MobilePhone Controlled Robot Complete Document

7/21/2019 MobilePhone Controlled Robot Complete Document

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Mobile Phone

Operated Land Rover

Raghavendra,Rahul

www.raghu.co.nr

[email protected]


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obotics is an interesting fieldwhereevery engineer can showcasehis creative and technical

skills.Pleasingaspectofrobotics isthatarobotcanbemade indigenouslybyanyone. Inthis

competitiveworldthereisneedforeveryenthusiastic,fromamateurtoprofessional,tomakea

simplerobothavinginnovatedapplicationsandwithrobustcontrol.

Mobilephones

today

became

an

essential

entity

for

one

and

all

and

so,

for

any

mobile

based

application

there isgreat reception. In this scenariomakingamobilephoneoperated land rover isagood idea.

Conventionallywireless controlled robotsutilize RF circuits,whichhad limitations like limited range,

limited frequency ranges and controls. But a mobile phone controlled robot can hold up these

limitations. Ithasarobustcontrol,unlimitedrange (coverageareaoftheserviceprovider),no fearof

interferingwithothercontrollersandwecanhaveasmuchas12controls.

Although the appearance and capabilities of robots vary vastly, all robots share the features of a

mechanical,movablestructureundersomeformofcontrol.Thiscontrolofrobotinvolvesthreedistinct

phases perception, processing and action. In common the preceptors are sensors mounted on the

robot,processing

is

done

by

on

board

microcontroller

or

processor

and

task

(action)

is

performed

using

motorsorwithsomeotheractuators.

ProjectOverview

Inthepresentprojecttherobotiscontrolledbyamobilephonewhichmakesacalltothemobilephone

attachedtotherobot.Inthecourseofacallifanybuttonispressedatonecorrespondingtothebutton

pressed isheardat theotherendof thecall.This tone iscalledDTMF tone.The robotperceives this

DTMFtonewiththehelpofaphonestackedintherobot.Theprocessingofthereceivedtoneisdoneby

Atmega32microcontrollerwith thehelpofDTMFdecoder,HT9170.Thedecoderdecodes theDTMF

tone in to its equivalent binary digit and this binary number is sent to the microcontroller. The

microcontrolleris

preprogrammed

to

take

adecision

for

any

given

input.

The

microcontroller

outputs

its

decisiontomotordriverstodrivethemotors inordertohaveforwardorbackwardmotionoraturn.

Anymobilewhichmakesacalltothemobilephonestackedintherobotwillactasremote.So,thisisa

simpleroboticprojectwhichevendoesnotrequiretheconstructionofreceiverandtransmitterkits,but

hasaninnovatedapplicationofcellphoneandrobustcontrol.

Dualtonemultifrequency (DTMF)signaling isused for telephone signalingover the line in thevoice

frequencyband to the call switching center.TheversionofDTMFused for telephone tonedialing is

known by the trademarked term TouchTone. DTMF assigns a specific frequency (consisting of two

separatetones)toeachkeysothatitcaneasilybeidentifiedbyamicroprocessor.Thesignalgenerated

byaDTMF

encoder

is

adirect

algebraic

summation,

in

real

time,

of

the

amplitudes

of

two

sine

(cosine)

wavesofdifferentfrequencies,i.e.pressing'5'willsendatonemadebyadding1336Hzand770Hzto

theotherendoftheline.


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InDTMFsystemthetonesandassignmentsareasfollows:

frequencies 1209Hz 1336Hz 1477Hz 1633Hz

697Hz 1 2 3 A

770Hz 4 5 6 B

852Hz 7 8 9 C

941Hz * 0 # D

CircuitDescription

Figure1showstheblockdiagramofthemobileoperatedlandrover.Theimportantcomponentsofthis

projectareDTMFdecoder,Microcontrolleranddriver.

TheHT9170seriesareDualToneMultiFrequencyreceivers(DTMFdecoders).All

typesoftheHT9170seriesusedigitalcountingtechniquestodetectanddecode

allthe16DTMFtonepairsintoa4bitcodeoutput.Abuiltindialtonerejection

circuit is provided to eliminate the need for prefiltering. When input signals

givenatVP(1)andVN(2)pinsarerecognizedtobeeffective,DV(15)becomes

high,andthecorrect4bitcodeofthetone(DTMF)istransferredtotheoutput

pins,D0(11)D3(14).Figure2showstheICspinassignment.Figure3showsthe

DTMFdataoutputtableofHT9170series.

