Upload
pvdai
View
35
Download
3
Embed Size (px)
DESCRIPTION
Sử dụng logic mờ và mạng neuron để điều khiển nhiệt độ
Citation preview
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 1 SVTH: Nguyen Phng Thao
CHNG 0: M AU
on ngi che tao ra dung cu e s dung cho muc ch cua ho
ong thi cung ngh en viec ieu khien chung theo y muon cua
mnh. Khai niem hoi tiep la khai niem het sc quan trong e ieu
khien dung cu. ng dung au tien het sc co y ngha la ieu khien toc o
ong c hi nc c James Watts phat minh 1769. Khi cac d an mi
vi nhieu au vao va nhieu au ra ngay cang tr nen phc tap hn th s
mo ta he thong ieu khien oi hoi mot so lng ln cac phng trnh kem
theo. Ly thuyet ieu khien co ien mot vao mot ra hoan toan khong co
gia tr vi he thong a vao a ra. T nam 1960, ly thuyet hien ai c
phat trien e thch ng vi mc o phc tap ngay cang tang cua cac d an
va nhng quy tac oi hoi tnh chnh xac, tai trong, gia thanh c dung
trong quan oi, khong gian va trong cong nghiep. S phat trien nay c
tang toc bi may tnh so v kha nang lap trnh giai quyet ong thi nhieu
phng trnh.
Ky thuat ieu khien da tren phng trnh toan hoc. Tuy nhien,
chung ta thng oi mat vi nhng d an hoa hoc, may moc va nhieu he
thong khac can c ieu khien, th viec mo ta ac tnh cua chung thong
qua cac phng trnh toan hoc la het sc kho khan v mc o phc tap qua
ln. Ngay ca nhng chuyen gia e hoan thanh viec ieu khien, ho phai
van dung, chat ep kien thc t nhng kinh nghiem lau dai e a ra nhng
phng phap, luat ieu khien thong qua ngon ng trc giac t nhien. Kien
thc ( b quyet ) c trnh bay vi ngon ng trc giac t nhien th c
giai thch mot cach de dang, de hieu bang nhan thc thong thng va do
o de nh. Trong nhieu trng hp, ngon ng trc giac t nhien co mot
ranh gii m ho ve ng ngha, no c e cap nh nhng so hang ngon
ng m va c at tnh hoa bi ham lien thuoc. Y tng thiet ke bo ieu
khien m ra i.
Vay dung m cho ta nhng li iem g?
C
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 2 SVTH: Nguyen Phng Thao
Mot phng phap thiet ke khac n gian hn, nhanh gon hn
e anh gia tai sao phng phap m c ban lai co sc hap dan at an
tng trong ng dung ieu khien , chung ta hay xem v du ve thiet ke ien
hnh:
Hnh tren minh hoa yeu cau cua cac bc tuan t e phat trien bo ieu
khien dung phng phap thong thng va phng phap m.
Dung phng phap thong thng th bc au tien la phai hieu c tnh
chat vat ly cua he thong va yeu cau ieu khien cua no. Da tren s hieu
biet o, bc th hai se phat trien mot mo hnh gom chng trnh, cam
bien, phan t chap hanh. Bc th ba la ap dung ly thuyet ieu khien
tuyen tnh e lam ro nhng chc nang n gian cua bo ieu khien chang
han nh cac thong so cua bo ieu khien PID. Bc th t la xay dng luat
Tnh chat vat ly
Yeu cau ieu khien
Tnh chat vat ly
Yeu cau ieu khien
Xay dng
mo hnh tuyen tnh
Xay dng luat cho
bo ieu khien
Xac nh bo ieu khien
n gian
Mo phong thiet ke
a phu hp cha?
Thiet ke bo ieu khien
bang luat m
Mo phong thiet ke
a phu hp cha?
Ky thuat thiet ke thong thng Ky thuat thiet ke m c ban
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 3 SVTH: Nguyen Phng Thao
cho bo ieu khien n gian. Va bc cuoi cung la mo phong thiet ke bao
gom ca nhng anh hng phi tuyen, nhieu va s thay oi cua cac thong
so. Neu viec thc hien khong thoa man ta can xac minh lai mo hnh cua
he thong, thiet ke lai bo ieu khien, viet lai luat ieu khien va th lai.
Vi logic m, bc au tien la hieu va at tnh hoa hanh vi cua he thong
bang nhng kien thc kinh nghiem tch luy. Bc th hai la trc tiep thiet
ke luat ieu khien trong moi quan he gia cac so hang vao/ra. Bc cuoi
cung la mo phong va tm sai sot cua khau thiet ke. Neu phan thc hien
khong thoa man chung ta ch can xac minh lai luat m va th lai.
Mac du hai phng phap thiet ke co nhieu iem tng ong, nhng
phng phap m c ban n gian chu ky thiet ke mot cach ang ke. Ket
qua nay co y ngha ve li nhuan chang han nh giam c thi gian phat
trien, thiet ke n gian va nhanh chong em ra th trng.
Logic m giam i viec thiet ke cac tien trnh phat trien cua
chu ky.
Vi phng phap thiet ke m, nhng bc dung trc ay b loai bo bt.
Hn the na trong qua trnh tm sai sot va chnh nh chu ky, ta co the thay
oi bang cac luat c xac minh n gian thay v thiet ke lai bo ieu
khien. Vi luat m ta co the thay c ng dung thay v chng trnh kho
khan. Ket qua cho thay dung logic m giam ang ke toan bo tien trnh
phat trien cua chu ky.
Logic m n gian hoa viec thiet ke phc tap.
Logic m cho phep ta mo ta he thong phc tap bang kien thc va kinh
nghiem thong qua luat m. No khong oi hoi bat ky mo hnh he thong nao
hay cac phng trnh toan hoc nam vai tro chu ao trong moi quan he
vao/ra. Luat m de hoc, de dung ngay khi ban khong phai la chuyen gia.
Mot cach ien hnh, no ch dung vai luat e mo ta he thong ma le ra phai
oi hoi nhieu dong vi phan mem thong thng.Ket qua la logic m het
sc co y ngha trong viec n gian hoa thiet ke phc tap.
