Final Report of Antenna Project

8/9/2019 Final Report of Antenna Project

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Satellite Tracking and 6.1 mDish Antenna Control System

ECE 4007 Senior Design Project Final ReportSection L04, SatTrack Team

Project Adisor Dr! "illiam #$nt

Dann% D$ong, P&$c #$n%&'an$el 'ende(, Sa&and )oori(ade&

Rodrigo *$interos

S$+mitted'a% 7, 0-0


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Table of Contents

Project .erie/!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Preliminar% Assessment!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1E2 '3 Encoders !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!5aria+le Fre6$enc% Dries 5FD8s9 and 'otors !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Control So:t/are and #ard/are !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!;

'otor Control S%stem!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!75FDs Setting and Speed Control!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!7T&e Rela% 1oard!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!<

Sa:et% =$ards!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!>Limit S/itc&es!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!>E3Stop 1$tton!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-0

#ard/are Control S$+s%stem !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!--1ackgro$nd !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-E?planation@Terminolog% !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!0S%stem Cali+ration!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!'aintenance 'ode .peration !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Remote 'ode .peration!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!4Proper S&$tdo/n o: t&e Control nit@ Control 1o?!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!4Bno/n 1$gs and Fi?es!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Code Flo/!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!;

1ackend So:t/are!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!0.erie/!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!0TLE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-

Description!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-.+taining and Storing t&e TLEs !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!P%t&on !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Fast Protot%ping !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!4.+ject .riented !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!4

Reada+ilit% and Sel: Doc$mentation !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1atteries incl$ded !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!P%Ep&em !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!;

1ackend 2n Detail !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!;ser 2nter:aces !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!>Re:erences !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!40


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Project Overview

T&e o+jectie o: t&is project /as to +$ild an a$tomated satellite@celestial o+ject tracking s%stem $sing

t&e e?isting ;!- m para+olic re:lector antenna +% designing and implementing a control s%stem /it& t&e ne/

and e?isting &ard/are!

Preliminary Assessment

T&e e?isting control s%stem o: t&e antenna is s&o/ in Fig$re -!

Figure 1. Existing system.

T&e antenna and its control s%stem &ad not +een $sed and maintained since 00 t&ere:ore, t&e :irst

step o: t&e project /as to determine /&ic& components o: t&e s%stem s&o/n in Fig$re - /ere :$nctional!

BEI M-25 Encoders

T&e e?isting encoders /ere t/o -;3+it optical a+sol$te encoder made +% 1E2 part n$m+er 'D3

F4#SS;;)3D-733S3C-43T39 one mo$nted on t&e a(im$t& a?is and one on t&e eleation a?is /it& no

enclos$re! D$e to t&e lack o: doc$mentation :rom t&e st$dent gro$p t&at &ad installed t&ese encoders in 00-,

t&e pint3o$t con:ig$ration o: t&ese encoders /ere $nkno/n! A:ter man% $ns$ccess:$l online searc& attempts

:or t&e datas&eet o: t&e '3 1E2 encoders, an application engineer named 'ark Bigerl at 1E2 /as

contacted! 2t /as :o$nd o$t t&at t&e '3 model &ad +een o+solete :or more t&an a decade and t&ere /ere no

digital doc$mentation aaila+le :or t&em! .ne /eek :ollo/ing o$r :irst contact /it& 'ark Bigerl, &e sent t&e

scanned datas&eet o: t&e '3 and a doc$mentation containing t&e pin3o$t con:ig$ration and t&e data

protocol! T&ese doc$ments are aaila+le in Appendi? !


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T&e data protocol o: t&e e?isting model 1E2 '3 is di::erential Serial S%nc&rono$s 2nter:ace SS29

and t&e +a$d rate is selected +% gro$nding one o: t&e :o$r preset clock pins! To test t&e encoders, t&e 400 #(

+a$d rate /as selected and t&e set3$p o: Fig$re /as $sed to monitor t&e o$tp$t data!

Figre !! 1E23' Test Set3$p!

Pin A o: t&e encoders is t&e positie data signal o: t&e di::erential SS2 and pins 5 and T are 5cc and

=nd pins respectiel%! T&e e?pected oscilloscope capt$res /ere repetition o: serial +inar% /ords - start

+it, < data +its, - stop +it9 as indicated +% t&e 1E2 doc$mentation! T&e s&a:ts o: t&e encoders /ere t$rned

appro?imatel% 4 degrees and a screen capt$re o: t&e oscilloscope displa% /as taken and saed to a S1

memor% stick! T&e screen capt$res :or eac& encoder /ere t&en compared side +% side to determine i: t&e +inar% data c&anges are proportional to ang$lar displacement o: t&e s&a:t! T&e screen capt$res o: t&e

eleation encoder are s&o/n in Fig$re !


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Figre ". Data signal screens&ots o: t&e eleation encoder/it& its s&a:t positioned at < di::erent angles!

T&e res$lts :or t&e a(im$t& encoder s&o/ed t&at at all t&e o$tp$t data stream is constant at angle

/&ic& lead to t&e concl$sion t&at it /as d%s:$nctional! T&e eleation encoder o$tp$t data stream did c&ange

/it& t&e angle o: t&e s&a:t and :$rt&er anal%sis o: t&e serial o$tp$t +inar% /ords s&o/ed t&at t&e angle data

c&anges are proportional to t&e ang$lar displacement o: t&e s&a:t! 2t /as concl$ded t&at t&e eleation encoder

/as :$nctional

Variable Frequency Drives (VFDs! and Motors

T&e po/er inp$ts R,S, and T9 o: t&e t/o e?isting 5FD8s /ere connected to t&e main 3p&ase po/er

lines o: t&e control panel t&ro$g& :$ses and t&eir o$tp$ts , 5, and "9! T&e control 2@. &ad t&e /irings o:

t&e preio$s s%stem /&ic& /as connected to t&e rela%s o: t&e proto+oard, +$t it /as no longer connected and

no /iring diagram o: it /as aaila+le! sing t&e datas&eet o: t&e 5FDs, t&e test circ$it s&o/n in Fig$re 4

/as $sed to test t&e motors and t&e 5FD8s!


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Figre #. Circ$it $sed to test t&e motors and motor dries!

T&e eleation 5FD /orked as e?pected and it ran t&e eleation motor +ot& in C" and CC"

direction and controlled t&e speed as t&e resistance o: t&e potentiometer c&anged! T&e same set$p /as $sed

:or t&e a(im$t& 5FD +$t it did not :$nction! T&e reset ro$tine as e?plained in t&e datas&eet /as per:ormed on

+ot& 5FD8s +$t t&e res$lts remained t&e same! Also t&e seen3segment screen o: t&e a(im$t& 5FD onl%

s&o/ed t&e middle das& lines! 1e:ore it /as concl$ded t&at t&e a(im$t& 5FD /as d%s:$nctional not t&e

motor, t&e 5FD8s /ere s/apped and t&e same test /as per:ormed +$t t&e s$spected 5FD did not r$n t&e

eleation motor eit&er! T&e :inal concl$sion /as t&at +ot& motors and t&e eleation 5FD /ere :$nctional +$t

t&e a(im$t& 5FD /as de:ectie!

"ontrol #o$t%are and &ard%are

T&e e?isting 5is$al 1asic3+ased control so:t/are named 'oon Track /as designed in ->>> in

conj$nction /it& a series o: transistor drien rela%s on a proto+oard to control t&e 5FD8s! 1ot& encoders /ere

directl% connected ia t/o separate RS3 ports to a Penti$m 2 PC t&at also &osted t&e control so:t/are and

controlled t&e 5FD8s t&ro$g& a DA* card and t&e rela%s on t&e proto+oard!

