3_Line Follower Robotic Doc _org

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Anurag Engineering College

1. INTRODUCTION

1.1 INTRODUCTION TO LINE FOLLING ROBOT

A line follower robot is basically a robot designed to follow a ‘line’ or path

already predetermined by the user. This line or path may be as simple as a physical white

line on the floor or as complex path marking schemes e.g. embedded lines, magnetic

markers and laser guide markers. n order to detect these specific markers or ‘lines’,

!arious sensing schemes can be employed. These schemes may !ary from simple low

cost line sensing circuit to expansi!e !ision systems. The choice of these schemes would

be dependent upon the sensing accuracy and flexibility re"uired. #rom the industrial point of !iew, line following robot has been implemented in semi to fully autonomous

plants. n this en!ironment, these robots functions as materials carrier to deli!er products

from one manufacturing point to another where rail, con!eyor and gantry solutions are

not possible. Apart from line following capabilities, these robots should also ha!e the

capability to na!igate $unctions and decide on which $unction to turn and which $unction

ignore. This would re"uire the robot to ha!e %& degree turn and also $unction counting

capabilities. To add on to the complexity of the problem, sensor positioning also plays a

role in optimi'ing the robots performance for the tasks mentioned earlier.

(ine)following robots with pick) and) placement capabilities are commonly used

in manufacturing plants. These mo!e on a specified path to pick the components from

specified locations and place them on desired locations. *asically, a line)following robot

is a self)operating robot that detects and follows a line drawn 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 man oeu!re the robot to stay on course while constantly correcting the wrong

mo!es using feedback mechanism, thus forming a simple yet effecti!e closed) loop

system. The figure +.+ represents the *lock iagram of line follower.

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-eset circuit

hoto /ensor

Array

0)*ridge

(eft 1otor -ight 1otor

AT2%/341icro controller

To All /ections

+4 ! (ead acid battery


1.2 BLOCK DIAGRAM

#ig +.+ *lock diagram of line follower

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1.3 INTRODUCTION TO EMBEDDED SYSTEMS

An embedded system is a system which is going to do a predefined specified task

is the embedded system and is e!en defined as combination of both software and

hardware. A general)purpose definition of embedded systems is that they are de!ices used

to control, monitor or assist the operation of e"uipment, machinery or plant. 5Embedded5

reflects the fact that they are an integral part of the system. At the other extreme a

general)purpose computer may be used to control the operation of a large complex

processing plant, and its presence will be ob!ious.

All embedded systems are including computers or microprocessors. /ome of

these computers are howe!er !ery simple systems as compared with a personal computer.

The simplest de!ices consist of a single microprocessor 6often called a 5chip78, which

may itself be packaged with other chips in a hybrid system or Application /pecific

ntegrated Circuit 6A/C8. ts input comes from a detector or sensor and its output goes to

a switch or acti!ator which 6for example8 may start or stop the operation of a machine or,

by operating a !al!e, may control the flow of fuel to an engine.

As the embedded system is the combination of both software and hardware as

shown in below figure +.4.

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Embedded

System

Sot!"#e $"#d!"#e

AL%

C

&B

Et'.(

%#o'esso#

%e#)*+e#",s

memo#y


#ig. +.4 *lock diagram of Embedded /ystem

/oftware deals with the languages like A(, C, and :* etc., and 0ardware deals with

rocessors, eripherals, and 1emory.

1emory; t is used to store data or address.

eripherals; These are the external de!ices connected

rocessor; t is an C which is used to perform some task

Applications of embedded systems

• 1anufacturing and process control

• Construction industry

•Transport

• *uildings and premises

• omestic ser!ice

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• Communications

• =ffice systems and mobile e"uipment

• *anking, finance and commercial

• 1edical diagnostics, monitoring and life support

• Testing, monitoring and diagnostic systems

2. LITERATURE SUR&EY

2.1 E-)st)/ Te'+o,o/y

(iterature -e!iew on the re!ious /tudy -esearch paper by Ardiyanto focused

on how to implement controller in low cost mobile robot . n this paper, the method

for algorithm is using (1/ 6(east 1ean /"uare8. *y using (1/ 6(east 1ean

/"uare8, there are only one constant that being ad$usted that is proportional constant

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6>p8. #or the experiments part, the experiment is conducted based on the tasks gi!en to

the robot, which are goal seeking test and wall following test. Each task is testing by

using different speed of the robot and each speed is testing for +& times. Then, for each

speed, the beha!ior of the robot in completing the task gi!en is obser!ed. As conclusion,

the mobile robot manages to complete the task gi!en although it uses maximum speed.

The most difficulties in designing line follower robot are to design the line follower robot

that can na!igate effecti!ely . The na!igation of line follower robot usually are effected

by the physicals kinematics constraints which are motor and sensor response, position

and the turning radius of the robot. n recent years, the designers ha!e faced problems to

design a line follower robot that can na!igate perfectly. n order to impro!e the

na!igation reliability of the differential dri!e for line follower robot, line sensor

configuration is implemented .

2.2 %#o*osed Te'+o,o/y

?ow a days, the application of mobile robot had been highly demanded in

different areas such as industries, hospitals, warehouses and nuclear waste facilities . The

de!elopment of mobile robot has faces large difficulties mostly in na!igation. =!er the

past, there are many methods for controller that has been de!eloped to increase the

performances of the robot in terms of na!igation such controller, fu''y logic and

neural network.

