Hoi nghi Khoa hoc ky- niem 35 ndm I'ien Khoa hoc vd Cong nghi Viet Nam - Hd Ngi 10 2010<br />
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HE MO PHONG BAN VAT LY XAC DINH VA DIEU K H I E N TlT THE<br />
VE TINH NHO<br />
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Nguvin Khoa So-n. Nguyen Due Cuong*, Pham Anh TuSn, Vo Due My, Nguyen Thanh<br />
Tuan, Bui Nam Duo-ng, Le Xuan Huy, Nguyen Huy Thuy<br />
Vien Cong nghe Vii tru; * Vien Khoa hoc va Cong nghe Quan su<br />
Email: nkson@.vast.ac.vn<br />
Tom t^t:<br />
Hi thdng xdc dinh vd diiu khiin tu thi vi tinh, (ADCS) Id mdt hi thdng con<br />
trong vi tinh, cd nhiem vu gid cho vi tinh cdn bdng vd diiu khiin ve tinh theo mdt<br />
huang mong muon. Bdi bdo ndy gidi thieu vi hi md phdng bdn vdt ly xdc dinh vd<br />
dieu khien tu thi ve tinh nhd. Hi md phdng bdn vdt ly ndy duac thiit ki vd chi tao<br />
vdi muc dich thuc nghiem qud trinh xdc dinh, diiu khiin tu thi vi tinh nhd trin<br />
mat ddt quadd phdn tich, ddnh gid vd edi tiin cdc thdnh phdn ciia he thdng. Cdc .<br />
loai cdm bien (cdm^ bien mdt trdi, cdm biin tir trudng,...) duac ditng di xdc dinh<br />
cdc thdng sd tu thi ciia vi tinh. He thdng ca cdu chdp hdnh diing cho diiu khiin<br />
tu thi gdm cd; ba bdnh xe ddng luang, ba thanh tit luc duo'c ddt vudng gdc vdi<br />
nhau, khdi truat vd hi thdng khi nen. Mdt dim khi dgng cdu duac su dung di tgo<br />
ra mdt trgng thdi ldm viic gdn nhu khdng cd ma sdt. Todn bd qud trinh thu<br />
nghiim duac gidm sdt, phdn tich vd hiin thi bdng phdn mim xdy dung trin mdy<br />
tinh thdng qua mgt thiit bi truyin nhdn du lieu khdng ddy. Mdt vi xu ly duac su<br />
dung ldm khdi dieu khien trung tdm cho hi md phdng bdn vdt ly ndy.<br />
Abstract:<br />
77?^ attitude determination and control system (ADCS) is the subsystem of a<br />
satellite which is responsible for stabilizing and orientating the satellite in the<br />
desired direction. The ADCS simulator for small satellite is introduced in this<br />
paper. This simulator is designed and manufactured for the purpose of carrying<br />
out the attitude determination and control process on the ground. Depending on<br />
the practical result, this simulator can be analyzed and improved. Different<br />
sensors (sun sensor, magnetometer,...) are used to measure the attitude parameter<br />
of satellite. A set of actuators consists of three inertial wheels, three mutually<br />
perpendiculgr magnetic coils, two sliding mass and a micro-thruster subsystem..<br />
The spherical air bearing is used to create near frictionless circumstances. The<br />
whole test is observed, analyzed and displayed by software on the computer. Data<br />
is transferred between computer and the simulator via a wireless device. The<br />
Rabbit 3000 micro-processor is used as the central processing unit of this<br />
simulator.<br />
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I. GIOT THIEU CHUNG<br />
He thong xac dinh va dilu khikn tu th6 ve tinh (ADCS) la mot he th6ng quan trong tren ve<br />
tinh. He thong nay co nhiern vu on dinh va dieu khien ve tinh quay theo mot huang mong<br />