A:ter :inding t&e details o: t&e :$nctionalit% o: t&e 'oon Track so:t/are +% reading t&e report o: t&e

st$dent gro$p t&at &ad modi:ied t&e so:t/are :or a di::erent project in 00 and &aing &ad a de:ectie 5FD

and encoder, it /as decided not to $se t&e 'oon Track so:t/are and t&e Penti$m 2 PC! 2n making t&is

decision, ot&er :actors s$c& as &aing &ad t&e goal o: designing a general p$rpose tracking s%stem and t&e


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need :or designing a ne/ so:t/are compati+le /it& t&e replacements o: t&e de:ectie components did

contri+$te as /ell!

$otor Control System

Fig$re s&o/s t&e +lock diagram o: t&e motor control s%stem /&ic& +$ilt aro$nd t&e Po/er Fle? 4

motor dries! T&e motor dries /ere speci:ied to take digital signals :rom t&e microcontroller $nit t&ro$g&t&e rela% +oard, send signals to stop@start t&e motors, and receie commands :rom t/o sa:et% component

limit s/itc&es and emergenc% stop!

Figure 5. Block diagram of the motor control system.

VFDs #ettin' and #eed "ontrol

T&e Po/er Fle? 4 motor dries /ere c&osen to /ork /it& t&e e?isting motors and to replace t&e t/o

+roken motors dries t&e% are 3p&ase, AC dries, /it& a 0053405 inp$t@o$tp$t rating! T&ese aria+le

:re6$enc% AC dries 5FDs9 allo/ a $ser to control t&e motors speeds man$all% +% c&anging a rotar%

potentiometer on t&e 5FD or +% inp$t signals :rom o$tside so$rces! T&e potentiometer on t&e 5FDs allo/s a

$ser to adj$st t&e speed o: t&e motors directl% t&ro$g& t&e 5FD! T&e internal circ$itr% o: t&e 5FDs allo/s a

microcontroller $nit to ena+le preset speeds /it& digital inp$t signals t&o$g& t&e rela% +oard! For eac& 5FD,

t&e microcontroller $nit /ill assign :ie inp$t signal to :ie rela%s! T&ese :ie inp$t signals are Stop, Start,

Direction, Speed -, and Speed 0! Fo$r di::erent preset :re6$encies@speeds can +e c&anged :rom t&e t/o inp$t

speed signals! Preset :re6$encies are set in t&e Adanced Program =ro$p :rom A0703A07! To control t&e

motor dries t&ro$g& t&e 5FDs $sing e?ternal inp$t signals, all o: t&e :ollo/ing parameters m$st +e

programmed into t&e 5FDs 3"ire setting in t&e starting so$rce P0;9, so$rce SRC9 $nder Dip S/itc&,

Coast to Stop $nder stop mode P079, and Preset Fre6 in speed re:erence P0


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)*e +elay Board

T&e 5FD8s are con:ig$red :or so$rce mode /&ic& $ses its o/n 45DC internal oltage :or control

signals! Controlling t&e 5FD8s +% t&e 'C co$ld not &ae +een done directl% +eca$se t&e 'C o$tp$t

oltage leel is 5DC and it is not s$::icient to control t&e 5FD8s in Sink mode! T&ere:ore, a rela% +oard

/as designed and assem+led /it& terminal +locks to receie inp$t signals :rom t&e 'C and control t&e

5FD +% s/itc&ing t&e logic control circ$it o: t&e 5FD8s!T&e inp$t c$rrent dra/ o: t&e rela%s alone are -7mA! 2n order not to oerload t&e o$tp$ts o: t&e

'C, t&e rela%s are drien /it& a general p$rpose )P) transistor +iased to operate as a solid state s/itc&! A

diode is reersed +iased in parallel /it& eac& rela%8s inp$t terminals in order to eliminate reerse c$rrent

:lo/s o: t&e solenoids o: t&e rela%s to t&e transistors8 collectors! A signal indicator LED circ$it is placed .n

t&e +ase o: eac& transistor! T&e circ$it diagram o: a single rela% drier circ$it is s&o/n in Fig$re ;! T&e

circ$it o: Fig$re ; red$ced t&e inp$t c$rrent dra/ to appro?imatel% mA!

Figre 6. Po/er ampli:ier circ$it to drie t&e rela%s


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Sa%ety &ards

"&en considering t&e design o: an% s%stem, it is important to eliminate as man% &a(ards as possi+le

and +% doing so red$cing t&e need :or an% sa:et% meas$res! Protectie g$ards are re6$ired to ens$re t&e

s%stems :$nctionalit% and t&e $sers sa:et%! T&e =2Trac motion control $nit implements t/o t%pes o: sa:et%

g$ards t&e limit s/itc&es, and t&e E3Stop +$tton!

,imit #%itc*es

T&is sa:et% g$ard preents t&e control $nit and t&e motors :rom displacing t&e antenna :art&er a/a%

:rom its sa:e3range a(im$t& displacement! T&e limit s/itc&es are located at t&e +ottom o: t&e antenna, +elo/

t&e antennas pole! Fig$re 7 s&o/s a pict$re o: t&is sa:et% s%stem! 2n t&e pict$re, t&e green s6$ares indicate

t&e location o: t&e metal plates t&at sere as t&e limit points :or t&e antennas a(im$t& displacement! T&e red

s6$are indicates t&e location o: t&e limit sensor t&at detects /&et&er t&e antennas a(im$t& displacement istoo :ar to t&e le:t or to t&e rig&t!

Figre '. Pict$re o: t&e LimitS/itc& Sa:et% S%stem!

.nce t&e limit sensor detects t&at t&e antennas displacement is too :ar to eit&er direction, it sends a

signal to t&e rela% +oard to c$t t&e po/er to t&e motors! T&e rela% circ$it opens t&e s/itc&es to t&e t&ree

p&ase oltage lines :eeding t&e control $nit! T&$s, t&e control $nit s&$ts do/n t&e motors! T&e control $nit

m$st t&en order t&e motion s%stem to moe t&e antenna in t&e opposite direction! Fig$re < s&o/s a sc&ematic

diagram o: t&e limit s/itc&es connected to t&e rela% +oard and t&e t&ree3p&ase oltage lines :eeding t&e

control $nit!


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Figre (. Sc&ematic Diagram o: t&e Limit S/itc& Sa:et%S%stem!

E-#to Button

T&e E3Stop sa:et% g$ard seres as a mec&anical means to stop t&e control $nit and t&e motors! T&is

g$ard is implemented to stop t&e s%stem in case o: $n3:oreseen incidents t&at ma% p$t in risk t&e $sers sa:et%

or t&e s%stems :$nctionalit%! T&e emergenc% stop, E3Stop, +$tton is easil% accessi+le, recogni(a+le and

/orks relia+le and sa:el%! 2t is located on t&e $pper corner o: t&e control $nits rig&t side! Fig$re > s&o/s t&e

E3Stop +$tton and its position relatiel% to t&e control $nit, /&ic& is indicated +% t&e red s6$are in t&e pict$re

on t&e rig&t!

a9 +9

Figre ). Pict$re o: t&e E3Stop +$tton a9 P&%sical location in control $nits +o?! +9 Relatie position o: +$tton /&en o+sering t&e control $nit!