@enerally, line follower robot is mobile robot that is designed to detect and follow

the line. The path or track is usually predetermined by user and the robot needs to

complete the path or track until the finish line. The path or track is basically physical

white line on the floor or as complex path marking schemes for example embedded line

magnetic markers and laser guide markers . The basic operations of line follower robot

are as follow;

+. The line follower robot will sense or detect the line position with optical sensors and

the optical sensors are usually placed at the front end of the robot.

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4. The robot will ha!e steering mechanism in order for the robot to mo!e straight, turn

left or turn right.

9. The speed of the robot will be controlled according to the lane condition. t means that

for cur!y lane, the speed of the robot is decrease in order to obtain smooth turn.

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3. $ARD0ARE E%LANATION

3.1 BASIC $ARD0ARE

3.1.1 Re'+"#/eb,e B"tt#y

A rechargeable battery or storage battery is a group of one ormore electrochemical

cells. They are known as secondary cells because their electrochemical reactions are

electrically re!ersible. -echargeable batteries come in many different shapes and si'es,

ranging anything from a button cell to megawatt systems connected to stabili'e an

electrical distribution network. /e!eral different combinations of chemicals are

commonly used, including; lead)acid, nickel cadmium6?iCd8, nickel metal

hydride 6?i108, lithium ion 6(i)ion8, and lithium ion polymer 6(i)ion polymer8.

#igure 9.+ represents the -echageble *attery.

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#ig.9.+-echargeble *attery

-echargeable batteries ha!e lower total cost of use and en!ironmental impact than

disposable batteries. /ome rechargeable battery types are a!ailable in the same si'es as

disposable types. -echargeable batteries ha!e higher initial cost, but can be recharged

!ery cheaply and used many times.

-echargeable batteries are used for automobile starters, portable consumer

de!ices, light !ehicles 6such as motori'ed wheelchairs, golf carts, electric bicycles, and

electric forklifts8, tools, and uninterruptible power supplies. Emerging applications

in hybrid electric !ehicles and electric !ehicles are dri!ing the technology to reduce cost

and weight and increase lifetime. ?ormally, new rechargeable batteries ha!e to be

charged before use newer low self)discharge batteries hold their charge for many

months, and are supplied charged to about B&D of their rated capacity.

The / ?ational Electrical 1anufacturers Association has estimated that ./. demand

for rechargeable batteries is growing twice as fast as demand for non)rechargeable.

C+"#/)/ "d D)s'+"#/)/

uring charging, the positi!e acti!e material is oxidi'ed, producing electrons, and

the negati!e material is reduced, consuming electrons is as shown in figure 9.4. These

electrons constitute the current flow in the external circuit. The electrolyte may ser!e as a

simple buffer for ion flow between the electrodes, as in lithium)ion and nickel)

cadmium cells, or it may be an acti!e participant in the electrochemical reaction, as

in lead)acid cells.

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#ig. 9.4 Charging of a secondary cell battery

#ig. 9.9 *attery charger

The energy used to charge rechargeable batteries usually comes from a battery

charger is as shown in figure 9.9 using AC mains electricity. Chargers take from a few

minutes 6rapid chargers8 to se!eral hours to charge a battery. 1ost batteries are capable of

being charged far faster than simple battery chargers are capable of there are chargers that

can charge consumer si'es of ?i10 batteries in +3 minutes. #ast charges must ha!e

multiple ways of detecting full charge 6!oltage, temperature, etc.8 to stop charging beforeonset of harmful o!ercharging. -echargeable multi)cell batteries are susceptible to cell

damage due to re!erse charging if they are fully discharged. #ully integrated battery

chargers that optimi'e the charging current are a!ailable. Attempting to recharge non)

rechargeable batteries with unsuitable e"uipment may cause battery explosion #low

batteries, used for specialised applications, are recharged by replacing the electrolyte

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li"uid.*attery manufacturersF technical notes often refer to :C this is !olts per cell, and

refers to the indi!idual secondary cells that make up the battery. #or example, to charge a

+4 : battery 6containing cells of 4 : each8 at 4.9 :C re"uires a !oltage of +9.2 :

across the batteryFs terminals .

?on)rechargeable alkaline and 'inc)carbon cells output +.3: when new, but this

!oltage gradually drops with use. 1ost ?i10 AA and AAA batteries rate their cells at

+.4 :, and can usually be used in e"uipment designed to use alkaline batteries up to an

end)point of &.% to +.4:

Ree#se '+"#/)/

/ub$ecting a discharged cell to a current in the direction which tends to discharge it

further, rather than charge it, is called re!erse charging this damages cells. -e!erse

charging can occur under a number of circumstances, the two most common being;

Ghen a battery or cell is connected to a charging circuit the wrong way round.

Ghen a battery made of se!eral cells connected in series is deeply discharged.

Re't))e#

The purpose of a rectifier is to con!ert an AC wa!eform into a C wa!eform

6=-8 -ectifier con!erts AC current or !oltages into C current or !oltage. There are two

different rectification circuits, known as half)wa!e and full)wa!e rectifiers. *oth use

components called diodes to con!ert AC into C.

T+e F4,,5!"e Re't))e#

The circuit in figure addresses the second of these problems since at no time is the

output !oltage &:. This time four diodes are arranged so that both the positi!e and

negati!e parts of the AC wa!eform are con!erted to C as shown in figure 9.


