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Quad-CopterAutonomous Surveillance Robot

EEL 4914 Senior Design I Documentationunder Dr. Samuel Richie

Group !David "algo#a

Engers $ Davance "ercedesStephen Smith%oshua &est

Summer'$all ()1)

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Contents

.................................................................................................................................I

CONTENTS............................................................................................................II

1 INTRODUCTION.................................................................................................1

1.1E*ecutive Summar+.......................................................................................11.( "otivation......................................................................................................(1.! Goals and ,b-ectives....................................................................................!1.4Reuirements and Speci/ications...................................................................01.0 Riss..............................................................................................................0

2 RESEARCH.........................................................................................................7

(.1 Aeronautics....................................................................................................2(.( 3oer Source..............................................................................................1!(.! "otors..........................................................................................................(5(.4 "icrocontrollers...........................................................................................!!(.0 So/tare......................................................................................................!2

(.6 &ireless 7ommunications...........................................................................!9(.2 Sensors.......................................................................................................01(.5 8ideo S+stem..............................................................................................66

3 DESIGN.............................................................................................................68

!.1 Linear 7ontrol S+stem.................................................................................65!.( &ireless 7ommunication S+stem...............................................................24!.! $light Stabilit+ S+stem.................................................................................5(!.4 Distance and ground sensors.....................................................................55!.0 Altitude "easurement and directional sensing...........................................9)!.6 Location:avigation S+stem ' G3S "odule................................................9(!.2 "7; 3ins....................................................................................................9!

!.5 8ideo S+stem..............................................................................................99!.9 Aeronautics................................................................................................1))

4DESIGN SUMMARY........................................................................................100

4.1 3oer........................................................................................................1)14.( "icrocontroller...........................................................................................1)!4.! Sensors.....................................................................................................1)04.4 Linear 7ontrol S+stem...............................................................................1)94.0 &ireless 7ommunication...........................................................................11)4.6 $rame........................................................................................................11!

5 PROTOTYPING..............................................................................................114

0.1 &ireless 7ommunication...........................................................................114

0.( Sensors.....................................................................................................1166 TESTING.........................................................................................................118

6.1 Linear 7ontrol S+stem...............................................................................1156.( &ireless 7ommunication...........................................................................1()6.! Sensors.....................................................................................................1(16.4 "7;..........................................................................................................1(!6.0 8ideo S+stem............................................................................................1(0

7 PROJECT MANAGEMENT............................................................................125

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2.1 Group ,rgani#ation...................................................................................1(62.( Estimated

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1 Introduction

1.1Executive Summary

The quad-copter could be described as a UAV (Unmanned Aerial Vehicle !ithautonomous subsystems. "t !ill be equipped !ith a video transmittin# subsystemso its purpose could be $or surveillance. "t also !ill have a small payload capacitythat could be applied to the emer#ency delivery o$ lo! !ei#ht supplies to remotelocations. %o!ever& perhaps the most si#ni$icant purpose o$ the quad-copter issimply the exercise in en#ineerin# desi#n that it is intended to be.

The motivations to choose the quad-copter as a senior desi#n pro'ect are variedamon# the #roup members. At some point a consensus arose to build a robot&then a robot !ith sensors and autonomous capabilities& and $inally the consensusshi$ted $rom a mobile #round robot to a $lyer. At $irst there !ere concerns about

the technical di$$iculties involved in desi#nin# and buildin# a $lyer ho!ever& theidea o$ a $lyer also #enerated enou#h excitement that ultimately the challen#e!as accepted.

As the quad-copter concept has developed& its characteristics and capabilitieshave become more de$ined. The quad-copter is a small li#ht!ei#ht hover-capable vehicle that can be controlled over a custom !ireless system. Thecustom !ireless protocol& developed by the #roup speci$ically $or the quad-copter& is li#ht in codin# and overhead. The quad-copter !ill have a robustsensor suite so that it can also operate in a more autonomous mode. Theautonomous mode includes subsystems such as a )S module so that the

quad-copter& once #iven a )S tar#et location& can ma*e its o!n !ay to thetar#et coordinates !ithout $urther human control. This $li#ht mode requiresadditional subsystems such as ultrasonic proximity sensors& so that the robot candetect and avoid obstacles (includin# the #round and a di#ital compass& so thatits direction can be ascertained and corrected. All o$ these sensors send a lot o$data to the +,U& the brain o$ the quad-copter& !hich must process thein$ormation accordin# to its al#orithms and prompt the appropriate subsystems toaction. An especially complex tas* assi#ned to the +,U is to maintain level $li#htby varyin# the speed o$ individual motors based upon the calculation o$ datareceived $rom the "+U ("nertial +easurement Unit. The "+U combines data $roma triple-axis accelerometer and a dual-axis #yroscope usin# a sensor $usion

al#orithm. The subsystems o$ the quad-copter are hi#hly interdependent& lin*edby the +,U& the physical $rame& and the po!er system. )o!er comes at apremium in an aerial vehicle !here $li#ht duration varies directly !ith its total!ei#ht. The $rame must be desi#ned stron# and ri#id enou#h to support all theother systems yet& li#ht enou#h to so as to prolon# $li#ht duration to acceptablelevels.

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1. +otivation

The initial motivation o$ this pro'ect !as to create a $lyer $or surveillancepurposes. "n decidin# on the quad-copter& the #roup measured the di$$erences

bet!een this pro'ect and a variation on the A..+./..0. pro'ect (a #roundvehicle $rom last semester. The #roup had to evaluate the $easibility o$ a $lyerversus a #round vehicle in terms o$ the #roups resources such as time& technical*no!led#e and $inances. The #roup had and still operates under the assumptiono$ not receivin# third-party $inancin# $or the pro'ect. 2o one in the #roup !as amember o$ the robotics club3 and only one member had built a basic robot& !hich!as a variation o$ the hoomba bot. The #roup consists o$ t!o electricalen#ineers and t!o computer en#ineers !hich should constitute enou#hcombined technical *no!led#e to desi#n thecontrol system $or either vehicle. Thequad-copter !as ultimately chosen based upon the reali4ation o$ $easibility& itspossible $uture applications& and the en'oyment o$ buildin#& testin#& and

implementin# a $lyer.

The #roup members *ne! the quad-copter !as a possible idea. 0urin# thedecisionprocess& the #roup members researched other #roups !hich hadattempted to build a similar type o$ quad-copter. The research yielded somevideo successes on 5ouTube& as !ell as a $e! $ailures !hich questioned the#roups6 ability to construct and test the quad-copter. To determine !hether or notthe #roup should press $or!ard& it !as decided to create an archetype byprototypin# a very basic t!o-rotor copter. 7ithin t!o !ee*s& the bi-copter !asconstructed out o$ )8, pipin#& t!o brushless 0, out-runners& an Atmelprocessor& t!o ,-batteries& and hoo*-up !ire connected to a car battery. The

initial test $li#ht& !hich !as done in 9une o$ this year& !as success$ul in terms o$expected po!er to !ei#ht ratios. The success$ul test !as si#ni$icant in that itsubstantiated the $easibility o$ the quad-copter thereby crystalli4in# the #roupsresolve to build an aerial vehicle rather than a #round vehicle.

"nitially& !hat the #roup !anted to do !as somethin# that !ould bene$it auser interms o$ application. /ne o$ the lon#-term up#rades to be considered !as thepossibility o$ usin# the $lyer $or carryin# li#ht!ei#ht payloads to unreachableareas. "n the military& this !ould mean a syrin#e o$ penicillin to a patient in adilapidated buildin# or mountain ran#e. This same application !ould also beused in civilian areas !hich are prone to natural disasters& such as areas

a$$ected by earthqua*es and tornados. Such disasters can destroy part o$ abuildin#& and can leave the rest o$ the buildin# structurally unsound. This !ouldalso ma*e it di$$icult $or $ire$i#hters and E+Ts to reach areas !hich require basicmedical attention. The on-board camera !ould also allo! the user to #et a visualperspective o$ the area bein# traversed. This !ould allo! users& such as$ire$i#hters& alternative routes to be able to reach the people& as !ell asdetermine to an approximation the structural dama#e to construct a time tablebe$ore a buildin# collapses.

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The #roup !anted to build a quad-copter over the A..+./..0. up#radebecause the #roup !anted to build a $lyer. "t !as the $irst experience mostmembers !ould have in buildin# a robot& and the experience in buildin#somethin# $or each member to test and $ly is remar*able. All the members o$ the

#roup have a love $or $lyin# planes and copters in simulation and #ames& so thisis a means o$ testin# ho! to $ly !ith a unique $lyer. The desi#n !ould also allo!$or #roup members to test interaction devices& !hich are the ultrasonic sensorsand the )S modules& to create a $lyer !hich could use ob'ect avoidance andestablish a $li#ht path& respectively and concurrently. 8ecause the quad-coptersho!s #reat vertical stability& it !ould be ideal desi#n $or testin# the paradi#m inan aeronautical situation. :or other members& the pro'ect pushes to desi#n acommunications protocol and see it in action. This allo!s $or certain desi#nchallen#es due to the motors ma#netic e$$ects& as !ell as determinin# the issueo$ inter$erin# !ith the on-board di#ital compass. 8ut the most important learnin#aspect& the #roup #ets to learn the basics o$ $li#ht in a live scenario& and ma*e

ad'ustments to the quad-copter to simpli$y the inter$ace $or the applicationsdiscussed above& as !ell as $or a re#ular consumer interested in $lyin# this quad-copter.

1.; oals and /b'ectives

The main #oal o$ this pro'ect is to create li#ht!ei#ht $lyer that can maintain asteady altitude in $li#ht& $ly in accordance to a pre-set $li#ht path& has a simpleinter$ace $or controllin#& and has the capability to carry a payload. The quad-copter is to be used by any user capable o$ responsibly usin# the $lyer.There$ore& a desi#n and controller based on a be#inner-level pilot6s s*ills are

essential to the pro'ect.