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Fig$re -0 s&o/s a sc&ematic diagram o: t&e E3Stop sa:et% g$ard s%stem! T&e sc&ematic s&o/s t&e E3

Stop +$tton, and t&e connection +et/een t&e 3p&ase oltage lines, t&e 5aria+le :re6$enc% Drie 5FD9

$nits, and t&e motors!

E3Stop +$tton G /ires9

Figre 1*. Sc&ematic diagram o: t&e E3Stop +$tton sa:et% g$ard!

T&e E3Stop +$tton acts as a mec&anical oltage s/itc& :or t&e motion control $nit in case an $n3

:oreseen incident occ$rs and t&e motion s%stem m$st +e immediatel% stopped! .nce t&e E3Stop +$tton is

pressed, it /ill open t&e 3p&ase oltage lines s/itc&! T&$s t&e motors /ill &ae no po/er to operate t&e

motion s%stem /ill +e stopped!

+ardware Control S,system


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Bac'round

T&e &ard/are control s$+s%stem is +ased aro$nd t&e Ard$ino 'ega microcontroller $nit 'C9! T&e

'C /as designed to resole t&e encoders, o+tain commands :rom t&e PC, and send control signals to t&e

motor dries! T&e :$nctional +lock diagram o: t&e &ard/are control s$+s%stem is s&o/n +elo/ in Fig$re --!

Figre 11. 1lock diagram o: t&e &ard/are control s$+s%stem!

.t&er possi+le candidates :or t&e control $nit /ere t&e P2C< and t&e P2C-7H;0 microcontrollers!

T&e Ard$ino /as c&osen oer t&e P2C microcontrollers d$e to t&e price o: t&e deelopment

+oards@programmers and t&e time re6$ired to implement an em+edded s%stem! T&e Ard$ino is a lo/ cost

complete deelopment +oard, programmed in a lang$age +ased on t&e C programming lang$age,

programma+le t&ro$g& standard S1 ports, /it& a large li+rar% o: pre3/ritten code aaila+le on t&e internet!

T&e Ard$ino 'ega /as c&osen oer ot&er Ard$ino ariants e!g!, D$emilanoe, 'ini, )ano, Pro9 +eca$se it

is t&e onl% Ard$ino +oard /it& a s$::icient amo$nt o: 2@. pins :or t&e entire control $nit! T&e 2@. pins are

a+le to /rite 5 digital signals, /&ic& are $sed to control t&e motor dries, and t&e% can also read 5 digitalsignals, /&ic& can +e o+tained or conerted :rom ind$str% standard encoder o$tp$ts! Complete Ard$ino

speci:ications are aaila+le on t&e Ard$ino /e+site IJ.

As o: Han$ar% 0-0, 1E2 ' series -; +it optical a+sol$te rotar% encoders /ere installed on t&e

a(im$t& and eleation a?es o: t&e antenna! T&ese encoders operated at an internal +a$d rate o: 400 to

--00 +a$d set +% s&orting pins on t&e connector9 IAppendi? Pg J and o$tp$t -; +it +inar% data t&ro$g&

SS2 protocol! "&en terminated properl% $sing an SS2 receier 2C, t&e o$tp$t o: t&e encoder looks like t&e

/ae:orm s&o/n in Fig$re -!


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Figre 1!. Encoder data o$tp$t!

T&e digital data can +e e?tracted :rom t&e /ae:orm in Fig$re < +% :ollo/ing t&e 1E2 data protocol

IAppendi? Pg 4J! T&e 1E2 data protocol sends t&e +inar% data in


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ran on an internal +a$d rate and o$tp$t +inar% data, t&e S2CB encoders m$st +e e?ternall% clocked /it& a

p$lse train to o+tain t&e data! A diagram o: t&e p$lse train is s&o/n in Fig$re - IAppendi? " Pg ->J!

Figre 1". Clock signal :or S2CB encoders!

From Fig$re -, t&e encoders +egin data transmission a:ter an initial lo/ p$lse, and c&ange to t&e

ne?t data +it on eer% s$+se6$ent rising edge! Timing o: t&e clocking signal is cr$cial :or acc$rate data

transmission a more detailed ie/ o: t&e clocking signal is s&o/n in Fig$re -4 IAppeni? N Pg J!

Figre 1#. 'ore detailed ie/ o: S2CB re6$ired clock signal!

From Fig$re -4, :o$r 49 timing aria+les are o: interest T, t, tm, and Tp! Since t&ere is a dela% time,

t, /&en t&e data +it +ecomes sta+le, t&e control $nit is programmed to read on t&e :alling edge o: a p$lse

period to ens$re t&at t&e data +it is sta+le! To ens$re clock p$lse trains are distinctl% separated, Tp is set to at

least t/o clock signal periods OT9 t&is time is increased d$e to intermediate processes o: t&e control $nit

program! Alt&o$g& not mentioned in an% S2CB Stegmann doc$mentation, t&e mono:lop time, tm, sets t&e

minim$m clock :re6$enc% or ma?im$m T9 :or relia+le data trans:er IAppendi? AA Pg-4J! Fig$re - s&o/s

an e?ample c%cles o: t&e inp$t clock signal to t&e S2CB encoder and positional data o$tp$t signal!


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Figre 1-. T/o c%cles o: S2CB clock, and data!

T&e S2CB encoders o$tp$t data as gra% code! T&is data :ormat is pre:erred oer t&e +inar% data

:ormat :or encoders, gra% code onl% c&anges one -9 +it per step t&$s t&e ma?im$m error in data

transmission is one -9 +it! To get an% n$merical data :rom t&e encoder, it m$st +e conerted to +inar% :rom

gra% code t&is can +e done $sing t&e rec$rsie :$nction s&o/n in E6$ation -!

n−m=n−m−-⊕Gnm E6$ation -!

2n E6$ation -, n is e?ponent o: t&e most signi:icant +it in +inar% code corresponding to t&e n$m+er o: gra%

code +its min$s one, m is a ector :rom 0 to n, = is t&e corresponding gra% code +it, and ⊕ corresponds to

an .R e?cl$sie .R9 :$nction! T&is is easil% implemented in t&e C3programming lang$age $sing t&e code

s&o/n in Fig$re -;!

795 uint16_t gray2bin(uint16_t num) {796 uint16_t temp = num ^ (num>>8);797 temp ^= (temp>>4);798 temp ^= (temp>>2);799 temp ^= (temp>>1);800 return temp;801 }

Figre 16. F$nction to conert :rom -; +it gra% code to +inar%!


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T&e S2CB encoders re6$ire a di::erential clock signal and o$tp$t a di::erential data signal IAppendi?

" Pg -


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Figre 1'. T&e Ard$ino 'ega and Et&ernet S&ield set$p $ses a9 S1:or programming, +9 a !-mm center3positie pl$g :or e?ternal po/er,c9 aCat3 ca+le :or Et&ernet connection, and d9 j$mper /ires :or an

Et&ernet S&ield &ack!