muon. Nha do, ve tinh eo the huong theo hudng anh sang mat trai hay tro den mot muc tieu<br />
xac dinh tren Trai dat. Tuy nhien, qua trinh thir nghiem kha nang boat dong ciia he thong nay<br />
tren Trai dat la rat kho khan vi de tao ra moi truang vQ tru tren mat dit la khong hk dl dang<br />
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Tieu ban: Cong nghi thong tin - Tu dong hod - Cong nghe VU tru ISBN: 978-604-913-010-6<br />
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Trong mot gioi ban nao do, co the su dung phuang phap mo phong ban vat ly de mo phong<br />
boat dong ciia he nay. Bang each su dung mot dem cau khong khi va diSu chinh sao cho tam<br />
khoi ciia san da trung vai tam hinh hoc cua khoi cau se lam giam dang ke mo men quay, tao<br />
ra mot moi truang gan giong moi truang vii try. Bai bao trinh bay cac ket qua da dat dugc<br />
trong qua trinh nghien cuu, thiet ke, che tao mot bo mo phong he ADCS su dung dem cau<br />
khong khi nhSm muc dich thii nghiem va phat trien cac loai cam bien, ca cau chap hanh, cac<br />
thuat toan mai cho viec xac dinh va dieu khien tu the ve tinh.<br />
II. TONG QUAN HE THONG<br />
Thiet ke co ban cho mot bo mo phong dieu khien va xac dinh tu the ve tinh bao gom mot san<br />
da dat tren mot dem cau khong khi. Mot tam phang dugc su dung de da cac thiet bi bao gom:<br />
cac cam bien, cac ca cau chap hanh, thiet hi thu phat radio, may tinh trung tam. He thong su<br />
dung ba banh xe lam ca cau chap hanh ca ban va co the boat dong a mgt trong hai che do:<br />
banh xe phan lire hoac banh xe dgng lugng. Ba thanh tu lire dat vuong goc vai nhau tung doi<br />
mot nham muc dich khu bao hoa cua cac banh xe dgng lugng, ciing nhu dugc sir dung lam he<br />
thong dieu khien du phong. Cong suat cua he thong dugc cung cap bai cac bg ac quy va bo<br />
chuyen doi DC-DC se giiip tao ra mgt nguon dien ap on dinh dam bao boat dgng cua cac cam<br />
bien do quan tinh. He thong can bang tu dgng se dich chuyen tam khoi vao gan tam hinh hgc<br />
ciia dem cau khong khi. May tinh trung tam chiu trach nhiem thu thap dir lieu, lgc va thuc<br />
hien thuat toan. Thong qua truyen thong khong day, mgt may tinh de ban a xa co the hien thi<br />
va luu trir cac goc lech ma san da tao ra trong suot qua trinh can bang hay trong qua trinh dieu<br />
khien huong.<br />
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III. CAC THANH PHAN CHINH VA HE THONG CON CUA HE ADCS<br />
I. Tdm phdng<br />
Mgt tam phang dugc thiet ke c6 dang hinh tron duong kinh ngoai 76 cm, day 17 mm. No<br />
dugc che tao tu vat lieu la cac tam bgt PVC dugc kep giira bai 3 tha sgi cac bon luong true va<br />
dugc trang ben ngoai bang nhua epoxy. Ket cau nay cho phep cac mo men du hi triet tieu, va<br />
sgi cac bon c6 he so ty le do cung/khoi lugng cao vai he s6 gian na nhiet 0,028 x 10-6<br />
cm/cm*C, trong khi nhom co gia tri la 25 x 10-6 cm/cm*C.<br />
2. Dim cdu khdng khi<br />
Dem cau khong khi dugc thiet ke va che tao bang chat lieu d6ng ph6t pho vai kha nang chiu<br />
tai 80 kg. Giira mat ban cau va chen da (xem hinh 3) ton tai mgt lop dem khong khi hep (day<br />
0.0254 mm). Khong khi vao va ra thong qua 6 lo khi (duang kinh 0.55mm) dugc phan b6 d8u<br />