The $irst #oal is so$t!are implementation and testin#. The t!o processors !illimplement a hi#h-level lan#ua#e to process commands and $or $ast debu##in#.The computer inter$ace !ill be a U"& or #raphical user inter$ace& developed on ahi#h-level lan#ua#e. )7+ si#nals are to be implemented and tested on theA1. A means o$ controllin# the si#nal in small steps !ill be used $or tiltmeasurements. A means o$ error-correction !ill be made to compensate $ortiltin# $or $or!ard& reverse& and turnin# by measurin# accelerometer and#yroscope measurements. ,hec*in# $or altitude !ill be accomplished by both anultrasonic sensor and by measurin# and estimatin# pressure and temperature

data usin# a pre-calculated array. The so$t!are !ill ta*e into consideration thesamplin# rate o$ all analo# inputs $rom their respected A0,s to con$irm the #ivendata.

The second #oal is to setup a remote communications device to communicate!ith the controller. The main controllin# device $or testin# the device !ill be donethrou#h a computer inter$ace& !ith the possibility o$ addin# a separate controller.The communications !ill be done usin# a customi4ed system o$ ?i#8ee&

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=@o!)an protocols& and point-to-point communications bet!een eachtransceiver. These protocols !ill be communicated $rom a micro!ave antenna& toa dedicated processor& to be sent via UAT to the main processor. The mainprocessor !ill then interpret the command to determine user-instructedcommands to determine !hether the command is either a non-autonomous& real-

time $li#ht controlled by the user3 or an autonomous command preset by thecomputer $or a demonstration or surveillance $li#ht.

The third #oal involves #ettin# the quad-copter in the air in stable $li#ht. This isde$ined as bein# able to li$t $rom the #round to a steady-state position !ith almostno lateral dri$t and no spinnin#. Simply put& !hat is assi#ned as the $ront stays$acin# the same direction until the user sends the command to move. This !ill be$irst used in an environment !hich allo!s $or more accurate readin#s under idealconditions& !hich are a controlled temperature in an enclosed space& pre$erably a#ara#e or indoor bas*etball court. To reach this #oal& tests must be done on themotors to determine the types o$ si#nals needed to stabili4e $li#ht. This !ould

mean testin# the si#nals to the accelerometer& #yroscope& and the di#italcompass to determine direction and tilt. These tests !ill handled by manipulatin#the )7+ si#nals bein# sent to each o$ the motors controlled via computerconnection. This !ill& at $irst& be done by connectin# the $rame !ith a prototypeboard onto an apparatus to allo! $or the quad-copter to tilt si#ni$icantly !ithoutcrashin# the copter.

The $ourth #oal is to #et real-time $li#ht telemetry. This !ould be done by testin#the $li#ht controller& !hich con$irms the )7+ si#nals sent to each motor. Thealtimeter& !hich is a pressure sensor& !ill be used to test the overall hei#ht !hichcan be reached !ithin tolerance o$ the transceiver. The transceiver6s ran#e $romthe base unit& !hich is in this case a +ac8oo*& !ill be tested in terms o$ indoorand outdoor communication limitations. The accelerometer and #yroscopecontrollers !ill be tested in outdoor areas to determine stability under li#htturbulence& or li#ht bree4e interactions& as !ell as testin# $or!ardreversemovement and turnin# and ho! it a$$ects stable $li#ht. The ultrasonic sensors !illtest the quad-copters auto-correction system to allo! $or autonomous $li#htcontrol in areas !here the user has little or no direct control. The mountedcamera system !ill be tested under airborne conditions to determine possiblevibrations and 'itterin# e$$ects& !hich !ill be compensated by a $oam bu$$er.:inally& $li#ht time !ill be monitored $or the quad-copter thus& determinin# theamount o$ practical application time and usa#e.:urther #oals and ob'ectives arebulleted belo!.

To create a li#ht !ei#ht& !ireless-controlled quad copter !ith a mountedcamera.

To build a quad-copter !hich can hover and maintain an altitude at arelatively stable position

The copter must have navi#ational capabilities $or trac*in# andpositionin#.

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The copter must be able to be controlled via computer inter$ace via aseparate controller.

The copter must be able to receive and interpret a preset $li#ht path.

The copter needs to use ob'ect sensin# to avoid collision and modi$y $li#htpath

The copter needs to return #yroscope and altimeter si#nals $or current$li#ht in$ormation (telemetry.

The copter must #ive po!er $eedbac*& $rom the en#ines and theprocessor& via !ireless connection (telemetry.

The quad-copter must have the capability to ta*e video or pictures.

1.>equirements and Speci$ications

The requirements and speci$ications $or speciali4ed subsystems o$ the quad-copter !ill be addressed individually in the appropriate research subsections o$

this document. eneral requirements and speci$ications $or the quad-copter arebulleted belo!B

+ust be able to li$t *# o$ mass& includin# the mass o$ the unit.

2avi#ation must be accurate to !ithin 1C $t. (< and 5 coordinates.

A .> %4 si#nal !ill be used to transmit telemetry and $or direct usercontrol.

The quad-copter must maintain $li#ht $or a minimum o$ D minutes.

The $rame must be li#ht!ei#ht& pre$erably less than CC# total.

The quad-copter should have a radius o$ less than C in.

The quad-copter must be able to detect ob'ects (includin# the #round!ithin a ran#e o$1 to = $t. minimum. The copter must be able to move in D basic directions $or!ard& rotate

le$t&rotate ri#ht& rise and descend.

The quad-copter should achieve a minimum speed o$ ; mph.

The copter must be able to be controlled via !ireless computer connectionusin# *eyboard commands $or direct control !ithin a 1CC $t. radius.

1.D is*s

The quad-copter as envisioned is a complex pro'ect !ith multiple potential pointso$ $ailure. The assumption that a *no!n ris* is pre$erable to an un*no!n ris*'usti$ies $urther analysis o$ the ris*s associated !ith the quad-copter. Accordin#to a text on so$t!are en#ineerin#& ris*s can be quanti$ied by equatin# ris*exposure !ith the product o$ ris* probability and ris* impact ()$lee#er& ch;.=.This approach is su$$icient as a basis $or assessin# ris*s and ultimately avoidin#ne#ative consequences pertainin# to the pro'ect. The ris*s involved in such apro'ect can come in many $orms ran#in# $rom issues o$ personal sa$ety& a hi#h

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impact ris*& all the !ay do!n to losin# a letter #rade& a lo!er impact& hi#herprobability ris*.

There are issues o$ personal sa$ety involved !ith the quad-copter such as thepotential combustion o$ the @i)o (@ithium )olymer battery i$ char#ed incorrectly.

This ris* can be overcome throu#h researchin# sa$ety precautions& implementin#the precautions& and by buyin# the most suitable equipment !ithout bein# overlys!ayed by price& i.e. by not buyin# a cheap char#er. Another& lo!er impact& ris*associated !ith the @i)o battery is that i$ the battery is drained too much then thebattery could become un-rechar#eable and there$ore a timemoney ris*. This ris*can be addressed throu#h po!er re#ulation and emer#ency shutdo!nprocedures but& it could still be considered as havin# a si#ni$icant de#ree o$probability and thus& havin# a si#ni$icant total modi$ied ris* exposure. /therpersonal sa$ety concerns include !or*in# !ith the substantial current o$ the @i)obatteriesand potential in'ury $rom the propellers. Also to be considered is that i$the quad-copter !ere to #et out o$ control and cause in'ury to the public then

liability !ould be a $actor. Another ris* that should be mentioned is that somemotorpropeller testin# !as underta*en usin# a car battery as a po!er source&!hich has a potentially $atal level o$ ampera#e. There are other ris*s moreuniquely associated !ith the quad-copter as the choice o$ a pro'ect. )revioussenior desi#n #roups have had #reat di$$iculty in achievin# $li#ht stability !ith aquad-copter. :rom their mista*es it is learned that early prototypin# should beunderta*en in order to reduce this ris*. "$ the quad-copter cannot maintain asteady hover in a time $rame compatible !ith the milestone chart then the ris* o$not havin# a success$ul pro'ect increases. Another hi#h probability pro'ectcompletion ris* is that the !ireless communication system& $or direct control o$the quad-copter& is to be an ori#inal& custom desi#ned system underta*en by a#roup member !ith substantially more enthusiasm than experience on thesub'ect. A#ain& previous senior desi#n #roups have had di$$iculties !ith similarsystems. Althou#h this custom !ireless system !ill undoubtedly be ri#orouslyattempted& there remains the ris* o$ $ailure. This ris* could be partially miti#atedby maintainin# a bac*up plan o$ substitutin# a predesi#ned system at the lastminute.

There are numerous hi#h probability pro'ect completion type ris*s associated!ith the quad-copterB +,U code development& parsin# ", serial data& po!erdistribution and re#ulation& Aeronautics& and the list #oes on. The quantitymultiplied by the probability multiplied by the impact level o$ these pro'ectcompletion ris*s !ould there$ore seem to #enerate a substantial level o$ ris*exposure accordin# to the ris* assessment rubric. "n conclusion& !hile hi#himpact ris*s should not be underrated& lo!er impact ris*s can accumulate tothreaten a pro'ect. The quad-copter is a technically demandin# endeavor that !illrequire all members o$ the #roup to $unction on a steep learnin# curve.

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2 Research

.1 Aeronautics

.1.1 :li#ht 8asicsA $e! basics !ill need to be discussed re#ardin# $li#ht capabilities. Aeronauticsutili4es concepts o$ air pressure and exploits them to create a li$t $orce. Thus& it!ill be bene$icial to revie! a $e! core concepts o$ pressure and ma*e someassumptions.

The $irst concept is the air pressure. 0eep sea divers are *no!n $or livin# underlar#er de#rees o$ !ater pressure $or days at a time. The deeper they #o& themore pressure they experience. This concept is similar to people !ho live in themountains. The hi#her they are& the less pressure they experience. The

observation can be made that aeronautical en#ineers& !hen desi#nin# a system$or $li#ht& re$er to a pressure ratio rather than simply to pressure. The air pressureratio relates the current pressure !ith the pressure at sea level& therebyestablishin#a relation bet!een air pressure and altitude& but not a directequation. Table 1 provides a basic set o$ data $or relatin# the air pressure toaltitude.

Altitude+easurements

Temperature +easurementsAtmospheric

)ressure:eet +eters :ahrenheit ,elsius *)a

-CCC -=1C == 1F 1C.