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Ta,le 1 Et&ernet S&ield To Ard$ino 'ega Pino$ts

Et&ernet S&ield Pin Ard$ino 'egaPin

)otes

Analog Pin 0 Analog Pin 0

Analog Pin - Analog Pin -

Analog Pin Analog Pin


Analog Pin 4 Analog Pin 4


Digital Pin 0 Digital Pin 0

Digital Pin - Digital Pin -

Digital Pin Digital Pin




Digital Pin ; Digital Pin ;


Digital Pin < Digital Pin <

Digital Pin > Digital Pin >

Digital Pin -0 Digital Pin SS signal +end Et&ernet S&ield pin to aoid contact /it& Ard$ino 'ega Digital Pin -0

Digital Pin -- Digital Pin - '.S2 signal +end Et&ernet S&ield pin to aoid contact /it& Ard$ino 'ega Digital Pin--

Digital Pin - Digital Pin 0 '2S. signal +end Et&ernet S&ield pin to aoid contact /it& Ard$ino 'ega Digital Pin-

Digital Pin - Digital Pin SCB signal +end Et&ernet S&ield pin to aoid contact /it& Ard$ino 'ega Digital Pin

-

T&e Ard$ino SP2 SCB, '2S., '.S2, and SS signals &ae +een relocated :rom pins -, -, --, and

-0 on t&e Ard$ino D$emilanoe to pins , 0, -, and on t&e Ard$ino 'ega respectiel% I-J! T&e &ack

allo/s Ard$inos Et&ernet li+rar% :$nctions to +e called /&ic& can +e $sed to esta+lis& connection, transmit,

and receie data ia Et&ernet IJ!

T&e 'C@PC comm$nication is esta+lis&ed and maintained as per Fig$re -


19/40

Figre 1(. 'C@PC comm$nication s$+ro$tine!

T&e +ackend so:t/are on t&e PC $tili(es a string protocol prod$ced +% t&e Pickle P%t&on mod$le,

descri+ed +elo/! T&e PC, or serer, transmits t&e target, a(im$t& coordinate, and eleation coordinate to t&e

'C, or client, :ollo/ing t&e :ormat +elo/

S target/n I aziumthcoordinate/n I elevationcoordinate/n

T&e 'C decodes t&e command +% t&e &eaders SQ and 2Q and t&e ne/3line delimiter @n!Q T&e

target is t&e name o: t&e target transmitted as a string! T&e a(im$t& and eleation coordinates are transmitted

as :ie digit integers t&e :irst t&ree integers correspond to t&e &$ndreds, tens, and ones digits, and t&e last

t/o integers correspond to t&e tent&s and &$ndredt&s digits! T&e connection and trans:er /as tested +%

o$tp$tting t&e receied data to t&e serial port and LCD!

T&e 'C $pdates t&e PC o: its c$rrent stat$s t&ro$g& anot&er Pickle string protocol, /&ose :ormat is

s&o/n +elo/

I status\n I el_cw\n I error\n I el_ccw\n I elevationangle\n I az_ccw\n I

azimuthangle\n I az_cw\n

Eac& o: t&e aria+les stat$s, elc/, elcc/, eleationangle, a(c/, a(cc/, a(im$t&angle9 is

transmitted as a +inar% n$m+er! T&e aria+les elc/, elcc/, a(c/, a(cc/ are +inar% - or 0 to denote

/&et&er t&e limit s/itc& :or t&e a(im$t& or eleation clock/ise or co$nter3clock/ise directions &ae +een

triggered! T&e a(im$t& and eleation are transmitted +ack to t&e PC :ollo/ing t&e same protocol :or

receiing t&e coordinates t&e :irst t&ree integers correspond to t&e &$ndreds, tens, and ones digits, and t&e

last t/o integers correspond to t&e tent&s and &$ndredt&s digits! T&e stat$s is a 3+it +inar% code /&ic& gies

t&e c$rrent stat$s o: t&e 'C t&is code is descri+ed in Ta+le !


20/40

Ta,le ! 31it 1inar% Stat$s Code

Decimal 1inar% 19 Stat$s

0 00 DoneQ

- 0- "orkingQ

-0 ErrorQ

T&e 'C onl% sends data to t&e PC /&en t&e stat$s o: t&e 'C or t&e position o: t&e antenna

c&anges! T&e complete set$p +et/een t&e 'C and t&e PC is s&o/n +elo/ in Fig$re ->!

Figre 1). T&is is a diagram o: t&e interconnections +et/een t&e PC and 'C ia an Et&ernet &$+ allinterconnections are Cat3 ca+les! T&e comp$ter acts as t&e serer and t&e 'C acts as a client!

T&e Et&ernet &$+ is $sed to allo/ t&e connection +et/een t&e Et&ernet compati+le PC and 'C! An

alternatie /o$ld +e to $se an Et&ernet crossoer ca+le to directl% connect t&e PC to t&e 'C &o/eer, t&e

&$+ and reg$lar Cat3 ca+le sol$tion /as c&osen +eca$se t&e PC onl% &as one natie Et&ernet port /&ic& is

$sed to connect to t&e internet!

2n t&e c$rrent program, t&e so:t/are +ackend serer comm$nicates $sing t&e :ollo/ing 2P address and

port ->!-;


21/40


22/40

T&e terminal +locks allo/ 6$ick e?ternal connections o: po/er and signals to t&e rela% +oard! T&e

sc&ematic o: all connections to t&e C terminal +lock is aaila+le in Appendi? I*J!

T&e Ard$ino da$g&ter+oard proides t&e j$mper /ires :or t&e Et&ernet s&ield to /ork /it& t&e

Ard$ino 'ega! 2t also &as connections to t&e :emale 43pin +ar connector $sed :or t&e LCD! T&is +oard is

$sed mainl% :or aest&etic reasons and to keep t&e C internals more compact and neat! A sc&ematic o: t&e

da$g&ter+oard is aaila+le in Appendi? IRJ!T&e LCD da$g&ter+oard is a small $niersal proto+oard attac&ed to t&e top o: t&e Et&ernet S&ield!

T&is +oard &as a -0 kK potentiometer /&ic& adj$sts t&e LCD contrast ratio! A sc&ematic o: t&is +oard is

aaila+le in Appendi? I.J!

T&e LCD connection :rom t&e Ard$ino to t&e LCD drier occ$rs in a m$ltistage connection! First t&e

pins :rom t&e Ard$ino are :ed to t&e Ard$ino da$g&ter+oard connected to a 43pin :emale +ar connector! T&e

male +ar connector is connected to a 43pin ri++on ca+le! 43pin ri++on ca+les /ere not readil% aaila+le so

one pin /as remoed :rom a 3pin ri++on ca+le! T&e ot&er end o: t&e ri++on ca+le is a standard D1 male

connector /it& onl% a 43pin ri++on ca+le, t&e :irst pin on t&e D1 connector is omitted! T&e male

connector connects to a D1 :emale connector /&ic& makes t&e :inal interconnections /it& t&e LCD drier!

T&e LCD is t&en mo$nted on t&e coer o: t&e C :or isi+ilit%! A pino$t c&art descri+ing all interconnects

and a :$nction description o: eac& pin is Aaila+le in appendi? ISJ!

T&e encoders, /&ic& comm$nicate t&ro$g& t&e SS2 line drier, attac& to t&e C t&ro$g& standard

D1> connectors! T&e pino$ts o: t&ese c$stom connectors is aaila+le in Appendi? ITJ!