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#ig. 9.< #ull)Ga!e -ectifier

Ghen the AC input is positi!e, diodes A and * are forward)biased, while diodes C

and are re!erse)biased. Ghen the AC input is negati!e, the opposite is true ) diodes C

and are forward)biased, while diodes A and * are re!erse)biased.

Ghile the full)wa!e rectifier is an impro!ement on the half)wa!e rectifier, its

output still isnFt suitable as a power supply for most circuits since the output !oltage still

!aries between &: and :s)+.


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A typical capacitor input filter consists of a filter capacitor C+, connected across

the rectifier output, an inductor (, in series and another filter capacitor connected across

the load.

&o,t"/e Re/4,"to#

A !oltage regulator is an electrical regulator designed to automatically maintain a

constant !oltage le!el as shown in figure 9.. t may use an electromechanical

mechanism, or passi!e or acti!e electronic components. epending on the design, it may

be used to regulate one or more AC or C !oltages. There are two types of regulator are

they.

ositi!e :oltage /eries 6B2xx8 and

?egati!e :oltage /eries 6B%xx8

67--

’B2’ indicate the positi!e series and ‘xx’indicates the !oltage rating. /uppose B2&3

produces the maximum 3:.’&3’indicates the regulator output is 3:.

68--

’B%’ indicate the negati!e series and ‘xx’indicates the !oltage rating. /uppose

B%&3 produces the maximum )3:.’&3’indicates the regulator output is )3:.

These regulators consists the three pins there are

%)1 t is used for input pin.

%)2 This is ground pin for regulator

%)3 t is used for output pin. Through this pin we get the output.

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http://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Regulator_(automatic_control)http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Regulator_(automatic_control)http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Capacitor


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#ig. 9. -egulator

3.2 AT78S92 MICROCONTROLLER

The AT2%/34 is a low)power, high)performance C1=/ 2)bit microcontroller

with 2> bytes of in system programmable #lash memory. The de!ice is manufactured

using Atmel’s high density non!olatile memory technology and is compatible with the

industry standard 2&C3+ instruction set and pinout. The on)chip #lash allows the

program memory to be reprogrammed in)system or by a con!entional non!olatile

memory programmer. *y combining a !ersatile 2)bit C with in)system programmable

#lash on a monolithic chip, the Atmel AT2%/34 is a powerful microcontroller which

pro!ides a highly)flexible and cost)effecti!e solution to many embedded control

applications.

St"d"#d Fe"t4#es

• 2> bytes of #lash,

• 43 bytes of -A1,

• 94 H= lines,

• Gatchdog timer,

• two data pointers,

• three +)bit timerHcounters,

• a six)!ector two)le!el interrupt architecture,

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• a full duplex serial port, on)chip oscillator, and

• clock circuitry.

n addition, the AT2%/34 is designed with static logic for operation down to 'ero

fre"uency and supports two software selectable power sa!ing modes. The dle 1ode stops the C while allowing the -A1, timerHcounters, serial port

and interrupt system to continue functioning. The ower)down mode sa!es the -A1

contents but free'es the oscillator, disabling all other chip functions until the next

interrupt or hardware reset.

%IN CONFIGURATIONS

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#ig. 9.B in Configuration of 1icrocontroller

%IN DESCRI%TION

The figure 9.B repesents the inConfiguration of 1icrocontroller

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&CC

/upply !oltage.

GND

@round.

%o#t :

ort & is an 2)bit open drain bidirectional H= port. As an output port, each pin can

sink eight TT( inputs. Ghen +s are written to port & pins, the pins can be used as high

impedance inputs. ort & can also be configured to be the multiplexed low order

addressHdata bus during accesses to external program and data memory. n this mode, &

has internal pullups. ort & also recei!es the code bytes during #lash programming and

outputs the code bytes during program !erification. External pullups are re"uired during

program !erification.

%o#t 1

ort + is an 2)bit bidirectional H= port with internal pullups. The ort + output

buffers can sinkHsource four TT( inputs. Ghen +s are written to ort + pins, they are

pulled high by the internal pullups and can be used as inputs. As inputs, ort + pins that

are externally being pulled low will source current 6(8 because of the internal pullups.

n addition, +.& and +.+ can be configured to be the timerHcounter 4 external count

input 6+.&HT48 and the timerHcounter 4 trigger input 6+.+HT4EI8, respecti!ely, as shown

in the following table 9.+. ort + also recei!es the low)order address bytes during #lash

programming and !erification.

Table;9.+ port + alternate pin functions

%o#t 2

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ort 4 is an 2)bit bidirectional H= port with internal pullups. The ort 4 output

buffers can sinkHsource four TT( inputs. Ghen +s are written to ort 4 pins, they are

pulled high by the internal pullups and can be used as inputs. As inputs, ort 4 pins that

are externally being pulled low will source current 6(8 because of the internal pullups.

ort 4 emits the high)order address byte during fetches from external program memory

and during accesses to external data memory that use +)bit addresses 61=:I J

T-8. n this application, ort 4 uses strong internal pull)ups when emitting +s. uring

accesses to external data memory that use 2)bit addresses 61=:I J -8, ort 4 emits

the contents of the 4 /pecial #unction -egister. ort 4 also recei!es the high)order

address bits and some control signals during #lash programming and !erification.

%o#t 3

ort 9 is an 2)bit bidirectional H= port with internal pullups. The ort 9 output

buffers can sinkHsource four TT( inputs. Ghen +s are written to ort 9 pins, they are

pulled high by the internal pullups and can be used as inputs. As inputs, ort 9 pins that

are externally being pulled low will source current 6(8 because of the pullups. ort 9

also ser!es the functions of !arious special features of the AT2%/34, as shown in the

following table 9.4. ort 9 also recei!es some control signals for #lash programming and

!erification.