Giai quyet ieu khien phi tuyen tot hn.
He thong trong cuoc song hang ngay cua chung ta eu la he phi tuyen.
Nhng phng phap thiet ke thong thng dung phng phap xap x e
nam bat phi tuyen. Cach chon la ien hnh la tuyen tnh, tuyen tnh tng
oan, tra bang. Ky thuat xap x tuyen tnh th hoan toan n gian,tuy
nhien no co khuynh hng gii han phan ieu khien va phan ln thc thi
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 4 SVTH: Nguyen Phng Thao
cho nhng ng dung chac chan. Ky thuat tuyen tnh tng oan th lam viec
tot hn mac du keo dai phan thc thi v no oi hoi phai thiet ke nhieu
oan tuyen tnh cua bo ieu khien. Ky thuat tra bang co the cai tien hieu
suat ieu khien, nhng rat kho khan e tm sai sot va chnh nh. Hn the
na oi vi he thong phc tap ton tai he so nhan au vao th viec tra bang
la khong thc te hoac qua at e thc thi v no oi hoi mot bo nh qua
ln.
Logic m cho ra mot cach giai quyet khac oi vi ieu khien phi tuyen
bi v no gan gui hn vi the gii thc ben ngoai. Phi tuyen c nam bat
bi luat, ham lien thuoc va qua trnh suy dien cai ma rat co ket qua trong
cai tien thc thi, thc hien n gian va giam dc gia thanh thiet ke.
Logic m cai tien viec thc hien ieu khien.
Nhieu ap dung logic m mang lai ket qua tot hn trong ieu khien tuyen
tnh, tuyen tnh tng oan, hay ky thuat tra bang. V du nh mot van e
ien hnh gan vi ieu khien co ien la thi gian ap ng cua bo ieu
khien vi o vot lo. Cho v du ve he thong ieu khien nhiet o mot vao
n gian c minh hoa sau:
ng tuyen tnh au tien xap x ng cong mong muon cho ra ap ng
cham va khong co vot lo, no ch ra rang nhiet o phong th qua lanh cho
mot khoang thi gian. ng tuyen tnh th hai co ap ng nhanh hn
nhng co vot lo va sau o la dao ong, no ch ra rang nhiet o khong on
nh trong mot khoang thi gian.
Vi logic m, ta co the dung luat, ham lien thuoc e xap x bat c ham
nao cho en chnh xac bat ky nhiet o nao. Da vao hnh minh hoa, ta co
the xap x ng cong mong muon cho bo ieu khien nhiet o bang cach
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 5 SVTH: Nguyen Phng Thao
dung 4 iem( 4 luat ). Chung ta co the them luat vao e tang o chnh xac
cua viec xap x. Nhng luat th n gian hn e thc thi va de dang tm sai
sot va chnh nh chung hn ky thuat tuyen tnh tng oan hay ky thuat tra
bang.
If temperature is cold then force is high.
If temperature is cool then force is medium.
If temperature is warm then force is low.
If temperature is hot then force is zero.
Nhng luat nay khong giong nh nhng bang tra bi v luat m lam gian
oan hnh dang cua ham phi tuyen. Viec ket hp bo nh yeu cau viec at
nhan va suy dien m th t hn ang ke so vi bang tra, at biet oi vi
nhng he thong a vao. Ket qua la toc o x ly co the c cai tien.
Tom lai ieu khien m co nhieu iem manh trong viec thiet ke he thong ieu khien cac oi tng phc tap, cac oi tng ma viec mo ta mo
hnh oi tng la cc ky kho khan, la cho phep thiet ke he thong n gian,
tiet kiem nhieu cong sc, thi gian, giam c gia thanh Ben canh nhng iem manh tren khi s dung logic m e thiet ke bo ieu
khien gap mot so han che trong viec toi u hoa he thong la do no oi hoi
phai co kinh nghiem va nghe thuat thiet ke he thong.
e khac phuc nhng nhc iem nay, ngi ta ket hp logic m vi
mang neuron. Mang neuron, mot he thong x ly thong tin ay ha
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 6 SVTH: Nguyen Phng Thao
hen,chng minh kha nang hoc, truy cap thong tin trong bo lu tr va tong
quat hoa t viec huan luyen mo hnh hay d lieu. Mang neuron nhan tao
la lnh vc va khoa hoc va ky thuat, trong o khoa hoc c nh ngha
nh la kien thc co cau truc va ky thuat chnh la khoa hoc ng dung. V ky
thuat n le khong giai quyet toi u nhng bai toan ma bc hien tai luon
la ket qua cua cac bc trc o. Cong nghe mang neuron nhan tao hnh
thanh, no thay the cho cac giai phap tnh toan truyen thong va a ra mot
vai kha nang e tiep can nhieu van e hien tai khong giai quyet c.
Mang neuron c ng dung rong rai trong cac nganh ky thuat nh: ky
thuat ieu khien, ien t vien thong, he thong ien va cong nghe thong
tin. Trong ky thuat ieu khien mang neuron nhan tao c ng dung e
nhan dang, d bao va nhan dang cac he thong ong. Trong ien t vien
thong mang neuron nhan tao c ng dung e nhan dang d bao va ieu
khien ca c tram bien apS phat trien cua mang neuron, mot lnh vc cua tr tue nhan tao, cho ta nhng thanh qua ang ke trong viec thiet ke he
thong co kha nang hoc nhng hanh vi ma ta mong muon. Nhng mang
neuron lai co khuyet iem la kho giai thch ro rang cac hoat ong cua he.