#ystem "alibration

1e:ore t&e 'C o$tp$ts an% acc$rate ang$lar positions relatie to Eart&, t&e s%stem m$st +e

cali+rated! T&e +asic steps :or cali+ration are descri+ed +elo/

• T$rn on t&e 3p&ase po/er circ$it +reaker in t&e control +o?!• Allo/ time :or t&e 'C to +oot $p it is :inis&ed /&en te?t on t&e LCD is isi+le!• Po/er t&e encoders +% toggling t&e E)CP"RQ s/itc& on t&e side o: t&e C!• Disconnect all %ello/ /ires t&ese connect t&e 'C to t&e rela% +oard9 :rom t&e T1!• "it& a j$mper /ire, connect 5 to t&e a(im$t& and eleation start rela%s to t$rn on t&e 5FDs

• 'an$all% moe antenna to le:tmost A(im$t&9 and +ottom Eleation9 positions $ntil t&e% are er%close to triggering t&e le:tmost and +ottom limit s/itc&es! T&is is done +% connecting 5 to one or +ot& o: t&e speed rela%s t&is /ill ar% t&e motor speed as preio$sl% descri+ed9

• At t&is point, connect 5 to t&e a(im$t& and eleation stop rela%s to t$rn o:: t&e 5FDs• Reset +ot& encoders +% $sing t&e reset +$ttons on t&e C t&is sets t&e gra% code to (ero at t&ese

positions9• Repeat step !• 'an$all% moe t&e antenna to t&e rig&tmost A(im$t&9 and top Eleation9 positions $ntil t&e% are

er% close to triggering t&e rig&tmost and top limit s/itc&es!• Repeat step 7!


23/40


24/40


25/40

2: at an% point t&e antenna control operation +ecomes $nsta+le or co$ld endanger near+%

&ard/are@personnel, po/er to t&e s%stem can +e 6$ickl% s&$t o:: +% engaging t&e emergenc% stop, as

preio$sl% descri+ed! An alternatie to t&is is to t$rn o:: t&e 3p&ase po/er circ$it +reaker! )ote t&at +ot& o:

t&ese actions, /&ile t&e motors9 are still moing, co$ld potentiall% damage t&e 5FDs, control $nit, or

encoders!

no%n Bu's and Fi.es

2: t&e s%stem &as not $ndergone t&e complete cali+ration proced$re /it& t&e A'C satellite, +$t t&e

encoders &ae +een reset at t&e le:tmost and +ottom limit s/itc&es, t&e ang$lar position o: t&e a(im$t& ma%

toggle +et/een t/o al$es as s&o/n on t&e LCD! T&is is onl% an iss$e $nder t&e :ollo/ing conditions

-! 1ot& encoders are connected to t&e C!! A(im$t& angle is X -!00V!

! Eleation angle is X -!00V!

"&en onl% one o: t&e encoders eit&er a(im$t& or eleation9 is connected to t&e C, t&e angle /ill

displa% properl% :or t&e /&ole ang$lar range 0!00V G >!>>V! #o/eer /&en +ot& encoders are connected

and t&e ot&er t/o re6$irements are met, t&e a(im$t& position /ill toggle +et/een t/o al$es! T&e iss$e &as

+een narro/ed do/n to t&e clock signal driing t&e encoders! "&en all t&ree conditions are met, t&e clock

signal /ill make one p$lse o: t&e p$lse train ro$g&l% t/ice as large eer% ot&er c%cle, ca$sing an error in data

transmission and toggling t&e data +et/een t/o al$es! "it& t&e so:t/are limits set +% cali+rating aria+les

ANC"L2'2T and ELC"L2'2T9, t&is toggling /ill make also toggle t&e 5FDs on and o:: i: t&e $ser

/ants t&e antenna to moe!

As a :$ll cali+ration proced$re &as not %et +een set, a temporar% :i? &as +een implemented! T&e

so:t/are limit :or t&e a(im$t& angle is slig&tl% greater t&an -!00V a+o$t -!-V9! Since t&e antenna can no/

no longer moe +elo/ -!-V a(im$t&, t&e t&ree conditions /ill neer +e satis:ied and t&e toggling iss$e no

longer occ$rs! For a long term :i? cali+ration mode /o$ld reset t&e encoder ang$lar position relatie to Eart&

rat&er t&an (ero, and t&is s&o$ld :i? t&e iss$e completel%!

Anot&er iss$e onl% occ$rs /&en t&e code :or remote mode is ena+led! "it& t&at ersion o: t&e code,

t&ere is no sa:eg$arding meas$re to ens$ring t&at all rela%s are set properl% and t&at t&e motor is completel%

stopped! T&e code to :i? t&is is s&o/n in Fig$re 0 +elo/!


26/40

213 if(reet!e"ay == true) {214 reet!e"ay = #a"e;215 etup!e"ay();216 }

Figre !*. nc&anged :lag code!

2n Fig$re 0, resetRela%s is a 1oolean :lag t&at is onl% tr$e /&en t&e maintenance@remote mode

selector s/itc& is toggled, and set$pRela%s9 is a :$nction t&at ens$res t&e motors and rela%s are set to

initiali(ed states! 'an% ariants o: t&is code &ae +een implemented &o/eer, t&e :lag resetRela%s neer

toggles to :alse, and set$pRela%s /ill contin$e to r$n eer% c%cle! T&is means t&at i: one o: t&e maintenance

mode moement s/itc&es is engaged, t&e C /ill contin$e to toggle t&e 5FDs +et/een moing :rom t&e

s/itc&9 and stopped :rom t&e :$nction set$pRela%s99!

2: remote mode is to /ork relia+l%, a ne/ :lag@:$nction needs to +e designed to reset t&e rela%s to

initiali(ed states /&eneer t&e mode is s/itc&ed :rom maintenance to remote and ice ersa!

"ode Flo%

Eer% c%cle, t&e 'C r$ns some initiali(ations and t&en t&e +$lk o: t&e code is r$n as a state mac&ine

as s&o/n in Fig$re -!


27/40

Figre !1. 'C code :lo/!

T&e initiali(ation step onl% occ$rs once /&en t&e 'C +oots $p a:ter receiing main po/er! 2n t&is

state, t&e 'C initiali(es t&e target to 2)2T2AL2NEDQ, t&e a(im$t& and eleation angles to 0, and r$ns t&e

:$nctions set$pPins9, set$pSerial9, set$pEt&ernet9, set$pLCD9, set$p5FD9, set$pClock9, and

set$pRela%9 /&ic& are all aaila+le in Appendi? I22J! Finall%, t&e program c&ecks i: maintenance mode is

engaged and sets $p t&e interr$pt :or t&e maintenance@remote toggle s/itc&!

T&e set$p :$nctions are descri+ed +elo/ in Ta+le


28/40

Ta,le " Set$p F$nctions

/ame Fnction Descri0tion

set$pPins Sets pins as 2)PT or .TPT

set$pSerial Sets t&e +a$d rate :or t&e serial monitor onl% $sea+le /&en connected iaS19

set$pEt&ernet .$tp$ts Et&ernet connection in:ormation to t&e serial monitor and esta+lis&esan initial connection /it& t&e serer

set$pLCD Prints persistent te?t to t&e LCD

set$p5FD Ens$res t&e motor is stopped at t$rn on

set$pClock 2nitiali(es encoder clocking signals &ig& +e:ore :irst p$lse train

set$pRela% 2nitiali(es all rela%s to open e?cept :or stop

A:ter t&e initiali(ation loop t&e program enters t&e main loop /&ic& /ill contin$e $ntil po/er is

disconnected to t&e 'C! T&e program +egins +% resoling t&e encoders, conerting t&e gra% al$es to

+inar%, conerting t&e +inar% n$m+er to split decimal :ormat, and t&en printing t&e al$es to t&e LCD $sing

t&e printLCD9 :$nction aaila+le in Appendi? I22J! T&e printLCD9 :$nction also prints o$t /&et&er or not an

Et&ernet connection /as made and t&e c$rrent target! For t&e :irst c%cle, t&e target /ill displa%

'A2)TE)A)CEQ i: in maintenance mode, or 2)22TAL2NEDQ i: in remote mode +eca$se no target &as

+een ac6$ired %et!