tren duong tron. Kich thuac ciia dem c4u khong khi la 99,9348 + 0,0414 mm , trong khi chen<br />
da CO duang kinh 100,472710,0235 mm. No co thk chuygn dgng t6i da 360 do quanh true<br />
Yaw, va 50 do quanh true Roll va Pitch. Ap suat lam viec cua ngu6n khi nen ben ngoai tiiy<br />
thugc vao tai trgng va khoang 3,2 kg/cm2 cho tai trgng 35 kg. Bg lgc khong khi la yeu ciu<br />
bat huge bai vi bui ban, cac phan tir dau, va hai am c6 the thg pha hong lap dem khong khi<br />
hep.<br />
3. Cdm biin do qudn tinh (IMU)<br />
Cam bien do quan tinh la sir tich hgp giira con quay hoi chuyen va gia toe kS (xem hinh 4).<br />
Gia toe ke dugc che tao vai kich thuac rat nho, vai dai boat dgng trong khoang ±G . Trong<br />
khi do con quay hoi chuyen la mgt thiet hi ap dien vai dai hoat dgng trong khoang ±100° / s.<br />
Cac bg loc thong thap Butterworth dugc sir dung de chong nhieu, dieu che tin hieu va dugc<br />
dau noi tiep vai con quay hoi chuyen va gia toe ke.<br />
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152<br />
Hgi nghi Khoa hoc ky niim 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Not 10/2010<br />
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4. Tit ke 3 true<br />
Mgt la ban dien tir, co trang hi hai cam bien do goc ngbieng, dugc thiet ke de do ba thanh<br />
phan vecta ciia tir truang trai dat. Cac dau ra ciia thiet hi nay bao gom goc phuong vi (do<br />
chinh xac 0,5 do), ba thanh phin vecta tir truang, goc ngbieng true kep (len tai ±80 do va do<br />
chinh xac 0,25 do), va dir lieu nhiet do. Truyen thong noi tiep dugc thuc hien thong qua cong<br />
RS232. Cam bien do do nghieng dugc sir dung trong qua trinh can bang tu dgng.<br />
5. Cdc bdnh xe ddng luang/phdn luc<br />
Cac banh xe dgng lugng din dgng bing cac dgng ca mgt chidu 24 V, 0.1 A. Banh xe dgng<br />
lugng thong thuang quay vai t6c tir 1400 tai 2200 vong/phiit va co thS dat van t6c t6i da 4200<br />
vong/phiit. Dgng ca dugc trang hi diy du t6c do kl va encoder dk do van t6c goc.<br />
6. Thanh tit lire<br />
He thong dieu khien thanh tir luc dugc sir dung hieu qua trong xoay huong ve tinh va 6n<br />
dinh tu the a bit ky quy dao trai dit nao. He th6ng dilu khiln tir nay co khdi lugng nhe va<br />
tuong doi don gian. Thanh tir luc phii hgp vai nhilu iing dung vu tru, tuy nhien giai ban<br />
huang xoay chi khoang ±3 do va do Ion ciia mo men quay dilu khiln phu thugc nhilu vao ba<br />
thanh phan vecta cua tir trudng. Thanh tir lire cd dang hinh dng gdm cudn day quin xung<br />
quanh ldi sit tir dugc md ta nhu hinh 5. Cdng suit danh dinh cua thanh tir lire la 12 A-m^.<br />
7. Hi thdng phut khi<br />
He th6ng phut khi (microthruster) gdm cd 6 van khi dugc tfch hgp trong he ADCS. Trong<br />
dd gom cd: 2 van cho dilu khien goc Yaw, 2 van cho dilu khiln gdc Pitch va 2 van cho dilu<br />
khien gdc Roll. Cac van nay dugc lip ddi xung nhau theo timg cap. Khi dugc nen diy trong<br />
cac binh cd ap suit Idn va dugc dua din cac van phut sau khi di qua mgt van dilu ap. Dilu<br />
nay giiip cho viec phut khi dn dinh hon.<br />
5. Hi thdng mdy tinh trung tdm<br />
He thong may tinh dilu khiln trung tam cua he ADCS la mdt mach KIT LP3500 dugc xay<br />