Table; 9.4 port 9 alternate functions

RST

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-eset input. A high on this pin for two machine cycles while the oscillator is

running resets the de!ice. This pin dri!es 0igh for % oscillator periods after the

Gatchdog times out. The /-T= bit in /#- AI- 6address 2E08 can be used to

disable this feature. n the default state of bit /-T=, the -E/ET 0@0 out feature is

enabled.

ALE;%ROG

Address (atch Enable 6A(E8 is an output pulse for latching the low byte of the

address during accesses to external memory. This pin is also the program pulse input

6-=@8 during #lash programming. n normal operation, A(E is emitted at a constant

rate of +H the oscillator fre"uency and may be used for external timing or clocking

purposes. ?ote, howe!er, that one A(E pulse is skipped during each access to external

data memory. f desired, A(E operation can be disabled by setting bit & of /#- location

2E0. Gith the bit set, A(E is acti!e only during a 1=:I or 1=:C instruction.

=therwise, the pin is weakly pulled high. /etting the A(E)disable bit has no effect if the

microcontroller is in external execution mode.

%SEN

rogram /tore Enable 6/E?8 is the read strobe to external program memory.

Ghen the AT2%/34 is executing code from external program memory, /E? is acti!ated

twice each machine cycle, except that two /E? acti!ations are skipped during each

access to external data memory.

EA;&%%

External Access Enable EA must be strapped to @? in order to enable the

de!ice to fetch code from external program memory locations starting at &&&&0 up to

####0. ?ote, howe!er, that if lock bit + is programmed, EA will be internally latched on

reset.

EA should be strapped to :CC for internal program executions. This pin also recei!es the

+4)!olt programming enable !oltage 6:8 during #lash programming.

TAL1

nput to the in!erting oscillator amplifier and input to the internal clock operating

circuit.

TAL2

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=utput from the in!erting oscillator amplifier.

MEMORY ORGANIb of -=1 and +42 or 43 bytes of

-A1 can be used. 0owe!er all 2&34 microcontrollers ha!e +)bit addressing bus and can

address < kb memory. t is neither a mistake nor a big ambition of engineers who were

working on basic core de!elopment. t is a matter of !ery cle!er memory organi'ation

which makes these controllers a real Kprogrammers’ tidbitK.

%#o/#"m Memo#y

The oldest models of the 2&34 microcontroller family did not ha!e any internal program

memory. t was added from outside as a separate chip. These models are recogni'able by

their label beginning with 2&9 6for ex. 2&9+ or 2&948. All later models ha!e a few >bytes

-=1 embedded, E!en though it is enough for writing most of the programs, there are

situations when additional memory is necessary. A typical example of it is the use of so

called lookup tables. They are used in cases when something is too complicated or when

there is no time for sol!ing e"uations describing some process. The example of it can be

totally exotic or totally common. n those cases all needed estimates and approximates

are executed in ad!ance and the final results are put in the tables 6similar to logarithmic

tables8.

EA=: n this case, internal program memory is completely ignored, only a

program stored in external memory is to be executed.

EA=1 n this case, a program from built)in -=1 is to be executed first 6to the last

location8. Afterwards, the execution is continued by reading additional memory.n both cases, & and 4 are not a!ailable to the user because they are used for

data and address transmission. *esides, the pins A(E and /E? are used too.

D"t" Memo#y

ata 1emory is used for temporarily storing and keeping data and intermediate

results created and used during microcontroller’s operating. *esides, this microcontroller

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family includes many other registers such as; hardware counters and timers, inputHoutput

ports, serial data buffers etc. The pre!ious !ersions ha!e the total memory si'e of 43

locations, while for later models this number is incremented by additional +42 a!ailable

registers. n both cases, these first 43 memory locations 6addresses &)##h8 are the base

of the memory Common to all types of the 2&34 microcontrollers. (ocations a!ailable to

the user occupy memory space with addresses from & to B#h. #irst +42 registers and this

part of -A1 are di!ided in se!eral blocks.

The first block consists of < banks each including 2 registers designated as -& to

-B. rior to access them, a bank containing that register must be selected. ?ext memory

block 6in the range of 4&h to 4#h8 is bit) addressable, which means that each bit being

there has its own address from & to B#h. /ince there are + such registers, this block

contains in total of +42 bits with separate addresses 6The &th bit of the 4&h byte has the

bit address & and the Bth bit of the 4#h byte has the bit address B#h8. The third groups of

registers occupy addresses 4#h)B#h 6in total of 2& locations8 and does not ha!e any

special purpose or feature.

n case on)chip memory is not enough, it is possible to add two external memory

chips with capacity of b each. H= ports 4 and 9 are used for their addressing and

data transmission.

/imilar occurs when it is a needed to read some location from external ata

1emory. Addressing is performed in the same way, while reading or writing is performed

!ia signals which appear on the control outputs - or G-.

Add#ess)/

Ghile operating, processor processes data according to the program instructions.

Each instruction consists of two parts. =ne part describes what should be done and

another part indicates what to use to do it. This later part can be data 6binary number8 or

address where the data is stored. All 2&34 microcontrollers use two ways of addressing

depending on which part of memory should be accessed.