Themicrocontrolleroutput isnot sufficient todrive theDCmotors, ahighvoltage andhigh current

drivers are required. The L293D is a quadruple high current half H driver designed to provide

Figure

1

,

Block

diagram

Headset

HT9170

DTMF

decoder

MICROCONTROLLER

ATmega32L

2

9

3

D

Left

motor

Right

motor

Robot

MotordriverMobileusedas

Remote

Figure

2,

Pin

Assignment


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bidirectionaldrivecurrentsofupto600mAatvoltagesfrom4.5Vto36V.Itwillbecomeeasiertodrive

dcmotorswithsuchdrivers.Refertothe logicaldiagramandthe functionaltableofthedrivershown

below.Drivers are enabled in pairs with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 are

enabledby3,4EN.Whenanenable input ishigh,theassociateddriversareenabled,theiroutputsare

active and in phase with their inputs. External highspeed output clamp diodes should be used for

inductivetransientsuppression.

Figure

3

DTMF

Data

Output

Table

Figure5 FunctionalTableofL293D

Figure4LogicaldiagramofL293D


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MicrocontrollerusedinthisprojectisATmega32.ItisalowpowerCMOS8bitAVRmicrocontrollerwith

32K bytes in system programmable Flash. It has EEPROM of 1024 bytes, 8 channel 10 bit ADC, 32

programmableI/Olines,Speedgradesof016MHzitisbasedontheAVRenhancedRISCarchitecture.

Thecompilerused forproject is ICCAVRcompiler.This isacrosscompilerand itstrialversioncanbe

downloadedfromtheImagecraftcompilerwebsite.Compilationandburningofthecodewillbeeasier

foramateurswiththissoftware.ThecircuitforprogrammingthemicrocontrollerandtheISPcablefor

parallelportisshownbelow.

SoftwareDescription

Withefficientsoftware,eveniftherearelimitedcontrols,wecanhaveanewcontrolwithcombination

oftwoormoreavailablecontrols.ThecrosscompilerusedinthisprojectsupportsCprogramming.The

Ccodeoftheprojectisgivenbelow.TheCprogramcodeiscrosscompiledintohexcodeandburnedin

tothemicrocontrollerusingtheparallelportISP.

Working

Theuserinordertocontroltherobotshouldmakeacalltothecellphoneattachedintherobot,from

anyphone,whichcansendDTMFtunesonpressingthenumericbuttons.Thecellphone intherobot

willbekept inautoanswermode.So,aftera ring thecellphoneaccepts thecall.Now theusermay

pressanybuttononhismobile.TheDTMFtonesthusproducedarereceivedbythecellphone in the

robot.Thesetonesarefedtothecircuitbyheadsetofthecellphone.HT9170decodesthereceived

tone and sends equivalent binary number to themicro controller.According to the program in the

microcontroller,therobotstartsmoving.

Figure6CircuitformicrocontrollerprogrammingFigure

7

ISP

cable

for

parallel

port


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Asshowninthecircuit,theinputtothecircuitfromtherobotscellphoneisgiventhroughheadsetat

the2nd&3rdpinsofHT9170.ThedecodeddigitaldatawillbegivenoutbytheHT9170at11,12,13&14

pins.Thesedigitsarenegatedusing4notgatesofa7404HEX INVERTER.This inverted inputwillbe

given to theportAofmicro controller at 37,38,39 and40pinswhich are PA3, PA2, PA1 andPA0

respectively.ThemicrocontrollerisprogrammedtogiveoutputatportD,tocontrolthemotordriver.

Asexplainedpreviously,themotordriverL293DcandriveaDCmotorwithanenableandtwocontrol

inputs.So,inputsat1A(2),2A(7)andenableat1,2EN(1)candriveaDCmotorconnectedat1Y(3)and

2Y(6).ThePD0 (14),PD1(15)andPD7(21)pinsofportDofmicrocontrollerareconnectedto1A,2A

and1,2ENpinsrespectively.So,with1,2ENpinenabledandif1A,2Apinsareprovidedwith1,0asinput

respectively,themotorrotates inadirectionand0,1 inputmakesthemotortorun inviceversa.And

the input1,1causeselectricalbrake.Themicrocontrollerisprogrammed insuchawaythatwhenthe

userpresses (for ex.) 2button, both thedriverswillbe activated tomake theirmotors tomake a

forwardmotion.Adetailedtable isgivenbelow,delineatingeverystep indatatransferwhenadigit is

pressed.