Ass$ming maintenance mode, t&e :$nction /ill t&en enter t&e 'A2)TC.))ECT state! 2n t&is state,

t&e program /ill attempt to make one Et&ernet connection and t&en moe into t&e 'A2)TE)A)CE state!

T&is state is onl% r$n once /&eneer t&e mode is s/itc&ed to maintenance mode!

2n 'A2)TE)A)CE mode, r$ns t&ro$g& an entire s$+ro$tine to read t&e maintenance mode s/itc&es

and control t&e rela%s@5FDs accordingl%! First t&e program adds a 0 ms dela% t&is is to ens$re t&at all 1HTs

and rela%s on t&e rela% +oard &ae &ad eno$g& time to reac& stead% state +e:ore c&anges are made! T&e

program t&en reads +ot& s/itc&es :or t&e a(im$t& onl% one can +e actie at a time +eca$se it is p&%sicall%

impossi+le to t&ro/ t&e s/itc& to le:t and rig&t sim$ltaneo$sl%! 2: one direction is triggered, t&e program t&en

c&ecks t&e so:t/are set limit s/itc& :or t&at direction onl% in t&is /a%, i: t&e le:t limit s/itc& is triggered

t&en t&e motor is stopped and error :lags are set$p :or t&e Et&ernet data string, +$t t&e antenna can still moe

to t&e rig&t, and ice ersa! 2: t&e so:t/are limit s/itc& &as not +een &it, t&en t&e program ens$res t&at t&e

stop signal to t&e 5FD is t$rned o::, sends t&e appropriate direction signal, sets t&e error :lags to .B, and

+egins ramping to t&e ma?im$m speed programmed into t&e 5FD! T&is t&o$g&t process is repeated :or +ot&

a(im$t& direction s/itc&es and +ot& eleation direction s/itc&es!

Finall%, i: t&ere is a PC Et&ernet connection t&en t&e 'C transmits its stat$s to t&e PC! T&e loop

t&en contin$es skipping t&e 'A2)TC.))ECT step!


29/40

Alt&o$g& t&e remote mode &as not +een tested or implemented, t&e code is aaila+le and +elieed to

/ork gien a :e/ minor de+$gging c&anges! 2: ena+led, t&e program /ill r$n t&e :ollo/ing states "A2T,

TRA)SLATE, START, '.5E, C#ECB, ST.PAN, ST.PEL, E)D!

2n t&e "A2T state, t&e 'C c&ecks :or an aaila+le Et&ernet connection to t&e so:t/are +ackend! 2:

t&e connection is made, t&en t&e 'C receies a command :rom t&e PC :ollo/ing t&e Pickle receie :ormat

descri+ed a+oe! T&e 'C /ill t&en conert t&e coordinates receied :rom t&e PC into +inar% :ormat! 2:t&ere is a di::erence +et/een t&e target coordinates and c$rrent position o: t&e antenna, t&e state /ill c&ange

to TRA)SLATE! 2: t&e PC sends t&e string )o TargetQ :ormatted e?actl% as s&o/n, t&en t&e program /ill

remain in t&e "A2T state! T&is is implemented +eca$se /&en t&e PC no longer &as a target to send, t&e target

name /ill +e )o TargetQ, and t&e coordinates /ill +e (ero! T&is /ill +e calc$lated as an ang$lar di::erence

+et/een t&e target coordinates and t&e c$rrent position, and t&e program /o$ld tr% to contin$e /it& t&e state

mac&ine! T&is :inal c&eck ens$res t&at a:ter a target &as +een reac&ed and no ot&er target is c&osen, t&e

antenna /ill remain in t&e same position!

Since t&e p&%sical limit s/itc&es are not /ired to t&e 'C, t&e TRA)SLATE state determines i: a

target coordinate sent +% t&e PC /o$ld trip a limit s/itc& and sets t&e error :lags accordingl%! 2: an% o: t&e

:lags s&o$ld c&ange, t&e program reerts to t&e "A2T state ot&er/ise t&e program contin$es to t&e START

state! 2n eit&er case, t&e 'C o$tp$ts t&e c$rrent stat$s o: an% error :lags to t&e PC t&ro$g& t&e Pickle send

:ormat descri+ed a+oe!

T&e START state t$rns o:: t&e stop signal and t$rns on t&e start signal :or t&e 5FDs according to

/&ic& direction t&e antenna needs to moe! T&ere is anot&er 0 ms dead time dela% +et/een t&e c&anging o:

t&ese signals to ens$re t&at t&e start and stop signals are not actie at t&e same time! T&e state mac&ine is

c&anged to t&e '.5E state!

2n t&e '.5E state, t&e program determines /&ic& direction t&e 5FDs need to +e set to reac& t&e

target coordinates! T&is is done /it& a simple e6$alit% statement +et/een t&e target coordinate and t&e

c$rrent antenna position! Depending on &o/ :ar a/a% t&e antenna is :rom t&e target, t&e antenna ma% moe

at one o: :o$r speeds set +% ??Speed09, ??Speed-9, ??Speed9, ??Speed9, /&ere ??Q corresponds to

a(Q :or a(im$t& or elQ :or eleation! T&e speed is c&osen depending on t&e ang$lar di::erence +et/een t&e

target and t&e c$rrent position as s&o/n in Ta+le 4, and t&e act$al speed in terms o: motor #( is determined

+% t&e 5FD programming!

Ta,le # Speed Settings

Di::erence +et/een target and c$rrent positions Speed F$nction

Y Z -0 Speed9

-0[ \ Y Z [ Speed9

[ \ Y Z [ Speed-9

Y ] [ Speed09


30/40

1% setting t&e direction and speed aria+les, t&e signals are sent to t&e rela% +oard /&ic& /ill control

t&e 5FDs accordingl%! T&e state mac&ine c&anges states to t&e C#ECB state!

2n t&e C#ECB state, t&e program recalc$lates t&e ang$lar di::erence +et/een t&e target coordinates

and t&e c$rrent position! 2: +ot& coordinates are reac&ed, t&e state c&anges to E)D! 2: onl% t&e a(im$t&

coordinate &as +een reac&ed, t&e state c&anges to ST.PAN similarl%, i: t&e eleation coordinate &as +een

reac&, +$t t&e a(im$t& &as not, t&e state c&anges to ST.PEL! 2: neit&er coordinate &as +een reac&ed t&en t&e program loops +ack to t&e '.5E state! 2n all cases, t&e 'C $pdates t&e antenna program stat$s to t&e PC

ia Et&ernet!

2n eit&er ST.PAN or ST.PEL states, a 0 ms dela% is applied and a stop signal is send to t&e

corresponding 5FD t&ro$g& t&e rela% +oard! T&e program /ill no/ loop +ack to t&e '.5E state &o/eer,

no/ t&at one partic$lar 5FD &as +een stopped, an% inadertent c&anges to t&e speed or direction o: t&at

motor drie /ill not a::ect t&e position +eca$se it is stopped!

2n t&e E)D state, t&e antenna &as reac&ed its target coordinate in +ot& a(im$t& and eleation! T&e

program again ens$res t&at t&e motor dries are stopped! T&e program stat$s :lag is set to DoneQ as

descri+ed +% Ta+le 4, and t&e 'C stat$s is sent to t&e PC ia Et&ernet! T&e state /ill c&ange +ack to t&e

"A2T state and /ait :or a ne/ target!