-1DCC ->D => 1 1C=.F-1CCC -;CD =; 1G 1CD.C-DCC -1D; =1 1= 1C;.1

C C DF 1D 1C1.;;DCC 1D; DG 1> FF.>F1CCC ;CD DD 1; FG.=;1DCC >D D> 1 FD.F1CCC =1C D 11 F>.1F

=able 1> http>.sables+s.combaro'altitude.html $rom Sable S+stems.

These are the calculations $ound at sea level. :or residents in :lorida& thetemperature $urther in land !ill be considerable hi#her and should be considered$or possible hi#her #round in other re#ions. 2otice ho! air pressure doesn6t dropto belo! hal$ until =*m above sea level.The next basic concept is temperature& !hich holds a direct relationship !ithpressure. 2otice the temperature is at approximately 1D ,& or DF :. :or most:lorida temperatures& this !ould not come close to !hat is expected on a normal

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day. :or the demonstration& because the initial demonstration is occurrin# !ithina $e! !ee*s o$ the ne! season& temperatures !ill drop to a relatively close ran#eto this temperature. @i*e pressure& desi#ners pre$er usin# ratios.0ensity& another basic concept& also $actors into the aeronautics o$ the quad-copter. Understandin# air pressure $acilitates a #rasp o$ tan#ential speed movin#

throu#h the air$oil& !hich in turn is needed to calculate li$t. 0ensity& in terms o$ air&is #iven in the $ollo!in# equationB

Densit+ euation:R=

3=

7here& is the #as constant& ) is pressure and T is temperature. Thus& a similarrelationship exists $or the density ratio. The calculations $or it on the table arere$erred to as Hsi#maI. The pressure and temperature ratios allo! $or thedetermination& !ithin a de#ree o$ error& the approximate value o$ the current airdensity $or analysis.

The $inal basic concept to consider in choosin# !in# and cra$t desi#n is airviscosity. This is the air $riction caused by a cra$t !hile $lyin# throu#h the air. Thisconstant becomes apparent at speeds close to and exceedin# the speed o$sound& !hich is approximately ;>; ms. At slo!er speeds& viscosity is present&but ne#li#ible in the presence o$ calmer !inds. There$ore& ideal conditions $orviscosity !ill be assumed in the desi#n o$ thequad-copter. "t !ill also be assumedthat the pressure is relatively equal to sea level& meanin# the pressure ratio is atC *m altitude (no si#ni$icant chan#es to pressure occur $or at about *m abovesea level. The table !ill act as a re$erence $or calculatin# air pressure at thedaily temperature. This !ill need to be chec*ed every day o$ prototypin# andtestin#.

Also to beconsidered are the e$$ects o$ pressure $rom airspeed at a cross-section& or the continuity and 8ernoulli6s equations. 8y the continuity equationpresented belo!& the pressure o$ a $luid passin# throu#h and area at a velocityremains constant throu#hout the systemB

7ontinuit+ euation pA8 ?

7here& p is static pressure& A is the cross-sectional area measured& and V is thevelocity o$ the $luid. 8ernoulli applied this *no!led#e to understand the e$$ects o$dynamic pressure& !hich relates air density to air speed& #iven asB

D+namic 3ressure euation> (8(1 J=

7here& J is the air density and V is the speed o$ the air. This equation$acilitatescalculation o$ the required tan#ential airspeed travellin# throu#h anair$oil that provides the required li$t. 8y this relation& li$t is related to an#ularspeed and centri$u#al $orce.

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.1. @i$t and $li#ht stabili4ation

To $acilitate $li#ht stability& t!o $orces must be consideredB @i$t $orce and the+a#nus e$$ect. The most important $orce pertainin# to $li#ht is the li$t $orce. @i$t isbased on the up!ard vertical component actin# on an air$oil6s aerodynamic

center. The $orce !hich reacts to the thrust o$ the air$oil moves in a perpendicularto the air$oil& !hich is represented as a vertical and hori4ontal $orce. Thehori4ontal vector is *no!n as the dra# $orce (as the name implies& it moves inopposition to the thrust. @i$t& !hich !ill need to be related to air density& is #ivenby the $ollo!in# equationB

Li/t euation> .S7L d=

7here& 7dis the li$t coe$$icient& is the dynamic pressure and Sis the plan$ormarea& or the area o$ the blade or air$oil. :or most air$oils& this is measured at thecenter o$ pressure& !hich is usually $ound at the center o$ the chord o$ the blade.

This concept !ill hold true $or most air$oils $ound on standard aircra$t.

"n terms o$ measurin# the li$t $or a helicopter& the propeller speed is consideredrather than the thrust. This is due to the $act that the propeller& !hich is !ith $e!exceptions virtually vertical& is no! operatin# on a hori4ontal plane. Thecentri$u#al $orce used to move a propeller plane $or!ard is no! the primary li$t$orce o$ the quad-copter. This calculation $acilitates optimi4ation o$ the motors inrelation to the propellers at hand. )ropeller desi#n also $actors inas the bladeturns out!ard $rom the center. This results in a chan#e o$ the an#le o$ attac* toits optimum an#le at the tips o$ each propeller blade. This !ould be adisadvanta#e to users !ho are more experienced !ith $li#ht stunts $or

helicopters. "n terms o$ usin# the copter as a surveillance device& it !ould beideal $or the most static picture $rom an aerial perspective.

The other $orce to consider $or is the lateral $orces bein# induced. 2ormally& thereis no dra# $orces $ound on the helicopter in hover. This is due to the dual bladepropeller movin# at such hi#h speeds. The torque #enerated $rom the motorcreates a rotational $orce& causin# the entire cra$t to spin& hence the secondblade to counteract the $orces o$ the torque (called the anti-torque blade. :or thequad-copter& the torques o$ the counter rotatin# blades cancelseach other outthus& protectin# the system $rom dri$t. Another desi#n consideration is the+a#nus e$$ect. This assumes a cylinder o$ in$inite len#th !hich rotates. 7hat !as

$ound !as the air !ould have a tendency to induce a li$t i$ the rotation o$ thecylinder !as movin# relatively up!ards. This is meant to explain !hy a baseballpitcher can curve a ball. :or the pro'ect& the $orce is ne#li#ible in still air at hoverbut& !hen turbulence occurs& it is possible $or this $orce to become imbalancedand create a dri$t $orce. This dri$t $orce is also somethin# to be considered !henin motion. "nitial ta*e-o$$ circumstances must also be ta*en into account. At start-up& the capability o$ a slo! increase in the propellers6 speed to avoid a $ast ta*e-o$$ is desirable.

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:ast ta*e-o$$s !ill have lon# term stress and shearin# e$$ects on the internal boltso$ the cra$t. roundin# e$$ects !ill also lead to a $aster ta*e-o$$ due to more airbein# pushed bac* into the air$lo! o$ the blades. This leads to an initial cyclonice$$ect surroundin# the blades& creatin# $urther stress on the $rame and the

propellers.

.1.; :or!ard +otion

:or!ard motion is still an issue involvin# propellers $or standard helicopters.2ormally& blades on the main rotor can tilt in a !ay to create $or!ard $li#ht. "n thequad-copter desi#n& the propeller blades !ill remain static. To compensate andcreate $or!ard $li#ht& the !hole copter !ill need to be tilted by reducin# the li$tspeed o$ at least one motor. Timin# o$ this is crucial $or maintainin# altitude. Tomaintain altitude& the optimum an#le that the copter can maintain& !ith amaximum $or!ard thrust& is no more than 1C-1D de#rees. There is also the

placement o$ the sensors $or $eedbac* to the processor. The accelerometer andthe #yroscope !ill be required to assist in this $aculty. :or optimal response& theaccelerometer !ill handle lateral and vertical $eedbac*& and a #yroscope !illhandle all rotation $eedbac*. /rientation o$ these devices must be considered $orcontrollin# $li#ht. :urther testin# in the si#nal processin# !ill allo! the user toobserve the required statistics needed to command $or!ard $li#ht.

As a basis $or $indin# the optimum orientation $or $or!ard $li#ht& the helicoptermodel is use$ul. :or the typical copter& the A/A (An#le /$ Attac* $or each bladeis assumed to be optimum $or li$t at 1D de#rees. Since $or!ard $li#ht !ould meana chan#e in an#le o$ the copter& it !ould also mean a chan#e in the A/A& !hich!ill cause a drop in the altitude. To compensate $or this& the above equation&

involvin# the centri$u#al $orce& is modi$ied by settin# the li$t used in hoverin# asthe $or!ard thrust. The ne! li$t is the vertical $orce up!ard& !hich must equatethe li$t in hover be$ore $or!ard motion to maintain altitude. The ne! equations#enerated $rom $or!ard thrust are as $ollo!sB

Li/t euation@Revised> KcosLL hover$ =

$orard =hrust euation> KsinL= hover$ =

7here Lhover is the li$t in hover be$ore $or!ard motion& !hich is calculated bycentri$u#al $orce& and K is the tilt an#le $or!ard. :or small an#les (belo!

de#rees it !ill only appear to be a dri$t& and must test all an#les bet!een D-1Dde#rees $or any clear results. The minimum value is #iven to distin#uish $rom thee$$ects o$ vibration and dri$t to the $or!ard thrust& and the maximum is considered1D since air$oils !hich are an#led at more than 1D de#rees be#in to stall. Thesesame considerations are also #iven $or reverse $li#ht& to allo! $or haltin# $or!ardmotion& as !ell as a reverse $unction $or the copter.

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/nce the copter is in a constant $or!ard motion& the net $orces are considered tobe4ero& and the velocity o$ the copter is re#arded in a linear perspective. Thiscan be said i$ it is assumed that the plane& in !hich the copter6s propellers arerotatin#& is a solid and the mass is centered. This allo!s $or a steady-statevelocity to be established& !hich can be determined by the linear momentum

equation. 2ext& turnin# is also an issue& since $or!ard $li#ht attitude requiresmore po!er. :or turnin#& the solution is the same relation !ith $or!ard $li#ht as!as discussed be$ore. Equations 1.D and 1.= are the same solutions o$ tiltrequired& includin# more thrust required $or $or!ard $li#ht. Since this !ouldrequire additional po!er& the revised equations $rom above are as $ollo!sB

Li/t euation @rev. (B LK coscosLL hover$= =

=hrust euation @rev. (> LK sinsinL= hover$= =

7here theta is the an#le o$ the pitch to be determined& a#ain& the ran#e o$ an#les

theta must be *ept at is bet!een D-1D de#rees& as discussed above.