S ket hp gia logic m va mang neuron la s ket hp hai u iem de
thiet ke va de toi u cho ta at c ket qua tot nhat ma ta mong
muon.Bo ieu khien m thch nghi ra i. Bo ieu khien ma trong qua
trnh lam viec co kha nang chnh nh thong so cua no cho phu hp vi s
thay oi cua oi tng c goi la bo ieu khien thch nghi. Bo ieu khien
m co kha nang chnh nh lai cac thong so cua bo ieu khien cho phu
hp vi oi tng cha biet ro a a he thch nghi tr thanh he ieu
khien thong minh. o chnh la bo ieu khien m thch nghi.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 7 SVTH: Nguyen Phng Thao
CHNG 1: TAP M
1.1 TAP M VA CAC PHEP TOAN TREN TAP M.
1.1.1 Tap m:
Trong khai niem tap hp kinh ien, viec xay dng cac phep anh xa
va cac mo hnh eu at tren c s logic hai gia tr Boolean. Tc la ham
phu thuoc F(x) nh ngha tren tap F ch co hai gia tr la 1 neu x thuoc F va la 0 neu x khong thuoc F. Kieu logic hai gia tr nay to ra rat hieu qua
va thanh cong trong viec giai quyet cac bai toan c nh ngha ro rang.
Tuy nhien trong thc te thng ton tai mot tap hp ma o phu thuoc
cua cac phan t trong tap hp co gia tr trong khoang [0,1]. T o khai
niem tap m ra i.
nh ngha: Tap m F xac nh tren tap kinh ien M la mot tap ma moi phan t cua no la mot cap cac gia tr (x, F(x) ) trong o x thuoc
M va F la anh xa: F : M [0,1]
Anh xa F c goi la ham lien thuoc cua tap m F.
Tap kinh ien M c goi la c s cua tap m F.
Ham lien thuoc cua cac tap m: Ham lien thuoc e tnh o phu thuoc cua mot phan t x nao o, co
hai cach: tnh trc tiep( neu F(x) cho trc di dang cong thc tng
minh ) hoac tra bang( neu F(x) cho di dang bang ).
Cac dang ham phu thuoc:
1. Dang tuyen tnh :
ay la dang tap m n gian nhat, thng c chon khi mo ta
cac khai niem cha biet hay cha hieu ro rang.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 8 SVTH: Nguyen Phng Thao
2. Dang ng cong S :
Mot tap m dang ng cong S co 3 thong so la cac gia tr , ,
co o phu thuoc tng ng la 0, 0.5 va1. Dang ng cong S thng
c dung e at trng cho ng cong phan bo chuan. A la iem
uon.
o phu thuoc tai iem x c tnh bi cong thc sau :
xkhi
xkhix
xkhix
xkhi
xS
1
)/()(21
)/()(2
0
),,;(2
2
Trong ky thuat ieu khien m thong thng cac ham lien thuoc
kieu S hay c thay gan ung bang mot ham tuyen tnh tng oan.
0.5
1
0
x
A
1
0
Tap m tuyen tnh tang Tap m tuyen tnh giam
1
0
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 9 SVTH: Nguyen Phng Thao
3.Dang ng cong hnh chuong :
Dang ng cong hnh chuong ac trng cho cac so m (xap x
mot gia tr trung tam), bao gom 2 ng cong dang S tang va S giam.
o rong hay hep cua mien khao sat cung nh o doc cua dang
hnh chuong tuy theo tnh chat cua hien tng c mo ta, cung nh
quyet nh cua ngi thiet ke.
T hai tap m dang ng cong S ta suy ra o phu thuoc tai
iem x cua tap m dang ng cong hnh chuong nh sau :
xkhixS
xkhixSx
),2/,;(1
),2/,;(),;(
4. Dang hnh tam giac, hnh thang va hnh vai :
Cung vi s gia tang cua cac bo vi ieu khien 8 bit va 16 bit,
dang tap m chuan hnh chuong c thay bang cac dang tap m
hnh tam giac va hnh thang do yeu cau tiet kiem bo nh von han che
cua cac bo vi ieu khien.
0.5
x
1
0
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 10 SVTH: Nguyen Phng Thao
Dang hnh thang :
Dang tam giac :
xkhi
xkhix
xkhix
xkhi
xT
0
)/()(
)/()(
0
),,;(
Dang hnh vai :
Thong thng vung gia cua bien mo hnh c ac trng bang
cac tap m co dang hnh tam giac v no lien quan ti cac khai niem
tang va giam. Tuy nhien vung bien cua bien khai niem khong b
thay oi. Luc nay can phai dung dang hnh vai e mo ta tnh chat cua
bien bien.
0
1
x
1
0
xA xB
x
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 11 SVTH: Nguyen Phng Thao
V du: Xet bien Nhiet o gom cac tap m LANH, MAT, TRUNG
BNH, AM, NONG nh hnh ve:
Khi ta at en NONG th tat ca nhiet o cao hn se la luon NONG.
Khi nhiet o cha at en LANH th nhiet o thap hn se la LANH.
Do o ta co hai tap m NONG, LANH dang hnh vai.
Cac tnh chat va at iem c ban cua tap m: 1.o cao va dang chnh tac cua tap m
o cao cua tap m F ( nh ngha tren c s M ) la gia tr
H = sup F(x) la gia tr cc ai o phu thuoc cua cac phan t tap m xM
0
1
edge floor
1
0
edge floor
Hnh vai trai Hnh vai phai
Lanh Mat
Trung
bnh Am Nong
X1 X2 X3 X4 X5 X6
1
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 12 SVTH: Nguyen Phng Thao
Mot tap m co t nhat mot phan t co o phu thuoc bang 1
c goi la tap m chnh tac, tc la H=1 va neu H < 1 la tap m
khong chnh tac.
Trong cac mo hnh bo ieu khien m, tat ca cac tap m c s
eu phai dang chnh tac nham khong lam suy giam ngo ra.
Tap m c a ve dang chnh tac bang cach ieu chnh lai tat
ca gia tr o phu thuoc mot cach t le quanh gia tr o phu thuoc cc
ai.
2.Mien xac nh cua tap m:
Mien xac nh cua tap m F ( nh ngha tren c U ), c ky
hieu bi S la tap con cua M thoa man:
S = { x M / F(x) > 0 }
3.Mien tin cay cua tap m:
Mien tin cay cua tap m F ( nh ngha tren c s U ), c ky
hieu bi T, la tap con cua M thoa man:
T = { x M / F(x) = 1 }
1
0,75
0 0
(a). Tap m A co o cao la 1 (b). Tap m B co o cao la 0,75
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 13 SVTH: Nguyen Phng Thao
Minh hoa ve mien xac nh va mien tin cay cua mot tap m.