2t is important to note t&at i: at an% point t&e mode is s/itc&ed +et/een maintenance and remote

mode, t&e program /ill reset to eit&er 'A2)TC.))ECT or "A2T states respectiel% een i: in t&e middle

o: a moement command! 2t is important to read t&e kno/n +$gs section to ens$re t&at appropriate :i?es are

made +e:ore ass$ming completel% sa:e operation!

2n t&eor% t&e remote mode code /orks &o/eer, d$e to a lack o: time t&is code remains $ntested! 2n

its c$rrent state, onl% a :e/ minor +$gs ma% e?ist and co$ld +e :i?ed /it& anot&er :e/ /eeks o: testing!

ackend So%tware

0vervie%

A c$stom so:t/are program /as /ritten in P%t&on I4J to :acilitate t&e comm$nication +et/een t&e

client so:t/are and t&e antenna controller! T&e +ackend receies commands :rom t&e client, processes t&e

command and $pdates t&e antenna as necessar%! T&e +ackend s%stem also $pdates t&e client /it& t&e

antenna8s c$rrent stat$s! Along /it& :acilitating comm$nication +et/een t&e t/o ends o: t&e s%stem t&e

+ackend m$st also manage t&e targets, incl$ding nig&tl% $pdates o: a local catalog o: Eart& or+iting o+jects!

Fig$re s&o/s a +lock diagram o: t&e main components o: t&e +ackend s%stem!


31/40

Figre !!. 1ackend so:t/are proiding a link +et/een major

components!

),E

Descri0tion

T&e T/o Line Element set TLE9 I7J is a set o: or+ital elements t&at descri+e t&e position and

elocit% o: Eart& or+iting o+jects, standardi(ed +% ).RAD! ).RAD is a +i3national nited States and

Canadian organi(ation c&arged /it& t&e missions o: aerospace /arning and aerospace control :or )ort&

America IJ! .nl% t&e S=P4@< or SDP4@< prediction models can +e $sed

I>J!


32/40

T&e title line is onl% meant :or &$man reada+ilit% and consists o: t&e name o: t&e or+iting o+ject! T&e

second and t&ird lines contain t&e or+ital elements along /it& an $ni6$e id :or t&e o+ject! Fig$re lists an

e?ample TLE, t&e 2nternational Space Station, /&ile a +reakdo/n o: eac& line are seen in Ta+les , ;, and 7!

2SS NARA9

- 44 >


33/40

Ta,le ' 1reakdo/n o: Contents o: Line

Field Colmns Content 23am0le

- 0-30- Line n$m+er

0307 Satellite n$m+er 44

0>3-; 2nclination IDegreesJ -!;4-;

4 -Ta,le ( Data+ase Sc&ema

5nteger Primary ey Datetime Test Te3t Te3t

$id lastpdate Line 0 Line - Line

Python

"&en c&oosing a programming lang$age to /rite t&e s%stem in C, CU, and P%t&on /ere

considered! C and CU /ere not c&osen +eca$se o: t&e steep learning c$re a non programmer /o$ld &ae


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to end$re in order to c$stomi(e t&e so:t/are :or an% speci:ic needs! P%t&on /as c&osen :or t&e :ollo/ing

reasons!

• Fast protot%ping• .+ject oriented• Reada+ilit% and sel: doc$menting• ^1atteries incl$ded^, t&e standard li+rar%• P%Ep&em mod$le

Fast Prototy0ing

P%t&on allo/s a programmer to easil% re:ine t&e so:t/are as t&e so:t/are eoles, allo/ing t&e

programmer to easil% tr% ne/ t&ings, or a di::erent met&od to implement an action! Rapid protot%ping is

especiall% eas% to do in P%t&on +eca$se it is an interpreted and d%namic lang$age, t&ere is no compiler

re6$iring to kno/ t&e datat%pes o: aria+les, :$nction arg$ments, or :$nction ret$rns! 1eca$se P%t&on is a

d%namic lang$age t&ere is no need to proide a seperate oerloaded :$nction :or eac& o: t&e possi+le

di::erent :$nction arg$ments to t&e P%t&on programmer i: it looks, smells, and :eels like an int t&en it m$st

+e an int!

O,ject Oriented

2n P%t&on eer%t&ing is an o+ject, incl$ding aria+les, classes, een :$nctions, and literals! Treating

eer%t&ing as an o+ject allo/s 6$icker design o: so:t/are +% not &aing to di::erentiate +et/een o+jects and

reg$lar aria+les, and +% allo/ing o+ject oriented design principles can +e applied an%/&ere in t&e program!

T&e :ollo/ing code snippet demonstrates P%t&ons treatment o: o+jects!

csv = ','.join("ello !orld".slit(##

A:ter e?ec$tion t&e al$e o: csv is "ello,!orld"!

T&e o+ject oriented nat$re o: P%t&on allo/s t&e +ackend so:t/are to +e /ritten so t&at di::erent

connection met&ods can +e $sed, s$c& as RS3, TCP@2P, or S1! Ass$ming t&e di::erent connections

implement t&e necessar% :$nctions and data attri+$tes, t&e so:t/are /ill +e a+le to $se t&e connection /it&o$t

an% modi:ication to t&e core! T&is is also $sed /&en calc$lating t&e position o: t&e t&e 4 di::erent targets!

Fig$re 4 s&o/s t&e :$nctions $sed comp$te t&e position o: di::erent targets, t&e ^)o Target^, and a TLE

+ased target!


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70 def get_angles(self, radians=None):71 """Return the home position"""72 return (0, 0)

23 def get_angles(self, radians=None):2!0 """al#ulate the lo#ation of this target as seen $%2!1 the o$ser&er'antenna2!2

2!3 Return a tuple of the angles in degrees $% default2!!2! """2!*2!7 selfo$ser&erdate = ephemno+()2! selfsat#ompute(selfo$ser&er)2! if radians is None:20 selfa-imuth = selfsata-21 selfele&ation = selfsatalt22 else:23 selfa-imuth = rad_2_deg(selfsata-)2! selfele&ation = rad_2_deg(selfsatalt)22* return (selfa-imuth, selfele&ation)

Figre !#. F$nctions :or calc$lating t&e position o: t&e targets, ^)o Target^ top9, and a TLE +ased +ottom9 s&o/n! Re:er to Appendi? ## :or t&e :$ll so$rce code!

7eada,ility and Sel% Docmentation

2t /as $nderstood t&at it /o$ld +e $nlikel% t&at t&e s%stem /o$ld +e completed in one semester o:

/ork, and t&at in order to eer &ae a complete s%stem t&e code m$st not +e re3/ritten +% eer% team! 2n

order to allo/ ot&er teams to e?tend t&e c$rrent code t&e% m$st +e a+le to easil% read and $nderstand it!P%t&on8s inentor =$ido an Ross$m states ^code is read m$c& more o:ten t&an it is /ritten^ in t&e o::icial

st%le g$ide :or P%t&on code I-0J! Anot&er :eat$re t&at improes P%t&on reada+ilit% is t&e treatment o: /&ite

space as important! Code +locks are descri+ed +% t&e indentation leel, making related statements e?plicitl%

o+io$s! Re:er +ack to Fig$re 4 :or an e?ample o: P%t&on code!