.1.> :rame

"n considerin# the $rame& the $irst consideration is the material to be used. "t mustbe li#ht!ei#ht& sturdy& and a$$ordable. The $orces !hich act on the aircra$tprimarily !ill be #ravity and air pressure. ravity allo!s $or construction under the#uidance o$ a limited mass to allo! $or structural stability on the #round& as !ellas control o$ the copter in the air. Air pressure& !hich is used to determine theairspeed& !ill a$$ect the quad-copter6s stress on the scre!s at hi#her altitudes.The hi#her the altitude& the li#hter the air& the smaller the $orces a#ainst the

$rame& !hich implies the copter6s $rame& is bein# stretched. This is !hat is *ept inmind !hen considerin# $or the base material $or our aircra$t. :or the pro'ect& threematerials are possibilities due to their popularity in the , 7orldB aluminum&!ood& and carbon $iber tubin#.

7ood is a very popular choice $or many , desi#ners due to its lo! cost and toits so$t nature. %o!ever& issues be#in to arise in an entirely !ooden cra$t&especially in :lorida summer heat and humidity !hich can lead to $urthercomplications in propeller and $rame desi#n. :urthermore& !ood& !ithout muchrein$orcement& has a tendency to bend over a short period o$ use such that thedesi#n !ould quic*ly #o out o$ tolerance. ein$orcin# the !ood is a

possibilityho!ever3 it !ould necessitate more mass bein# added to the system.This !ould be better suited $or an airplane system& but not $or a helicopter.There$ore& a purely !ooden system !ould not be the most prudent approach.

Aluminum !as the next best choice& due to its tolerance to :lorida6s environment.7ith aluminum& test $li#hts can be per$ormed repeatedly !ithout requirin#rein$orcement $rom another source. :urthermore& due to its increased stren#th tostress& aluminum is less li*ely to bend due to ta*e-o$$ or stable $li#ht3 also& it

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carries a stron#er stability to the $rame. This !ould mean a lon#er li$e $or the$rame in re#ard to its basic structure. )roblems arise concernin# the !ei#ht o$ thealuminum beams to meet the minimum quad-copter requirements. "t is advisableto use a minimal amount o$ aluminum& due to its more expensive nature& relativeto !ood. Aluminum could also act as a plate !hich can stabili4e the main board&

as !ell as rein$orce the $rame.

,arbon $iber tubin# !as $ound to be best option $or the quad-copter due to t!o o$its stren#thsB it can handle stretchin# better than !ood& and it is more li#ht!ei#htthan aluminum. 7ood operates better !hen it6s bein# compressed& !hich ma*esit per$ect $or internal structure o$ a lar#er version o$ the cra$t. "t !ould be lesse$$ective $or the quad-copter re#ardin# lon#-term and maintenance issues.

Aluminum !ould be a solution to these issues o$ structure& since most metals(especially aluminum can handle external stretchin# on the structure.

.1.D )ropellers

e#ardin# the propellers used $or this pro'ect& a choice emer#ed as to purchasepremade blades& or to desi#n them $rom scratch. 0esi#nin# them had one ma'oradvanta#e& namely& any si4e and pitch blades could be $ashioned !ithoutconstraint. "n addition& an attachment to the rotor could be created& !hich !ouldmimic a helicopter6s structure. The ma'or disadvanta#es !ere that the onlymaterials conducive to this type o$ experimentation !ould be !ood& and the $actthat no #roup members had ever desi#ned or balanced an , propeller blade$rom scratch. )urchasin# premade blades !ould allo! the use o$stron#er& li#hterplastic as !ell as be a more e$$icient use o$ the #roups time. "t is $or thesereasons that premade propeller blades !ill be bou#ht.

+ost o$ the available propeller blades have a maximum chord len#th& the len#th$rom the $ront tip to the bac* tip o$ the propeller blade& o$ 1 inch. 8y usin# theassumptions above& the best type o$ blade $or the quad-copter can bedetermined. To provide enou#h room $or the centerpiece& !hich !ill house thebatteries and main controllin# unit& and to prevent inter$ere amon# the blades& it!as decided to choose blades !hich !ere at the radial len#th. :or an 1 in.radius $rame& as hi#h as F in. radius blades !ould be acceptable. @ar#er blades!ould mean a possible #reater ris* to the inexperienced pilot& the en#ineersinvolved in testin#& as !ell as any nearby spectators. At the current state o$analysis& a 1 in. radius blade seems the best candidate $or the quad-copter&

bein# less costly and easier to maneuver than !ith a lar#er blade. This smallerdesi#n can allo! $or more versatility in mobility& and can be an implementation $or$uture development. There$ore& = in. radius blades !ould be lar#est blade $or thissi4e o$ copter.

:inally& there is an issue !ith the material $or the propellers. :our materials arevery popular $or useB plastic& !ood& $iber#lass& and carbon $iber. :iber#lass andcarbon $iber !ill do $or the purposes o$ a demonstration ho!ever& these materials

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are more expensive to acquire. 7ood is still popular !ith most , $lyers& and canbe used $or stunts. 7ood& as an , propeller is been prone to brea*in# veryeasily at hi#h speeds. 7ood also needs to be #lued onto the rotor sha$t usin# atype o$ plastic !ed#e. This ma*es replacin# a bro*en propeller di$$icult and time-ine$$icient. )lastic& li*e $iber#lass and carbon $iber& doesn6t su$$er $rom the use o$

#lue. A simple !asher and scre! !ill hold the blade in place. :urthermore&replacement o$ the blade is quic* and simple. There$ore& a plastic blade is thebest choice $or the quad-copter.

. )o!er Source

/ne o$ the most essential items considered in desi#nin#the quad-copteris thepo!er source3 !hich must providea si#ni$icant current to accommodate the $ourmotors. An auxiliary&lo!-7att battery system may be used $or the main board&sensors& !ireless communication& and video systems. Speci$ications andrequirements $or the primary po!er source includeB

%i#h po!er , battery M bet!een 1C.DV to 1V at operational amperes(varies $rom motor to motor.

2o more than CC# o$ mass dedicated to!ards po!er.

+ust be able to sustain a $li#ht time o$ 1C minutes or more.

e#ardin# the types o$ batteries $or the particular motors researched& there !asa trend $ound o$ requirin# a minimal volta#e o$ 1C.D V $or operation. This !as dueto the e$$ects o$ the motor !hich& !hen read $rom a multimeter& le$t a drop inoverall volta#e& !hich !as due to the motor. The motor is a three-phase load&and thus $ollo!s @ens6s @a! o$ inductive ener#y. This !ould ideally create anequivalent reverse $orce on the battery& assumin# no impedances $rom thebattery or the inductive load. The equivalent series net!or* bet!een the batteryand the motor create a loss in this $orce& or 8E+: (8ac* E+:& and allo!s $or adrop in volta#e.

:or the initial test motor& the To!er)ro >1C-CF@ 8rushless /utrunner& thevolta#e !ould drop by approximately .DV. 8y then droppin# the volta#e& thedetermination can be made that 1C.D V is the optimum. /nce it dropped belo!.CV on the multimeter& the en#ine had stopped. /ne member read the actualvolta#e a$ter disconnectin# the motor $rom the system& and it read 1C.>V.This!as also measured at C percent duty cycle $rom the controller. This made thechoice o$$icialB $or the motor to run optimally& the required source should have avolta#e no smaller than 1C.DV.The maximum o$ 1 V can be used ho!ever3anythin# hi#her !ould come !ith a considerably #reater $inancial cost and !iththe added ris* o$ burnin# out the motors and the system.

The next issue !as the current& !hich is the *ey $or calculatin# the approximate$li#ht time. +ost batteries aren6t rated by their current& but their char#e in terms o$current-time (usually mA% or A% in , po!er supplies. "$ $li#ht time is assumed

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as a linear $unction o$ the battery& then the maximum time is easy to calculate assho!nin equation ..1B

"otor ,peration euation> minin@t6)Ain@I

hrAin@Bmotor

mo

eargch=

7here Nchar#eis the char#e held by the battery& "mo is the motor6s standard (ormaximum e$$iciency operational current& =C is the conversion $actor $rom hoursto minutes& and tmotoris the time the maximum time the motor !ill remain on. This$ormula !ill also hold $or the maximum current output in considerin# a !orst casescenario.

Since there are > motors operatin#& three options need to be considered as$ollo!s (!ith the operational motor time bein# tm$or each calculationB

/ption 1 M each motor has its o!n battery source. "n !hich case& the$ormula above !ould apply to each motor. The do!nside is that the added

mass !ould be unacceptable due to the possibility that the batteries !ouldli*ely consume up to 1 *# o$ !ei#ht (!ell over the speci$ication tolerance.Thus& tmO tmotor.

/ption M one battery $or every t!o motors. "n essence& hal$ the po!er#oin# to each ES, and motor. The !ei#ht !ill be closer to DCC#& and!ithin speci$ication. "ssues may arise in desi#nin# the po!er supplied tothe main board. There$ore& tmOtmotor .

/ption ; M one battery $or all motors. This !ould be the ideal desi#n inconsiderin# a battery to po!er the motors and the processor due tosimplicity. The issue o$ usin# a sin#le po!er source $or all the components!ould pose a problem $or batteries near shutdo!n. "$ a volta#e detector is

used& the microprocessor !ill need time to shut do!n po!er to the othersubsystems to protect the system. A separate po!er module may berequired $or this con$i#uration to !or*. Thus& tmO tmotor>& approximately.

:inally& there is the mass to consider. Since it is ideal to *eep the quad-copter ata lo! mass& havin# po!er e$$icient batteries !ith a $ast rechar#e time& reliabilityin battery li$e-lon#evity& and practical application o$ po!er be considered indesi#n. A per$ect example !ould be po!erin# the main board& !hich house theprocessor and sensor control $unctions& to be turned on and o$$ by either a mainbattery& or a separate battery and allo! $or a dedicated po!er supply to themotors. This !ill be considered more in the desi#n section o$ the documentation.