Cac phep toan tren tap m : Cac phep toan tren tap m c xay dng thong qua cac ham
lien thuoc tng t nh cac phep toan tren tap hp kinh ien :
Phep toan bang nhau: Cho A va B la hai tap hp m trong khong
gian M, A va B c goi la bang nhau neu va ch neu:
A(x) = B(x) cho tat ca x thuoc M
Phep hp hai tap m :Hp cua hai tap m A va B co cung c s M
la mot tap m cung xac nh tren c s M vi ham lien thuoc:
AUB(x) = MAX { A(x), B(x) }
Tong quat: Hp cua tap m A co ham lien thuoc A(x) ( nh
ngha tren c s M ) vi tap m B co ham lien thuoc B(y) ( nh ngha tren c s N) la mot tap m xac nh tren c s MxN vi ham
lien thuoc :
AUB(x,y) = MAX { A(x,y) , B(x,y) }
trong o :
A(x,y) = A(x) vi moi y N va
B(x,y) = B(y) vi moi x M.
0
1
Mien tin cay
Mien xac nh
x
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 14 SVTH: Nguyen Phng Thao
Phep giao hai tap m :Giao cua hai tap m A va B co cung c s
M la mot tap m cung xac nh tren c s M vi ham lien thuoc :
AB(x) = MIN { A(x), B(x) }
Tong quat: Giao cua tap m A co ham lien thuoc A(x) ( nh
ngha tren co c s M ) vi tap m B co ham lien thuoc B(y) (nh ngha tren co c s N) la mot tap m xac nh tren c s MxN co
ham lien thuoc :
AB(x,y) = MIN { A(x,y), B(x.y) }
trong o :
A(x,y) = A(x) vi moi y N va
B(x,y) = B(y) vi moi x M
AB A B
AB A B
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 15 SVTH: Nguyen Phng Thao
Phep bu cua mot tap m :Bu cua tap m A co c s M va ham lien
thuoc A(x) la mot tap m Ac
xac nh tren cung co c s M vi ham
lien thuoc :
( ) 1 ( )C AA x x
Tch catesian : Cho A1, A2, , An la cac tap m trong M1, M2, ,
Mn. Tch Catesian cua cac tap m A1, A2,, An la mot tap m trong khong gian tch M1.M2.M3Mn vi ham lien thuoc cua no c nh
ngha bi :
1 2 1 2... 1 2( ) { ( ), ( ),..., ( )}
n nA xA x xA A A A nx MIN x x x
cho tat ca x1, x2 ,,xn thuoc M.
Tch ai so : Tch ai so cua 2 tap m A va B vi cac ham lien
thuoc A(x) va B(x) la mot tap m ma ham lien thuoc cua noA.B(x) c cho bi :
A.B(x) = A(x).B(x)
1.2 QUAN HE M VA CAC PHEP TOAN TREN QUAN HE M:
1.2.1 Quan he m:
Khong gian tch: Cho xX va yY , khong gian cua tch X va Y c nh ngha la:
XxY= { (x,y)| xX va yY }.
A AC
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 16 SVTH: Nguyen Phng Thao
Quan he ro: Cho R la tap con cua khong gian tch XxY, R c goi la quan he ro neu Rc nh ngha bang ham at tnh cua no sao cho:
1 ( , )
0 ( , )( , )khi x y R
R khi x y RX x y
Neu X co kch thc M va Y co kch thc N th quan he nay co the c
bieu dien di dang ma tran MxN.
Quan he m: Cho R la tap con cua khong gian tch XxY, Rc goi la quan he m gia hai khong gian X va Y, neu R c nh ngha bang ham
lien thuoc cua no sao cho R(x,y) co the lay bat ky gia tr nao trong khoang [0,1].
Neu X co kch thc M, Y co kch thc N th quan he nay co the
c bieu dien di dang ma tran MxN.
1.Thuat toan xay dng quan he m R:
Cho menh e hp thanh mot ieu kien R: AB
Neu =A th =B,
trong o so chieu cua R phu thuoc vao so iem lay mau cua A(x)
va B(y) khi ri rac cac ham lien thuoc tap m A va B.
Chang han vi n iem x1, x2 , ,xn cua ham A(x) va m iem mau
y1, y2,, ym cua ham B(y) th luat hp thanh R la mot ma tran n hang, m cot nh sau:
1 1 1 11 1
1 1
( , ) ( , )
( , ) ( , )
R R m n
R n R n m n nm
x y x y r r
R
x y x y r r
Cho menh e hp thanh nhieu ieu kien R: 1 2 ... nA A A B
Neu 1 =A1 va 2 =A2 va n =An th =B bao gom n menh e
ieu kien. Lien ket VA trong menh e ieu kien chnh la phep giao
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 17 SVTH: Nguyen Phng Thao
cac tap m A1, A2, ,An vi nhau. Va ket qua cua phep giao se la o thoa man H.
o thoa man H = MIN 1 21 2( ), ( ),..., ( )
nA A A nc c c vi cac
vector gia tr au vao:
1
n
c
x
c
trong o ci , i = 1n la mot trong cac iem
mau mien xac nh cua ( )iA ix .
Khong nh luat hp thanh co mot menh e ieu kien luat hp
thanh cua menh e vi n ieu kien khong the bieu dien di dang
ma tran c na ma thanh mot li trong khong gian n+1 chieu.
Xet mot menh e hp thanh hai ieu kien sau:
Neu = A va = B th = C
R: A B C
Ri rac hoa cac ham lien thuoc:
A(x) c ri rac hoa tai 5 iem , x{0,2; ..; 0.6}
B(x) c ri rac hoa tai 5 iem , x{0,3; ..; 0.7}
A(x) c ri rac hoa tai 5 iem , x{0,2; ..; 1.0}
1
0.5
A(x)
0.2 0.4 0.6 0.3 0.5 0.7 0.2 0.4 0.6 0.8 1
B(y) C(z)
x y
z
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 18 SVTH: Nguyen Phng Thao
Lap R gom cac ham lien thuoc cho tng vector gia tr au vao:
V du nh cap iem (x=0.3, y=0.5)
o thoa man H se la : H = MIN{A(x= 0.3), B(y= 0.5)}
= MIN{0.5; 1.0} = 0.5
va R(0.3; 0.5) = {0; 0.5; 0.5; 0.5; 0}
Nh vay tren khong gian R3
th R se la mot li ba chieu, trong o tai
moi iem nut tren li la mot gia tr cua R(x,y).