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#ig. 9.2 1emory =rganisation

REGISTERS

SFRs >S*e')", F4't)o Re/)ste#s?

/#-s are a kind of control table used for running and monitoring

microcontroller’s operating. Each of these registers, e!en each bit they include, has its

name, address in the scope of -A1 and clearly defined purpose 6 for example; timer

control, interrupt, serial connection etc.8. E!en though there are +42 free memory

locations intended for their storage, the basic core, shared by all types of 2&34

controllers, has only 4+ such registers. -est of locations are intentionally left free in order

to enable the producers to further impro!ed models keeping at the same time

compatibility with the pre!ious !ersions. t also enables the use of programs written a

long time ago for the microcontrollers which are out of production now.

A Re/)ste# >A''4m4,"to#?

This is a general)purpose register which ser!es for storing intermediate results

during operating. A number 6an operand8 should be added to the accumulator prior to

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execute an instruction upon it. =nce an arithmetical operation is preformed by the A(,

the result is placed into the accumulator. f a data should be transferred from one register

to another, it must go through accumulator. #or such uni!ersal purpose, this is the most

commonly used register that none microcontroller can be imagined without 6more than a

half 2&34 microcontrollerFs instructions used use the accumulator in some way8.

B Re/)ste#

* register is used during multiply and di!ide operations which can be performed

only upon numbers stored in the A and * registers. All other instructions in the program

can use this register as a spare accumulator 6A8.uring programming, each of registers is

called by name so that their exact address is not so important for the user. uring

compiling into machine code 6series of hexadecimal numbers recogni'ed as instructions

by the microcontroller8, C will automatically, instead of registers’ name, write necessary

addresses into the microcontroller.

R Re/)ste#s >R:5R6?

This is a common name for the total 2 general purpose registers 6-&, -+, -4

...-B8. E!en they are not true /#-s, they deser!e to be discussed here because of their

purpose. The bank is acti!e when the - registers it includes are in use. /imilar to the

accumulator, they are used for temporary storing !ariables and intermediate results.

Ghich of the banks will be acti!e depends on two bits included in the /G -egister.

These registers are stored in four banks in the scope of -A1.

3.3 IR SECTION

IR GENERATION

To generate a 9 >0' pulsating infrared is "uite easy, more difficult is to recei!e

and identify this fre"uency. This is why some companies produce infrared recei!es, that

contains the filters, decoding circuits and the output shaper, that deli!ers a s"uare wa!e,

meaning the existence or not of the 9k0' incoming pulsating infrared .

#ig. 9.% - transmitter

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t means that those 9 dollars small units, ha!e an output pin that goes high 6L3:8

when there is a pulsating 9k0' infrared in front of it, and 'ero !olts when there is not

this radiation is asshown in figure 9.%.

A s"uare wa!e of approximately 4Bu/ 6microseconds8 in$ected at the base of a

transistor as shown in figure 9.+&, can dri!e an infrared (E to transmit this pulsating

light wa!e. pon its presence, the commercial recei!er will switch its output to high

le!el 6L3:8.f you can turn on and off this fre"uency at the transmitter, your recei!erFs

output will indicate when the transmitter is on or off.

#ig. 9.+& Ga!eform for transmitter

Those - demodulators ha!e in!erted logic at its output, when a burst of - is

sensed it dri!es its output to low le!el, meaning logic le!el M +.

The T:, :C-, and Audio e"uipment manufacturers for long use infra)red at their

remote controls. To a!oid a hilips remote control to change channels in a anasonic T:,

they use different codification at the infrared, e!en that all of them use basically the same

transmitted fre"uency, from 9 to 3& >0'. /o, all of them use a different combination of

bits or how to code the transmitted data to a!oid interference.

RC59

epartment of ECE 4


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:arious remote control systems are used in electronic e"uipment today. The -C3

control protocol is one of the most popular and is widely used to control numerous home

appliances, entertainment systems and some industrial applications including utility

consumption remote meter reading, contact)less apparatus control, telemetry data

transmission, and car security systems. hilips originally in!ented this protocol and

!irtually all hilips’ remotes use this protocol. #ollowing is a description of the -C3.

Ghen the user pushes a button on the hand)held remote, the de!ice is acti!ated and sends

modulated infrared light to transmit the command. The remote separates command data

into packets. Each data packet consists of a +


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The recei!er performs the re!erse function. The photo detector con!erts optical

transmission into electric signals, filters it and executes amplitude demodulation. The

recei!er output bit stream can be used to decode the -C3 data word. This operation is

done by the microprocessor typically, but complete hardware implementations are present

on the market as well. /ingle)die optical recei!ers are being mass produced by a number

of companies such as /iemens, Temic, /harp, Iiamen 0ualian, Napanese Electric and

others. lease note that the recei!er output is in!erted 6logic)+corresponds to illumination

absence8.

IR TRANSMITTER

The - (E emitting infrared light is put on in the transmitting unit. To generate

- signal, 333 C based astable multi!ibrator is used. nfrared (E is dri!en through

transistor *C 3


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The 333 is an integrated circuit 6chip8 implementing a !ariety of timer and

multi!ibrator applications, as shown in figure 9.++. t was designed in +%B& and

introduced in +%B+ by /ignetics 6later ac"uired by hilips8. The original name was the

/E333H?E333 and was called 5The C Time 1achine5. t is still in wide use, thanks to its

ease of use, low price and good stability. As of 4&&9, + billion units are manufactured

e!ery year.