..1 8atteries

There are $ive battery types used by all , be#inners& hobbyists& andenthusiastsB

1. Al*aline

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. 2ic*el +etal-%ydride (2i+%;. 2ic*el ,admium (2i,ad>. 2ic*el ?inc (2i?nD. @ithium )olymer(@i)o

:or most electromechanical systems& such as , helicopters& batteries arerequired $or en#ine start-up and si#nal mana#ement. Since all cars run o$$ o$ a0, source& the electric net!or* may be required to convert the 0, ener#y to A,by means o$ relays and inverter net!or*s. :rom an analysis perspective& thisrequires both 0, and A, analysis& in terms o$ volta#e& current& and po!er.These e$$ects can also e$$ect 0, po!er consumption& as !ell as thermal e$$ectsthat can result in component shutdo!n (the motors especially.

The ar#ument is simpleB H7hich is more importantB motors& the processor& thesensors& or the video systemP 7hen is there an exceptionPI At this point& it isassumed the video system has its o!n po!er source. There$ore& !e only need to

concern ourselves !ith the motors& the processor& and the sensors. The sensorsthemselves are auxiliary systems !hich operate !ith the processor& and are notentirely necessary $or $lyin# the cra$t. %o!ever& it does #ive the user essentialdata re#ardin# $li#ht data and analysis $or control. :or this section& consider thesensors and processor as the main board.

+ost o$ the components on the main board are lo!-po!er devices& operatin# incurrent ratin#s as hi#h as the mA to as lo! as the nA ran#e. This !ould ma*emost po!er dissipation $rom the source minimal& at best. %o!ever& it !ill be anissue in re#ards to initial start-up& and at shut-do!n. The e$$ects o$ current andvolta#e spi*es due to an under-damped system& and the reverse current onre#ulators can be an issue re#ardin# the li$e o$ the components. 7ith theexception o$ the )S and the compass module all the sensors are desi#ned asanalo# parts. These parts are ",s !hich can easily overheat due to unre#ulatedcurrent and volta#e. :urthermore& the di#ital components& !hich are theprocessor& the )S& and the di#ital compass3 cannot su$$er $rom under-damped0, e$$ects (overshootin# nominal operatin#& standin# !ave e$$ect&electroma#netic inter$erence due to si#nal lea*a#e or improper shieldin#.

The parts themselves may not necessarily have the same volta#e and po!erneeds. The processors !hich !ould be optimal $or the application ran#e in then7 ran#e& !ith an operational volta#e o$ ;V to DV (operatin# !ith nAQ. Thesensors& ho!ever& !ill require more po!er (mA operatin# ran#e to #ive therequired $eedbac* si#nals to the processor and to the user. This !ould mean&!ithout any hard values& to calculate the overall po!er dissipation o$ the board.There is also the issue o$ thermal e$$ects $rom the parts& !hich !ill be able tooperate at D , n !ith no e$$ort. :or our $inal demonstration& !hich !ill be held inan outdoor environment& the thermal equations must be ta*en into account. :or:lorida& the ambient temperature is bet!een =C to 11C: year round. As a solution

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to most o$ these issues& volta#e re#ulators !ill be required $or distributin# po!erto the main board. This !ill be discussed $urther in the Volta#e e#ulator section.The $ollo!in# !ill #ive the recommended speci$ics $or each battery and theirapplications to !hich they may be the best $it. )lease note that all batteriesrelated to the motors !ill use a ,-cell con$i#uration (!ith certain exception in the

@i)o cell batteries. All o$ these batteries !ill have massive overlap in theirapplications. "t is important to consider e$$ects o$ each batteries !ei#ht& overallchar#e& and best application. Thus& the batteries themselves are considered intheir li$e-lon#evity& $easibility& and reusability.

Al*aline 8atteries

The most basic o$ all o$ these batteries is the most commonly used battery in the!orld& al*aline batteries. "n usin# a system !hich is entirely al*aline& the quad-copter can #et an overall li$e based on a non-rechar#in# source& !hich !ould beoptimal $or environments !here battery char#in# is not an option (urban areas

!ith poor in$rastructure& rural areas !ith no electric po!er& 'un#les& deserts& andother uninhabitable or inhospitable terrain. :urthermore& they6re cheap. Theycan be acquired in almost any store in the US and in most $irst !orld stores. Thebi##est problem !ith al*aline batteries is their lo! char#e. +ost batteries carryabout 1.DV !ith a current o$ GCCmA or more (dependin# on the load. This is dueto battery architecture and personal sa$ety issues. 2oteB the minimum currentrequired $or stoppin# a human heart inside the human body is bet!een 1CC-DCCmA. :or desi#nin# a po!er source $or the motors& the amount o$ batteriesrequired to operate the motors !ould be considerable.

To demonstrate& this example !ill use the ideal conditions $or dealin# !ith the

load. @et6s say there is a motor !hich requires 1C.DV at A. :or ar#uments sa*e&assume a source o$ up to 1C.DV composed o$ brand ne! AA Ener#i4er +axE1F8)-1=% batteries& (rated !ith an advertised char#e o$ DCmA%.:urthermore& assume ideal conditions $or the battery. ThusB

batteries2

batter+80.1

80.1)=

Usin# the $ormula $rom above& all > motors can run $or approximately D minutesunder standard operatin# current. This may not seem an unreasonable $li#ht time%o!ever& there is a cost issue o$ usin# too many disposable batteries. A$ter a

trial o$ ten $li#hts !ith this battery setup& over GC batteries have been used& !hich!ould retail at about R>C. This doesn6t mean the al*aline is not !ithout use in thispro'ect. 8ecause it doesn6t have much po!er to dra!& the overall po!er supplied!ould be a per$ect match $or the main board. This !ould allo! $or a dedicatedpo!er supply to allo! $or the maximum $li#ht time o$ the copter. )lus& since 0,batteries are not prone to the same issues o$ rechar#in#& they can be replaced!ithout e$$ectin# si#ni$icant extra overhead.

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2ic*el +etal-%ydride (2i+% 8atteries

The next alternative& 2i+% batteries& arestill common in most cordless phones.This !as one o$ the $irst rechar#eable battery sources discovered and is stillconsidered as one o$ the most reliable sources $or lon#evity and reliability. This is

still a very common source to use in some , toys and basic models o$ ,.These batteries are more expensive than their al*aline equivalents& and cannothold a char#e $or as lon#. 7hat they lac* in char#e& they ma*e up $or inreusability. 7ith these batteries& there are t!o issues re#ardin# po!er. :irst& thehi#hest you typically see these batteries rated is at F.=V. This does pose anissue !ith a volta#e limited ES, and motor& since there may be a volta#e drop o$.DV due to bac* E+:. As a solution& t!o batteries can becon$i#uredin series tohandle the same tas*. This can cause issues involvin# current and heatin# dueto E+: e$$ects. This leads to an issue o$ !ei#ht. Even i$ the batteries !ill allo!$or the volta#e !ith no e$$ects& the !ei#ht !ould still be exceedin# the maximumspeci$ied tolerance o$ CC#. And second& rechar#e time is considerable lon#er

than any other popular rechar#eable device. This !ould mean lon#er timebet!een $li#ht tests& possibly one a day.

@i*e !ithal*aline& the 2i+% batteries can be used $or po!erin# smaller devices!ith ease. As stated be$ore& these batteries are used on cordless phones& !hichcan be used constantly $or approximately -> hours& dependin# on the phone.+ost 2i+% batteries are rated hi#her than their al*aline counterparts& bein#ran*ed $rom 1CCmA% to CCCmA% o$ capacitance $or most , and 0 classbatteries. This !ould be a #ood recommendation $or a rechar#eable source. Thetypical volta#e $or AA and sub-, batteries used is rated at 1.V& !hich !ouldmean more batteries required i$ hi#her volta#es are a necessity. This can be

solved by the application o$ a boost re#ulator i$ the desi#n requires.

2ic*el ,admium 8atteries

The more popular brand o$ rechar#eable batteries $or , 0esi#ners is still the2ic*el ,admium batteries as they are sli#htly cheaper than 2i+%& and havin# a$aster rechar#e time. These batteries !ere once the po!er supply o$ most laptopcomputers durin# its earlier years. They !ere chosen $or their $ast char#e time&!hich !as ideal $or earlier laptop users& such as the military $or $ield analysis andcomputer communication.

e#ardin#the quad-copter& most prepac*a#ed batteries come in =.CV (D cell&G.V (= cell& and F.=V ( cell pac*s& usually rated at approximately CCmA%per battery (the Sub-, battery $rom Tener#y is considered as a basis& thou#hthere are pac*s !ith capacitance as hi#h as >CCmA%. @i*e 2i+% batteries&these batteries hold a smaller potential o$ 1.V& opposed to the al*aline !ithapproximately 1.DV. There$ore& F batteries in series !ould be required to#enerate the minimum required volta#e $or the motors under consideration. Thiscould be done by settin# up batteries in series !ith one another to the desired

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amount. %o!ever& this means rechar#in# must be done individually& or morepractically usin# a combination o$ a balancer and a char#er to *eep an evenchar#eamon# the batteries.

2i,ad batteries have lost a lot o$ popularity due to problems involved in char#in#

and li$etime per$ormance such asB

+emory "ssues in char#in#

0endrite $ormations

%eavy +etal )oisonin#

everse ,urrent

These issues are discussed in $urther detail in the 8attery is*s section. 0espitethese issues& people still use 2i,ad batteries to this day. 8ecause they arecheaper and rechar#e $aster than the 2i+% batteries& they are still popular !ithmost cordless phone desi#ners. As such& it too is also an excellent choice $or the

main board as a separate source. @i*e the 2i+%& they hold a 1.V& typically& andthe same desi#n consideration o$ the boost re#ulator is a viable option i$ batteriesbecome too heavy.

2ic*el ?inc (2i?n 8atteries

A brand o$ batteries no! ma*in# a comebac* is the 2i?n batteries. Thesebatteries have been $ound in applications $or electric bi*es and vehicles& and areno! bein# scaled $or smaller applications such as cordless phones. The si4es o$the batteries are similar to that o$ the 2i+% or 2i,ad batteries& except they arecurrently distributed very popularly in AA and sub-, si4es. The volta#e on a

sin#le AA or sub-, battery is approximately 1.=V& a ;; #ain in volta#e over its2ic*el-based counterparts.