Cho nhieu menh e hp thanh: Cho p menh e hp thanh gom:
R1 : 1 =A1 th =B1 hoac
R2 : =A2 th =B2 hoac
Rp : p =Ap th =Bp ,
trong oA1, A2,, Ap co cung c s X ; B1, B2,, Bp co cung c s Y.
Quan he R se la hoi cua tat ca cac luat hp thanh con:
1 2 ... pR R R R
1.2.2 Cac phep toan tren quan he m:
Neu P va Q la hai quan he m tren khong gian XxY va YxZ th
quanhe m tren khong gian XxZ o la s hp thanh cua hai quan he m P
va Q, c viet la : oR PQ , trong o ky hieu o la toan t hp thanh.
Co ba loai toan t hp thanh m thong dung nhat o la MAX_MIN,
MAX_PROD, MIN_MAX.
Neu toan t hp thanh la toan t MAX_MIN th ham lien thuoc
cua quan he m R c nh ngha bi:
( , ) ( , ) _ [ ( , ), ( , )]R PoQ P Qx z x z MAX MIN x y y z
Neu toan t hp thanh la toan t MIN_MAX th ham lien thuoc
cua quan he m R c nh ngha bi:
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 19 SVTH: Nguyen Phng Thao
( , ) ( , ) _ [ ( , ), ( , )]R PoQ P Qx z x z MIN MAX x y y z
Neu toan t hp thanh la toan t MAX_PROD th ham lien
thuoc cua quan he m R c nh ngha bi:
( , ) ( , ) [ ( , ) ( , )]R PoQ P Qx z x z MAX x y y z
trong o: P(x,y) la ham lien thuoc cua P
Q(y,z) la ham lien thuoc cua Q.
1.2.3 Phng trnh quan he m:
Cho A la tap m trong khong gian X va R la quan he m trong khong
gian tch XxY.Tap m au ra B trong khong gian Y c bieu dien bang
quan he m o la:AoR=B, trong o ky hieu o la toan t hp thanh. Neu toan t hp thanh nay la MAX_MIN, th ham lien thuoc cua tap m B o
la: ( ) _ [ ( ), ( , )]B A Ry MAX MIN x x y
1.3 CAC PHNG PHAP HOA M VA GIAI M:
1.3.1 M hoa:
Hoa m la qua trnh lam m mot ai lng ro, ngha la dung nhng
ham phu thuoc cua cac bien ngon ng e tnh mc o phu thuoc cho tng
tap m oi vi mot gia tr cu the au vao. M hoa la bc au tien trong
qua trnh tnh toan cua he m. Ket qua cua no c dung lam au vao e
tnh cac luat m.
Bien ngon ng: La phan chu ao trong cac he thong dung logic m. Bien ngon ng c xac nh thong qua tap cac gia tr m cua no. Bien
ngon ng co hai mien gia tr khac nhau:
Mien cac gia tr ngon ng
Mien cac gia tr vat ly( mien cac gia tr ro ) .
V du : Trong ai lng nhiet o, gia tr c nhac en di dang ngon
ng :
-rat nong
-hi nong
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 20 SVTH: Nguyen Phng Thao
-trung bnh
-hi lanh
-rat lanh
Moi gia tr ngon ng o cua bien nhiet o c xac nh bang mot
tap m nh ngha tren c s la tap cac so thc dng ch gia tr vat ly x
(n v o) cua bien nhiet o . Ham lien thuoc tng ng cua chung c
ky hieu bang :
Vi x V la mien cac gia tr vat ly ( mien gia tr ro), ta co c
mot vector gom cac o phu thuoc cua x nh sau :
-rat nong(x)
-hi nong(x)
-trung bnh (x) =
-hi lanh (x)
-rat lanh (x)
Anh xa nay c goi la qua trnh Fuzzy hoa cua gia tr ro x.
Tnh o phu thuoc: T cac gia tr ro au vao ta suy ra o phu thuoc cua tap m theo ham phu thuoc. Cac loai ham phu thuoc thong dung: dang
ch Z, dang ch S, dang tam giac, dang hnh thang.
rat nong(x)
hi nong(x)
trung binh(x)
hi lanh (x)
rat lanh (x)
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 21 SVTH: Nguyen Phng Thao
Dang ch Z Dang tam giac Dang hnh thang Dang ch S
a.Tnh o phu thuoc theo ham dang ch Z:
Ham dang ch Z c ac trng bi hai iem x1, x2 .
- Neu ai lng can tnh o phu thuoc nho hn x1 th o phu thuoc la
mot.
- Neu ai lng can tnh o phu thuoc ln hn x1 nhng nho hn x2 th o phu thuoc theo ham doc xuong.
- Neu ai lng can tnh o phu thuoc ln hn x2 th o phu thuoc la
khong.
1
11 2
1 2
2
1
( ) 1
0
khix x
x xx khix x x
x x
khix x
b.Tnh o phu thuoc theo ham dang tam giac:
Ham dang Tam Giac c ac trng bi ba iem x1, x2, x3 .
- Neu ai lng can tnh o phu thuoc nho hn x1 th o phu thuoc la
khong.
- Neu ai lng can tnh o phu thuoc ln hn x1 nhng nho hn x2 th o phu thuoc theo ham doc len.
X1
X2
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 22 SVTH: Nguyen Phng Thao
- Neu ai lng can tnh o phu thuoc ln hn x2 nhng nho hn x3 th o phu thuoc theo ham doc xuong.
- Neu ai lng can tnh o phu thuoc ln hn x3 th o phu thuoc la
khong.
1
11 2
1 2
22 3
2 3
3
0
( )
1
0
khix x
x xkhix x x
x xx
x xkhix x x
x x
khix x
c.Tnh o phu thuoc theo ham dang hnh thang:
Ham dang Hnh Thang c ac trng bi bon iem x1, x2, x3, x4 .