P%t&on also &as +$ilt3in s$pport :or accessing t&e doc$mentation o: a class, :$nction, or mod$le, kno/n as

docstrings! P%t&on docstrings are enclosed /it&in a matc&ing pair o: ^^^ triple do$+le 6$otes9 and occ$r as

t&e :irst statement a:ter t&e declaration o: a class, :$nction, or mod$le! Re:er to t&e one line docstring on line

n$m+er 7- and t&e m$lti3line docstring on lines 4034 in Fig$re 4! T&e docstrings are $se:$l /&ile

protot%ping code in t&e P%t&on interpreter, and can +e accessed +% t%ping &elp:$nction9!

atteries inclded

P%t&on8s standard li+rar% coers a /ide range o: :$nctions incl$ding a +$ilt in S*Lite data+ase

engine, ra/ net/ork sockets, t&reading, and TCP@DP serers! T&e standard li+rar% /as $sed to implement


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t&e antenna@client TCP serers in di::erent t&reads, comm$nication +et/een t&e serers and t&eir clients, and

to access t&e TLE data+ase! Fig$re lists a part o: t&e TCP serer class t&at in&erits :rom t&e TCP serer

class in order to listen :or connections :rom t&e antenna!

1 class .ntenna(/o#et/er&erhreading/er&er):

20 """lient ' #ommuni#ation ser&er21

22 his #lass +ill set up and maintain #onne#tions to the antenna, +hile

23 also ser&ing as an o$4e#t interfa#e to the antenna for the outside+orld2!

2 """

Figre !-. TCP serer class listening :or antenna connections! For :$ll so$rce code seeAppendi? IEEJ!

Py20hem

P%Ep&em is $sed :or all t&e astronomical calc$lations and is a P%t&on /rapper :or t&e Ep&em C

li+rar%! P%Ep&em /orks +% comp$ting t&e a+sol$te position o: target in t&e sk% and conerting t&e rig&ts

ascension and declination similar to latit$de and longit$de e6$ialent9 to a(im$t& and eleation +ased $pon

t&e o+serer8s location, it is also $sed to determine t&e ne?t time t&e target is aaila+le /it&in t&e antenna8s

look angle! P%Ep&em &as +$ilt in kno/ledge o: t&e major +odies, s$c& as t&e s$n, planets and moons, and

proides ro$tines to load $ser ac6$ired or+ital elements in ).RAD TLE or ep&em data+ase :ormat! For

o+jects t&at cannot +e :o$nd in eit&er :ormat, t&e o+ject can +e created and it8s elements set indiid$all%!P%Ep&em and Ep&em /ere tested :or acc$rac% +% comparing t&e res$lts o: di::erent satellite positions

against res$lts o+tain :rom )ASA8s Sk%"atc& jaa applet, and /as proen to +e acc$rate!

Bacend In Detail

T&e +ackend so:t/are is composed o: TCP@2P serers r$nning in di::erent t&reads, and t&e main

t&read o: e?ec$tion t&at &andles t&e comm$nication +et/een t&e client and antenna! T&e main loop is /ritten

to +e o+liio$s to t&e connection protocols or t&e $nderl%ing met&od to calc$late t&e target position! T&is:acilitates possi+le control o: m$ltiple antennas, connected to m$ltiple clients, tracking targets o: di::erent

t%pes! Fig$re ; s&o/s a more detailed ersion o: t&e +lock diagram o: t&e +ackend s%stem!


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Figre !6. Detailed +lock diagram o: +ackend s%stem!

T&e clients connect ia TCP@2P to t&e TCP serer marked 8Client T&read8 in Fig$re , t&e

client so:t/are can t&en send commands to t&e antenna +% sending a pickled ersion o: a P%t&on data t%pe

called a dictionar%, /&ic& is an $nordered mapping +et/een ke%Wal$e pairs! Pickling is a P%t&on term :or

trans:orming almost an% o+ject &ierarc&% into a +%te stream or string, /&ic& can t&en +e saed to a :ile or

sent oer net/ork connections! Pickling o+jects circ$ments &aing to de:ine a c$stom protocol to delimit

t&e transmitted data! T&e antennas connect in a similar :as&ion! Fig$re 7 s&o/s a P%t&on dictionar% and later

t&e pickled ersion o: t&e dictionar%!

$$$ imort c%ic&le as ic&le$$$ command = 'target')**++, 'jocode'-012

$$$ ic&le.dums(command#"(d3\nS'jocode'\n)\nI+45-6\nsS'target'\n7\nI)**++\ns."$$$ ic&le.loads(ic&le.dums(command##'jocode' +45-6, 'target' )**++2

Figre !'. P%t&on code snippet demonstrating 8pickling8, and 8$npickling8 a dictionar%!

T&e main loop t&read :or/ards t&e target position to t&e antenna, and t&en :or/ards t&e antenna stat$s

to t&e client! Fig$re < is a :lo/ c&art o: t&e main loop!


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Figre !(. Flo/ c&art o: t&e main loop e?ec$tion pat&!

T&e main loop /aits :or a connection :rom t&e client or t&e antenna! 2: t&e antenna is connected /&ilet&ere is no client connected t&e +ackend /ill send a target named 8)o Target8, and tell it to moe to its &ome

position! 2: t&e client connects /&ile t&ere is no antenna connected t&e +ackend s%stem /ill $pdate t&e client

/it& an antenna stat$s o: 8)ot Connected8! .nce +ot& t&e antenna and clients are connected t&e +ackend /ill

monitor t&e client :or an% ne/ commands, t&e onl% ne/ command implemented is a c&ange o: target, i: t&ere

is a ne/ target it /ill $pdate t&e antenna accordingl%! 2: t&ere are no ne/ commands and t&e antenna &as

:inis&ed moing to t&e last sent position t&e +ackend /ill calc$late t&e ne/ position and send t&e command

to t&e antenna!

T&e cli ent command is a dictionar%!

89::0;


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S0S = 'status'S0>S?"done"@, 'connected' Aalse,

'az_cw'Aalse, 'az_ccw'Aalse,

'el_cw'Aalse, 'el_ccw'Aalse,

'error'Aalse, 'az'-.-, 'el' -.-2

Re:er to Appendi? IFFJ :or t&e meaning o: t&e al$es o: eac& :ield!

8ser 5nter%aces

T/o $ser inter:aces /ere started to connect to t&e +ackend s%stem! T&ere is a P%t&on +ased =2 $sing t&e

P%=TB toolkit, and a command line inter:ace! See Appendi? I==J :or t&e =2 code, and Appendi? I##J :or

t&e CL2 code!


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7e%erences

-! Et&ernet S&ield #ack 3 &ttp@@mc$kits!com@00>@04@0;@ard$ino3et&ernet3s&ield3mega3&ack@

! Ard$ino Et&ernet Code 3 &ttp@@///!ard$ino!cc@en@Re:erence@Et&ernet

! Ard$ino 'ega 1oard Sc&ematic 3 &ttp@@ard$ino!cc@en@'ain@Ard$ino1oard'ega

4! LCD 2n:ormation 3 &ttp@@///!spark:$n!com@commerce@prod$ctin:o!p&pprod$ctsidW7-0! P%t&on 3 &ttp@@///!p%t&on!org

;! P%Ep&em 3 &ttp@@///!r&odesmill!org@p%ep&em@

7! TLE 3 &ttp@@celestrak!com@).RAD@doc$mentation@tle3:mt!asp

>! S=P4@

Documents

Final Report of Antenna Project