/wiki/Brazinghttp://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Soldering#cite_note-indiumcorporation-1http://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Wettinghttp://en.wikipedia.org/wiki/Alloyhttp://en.wikipedia.org/wiki/Eutectichttp://en.wikipedia.org/wiki/Liquidushttp://en.wikipedia.org/wiki/Solidus_(chemistry)http://en.wikipedia.org/wiki/Bismuthhttp://en.wikipedia.org/wiki/Silver


26/37


9.42 Flux:

In high-temperature metal joining processes (welding, brazing and soldering), the primary

purpose offlux is to prevent oxidation of the base and filler materials. Tin-lead solder, for

example, attaches very well to copper, but poorly to copper oxides (which form quickly at

soldering temperatures). Flux is nearly inert at room temperature, yet becomes strongly

reductive when heated. This helps remove oxidation from the metals to be joined, and

inhibits

oxidation of the base and filler materials. Secondarily, flux acts as a wetting agent in the

soldering process, reducing the surface tensionof the molten solder and causing it to better

wet out the parts to be joined.

10.CONSTRUCTION

Three wheels can be used fr this robot-one on the front and two at the rear. Front wheel can

rotate in any direction as specified by the rear wheel. Construction also requires two side

brackets for mounting motors,chasis etc. Castor wheel can be used for front wheel.

http://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Wetting_agenthttp://en.wikipedia.org/wiki/Surface_tensionhttp://en.wikipedia.org/wiki/Surface_tensionhttp://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Wetting_agenthttp://en.wikipedia.org/wiki/Surface_tension


27/37


11.PCB LAYOUT



28/37


12.COMPONENT LAYOUT



29/37


13.LIST OF TOOLS AND INTRUMENTS REQUIRED

Following tools and instruments are used for preparing the project

1. Soldering iron

2. Desoldering pump

3. Drill Machine

4. Multimeter

5. Filer

6. Tweezers

7. Screw driver

8. Power supply

9. Flux

10. Desoldering wick

11. Petrol

12. Brush

13. Soldering Wire



30/37


14.COMPONENTS REQUIRED

SI.No NAME OF THE COMPONENT QUANTITY PRICE

1. AT89C51 1 55

2. IC L293D 1 80

3. IC LM324 1 18

4. L14F1 PHOTOTRANSISTOR 2 40

5. IN 4007 DIODE 1 2

6. 5MM LED 2 1.50

7. RESISTOR 10K 3 .25

8. RESISTOR 5.6K 2 .25

9. RESISTOR 330 1 .25

10. RESISTOR 220 1 .25

11. RESISTOR 10K-PRESET 2 5

12. CAPACITORS 10 F/16V ELECTROLYTIC 1 .5

13. CAPACITORS 33 pF CERAMIC 2 .75

14. CAPACITORS 47 F/16V ELECTROLYTIC 1 .5

15. CAPACITORS .1F CERAMIC 1 .75

16. ON/OFF SWITCH 1 2

17. PUSH TO ON SWITCH 1 10

18. CRYTAL OSCILLATOR 12 MHz 1 15

19. 6V DC GEARED MOTOR 2 20



31/37


20. BATTERY 1.5V 4 9

21. 40 PIN IC BASE 1 1



TOTAL=260



32/37


15.PRECAUTION

As we were dealing with a phototransistor we need to control the natural light, since

our sensor is even sensitive to sun light. So we need to place our sensor under the chasis.

Position of LED is quite important to us since it is the source of light to be reflected back to

sensors.



33/37


16.APPLICATIONS

Industrial automated equipment carriers

Entertainment and small household applications.

Automated cars.

Tour guides in museums and other similar applications.

Second wave robotic reconnaissance operations.

Future application:-can replaces trolleys in indudtries,road trains....



34/37


17.LIMITATIONS

Choice of line is made in the hardware abstraction and cannot be changed by

software.

Calibration is difficult, and it is not easy to set a perfect value.

The steering mechanism is not easily implemented in huge vehicles and

impossible for non-electric vehicles (petrol powered).

Few curves are not made efficiently, and must be avoided.

Lack of a four wheel drive, makes it not suitable for a rough terrain.

Use of IR even though solves a lot of problems pertaining to interference, makes it

hard to debug a faulty sensor.

Lack of speed control makes the robot unstable at times.



35/37


18.CONCLUSION

For a test, I held my robot in the air then two wheels rotated as expected and I

approached a white paper to sensors. Then, corresponding wheels stopped as expected.

Hence our product is working as per theory . Next, I put it down on the track, but

unfortunately, it didnt move. I found the torque of motors not enough to drive my robot.

Even though the chosen DC motor was slowest and gave highest torque among other DC

motors in the lab, it wasnt enough. For solving this problem, I will have to find a suitable

DC motor with large torque and it even moves through perfect plains.

Overall, the robot project wasnt successful, but it was quite a fun to go through all the

process. I also realized that there were many things to consider practically such as installation

of motors, building up a circuit by soldering and putting all parts together. This experience

hopefully would be helpful in the future work.



36/37


19.REFERENCE/BIBILOGRAPHY

Efy magazine september 2009

1. [Online] // Wikipedia. - www.wikipedia.com.

2. [Online] // circuits today. - www.circuitstoday.com.

3. [Online] // electronics schematics. - www.electroschematic.com.

4. [Online] // electronics for you. - www.efy.com.

http://www.efy.com/http://www.efy.com/


37/37


20.APPENDIX

Documents

Line Follower Robot45