No.pressed

by

user

O/pofHT9170

DTMF

decoder

I/ptothe

microcontroller

o/pfrom

microcontroller

ActionPerformed

2 0x02

00000010

0xFD

11111101

0x09

00001001

Forwardmotion

4 0x04

00000100

0XFB

11111011

0x05

00000101

Leftturn

Rightmotorforwarded

Leftmotorbackwarded

6 0x06

00000110

0XF9

11111001

0x0A

00001010

Rightturn

Rightmotorbackwarded

Leftmotorforwarded

8

0x08

000010000XF7

111101110x06

00000110Backward

motion

5 0x05

00000101

0XFA

11111010

0x00

00000000

Brake

Figure

8

Detailed

data

of

every

step

Applicationdevelopment

The generic purpose land rover delineated in this project can be further improved to have specific

purposes. For a land rover we need to have 4 controls, to make it roam around. The remaining 8

controlscan

be

configured

for

other

purposes,

by

some

modifications

in

the

software

code

of

microcontroller.

Letsnowupgradeourlandrovertoasumorobot,whichhastofightordefenditselfinagivenarena.

Thebasicmovementofforward,backward,turnrightandturnleftcanbeassignedto2,8,4and6.For5

wecanhaveabreak.Nowweshouldaddsomeweapontomaketherobotcapableofattacking.Lets

take some longwooden ruler and adcmotor.Ahole ismade at the centerofwooden ruler and is


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pivotedtightlytotheaxleofmotor,suchthattheaxlewillbecomeperpendiculartothesurfaceofruler.

Withthisarrangementtherulerwillrotatealongaverticalaxispassingthroughitscenter,sothatitcan

attackanyrobotcomingwithinthisarea.Anadditionalmotordrivershouldbeemployedtodrivethis

motor.Andnowweshouldengagetwomorekeys(*,#)tocontroltherotationofthisruler.Forthiswe

needtoprogramthemicrocontrollertodrivethemotorsinonedirectionif* ispressedonceandstop

therotationifthesame*ispressedagain;if#ispressedthemotorshoulddriveinotherdirectionand

shouldbe

stopped

if

pressed

again.

Inthisfashiononecaninnovativethelandroverinanywaytheapplicationdemands.Wecanaddsome

ball holding mechanism to make a ball picking and dropping robot. If we add some ball pushing

mechanism,thenthelandroverwillbecomeasoccerrobot.Likethiswecangoonimprovingtheland

roverfordifferentapplications.

MechanicalConstruction

For constructionof any robot, the importantmechanical constraint is thenumberofmotorswe are

goingtousing.Onecanhaveeithertwowheeldriveorafourwheeldrive.Fourwheeldriveeventhough

iscomplex

than

two

wheel

drive

will

provide

more

torque

and

good

control.

Two

wheel

drive

is

very

easytoconstruct.

Topandbottomviewsofalandrover,fourwheeldriven,isshowninthefigurefIg10.Thechassisused

inthatmodelisasheetmadeupofparaxandisofsize9x20cm.Motorsarefixedtothebottomofthis

sheetandcircuit isplacedabovethissheetand it isaffixedfirmly.Acellphone isalsoplacedoverthe

sheetasshowninthefigure.

Inthefourwheeldrivesystemthetwomotorsinasidearecontrolledparallel.SoasingleL293Ddriver

Figure

10

top

view

of

the

rover

Figure

9 bottom view


8/10

IC candrive the rover.But in twowheeldrive thepairofmotorsona side is replacedwitha single

motor.Some supportingwheels like castorwheelsareused to support the robot in twowheeldrive

mechanism.A twowheeldriven land rover isdisplayed in the figure10,11.For this robotbeadsare

affixedwithglue,willactassupportwheels.

Figure

12.

front

view

of

the

chassis

and

a

land

rover.

Thecircuit,whichisusedintheproject,isshownbelow. Aschematicofthecircuitisalsoshown,to

haveaclearidea.

I/pfromheadsetto

decoderHT9170,DTMFdecoder

IC7404hexinverter

Atmega32,microcontroller

L293D,motordriver

Inputtomotorfromdriver.

Figure

11.

land

rover

with

a

2

wheel

drive


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Figure

13.

The

entire

schematic

of

the

circuit

i/pfromheadset


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CProgramcode

#i ncl ude#i ncl udevoi d del ay( unsi gned i nt i ){unsi gned i nt j ;whi l e( i - - )f or ( j =0; j

MobilePhone Controlled Robot Complete Document

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