dung vdi vi xir ly trung tam Rabbit 3000. Day la mdt vi xu ly cd tdc do xir ly nhanh, dugc<br />
thilt kl chuyen dung cho cac he th6ng nhiing va giao tilp. He thdng may tinh trung tam cd<br />
nhifm vu rihan dir lieu tir cac cam bien dugc tich hgp trong he th6ng, xac dinh tu thi va dilu<br />
khien ca cau chap hanh. He thong nay ciing dong vai tro giao tilp vdi phin mim dilu khiln<br />
tren may tinh PC.<br />
9. Truyin thdng khdng ddy vd hi thdng gidm sdt<br />
Truyin thong giira ADCS vdi may tinh PC, dugc thuc hien bing sdng radio hai chilu<br />
thdng qua hai bd thu va phat tin hieu. Hai thilt hi thu phat nay cd thi xir ly tin hieu s6 va<br />
tuong tu thong qua 8 kenh ddc lap vdi khoang each lam viec la 100 m sir dung dilu cbl va<br />
giai dieu che FSK. De xac dinh tu the va danh gia dilu khiln thi nhit thilt phai xay dung<br />
phin mem luu trir toan bd qua trinh thay ddi tu thi ciia ADCS ddng thdi phai thi hien tren<br />
man hinh thdi gian thuc ba gdc lech tren ba true. Tit ca thdng tin vl tu the diu dugc nhan<br />
thong qua giao dien khong day va dugc luu trir thanh file dir lieu.<br />
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153<br />
Tiiu ban: Cong nghi thong tin - Tir dong hod - Cong nghe Vii tru ISBN: 978-604-913-010-6<br />
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Hinh I. Giao diin diiu khiin ciia hi thdng<br />
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IV. PHUONG TRINH DONG HOC HE THONG<br />
Cac phuang trinh Ole va gdc Ole dugc sir dung de mo hinh dgng lire hgc cua he mo phong<br />
ADCS thong qua viec tinh toan ma tran quay (theo thir tu ZYX). Tat ea cac phuong trinh Ole<br />
va goc Ole nay deu dugc xet trong he quy chieu quan tinh. Dang chung ciia phuang trinh van<br />
toe Ole duac xac dinh nhu sau<br />
sin^ cosip<br />
0<br />
¥ cos^ cos 9 '«/<br />
<br />
e - 0 cos^ -sin^ ^y (1)<br />
^. 1 sin (/) tan 6 cos ^ tan 6* 0)_<br />
<br />
<br />
[mg 11^ ] {-r^ cos ^ cos 0 + r^ sin ^ cos 0)<br />
6) [mg I Iyy\ (r^ cos ip cos 0-^r^ sin ^) (2)<br />
[mg I f^ ] (-?; sin ^ cos 0-ry sin (j))<br />
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V. HE THONG CAN BANG<br />
He thong can bang la mgt he thong khong the thilu d6i vdi ADCS vi no triet tieu toan bg mo<br />
men quay trgng lire tac dung Ien bg mo phong. Qua trinh can bing ciing rit khd khan do do<br />
phuc tap ve mat hinh hgc ciia cac bg phan. Sir mit can bing xuit hien khi trgng tam va/hoac<br />
cac tryc quan tinh ca sd co sir dich chuyen so vdi true quay. D I cd thi mo ta diy dii he thdng<br />
can bang dgng chiing ta cin thiet phai bilt: tong khdi lugng toan he, ma tran quan tinh, tu thi<br />
san dd, va md hinh dgng lire hgc. Trong bai bao nay chung toi dl cap tdi mgt phuang phap<br />
can bang bg mo phong, ma trong d6 ma tran quan tinh va tam khdi dugc udc lugng thdng qua<br />
nhan biet h? thong sir dung cam bien van toe va gia toe goc, dong thdi giai he cac phuang<br />
trinh Ole ve chuyen dong doi vdi vat ran. Mgt bg cac khoi trugt dugc sir dung nhim dilu<br />
chinli tam khoi theo ba true. Hoat ddng cua chiing gidng nhu chuyen ddng ciia true cudn giiy<br />