- Neu ai lng can tnh o phu thuoc nho hn x1 th o phu thuoc la
khong.
- Neu ai lng can tnh o phu thuoc ln hn x1 nhng nho hn x2 th o phu thuoc theo ham doc len.
- Neu ai lng can tnh o phu thuoc ln hn x2 nhng nho hn x3 th o phu thuoc la 1.
- Neu ai lng can tnh o phu thuoc ln hn x3 nhng nho hn x4 th o phu thuoc theo ham doc xuong.
- Neu ai lng can tnh o phu thuoc ln hn x4 th o phu thuoc la
khong.
X1 X3
X2
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 23 SVTH: Nguyen Phng Thao
1
11 2
1 2
2 3
33 4
3 4
4
0
( ) 1
1
0
khix x
x xkhix x x
x x
x khix x x
x xkhix x x
x x
khix x
d.Tnh o phu thuoc theo ham dang ch Z:
Ham dang ch Z c ac trng bi hai iem x1, x2 .
- Neu ai lng can tnh o phu thuoc nho hn x1 th o phu thuoc
lakhong.
- Neu ai lng can tnh o phu thuoc ln hn x1 nhng nho hn x2 th o phu thuoc theo ham doc len.
- Neu ai lng can tnh o phu thuoc ln hn x2 th o phu thuoc la
mot.
1
11 2
1 2
2
0
( )
1
khix x
x xx khix x x
x x
khix x
1.3.2 Giai m:
Qua trnh x ly m tao mot mien m bien ra. Giai m la tm ra mot
gia tr vat ly (gia tr ro) ac trng cho thong tin cha trong mien m o.
X1
X3 X2
X4
X1
X2
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 24 SVTH: Nguyen Phng Thao
1. Phng phap iem trong tam :
Phng phap nay c ap dung khi mien m bien ra la mot
mien lien thong. Gia tr ro cua bien ra la hoanh o cua iem trong
tam cua mien m bien ra.
Cong thc xac nh x' theo phng phap iem trong tam nh sau :
trong o : l la mien xac nh cua tap m A
l
dx*(x)
dx*(x)*x
x'
A
l
A
2. Phng phap cc ai :
Gia tr ro cua bien ra la iem co o phu thuoc ln nhat.
x x'
A
l
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 25 SVTH: Nguyen Phng Thao
Trong trng hp cac iem co o phu thuoc ln nhat trai dai
tren mot oan thang nam ngang [x1;x2] gia tr ro cua bien ra la trung
iem cua oan [x1;x2] nh hnh ve :
3. Phng phap o cao :
Tap m dang Singleton la mot dang n gian hoa cho phep x
ly m va giai m c de dang hn, thng c dung trong cac he
thong dung vi ieu khien, a c tch hp trong tap lenh cua MCU
68HC12 cua hang Motorola.
Moi tap m ket qua cua cac menh e ieu kien c thay bang
mot oan thang (x,(x)) vi (x) la o cao cua tap m tng ng.
A
x' x
x1 x
A
x2 x'
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 26 SVTH: Nguyen Phng Thao
Th du : xet bien NHIET O gom cac tap m
LANH,MAT,AM,NONG.
Phng phap o cao chnh la ap dung giai m theo phng
phap iem trong tam oi vi cac tap m bien ra dang Singleton.
Do cac tap m cua mien m bien ra khong chong lap len nhau
nen khi giai m cong viec tnh tch phan rat mat thi gian a c
thay bang viec tnh tong so hoc nh sau :
n
1i
i
n
i
ii
H
H*x
x'1
trong o: xi la v tr cac singleton
Hi la o cao cua cac singleton tng ng
n la so tap m bien ra
1
0
x1 x2 x3 x4 x5 x6
MAT AM NONG LANH
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 27 SVTH: Nguyen Phng Thao
CHNG 2: LOGIC M
2.1 LOGIC RO VA LOGIC M
2.1.1 Logic ro: : [0,1]T u U la logic hai ch so 0 va 1.
c bieu dien thong qua hai gia tr 0, 1 tc la ung hay sai. ieu o
co ngha la vi mot s viec ch co the co hai trang thai co hay khong ma
thoi.
Cho hai e xuat P va Q, cac gia tr chan ly cua e xuat nay c cho
nh sau:
Neu , ( ) 1;x A T P mat khac T(P)=0.
Neu , ( ) 1;x B T Q mat khac T(Q)=0.
Cac phep toan trong logic ro: Phep toan hp:
:P Q x A hoac x B
V the ( ) max{ ( ), ( )}T P Q T P T Q
Phep toan giao:
:P Q x A va x B
V the ( ) min{ ( ), ( )}T P Q T P T Q
Phep toan phu nh:
Neu T(P)=1 th T( ~P )=0;
Neu T(P)=0 th T( ~P )=1;
Phep toan keo theo:
(PQ): x A hoac x B
V the ( ) ( )T P Q T P Q
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 28 SVTH: Nguyen Phng Thao
Phep toan tng ng:
1 ( ) ( )( ) : ( )
0 ( ) ( )
khiT P T QP Q T P Q
khiT P T Q
Tuy nhien, trong thc te ta thng bat gap mot s viec ma khong ch
mieu ta bang hai trang thai ung hay sai . Cac ngng cua cac trang thai
nhieu khi khong ro rang, chang han nh: gan ung, ung t, sai t, sai
nhieu Do o logic m ra i.
2.1.2 Logic m:
Logic m la s m rong cua logic ro hay con goi la logic nhieu ch
so, v gia tr chan ly cua mot e xuat trong khong gian co the lay gia tr
bat ky trong khoang [0,1] ma khong b gii han bi hai ch so 0 va 1. Gia
s e xuat P trong tap m A, th gia tr chan ly trong e xuat P c ky
hieu la T(P), co the c cho bi ( ) ( )AT P x , trong o 0 ( ) 1A x .
Neu nh ngha gia tr chan ly cua e xuat P trong tap m A o la:
TN(P)={0,..,i/(N-1),.1}
trong o N la so nguyen va 0 i N .