The 333 timer is one of the most popular and !ersatile integrated circuits e!er

produced. t includes 49 transistors, 4 diodes and + resistors on a silicon chip installed in

an 2)pin mini dual)in)line package 6)28. The 33 is a +


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• Astable mode; #ree -unning mode; the 333 can operate as an oscillator. ses

include (E and lamp flashers, pulse generation, logic clocks, tone generation,

security alarms, pulse position modulation, etc.

• *istable mode; The 333 can operate as a flip)flop, if the / pin is not connected

and no capacitor is used. ses include bounce free latched switches, etc.

The figure9.+4 shows how a 333 timer C is configured to function as an astable

multi!ibrator. An astable multi!ibrator is a timing circuit whose FlowF and FhighF states are

both unstable. As such, the output of an astable multi!ibrator toggles between FlowF and

FhighF continuously, in effect generating a train of pulses. This circuit is therefore also

known as a Fpulse generatorF circuit.n this circuit, capacitor C+ charges through -+ and

-4, e!entually building up enough !oltage to trigger an internal comparator to toggle the

output flip)flop. =nce toggled, the flip)flop discharges C+ through -4 into pin B, which

is the discharge pin. Ghen C+Fs !oltage becomes low enough, another internal

comparator is triggered to toggle the output flip)flop. This once again allows C+ to charge

up through -+ and -4 and the cycle starts all o!er again.

C+Fs charge)up time t+ is gi!en by; t+ M &.%96-+L-48 C+. C+Fs discharge time t4

is gi!en by; t4 M &.%96-48 C+. Thus, the total period of one cycle is t+Lt4 M &.%9 C+

6-+L4-48. The fre"uency f of the output wa!e is the reciprocal of this period, and is

therefore gi!en by;

f =1 .44/(C 1( R1+2 R2))

where f is in 0' if -+ and -4 are in megaohms and C+ is in microfarads.

epartment of ECE 42


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#ig. 9.+4 Astable multi!ibrater

IR RECEI&ER

The T/=+B /eries are miniaturi'ed recei!ers for infrared remote control

systems. ? diode and preamplifier are assembled on lead frame, the epoxy package is

designed as - filter is as sown figure 9.+<

The demodulated output signal can directly be decoded by a microprocessor.

T/=+B is the standard - remote control recei!er series, supporting all ma$or

transmission codes.

Fe"t4#es

• hoto detector and preamplifier in one package

• nternal filter for C1 fre"uency

• mpro!ed shielding against electrical field disturbance

• TT( and C1=/ compatibility

• =utput acti!e low

• (ow power consumption

• 0igh immunity against ambient light

• Continuous data transmission possible 6up to 4


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#ig. 9.+9 *lock diagram of - recei!er

#ig. 9.+< Application circuit

S4)t"b,e D"t" Fo#m"t

The circuit of the T/=+B is designed in that way that unexpected output pulses

due to noise or disturbance signals are a!oided. A bandpass filter, an integrator stage and

an automatic gain control are used to suppress such disturbances. The distinguishing

mark between data signal and disturbance signal are carrier fre"uency, burst length and

duty cycle. The data signal should fulfill the following condition;

O Carrier fre"uency should be close to center fre"uency of the bandpass 6e.g. 92 >0'8.

O *urst length should be +& cyclesHburst or longer.

O After each burst which is between +& cycles and B& cycles a gap time of at least +<

cycles is necessary.

O #or each burst which is longer than +.2ms a corresponding gap time is necessary at

some time in the data stream. This gap time should ha!e at least same length as the burst.

epartment of ECE 9&


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O p to +


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%+oto Seso#s "##"y

- reflectance sensors contain a matched infrared transmitter and infrared recei!er

pair as shown in figures 9.+ and 9.+B. These de!ices work by measuring the amount of

light that is reflected into the recei!er. *ecause the recei!er also responds to ambient

light, the de!ice works best when well shielded from ambient light, and when the

distance between the sensor and the reflecti!e surface is small6less than 3mm8. -

reflectance sensors are often used to detect white and black surfaces. Ghite surfaces

generally reflect well, while black surfaces reflect poorly. =ne of such applications is the

line follower of a robot.

#ig; 9.+ - Emittet detector circuit

#ig; 9.+B /chematic for a /ingle air of nfrared Transmitter and -ecei!er

epartment of ECE 94


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@.@ LM 32@ COM%ARATOR

FEATURES

• Gide gain bandwidth ; +.910Q input common)mode !oltage range

• ncludes ground large!oltage gain ; +&&* .!ery lowsupply currentHampli ;

9B3ma .low input bias current 4&?A low input offset !oltage ; 3m! max.

• (ow input offset current ; 4?A wide power supply range

• /ingle supply ; L9! to L9&!

• ual supplies ; R+.3! to R+3!

DESCRI%TION

These circuits consist of four independent, high gain, internally fre"uency

compensated operational amplifiers as shown fig 9.+2 .They operate from a single power

supply o!er a wide range of !oltages. =peration from split power supplies is also possible

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

supply !oltage.

#ig. 9.+2 pin connections 6top !iew8

3.9 DC GEARED MOTORS

DC moto#

A C motor is an electric motor that runs on direct current 6C8 electricity.

epartment of ECE 99


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DC Moto# Coe't)os

#igure 9.+% shows schematically the different methods of connecting the field and

armature circuits in a C 1otor. The circular symbol represents the armature circuit,

and the s"uares at the side of the circle represent the brush commutator system. The

direction of the arrows indicates the direction of the magnetic fields.