Accordin# to )o!er#enix& one o$ the main developers o$ 2i?n batteries& thesebatteries hold a capacitance o$ 1CCmA% minimum& and a CCCmA% typically.The char#e time on these batteries is .D hours& typically& !hich ma*es itcomparable to that o$ the 2i,ad char#in# capabilities. The battery still containsheavy metals and should be #iven caution i$ its contents spill out o$ the battery.)lease re$er to the H8attery is*sI section $or $urther details.

8ecause these batteries have be#un circulation in this condition& 2i?n batteries

have not been tested or $itted to an ,. This is due to its recommended char#in#capabilities. +ost o$ these #uidelines are stated belo! in the 8attery ,har#in#and 8attery is*s sections. The recommended char#e time per cell is no morethan .D hours (1C min.There is also an issue o$ the hi#her dischar#e rate. Thebatteries have a minimum avera#e capacitance o$ 1CCmA%. 7ith a hi#hdischar#e $ound per battery& it naturally !ould decay the operatin# time o$ thebattery. "t is recommended to use this system provided the maximum dra! usedbattery is no more than 1A per cell. 8eyond this& there is very little *no!n about

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the 2i?n batteries that can be con$irmed at this time. 0ue primarily to the support#iven by the spec sheet& it is concluded that 2i?n batteries are a #ood option $orpo!erin# the processor& sensors& and transceiver system o$ the quad-copter.

@ithium )olymer (@i)o 8atteries

:or the best choice in batteries& there are the @i)o batteries& thepredominatin#rechar#eable battery. @i)o batteries have a much hi#her volta#eratin# in one cell than in its predecessors& as !ell as sli#htly lar#er !ei#ht.%o!ever& the char#e typically $ound in these batteries is bet!een ;.=V to >.GVper cell. This allo!s $or the construction o$ a po!er$ul battery !ith a minimumnumber o$ cells required. This is also use$ul $or issues concernin# overall !ei#ht&!hich is an issue !ith the other considered sources.The only concerns !ith the batteries themselves are the cost and the sa$etyissues. The cost o$ most batteries !ill vary dependin# on the char#e capacitanceused. ;CCmA% at 11.1V typically #o $or R;.FF to R;.FF& !hile the DDCCmA% at

the same volta#e ran#e $rom RFF.FF to R1>F.FF. ,are$ul desi#n and timin#considerations must be #iven to these batteries to ensure these batteries do notdrain too much durin# char#in# (discussed more in 8attery ,har#in#. ,urrently&the t!o main distributers o$ batteries are Thunder)o!er and acer6s Ed#e.Thou#h there are other distributers !hich at times o$$er better deals& theseprovide a more consistent supply o$ their batteries& and are the recommendedchoice $or purchasin#. Table sho!s some o$ the recommended pac*s $or thequad-copter !hich !ould !or* best. )lease note& all o$ the $ollo!in# cells #ive amaximum continuous dischar#e o$ ;C,.

8attery 0imensions (mm; +ass (# )rice

acer6s Ed#e ;>CCmA% >G < 1; < ;.D 2A R>G.FFacer6s Ed#e DCCmA% >G < 1; < ;.D 2A R1>F.FFThunder)o!er > @ite @ite ; < 1;= GC R1CF.FF

Thunder)o!er > @ite G < 1=C ;FF R1=>.FF

=able (> A list o/ !'7ell 11.18 Li3o 3acs @recommendedCC Available as o/ 6'10'()1).

The other issue is the sa$ety issue in char#in# these batteries. Some @i)o pac*scome !ith their o!n char#er& !hich is desired $or the pro'ect. %o!ever& in casethe pac* does not come !ith a char#er& it may be because the battery pac* is acustomi4ed pac*& and requires special attention. "$ this is not care$ully monitored&these batteries can catch $ire and can create severe property dama#e or in'ury.This !ill be discussed more in the 8attery is*s Section. 8ecause the batterypac*s hold a lot o$ po!er& they can be !ired to the main board $or po!erin# the

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components. "ssues arise in the po!er bein# supplied to the main board. Sincethere is a #reat deal o$ po!er bein# sent to the board& it6s possible to melt theboard and overheat the components !ell beyond their operatin# temperaturetolerances. A volta#e re#ulator !ith a heat sin* !ill be the best option& i$ testin#sho!s it is required. "t6s possible this may necessitate placement o$ a $use to

protect the main board and its components. This !ill require $urther consultation!ith the ),8 manu$acturer and the Amateur adio club.

.. 8attery ,har#in#

7hen it comes to the most common rechar#eable batteries& most times all that isrequired is a premade char#er. This is the recommended method $or char#in#any type o$ AA& AAA& ,& or 0 class rechar#eable batteries. They6re easy to $indand typically are $airly cheap at most stores. +ost battery dealers (0uracell&Ener#i4er& and adio Shac* to name a $e! !ill sell these char#ers $or any!here$rom R1C to RDC. This is a recommended method only $or batteries !ith al*aline

battery holders. :or , battery pac*s& some o$ these come !ith A, adapters $orquic*& easy char#in#. These exist $or some o$ the smaller pac*s (=.CV typically&F.=V at best. These are usually pac*s o$ Htrue-,I cells comprised o$ 2i,ad or2i+%. :or the quad-copter& this is an insu$$icient volta#e due to bac* E+: e$$ects$rom the motor. @i)o battery pac*s and customi4ed 2i,ad and 2i+% pac*s usechar#ers !hich can control the volta#e and the current bein# sent to the battery.Since @i)o batteries are the pre$erred choice o$ battery $or this pro'ect& thebattery li$e and sa$ety must be considered& dependin# on the battery.

+ost computers and cell phones !hich use @i-"on batteries have a po!erre#ulation controller called a 8+S (8attery +ana#ement System& !hich allo!s

$or volta#e and current to be sent to the cells !hich require char#in#. ,batteries still require this type o$ char#in# $or per$ormance durin# use. +ost o$these batteries do not have the capabilities o$ supportin# a controller $rom theirrespected manu$acturers. The best option is to use a balancer& !hich does theexact same 'ob as the controllers on a motherboard. 8ecause these are morecostly& it is recommended to use !hat the manu$acturer recommends to allamateurs in this venture.

..; 8attery is*s

Each battery is *no!n $or its $aults re#ardin# sa$ety and usa#e. 7ithout

considerin# this& batteries !ill at best be $inancially costly& and at !orst causeserious harm to the en#ineers& testers& and the user. This section is meant tosummari4e most o$ the concerns !ith handlin# all o$ the batteries listed above.

Overusing the batteries. e#ardin# rechar#eable batteries& once thebattery is dead& it6s dead. This is especially true $or the @i)o and 2i+%batteries. This is usually true $or 2i,ad and 2i?n batteries& !ith certainexception o$ dendrite $ormations. These dendrites cause a short circuit

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bet!een the cathode and anode. A shot o$ lar#e current could $ix theproblem& but this is somethin# that is not recommended i$ there is morethan one dendrite $ormation. Al*aline batteries have a tendency o$ lea*in#$luid i$ *ept unchec*ed $or lon# periods o$ use.

Overcharging batteries. As stated be$ore& more complex electronics

have a means o$ recoverin# char#e to a battery. "$ a battery becomesoverchar#ed& it !ill be#in to #et hot. "n some cases& there have been $iresstarted by improper char#in# techniques. 8e present !hen char#in# allbatteries. 0o not let them sit on a char#er overni#ht.

Improper or misuse of batteries."t is extremely important to doublechec* all device connections throu#hout desi#nin#& prototypin#& andtestin#. "t should be noted to possibly #round onesel$ as an extraprecaution to not incur a shoc*.

Heavy Metal Poisoning.+ost o$ these batteries are comprised o$ metalsnot naturally $ound in the human body !ith any abundance. This isespecially true $or ,admium. A battery lea* o$ a 2i,ad&

necessitatescallin# F11 to in$orm them o$ possible ,admium poisonin#.

Tips $or protectin# the battery& the user& and the desi#nerB

:or the desi#ners considerationsB !ith every use& the batterys operatin#time should be recorded. The statistical analysis $or handlin# an avera#etime !ill both con$irm the calculations above and allo! $or more accuratetestin# and $li#ht time.

/nce the battery is lo! on ener#y& the user should stop operations andbe#in char#in#.

The best choice $or char#in# a multiple- cell battery pac* is a balancer.

The user should use this to allo! $or maximum char#in# o$ each cell.ememberB observe the battery !hen char#in# to ma*e sure it doesn6tbecome overchar#ed.

"$ a battery dies in the process o$ testin#& the user must dispose o$ itproperly at the local !aste mana#ement $acility.

"$ exposed to battery contents& the user must contact F11 and the labsupervisor.

"$ the user start to $eel di44y& hard to breath& dry sore throat& or nauseous&the battery must be stored in a sealed& cool container& as it may be due toa lea*.

"t is hi#hly recommended $or the user to double and triple chec* allconnections throu#hout the pro'ect.

The user and the desi#ner must test $or any inconsistencies intemperature& current& or volta#e in the circuit.

The user must al!ays chec* the temperature o$ the battery. (Atemperature sensor is pre$erred& but not required.

The user must ma*e sure the battery stored a!ay in a cool and drystora#e container in a dry area.

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Users must properly #round themselves !hen handlin# the battery !iththe copter.

..> Volta#e e#ulators

0istributin# po!er to all elements o$ the system requires the care$ul application o$volta#e and current runnin# throu#h each device. +aximi4in# the current runnin#throu#h the motors& !hich is the basis o$ calculatin# the ma'ority o$ the po!er&leaves little room $or hi#h po!ered components else!here. As stated earlier& thebest !ay to eliminate this concern is to setup a separate po!er source $or thecomponents. This limits the main board and all o$ its subcomponents o$ po!er&so usin# local ampli$iers may not be the most advanta#eous decision. Even i$ thequad-copter uses a sin#le ;-cell @i)o battery to po!er the !hole system& thebattery6s current !ould be too #reat& and can lead to thermal issues in desi#n.The best !ay to solve this is !ith a volta#e re#ulator& in either case.A volta#ere#ulator is a device !hich utili4es the #round to maintain an output volta#e !hile

maintainin# the same current across itsel$. Volta#e re#ulators hold t!o veryexcellent characteristicsB

1. e#ulators can maintain a volta#e !ith a steady-state current.. e#ulators can dissipate ener#y $rom the system !ith the use o$ a heat

sin*.