Trong logic ro N=2(hai ch so) va i=0, do o T2(P) = {0,1}
Trong logic m N=nhieu ch so cu the nh sau:
- N = 3, i= 1, th T3(P)= {0, , 1} ng vi {False, Maybe, True}
- N= 4, i= 1, 2 th T4(P)= {0, 1/3, 2/3, 1} ng vi {False,
Almost_False, Almost_True, True}
- N=5, i= 1, 2, 3 th T5(P)={0, 1/4, 2/4, , 1} ng vi {False,
Almost_False, Maybe, Almost_True, True}
Cac phep toan trong logic m: Phep toan phu nh:
( ) 1 ( )T notP T P
Phep toan hp:
P Q : x is A or B ( ) max{ ( ), ( )}T P Q T P T Q
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 29 SVTH: Nguyen Phng Thao
Phep toan giao:
P Q : x is A and B ( ) min{ ( ), ( )}T P Q T P T Q
Phep toan suy dien:
PQ : x is A then x is B
( ) ( ) max{ ( ), ( )}T P Q T notP Q T notP T Q
2.2 C S TRI THC M:
C s tri thc m c bieu dien thong qua luat.
Luat hp thanh m.
Hau het cac he thong hoat ong da tren nen tang logic m eu dung
luat e bieu dien moi quan he gia cac bien ngon ng va e rut ra hanh
ong tng ng vi moi au vao.
Mot luat bao gom 2 phan :
- Phan ieu kien ( phan if ) : co the gom nhieu ieu kien ket hp vi
nhau bang cac lien t And, Or menh e ieu kien.
- Phan ket luan ( phan then ) : menh e ket luan.
Menh e hp thanh :
Cho 2 bien ngon ng , . Neu:
- nhan gia tr (m) A co ham lien thuoc A(x)
- nhan gia tr (m) A co ham lien thuoc B(y)
Th 2 bieu thc :
= A
= B c goi la 2 menh e p, q.
Menh e hp thanh p => q hoan toan tng ng vi luat ieu khien (
menh e hp thanh 1 ieu kien):
Neu = A th = B
Trong o : p : menh e ieu kien
q : menh e ket luan
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 30 SVTH: Nguyen Phng Thao
Ham lien thuoc cua menh e hp thanh anh xa A(xo) B(y) c goi la ham lien thuoc cua luat hp thanh vi B la mot tap m cung c s vi B, bieu dien he so thoa man menh e q cua y.
Nguyen tac Mamdani : o phu thuoc cua ket luan khong c ln hn o phu thuoc cua ieu kien
Xac nh ham lien thuoc sau cho menh e hp thanh A B
1) A==>B(x,y) = MIN { A(x), B(y) } cong thc MAX MIN
2) A==>B(x,y) = A(x).B(y) cong thc MAX PROD
Tong quat : C s tri thc m uc thiet ke dui dang n luat m IF-
THEN nh sau:
If A11 . . . . . .A1i . . . . . . . A1n Then B11 . . . . . B1j . . . . . . B1m
If A21 . . . . . .A2i . . . . . . . A2n Then B21 . . . . . B2j . . . . . . B2m
. . . . . . . .
If Ak1 . . . . . .Aki . . . . . . . Akn Then Bk1 . . . . . Bkj . . . . . . Bkm
If AN1 . . . . . ANi . . . . . . . ANn Then BN1 . . . . . BNj . . . . . . BNm
Neu he co nhieu au vao va nhieu au ra th 2, 2m n ,
Neu he co nhieu au vao va mot au ra th 1, 2m n .
Neu luat co dang If x is A1 and A2 . . . . . and AL Then y is BS, ta co
the viet lai : If AS Then BS
Trong o, 1 2.......S LA A A A va ham lien thuoc cua no c cho bi:
1 2( ) min{ ( ), ( ),..... ( )}
S LA A A Ax x x x
Neu luat co dang If x is A1 or A2 . . . . . or AL Then y is BS, ta co the
viet lai : If AS Then BS
Trong o, 1 2.......S LA A A A va ham lien thuoc cua no c cho bi :
1 2( ) max{ ( ), ( ),..... ( )}
S LA A A Ax x x x
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 31 SVTH: Nguyen Phng Thao
2.3 KY NGHE SUY DIEN M BANG TAY:
Neu luat co dang If x is A Then y is B, no tng ng vi quan he
m ( ) ( )R A B notA Y va ham lien thuoc cua quan he nay c
nh ngha bi: ( , ) {[ ( ) ( )],[1 ( )]}R A B Ax y max x y x
Do o, neu biet tap m A, ta co the xac nh tap m au ra B s dung
cong thc: ' ' ' [( ) ( )]B A R A A B notA Y
Neu luat co dang If x is A Then y is B Else y is C th no tng
ng vi quan he m ( ) ( )R A B notA C va ham lien thuoc cua
quan he nay c nh ngha bi:
( , ) ( ) ( ) , 1 ( ) ( )R A B A Cx y max x y x y Tng t, neu biet c tien ieu kien A, th ta co the tnh c tap m
B thong qua cong thc ' ' 'B A R A A B notA C
Trong o o la toan t hp thanh Max_Min hay Max_Prod.
2.3 S suy dien m nh ky thuat o th (Cach xac nh tap m
au ra B bang may):
Ly giai xap x m la phng phap tnh tap m au ra bang tay neu
biet tap m au vao va quan he m. Neu a phng phap nay vao may
se ton rat nhieu thi gian tnh toan cac ma tran va vector, va neu kch
thc cua cac ma tran va vector ln se ton rat nhieu bo nh. V le o, mot
phng phap xap x m khac c a ra cho may tnh toan e xac nh
tap m au ra o la phng phap suy dien m nh ky thuat o th c
trnh bay sau. Cho hai luat m o la:
Luat 1: If x1 is A11 and x2 is A12 Then y is B1
Luat 2: If x1 is A21 and x2 is A22 Then y is B2
Trng hp 1: Cac au vao x1, x2 la cac gia tr ro s dung phep toan hp thanh Max_Min.