va dugc dieu khien bang ddng ca budc.<br />
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154<br />
Hoi nghi Khoa hoc ky- niim 35 ndm I 'iin Khoa hoc vd Cong nghe Viet Nam - Hd Noi 10 2010<br />
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Cac budc chinh trong phuong phap can bang he md phdng bao gdm: Tdng khdi lugng cua he<br />
thdng dugc tinh toan. Nhirng can chinh ban dau ve van tdc gdc va hudng phai dugc thuc<br />
hien. va may tinh trung tam se gui lenh dieu khien md men quay, dgc va ghi dCr lieu \h. Cac<br />
tinh toan dir lieu dau vao/ dau ra cho ta udc lugng hien thdi cua ma tran quan tinli. ciing nhu<br />
dg sai lech giira tam khdi (CM) va tam quay (CR) ciia san dd. Cac khoi trugt se dich chuyin<br />
de dich tam khdi vao gan vdi tam quay (tam hinli hgc cua dem ciu khdng khi). Qua trinh nay<br />
se lap di lap lai cho tdi.Khi dat dugc ngudng gidi han 0,025mm va sau khi can bing md men<br />
quay du cdn khoang 50 g-cm.<br />
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FTinh 2 Hi md phdng bdn vdt ly ADCS<br />
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VL KET QUA<br />
Dudi day la nhirng kit qua budc diu dat dugc khi thuc hien dilu khiln gdc phuang vi theo<br />
gia tri goc mong mudn.<br />
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Hinh 3 Dieu khiin gdc phuang vi vi 0 do<br />
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Hinh 4 Diiu khiin gdc phucmg vi tdi 30 do<br />
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Tiiuban: Cong nghi thong tin - Tu dong hod - Cong nghe VU tru ISBN: 978-604-913-010-6<br />
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VH. KET LUAN<br />
Bai bao trinh bay kha chi tiet mdt he md phdng ban vat ly tu thi ve tinh qua do tao nen tang<br />
cho nhimg nghien cim sau nay ve cac cdng nghe ciing nhu thuat toan dilu khien tu the ve<br />
tinh. Bd md phdng ban vat Iy dugc tich hgp kha day dii cac thilt bi tien tiln ddng vai trd quan<br />
trgng trong muc tieu can bang va dieu khien he thdng nhu: cam biln mat trdi, cam bien do<br />
quan tinh, thanh tir lire, dem cau khdng khi, may tinh trung tam. Bai bao cung da neu phuong<br />
phap can bang he thdng, cac thi nghiem ciing nhu cac ket qua da dat dugc trong xac dinh va<br />
dieu khien tu the. Bd md phdng ban vat Iy cimg vdi nhung ket qua budc dau kha quan se thiic<br />
day cac ke hoach phat trien tiep theo bao gdm: dieu khien tu dgng sir dung he thdng phut, he<br />
thdng banh xe ddng lugng, img dung cac cam bien trai dat, cam bien sao...<br />
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TAI LIEU THAM KHAO<br />
1. Prado J., Bisiacchi G., Reyes L., Vicente E., Contreras F., Mesinas M and Juarez A.<br />
"Three-axis Air-bearing Based Platform for Small Satellite Attitude Determination<br />
and Control Simulation ". Joumal of Applied Research and Technology. Vol. 3 No. 3<br />
December. 2005. pp222-237.<br />
2. Prado J., Bisiacchi G., "Dynamic Balancing for a Satellite Attitude Control<br />
Simulator". Instrumentation and Development. Joumal of the Mexican Society of<br />
Instrumentafion. SOMI. Vol 4. No 5. 2000. pp 76-81<br />
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