"n choosin# a re#ulator& !hat is considered is !hat *ind o$ volta#e and currenteach part o$ the main board requires. The motors are bein# controlled by theES,& and require the $ull amount o$ char#e needed to handle bac* E+: e$$ects.That is !hy the only need is to consider the components o$ the main board $or

the desi#n. +ost o$ the parts are #oin# to be pre-mounted sensors& so all that isrequired are the individual components and their po!er ratin#s. This in$ormation!ill be available $rom the datasheets o$ each sensor& the )S& the processors&and the components $or the !ireless system.

"n !or*in# !ith a re#ulator& there are three di$$erent characteristics !hichtypically control the operation o$ the re#ulator. "n !or*in# !ith this protocol& the#roup can also establish and predict certain issues arisin# $rom the desi#n o$ themain board. The three *ey issues !ould beB

1. Thermal Analysis

. @oad ,urrent;. +aximum Volta#e

This is also the chain o$ command $or volta#e re#ulator shutdo!n and protection$or the re#ulators at 2ational Semiconductor. Thermal values allo! thedetermination o$ the necessity o$ a heat sin*& and allo! help inchoosin# theproper re#ulator(s $or the copter. 2oteB more than one heat sin* can #reatlya$$ect the temperature o$ the sensors on the main board in an enclosed space.

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To summari4e& the re#ulators !hich !ould quali$y $or the quad-copter6s#uidelines are the $ollo!in#B

A volta#e re#ulator !hich can ta*e in a hi#h input volta#e (1C-1V max

+ust be able to maintain current in mA ran#e& nominally.

Space is an issue on the main board. Usin# as $e! re#ulators as possibleis pre$erred.

Temperature must be *ept to a minimum. ,onsideration o$ $ans may berequired i$ the source is too po!er$ul.

..D @inear e#ulators

@inear volta#e re#ulators are devices !hich allo! $or an un*no!n input volta#e tostream !hile maintainin# a steady-state current. :or this reason& this type o$re#ulator has been called a Hvariable resistorI. This re#ulator received its nameby operatin# !ithin the linear re#ions o$ its internal transistors and o$ active loadsbein# applied. There are typically three pins !hich use a T/-C pac*a#in#&usually no !ider than 1.D cm. These are easily obtainable at any convenientelectronic supplier (adio Shac* and S*ycra$t bein# local retailers.

/ther re#ulator desi#ns allo! $or space constrained areas !hich allo! $or adesi#n !ith more space $or other sensors& i$ onboard sensors are recommended&*no!n as T/-=; pac*a#in#. These are sur$ace mounted re#ulators !hich aresoldered directly to the board and can allo! $or any other components& be itampli$iers& bu$$ers& inverters& sensors& or other processors& more space. This !illalso ma*e desi#n analysis easier throu#h observin# the ),8 directly in terms o$tracin#. The one constraint is the heat sin* $or this device is the copper plane onthe ),8. :or lo!er po!er devices& especially battery po!ered devices& this canused to setup to handle the heatin#. "ssues !ill arise $rom improper desi#n in the),8 !ithout re#ardin# the copper plate as the heat sin*. Another smallpac*a#in# schema is the micro S+0 pac*a#in#. This uses the same concept asthe T/-=; and simpli$ies the structure even $urther by usin# a sur$ace mountdevice !ith a 8A (8all rid Array. This has $ound a #reat deal more popularity!ith processor desi#n. The $ourth alternative !ould be to #o !ith an @@0 device&!hich is a solder-mounted ", device. This !ould allo! $or the same issue !ithroom mana#ement !ithout havin# to deal !ith any pins directly. 8est o$ all& thedevices are set $or ener#y dissipation. There is no heat sin* the device !oulddirectly need to inter$ace& since the po!er needed $or these devices uses a smallcurrent. There$ore& a heat sin* !ould not be necessary at lo!er temperatures.

"ssues arise !ith the latter t!o desi#ns involvin# current limitation. Even i$thermally it doesn6t exceed this limit& the device is still !or*in# !ith a hi#herpo!er battery (11.1V !ith a minimum ;CCmA%. :urthermore& most sur$acemounted technolo#ies don6t normally re#ulate such hi#h input volta#es& due totheir possible hi#h currents. "t is recommended to use the T/-C or the T/-=;pac*a#in# to handle thermal issues at hi#her currents and volta#es. 8ecause the

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po!er o$ the @i)o battery is too much $or most linear re#ulators to handle& andsince current is less than CCmA $or most components& a 1A re#ulator is all thatis required $or either di#ital or analo# outputs. +ore than one re#ulator !ill berequired& and must be considered re#ardin# the ultrasonic sensors.

T!o types o$ re#ulation are required due to the requirements $or the )S& !hich!ill be #iven the maximum recommended volta#e o$ DV. The rest o$ thearchitecture !ill be in at ;.;V& typically. A #ood $irst choice is the @);F by2ational Semiconductor& !hich is rated at a maximum 1.DA load current. This isan @0/ architecture !hich allo!s $or a lo!-volta#e drop o$ 1>CmV at themaximum current& 1.DA. This type o$ linear re#ulator is used $or more po!er$ulapplications compared to battery-po!ered versions& and there$ore has its o!nshutdo!n lead to connect !ith a microprocessor. Stand-alone versions $or theprocessors are an excellent !ay to re#ulate the po!er sa$ely to these chip& butnot necessary i$ a dedicated volta#e sensor $or the @i)o batteries is alreadyestablished.

Unisonic Technolo#ies @+G;; is also a #ood choice due to its simplicity. This isa standard linear re#ulator rated at 1A& !hich is still above the maximum loadcurrent. The architecture is a standard linear re#ulator& !hich stipulates a hi#herdropout volta#e at .CV typically. This is a concern re#ardin# the source& sincethe re#ulator must be bet!een D-GV to operate !ithin tolerance. The bene$it isthere is very lo! noise attached to this re#ulator& !hich is typically DDV $or thisparticular device. This ma*es it an excellent device $or the analo# and di#italcomponents& allo!in# $or very little E+: inter$erence !ith other parts. A source o$GV or more is recommended $or DV devices.

An alternative to this !ould be to use an ad'ustable re#ulator& such as :airchildSemiconductor6s @+;1G& !hich allo!s $or an ad'ustable output volta#e. Usin# thead'ustable !ould simpli$y desi#n and $inance at once& and there$ore only dependon the resistors themselves (D resistors !ill be $ine $or demonstrationpurposes. The current ratin# is the same as the @);F& so both options arecomparable. This !ould require more prototypin#& as this type o$ re#ulator istypically used $or testin# purposes. This also holds $or @inear Technolo#y6s@T11D& !hich is current rated at ;CCCmA& is !ell beyond the scope o$ theminimum requirements. This is an ad'ustable @0/ re#ulator& !ith a smallschematic o$ ; resistors and capacitors are $or the desi#n o$ our board in termso$ space. This doesn6t come in a $ixed-volta#e version& !hich is the onlydisadvanta#e to usin# this re#ulator.

+ost o$ the linear re#ulators are desi#ned $or lo!-po!er applications& !herecurrent is typically in the ran#e o$ less than 1A. 7hat !ill determine !hether ornot the desi#n is $easible to the pro'ect !ill be le$t to the po!er source decidedupon $or the board. Since all the components o$ the board are considered lo!po!er& the @i)o source could be over!helmin#. "t is hi#hly recommended to usea separate po!er source $or the main board to protect the board $rom dama#e

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created by the current supplied by the @i)o. A set o$ al*aline or smallrechar#eable batteries& li*e the 2i+%& in a set o$ > AAs !ill su$$ice $or @0/6s. "nre#ard to the standard linear re#ulators& al*aline or the 2i?n batteries arerecommended due to their hi#her volta#es.

..= S!itchin# e#ulatorsThese re#ulators are *no!n $or operations outside o$ the linear re#ions. 0ue tothis e$$ect& the desi#ns o$ these re#ulators are *no!n $or operatin# !ith a )7+&allo!in# it to constantly shut ono$$ at considerable hi#her speeds. This alsoimplies a control o$ the po!er supplied to the system bein# controlled by a dutycycle3 and not bein# solely #overned by the direct po!er ratin# o$ the source.Thou#h po!er is controlled by usin# the )7+ as a s!itch& inductors andcapacitors handle the po!er stora#e side o$ the equation. +any o$ these come ina T/-C pac*a#in#& due to their hi#h po!er handlin#. There are t!o types o$s!itchin# re#ulators !hich !ould !or* excellent $or our purposes. These !ere

narro!ed do!n based on their applications to!ards this pro'ect. They are the$ollo!in#B

8uc* e#ulator M These are step-do!n re#ulators& meanin# they arere#ulators !hich !ill cause a drop in volta#e. This is the closest re#ulatortype to that o$ the linear re#ulator.

8oost e#ulator M e#ulators !hich increase the volta#e $rom the source./ther!ise *no!n as the step-up re#ulator

:lybac* e#ulator M A more complex re#ulator !hich can allo! $ormultiple outputs based on desi#n. "t may also be used in tandem !ithother linear and s!itchin# re#ulators.

The buc* re#ulator is the most common o$ all s!itchin# re#ulators& in that it is adrop in volta#e. 8y creatin# a drop in the volta#e& lo! po!ered devices incon'unction !ith a hi#her po!ered device can be controlled !ithout the !orry o$overloadin# the components o$ the board. 2ational Semiconductor has a !holearray o$ buc* re#ulators& li*e the @+DGD re#ulator. This type o$ re#ulator uses$ixed volta#es at ;.;V or DV& dependin# on the version ordered. This uses aninternal cloc* $or its s!itchin# $requency at D*%4& !hich !ill need to beconsidered in desi#n i$ po!er concerns arise. The architecture o$ the s!itcherapplication circuit is very simple and small& an excellent choice $or the board.There is an ad'ustable version sold !hich is accurate to !ithin > o$ the rated

volta#e& and should be considered $or simplicity.