#ig. 9.+% C motor connections

%#)')*,es o o*e#"t)o

n 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 6?orth and /outh8 polarities attract, while like polarities

6?orth and ?orth, /outh and /outh8 repel. The internal configuration of a C motor is as

shown in fig 9.4& , designed to harness the magnetic interaction between a current)

carrying conductor and an external magnetic field to generate rotational motion.(etFs start by looking at a simple 4)pole C electric motor 6here red represents a

magnet or winding with a 5?orth5 polari'ation, while green represents a magnet or

winding with a 5/outh5 polari'ation8.

#ig. 9.4& nternal structure of motor

epartment of ECE 9


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E!ery C motor has six basic parts axle, rotor 6a.k.a., armature8, stator,

commutator, field magnet6s8, and brushes. n most common C motors 6and all that

*eamers will see8, the external magnetic field is produced by high)strength permanent

magnets. 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 6together with the axle and

attached commutator8 rotates with respect to the stator. The rotor consists of windings

6generally on a core8, the windings being electrically connected to the commutator. The

abo!e diagram shows a common motor layout with the rotor inside the stator 6field8

magnets.The geometry of the brushes, commutator contacts, and rotor windings are such

that when power is applied, the polarities of the energi'ed winding and the stator

magnet6s8 are misaligned, and the rotor will rotate until it is almost aligned with thestatorFs field magnets. As the rotor reaches alignment, the brushes mo!e to the next

commutator contacts, and energi'e the next winding. @i!en our example two)pole motor,

the rotation re!erses the direction of current through the rotor winding, leading to a 5flip5

of the rotorFs magnetic field, dri!ing it to continue rotating.

n real life, though, C motors will always ha!e more than two poles 6three is a

!ery common number8. n particular, this a!oids 5dead spots5 in the commutator. Sou can

imagine how with our example two)pole motor, if the rotor is exactly at the middle of its

rotation 6perfectly aligned with the field magnets8, it will get 5stuck5 there. 1eanwhile,

with a two)pole motor, there is a moment where the commutator shorts out the power

supply 6i.e., both brushes touch both commutator contacts simultaneously8. This would

be bad for the power supply, waste energy, and damage motor components as well. Set

another disad!antage of such a simple motor is that it would exhibit a high amount of

tor"ue 5ripple5 6the amount of tor"ue it could produce is cyclic with the position of the

rotor8.

#ig. 9.4+ 1otor rotation in clockwise direction

epartment of ECE 93


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since most small C motors are of a three)pole design, letFs tinker with the

workings of one !ia an interacti!e animation as shown in figure 9.4+.

#ig. 9.44 9)pole design

SouFll notice a few things from this namely as shown in fig 9.44, one pole is fully

energi'ed at a time 6but two others are 5partially5 energi'ed8. As each brush transitions

from one commutator contact to the next, one coilFs field will rapidly collapse, as the next

coilFs field will rapidly charge up 6this occurs within a few microsecond8. GeFll see more

about the effects of this later, but in the meantime you can see that this is a direct result of

the coil windingsF series wiring .

#ig. 9.49 ron core amature

The use of an iron core armature 6as in the 1abuchi, abo!e8 is "uite common, and

as shown in figure 9.49. #irst off, the iron core pro!ides a strong, rigid support for the

windings a particularly important consideration for high)tor"ue motors. The core also

conducts heat away from the rotor windings, allowing the motor to be dri!en harder than

might otherwise be the case. ron core construction is also relati!ely inexpensi!ecompared with other construction types.

*ut iron core construction also has se!eral disad!antages. The iron armature has a

relati!ely high inertia which limits motor acceleration. This construction also results in

high winding inductances which limit brush and commutator life.

epartment of ECE 9


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n small motors, an alternati!e design is often used which features a FcorelessF

armature winding. This design depends upon the coil wire itself for structural integrity.

As shown in figure 9.4


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#ig. 9.43 0)bridge /witch iagram

The two basic states of a 0)bridge. The term 50)bridge5 is deri!ed from the

typical graphical representation of such a circuit. An 0)bridge is built with four switches

6solid)state or mechanical8 as shown in figure 9.43. Ghen the switches /+ and /<

6according to the first figure8 are closed 6and /4 and /9 are open8 a positi!e !oltage will

be applied across the motor. *y opening /+ and /< switches and closing /4 and /9

switches, this !oltage is re!ersed, allowing re!erse operation of the motor.

sing the nomenclature abo!e, the switches /+ and /4 should ne!er be closed at

the same time, as this would cause a short circuit on the input !oltage source. The same

applies to the switches /9 and /


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The switching property of this 0)*ridge can be replaced by a Transistor or a

-elay or a 1osfet or e!en by an C. 0ere we are replacing this with an C named (4%9

as the dri!er whose description is as gi!en below.

Fe"t4#es

• &&mA =TT C--E?T CAA*(TS

• E- C0A??E(

• +.4A EA> =TT C--E?T 6non repetiti!e8

• E- C0A??E(

• E?A*(E #AC(TS

• =:E-TE1E-AT-E -=TECT=?