@inear Technolo#ies has some excellent counterparts& such as the @T,;;C&!hich also uses an ad'ustable volta#e. This is a more robust desi#n to considersince it uses ?ener 0iodes and )o!er +/S:ETs to re#ulate oscillation. This is adevice used more $or hi#her po!er systems& such as ,)U devices. "t also usesan S/- pac*a#in# schema& !hich is excellent $or space consumption. The ;.;V$ixed version o$ the s!itcher is hi#hly stable at currents rate at 1DA& as !ell as

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stable bet!een most temperatures $rom C M DC ,. 0espite the amount o$ spacethe application circuit !ould occupy& this !ould be able to yield a very stron#&stable volta#e source !hich can handle most temperatures. There is anad'ustable version !hich is an S/-1= pac*a#in#& !hich is allo!s $or apro#rammable s!itchin# $requency ran#e o$ 1CC M DCC*%4. Since this !ould ta*e

up more space& it !ould be better to #et the $ixed volta#e version& i$ this re#ulatoris selected.

The boost re#ulator is the next most common s!itcher. Since these create anincrease in volta#e3 a smaller volta#e source can be used as opposed to a lar#erone. This !ould be an excellent device to use in terms o$ $indin# a lo! volta#edevice to handle more po!er. An issue o$ current arises !hen considerin# thedesi#n o$ this re#ulator. The boost s!itcher uses its inductor to ramp up current&thus rampin# up volta#eThe third device is the $lybac* re#ulator& !hich uses theinductor to store and release volta#e. This allo!s $or more than one outputsource to be used& since mutual inductance only requires coils. :urthermore& the

desi#n can incorporateother types o$ re#ulatorssuch as the ones listed aboveinaddition to au#ment the $lybac*6s ability to !or* as a boost re#ulator. This couldbe used i$ re#ulation is needed $or a constant current. The only issue bein# thatone more re#ulator is needed $or the board. "t is e$$icient in terms o$ desi#n& butnot space. This is an excellent alternative& but not a necessary one i$ the use o$s!itchers is decided upon.

2ational Semiconductor6s @+DD allo!s $or this type o$ re#ulation. Thisre#ulator has several recommended trans$ormers&and their con$i#urations& basedon the type o$ application desi#n required. This allo!s $or multiple outputs !ith#reater distinction o$ volta#es ran#in# as lo! as D.CV to as hi#h as 1V. Since itutili4es the trans$ormer6s mutual inductance& it is possible to increase the volta#eacross the receivin# inductor by usin# a hi#her number o$ coils on the inductorand puttin# the re$erence #round to the ne#ative lead. This !ould be anothermeans o$ boostin# the volta#e other than the one outlined in the datasheet. Thes!itchin# occurs at 1CC *%4& usin# an internal cloc* to operate the s!itcher&!hich is bene$icial in terms o$ desi#n.

@inear Technolo#ies @T;DG; is an excellent counterpart to the @+DD. Thisre#ulator !as made to re#ulate more volta#e than its 2ational Semiconductorcounterpart& due to its adaptive nature. This re#ulator uses an +SE 1=-pin ",pac*a#in# to handle a pro#rammable po!er s!itch current limit. This device !asinitially intended $or the industrial and medical $ields& dealin# !ith applicationsinvolvin# hi#her po!er !ith sensitive requirements. This also contains ashutdo!n pin $or the processor& !hich is essential $or the applications stated& butnot $or the quad-copter. The maximum output current #oes to 1.=A at D,ambient temperature. Volta#e slo!ly decays as it approaches 1CC,& but #oes aslo! as >.FFV. This is the recommended re#ulator $or testin# current limitations o$the microprocessor& the !ireless control system& and the sensors. This !ould beconsidered $or more advanced versions o$ the quad-copter in redesi#n.

=

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An issue arisesconcernin# the ma#netic $ield bein# produced by the inductor o$the s!itchin# re#ulators. The sensitivity o$ the di#ital compass to ma#netic $lux isat a maximum o$ D.D #auss. Small inductors too close to the di#ital compass!ould #enerate inaccurate readin#s at lo!er levels& !hich !ill lead to errors in

interpretin# $li#ht paths and re$erence points& such as !ith )S coordinates.Since $lybac*s use trans$ormers& more ma#netic $lux is #enerated $or the di#italcompass to overcome. There$ore& the s!itchin# re#ulator& thou#h bein# moreversatile than the linear re#ulator& !ould not be the ri#ht $it $or the quad-copter.

..G Volta#e Sensors

There are t!o critical po!er issues to consider& the source to the processor& andto the main battery. The processor requires po!er to remain !ithin its toleratedvolta#e ran#e to avoid bro!n-out issues. The main battery needs monitorin# todetermine i$ the volta#e drops too lo!. Since @i)o batteries are *no!n $or havin#

sudden drops in volta#e& the sensor must be capable o$ handlin# volta#e drops!ith an adequate level o$ sensitivity. The best !ay !ould be to use a hi#herpo!er volta#e detector ho!ever3 the only one $ound !as used $or monitorin# andchar#in# the @i)o batteries $ound in hybrid cars& !hich is made by @inearTechnolo#ies. :or it to be possible to handle this *ind o$ po!er !ith the requiredsensitivity& it becomes necessary to create an impedance net!or* to reduce thevolta#e do!n to a tolerable level& !ith a button battery system to act as there$erence. A ,C; button battery can act as such a volta#e re$erence $or boththe processor and the battery.

:or the processor and the po!er supply& the :airchild AGD.DCV. As the applicationnotes state& the desi#n is meant to connect to a microprocessor in order to sendthe messa#e o$ a volta#e drop. The processor uses the AGDFC& since itsminimum level o$ accuracy is at .GDV& !hich is relatively close to the minimumvalue is approximately .GV minimum. The po!er supply is a di$$erent story.Since this is a hi#her po!er device& relative to most o$ the components on theboard& the solution is to use a volta#e divider circuit to drop the volta#e do!n to alo!er volta#e node. To assist in droppin# the current& hi#her resistance rated athi#her po!er ratin# !ill help drop the volta#e !hile maintainin# a lo! po!ersource. To protect the main board& it is recommended to use this as a separatemodule& !ith the possibility o$ usin# a separate microprocessor (an ATtiny or a

)",1 module are recommended. As stated be$ore& a timer embedded in themain processor is recommended to determine an approximate avera#e time o$lo! battery li$e.

Analo# 0evices has an excellent selection o$ lo!-po!er comparators& but theone that $its the needs o$ the pro'ect best is the A0,+);>1. This is amulticomparator volta#e detector !hich can determine and anticipate the nextdrop in po!er. This !ill allo!s prediction o$ !hen the battery is near death. @i*e

G

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the AGDFC& it !as desi#ned to handle lo!-po!er applications. The maximumsupply volta#e is D.DV& 'ust under hal$ the volta#e o$ the @i)o source. @i*e theAGDFC& the best !ay to approach this is to create a volta#e divider and usevalues to #ive a sensitive enou#h $eedbac* to create its compare calculations!ithin tolerance o$ the comparators& to simulate the drain o$ the battery.

.. )o!er 0istribution

The motors !ill be po!ered solely by a @i)o 8attery )ac*. Since most o$ themotors typically use over 1CV minimum& it6s advisable to use an 11.1V @i)obattery pac* to po!er them. This is a more costly solution in terms o$ mass andcost. acer6s Ed#e 11.1V DCCmA% are an excellent source $or all $our motors.The alternative is the lesser rated ;>CCmA%& also $rom by acer6s Ed#e& !hich!e can connect to one to t!o motors& #ivin# each motor more po!er. This !ouldalso require more o$ the :airchild AGDFC custom boards $or each battery&!hich !ould be simpler $or the battery but not $or the processor. :or the

processor and the sensors there are t!o volta#es to be considered& ;.;V and ;V.Since these devices use very little po!er (less than 1A& a >-AA source o$al*aline batteries !ith a rated capacitance o$ DCCmA% is the best course o$action& due to the plenti$ul supply and reliability o$ these batteries at cost. TheEner#i4er +ax EF18) is the best choice $or prototypin# and testin#. e#ardin#the re#ulators and volta#e sensor& the re#ulators !ill need to be rated $or at least1A and cannot consume a #reat deal o$ space. They also require a heat sin*capability to allo! $or hi#her heat trans$er $rom the components& !hich is !hy aT/-C pac*a#in# is pre$erred. :or the quad-copter& the Unisonic @+G;; is thebest pic*. "t can handle up to 1A& !hich !ill be more than enou#h $or a battery-po!ered source. The best choice $or the sensor !ill be the A0,+);>1& due to

its versatility and price over the AG

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system to handle po!er conversion. +otors typically considered$or 0,applications vary in type $rom brushed motors& to stepper motors& to servomotors& and to brushless motors. 8rushed motors are 0, synchronous motors!hich use a commutator& a thin& small& copper sheet used to reverse current onthe po!er supply. The 8rushless motor is a three-phase device !hich uses no

commutator. The stepper and the servo motors are devices !hich rotate andhold a position based on the pulse !idth bein# received. "n terms o$ the quad-copter& the stepper and servo motors operate best as a testin# device $or the)7+ pins used on the main board3 ho!ever& they have no more relevanceto!ards this particular pro'ect.

Some common elements $ound in both motors to help determine the type o$motor to be used $or our pro'ect. This must be speci$ied be$ore !e6re loo*in# $ormotors !hich are synchroni4ed. "deally& a synchronous motor is a motor !hoseelectrical po!er matches and ali#ns !ith the mechanical po!er. Under thesecircumstances& it is necessary to #et a closer loo* at po!er $rom a mechanical

point o$ vie!. )o!er is de$ined as the ener#y stored or dissipated over time.

"echanical 3oer euation>t

DE3mech =

"n themechanical po!er equation& the ener#y is assumed to be *inetic& !hichyields t!o interpretations. /ne& the *inetic ener#y is $ound to be an inte#ral o$momentum. This allo!s $or the use o$ density as a $actor in calculatin# theener#y bein# used. This can also be applied to calculatin# the ener#y required$o