• (=@CA( 5&5 ?T :=(TA@E T= +.3 :

• 60@0 ?=/E 11?TS8

• ?TE-?A( C(A1 =E/

DESCRI%TION

The e!ice is a monolithic integrated high !oltage, high current four channel

dri!er designed to accept standard T( or TT( logic le!els and dri!e inducti!e loads

6such as relays solenoides, C and stepping motors8 and switching power transistors. To

simplify use as two bridges each pair of channels is e"uipped with an enable input. A

separate supply input is pro!ided for the logic, allowing operation at a lower !oltage and

internal clamp diodes are included. This de!ice is suitable for use in switching

applications at fre"uencies up to 3 k0'. The (4%9 is assembled in a + lead plastic

package which has < center pins connected together and used for heat sinking The

(4%9 is assembled in a 4& lead surface mount which has 2 center pins connected

together and used for heat sinking as shown in figure 9.4 .

BLOCK DIAGRAM

epartment of ECE 9%


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#ig. 9.4 *lock diagram of 0)bridge

%IN CONNECTIONS

#ig. 9.4B in configuration of 0)bridge

@ .0ORKING %ROCEDURE

@.1 0ORKING %ROCEDURE

-obotics is an interesting sub$ect to discuss about and in this ad!anced world

-obots are becoming a part of our life. n this pro$ect we are going to discuss about a

robot which is capable of following a line without the help of any external source.

The Embedded (ine following robot uses two motors to control rear wheels and

the single front wheel is free. t has 9)infrared sensors on the bottom for detection of

black tracking tape. Ghen the middle sensor detects the black color, this sensor output is

gi!en to the comparator (194


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Ge follow a simple logic to implement this pro$ect. As we know that black colour

is capable of absorbing the radiation and white colour or a bright colour reflects the

radiation back. 0ere we use 9 pairs of - TI and -x .The robot uses these - sensors to

sense the line and the arrangement is made such that sensors face the ground. The output

from the sensors is an analog signal which depends on the amount of light reflected back

and this analog signal is gi!en to the comparator to produce &s and +s.

nternally we ha!e an =T 6one time programmable8 processor which is used to

control the rotation of the wheels. The rotation of these wheels depends up on the

response from the comparator. (et us assume that when a sensor is on the black line it

reads & and when it is on the bright surface it reads +.

0ere we can get three different cases, they are;

+. /traight direction

4. -ight cur!e

9. (eft cur!e

epartment of ECE


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@.1.1 St#")/+t d)#e't)o

Ge can expect our robot to mo!e in straight direction when the middle sensors

response is low and the remaining two sensors response is high. i.e., according to our

arrangement the middle sensor will always be on the line and as the line is black in colour

it will not reflect the emitted radiation back and the response of the sensor will be low

and the response of the remaining two sensors will be high as they will be on the bright

surface.

@.1.2 R)/+t '4#e

Ghen a right cur!e is found on the line the responses will change i.e. the response

of the first sensor which is to the right will become low as that sensor will be facing the

black line and the reaming sensors response will be high. Ge this data is achie!ed the

control of the wheels is changed i.e. the right wheel is held and the left wheel is made to

mo!e freely until the response from the middle sensor becomes low. Then the same

process repeats again.

@.1.3 Let '4#e

Ghen a left cur!e is found on the line the response of the left most sensor will be

changed from high to low as the sensor will now face the black or the dark surface. Then

the control of the wheel changes i.e. by holding the left wheel and allowing the right

wheel to mo!e freely until the middle sensor changes it’s response from high to low.

The same process continues for all the turns and the robot mo!es continuously until the

supply is remo!e

@.2 STE%S TO FOLLO0 T$E LINE >USING SINGLE SENSOR?

• /tart

• Check for line

• (ine detected go right

•

Check for line

• f no line turn left till line detected

epartment of ECE


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9. A%%LICATIONS

Id4st#)", A**,)'"t)os

These robots can be used as automated e"uipment carriers in industries replacing

traditional con!eyer belts.

A4tomob),e A**,)'"t)os

These robots can also be used as automatic cars running on roads with embedded

magnets.

Domest)' A**,)'"t)os

These can also be used at homes for domestic purposes like floor cleaning ,0ome

applications etc.

G4)d"'e A**,)'"t)os

These can be used in public places like shopping malls ,museums and other

applications.

epartment of ECE


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. AD&ANTAGES

-obot mo!ement is automatic. #it and #orget system.

sed for long distance applications. efense applications. sed in home, industrial automation. Cost effecti!e. /implicity of building.

epartment of ECE


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6. RESULT

The ob$ecti!e of the line following robot is to follow a line on its gi!en path

which is obtained for which it uses - sensors which detects the line and sends the

information to (194< comparator and then to 0 bridge which controls the working of

the wheel’s. 1icrocontroller controls the other operations.

#igure B.+ represents the out put of line follower robot.

O4t*4t o L)e Fo,,o!e# Robot

#ig. B.+ =utput =f line #ollower -obot

epartment of ECE


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7. CONCLUSION

n this pro$ect we ha!e studied and implemented a (ine #ollowing -obot using a

1icrocontroller for blind people. The programming and interfacing of microcontroller

has been mastered during the implementation.

epartment of ECE


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8. FUTURE SCO%E

• /marter !ersions of line followers are used to deli!er mails within office building

and deli!er medications in a hospital.

• This technology has been suggested for running buses and other mass transit

systems and may end up as a part of autonomous cars na!igating the freeway.

epartment of ECE


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1:. REFERENCES

+. Embedded /ystems *y -a$ >amal

4. 2&3+ 1icrocontroller and Embedded /ystems *y 1a''di

9. 1aga'ines)Electronics for you

3_Line Follower Robotic Doc _org

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