Cng o ban cua luat 1 c cho bi:
11 12 11 121 1 2 1 2( ) ( ) min ( ), ( )A A A Ax x x x
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 32 SVTH: Nguyen Phng Thao
Do o,tap m au ra B1 cua luat 1 c xac nh bang ham lien thuoc cua no o la:
1 1 1' 1 1( ) ( ) min , ( )B B By y y
Cng o ban cua luat 2 c cho bi:
21 22 21 222 1 2 1 2( ) ( ) min ( ), ( )A A A Ax x x x
Do o,tap m au ra B2 cua luat 2 c xac nh bang ham lien thuoc cua no o la:
2 2 2' 2 2( ) ( ) min , ( )B B By y y
Tap m au ra B cua he thong la s hp nhau cua cac tap m au ra B1
va B2 o la:
1 2' ' 'B B B
vi ham lien thuoc cua no:
x1 x2 y
A11 A12 B1
B1
x1 x2 y
A21 A22 B2
B2
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 33 SVTH: Nguyen Phng Thao
1 2'( ) ' '
max ( ), ( )B y B By y
Ket qua tap m au ra B cua he thong dc mo ta hnh:
Trng hp 2: Cac au vao x1 va x2 la cac gia tr ro (crisp) va s dung phep toan suy dien Max_Prod.
Cng o ban cua luat 1 c cho bi:
11 12 11 121 1 2 1 2( ) ( ) min ( ), ( )A A A Ax x x x
Do o,tap m au ra B1 cua luat 1 c xac nh bang ham lien thuoc
cua no o la:
1 1' 1( ) ( )B By y
Cng o ban cua luat 2 c cho bi:
21 22 21 222 1 2 1 2( ) ( ) min ( ), ( )A A A Ax x x x
Do o,tap m au ra B2 cua luat 2 c xac nh bang ham lien thuoc
cua no o la:
y
B
x1 x2 y
A11 A12 B1
B1
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 34 SVTH: Nguyen Phng Thao
2 2' 2( ) ( )B By y
Tap m au ra B cua he thong la s hp nhau cua cac tap m au ra B1 va B2 o la:
1 2' ' 'B B B
vi ham lien thuoc cua no:
1 2'( ) ' '
max ( ), ( )B y B By y
Ket qua tap m au ra B cua he thong c mo ta hnh:
x1 x2 y
A21 A22 B2
B2
y
B
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 35 SVTH: Nguyen Phng Thao
CHNG 3: THIET KE PHAN CNG
HE THONG O NHIET O
Phan tren a gii thieu ve bo ieu khien m, sau ay la phan ket noi
gia bo ieu khien vi oi tng lo nhiet thong qua mach ong lc (mach
kch cong suat cho lo), cap nhiet ien (TC lay thong so nhiet o lo) va
mach gia cong chuyen oi so lieu can thiet e a ve bo ieu khien x ly.
Thiet ke he thong ieu khien nhiet o thong qua lo ien :
3.1 Mach ong lc:
Vi quan tnh lo nhiet kha ln ngi ta thng ong ngat nguon e
thay oi cong suat at vao lo thay v ieu khien ien ap. Do o t mach
ieu khien se xuat ra xung co o rong thay oi trong khoang thi gian T
nhat nh e thay oi cong suat cung cap cho lo .
Bo ieu
khien
Mach
ong lc
Cap nhiet
ien
Mach gia cong
chuyen oi
Lo ien
Nhiet
o at
Nhiet
do lo
Sai soE
Bo ieu
khien
T0
T
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 36 SVTH: Nguyen Phng Thao
Nh vay trong thi gian T0 lo ong, T-T0 lo tat. ng vi s thay oi
cua T0 t 0 en T th cong suat cung cap Pcc = (T0/T).Pmax thay oi t 0
en Pmax.
Mach ong lc dung Opto_Triac ong ngat nguon ien li cung cap
cho lo :
Trong thi gian Ton C815 tch cc mc cao kch dan diod cua
Opto_Triac lam Diod phat quang kch dan Triac nen lo c cap nguon
trong suot khoang thi gian nay .
Hoat ong cua mach kch lo:
Transistor BJT thng lam viec 2 che o:
- Khuech ai.
- ong ngat.
che o khuech ai: Transistor hoat ong vung tch cc, tng
ng vi cac gia tr lam viec uCE > uCESAT va dong iC phu thuoc vao
tai va dong i B.
He so khuech ai tnh cua dong c nh ngha tai mot iem lam
viec IC, IB bi he thc hFE = IC / IB khi UCE = hang so.
Q3
Opto_Triac
R_LO
1 2
D2
LED
12
R9
1K
C815
13
2
+12V
OPTOTRIAC
MACH KICH LO
~220V
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 37 SVTH: Nguyen Phng Thao
che o ong ngat: Transistor hoat ong vung bao hoa, la vung
nam gia ng thang gii han mat phang va gii han bao hoa.
Trong vung nay, ta xac nh gia tr hieu ien the nho nhat
uCE=uCESAT ng vi IC cho trc va uCB >0, uCB = 0 . Transistor se
ong, dong iC dan va ien the uCE at gia tr uCESAT nho khong ang
ke(khoang 1-2 V ), luc nay transistor trang thai bao hoa.
Nh vay e tao mach kch cho lo ta phai tao ra dong iB u ln e
uCE 0.
Luc o, tren ien cc B, E la ien ap ieu khien, cac ien cc C,
E c s dung lam cong tac ong m mach cong suat.
- ong: VCE > 0
IB > 0
- Ngat: IB =< 0
Khi transistor ong, dong IC se phu thuoc tai, ng vi nguon cung
cap la 12V, ap tren LED khoang 2V, UCE khoang 0.2V, ap qua Opto
4-5 V ap tren ien tr 1K t 3-5 V va dong khoang 3-6 mA u
kch dan cho Triac hoat ong ong lo.
3.2 Cam bien:
Nh chung ta a biet nhiet o la ai lng gia tang khong tuyen tnh
viec nhan hay chia nhiet o se khong co mot y ngha ro rang nao. Do o
e co the xac nh gia tr chnh xac cua nhiet o la van e khong n
gian. Tuy vay nhieu ai lng vat ly phu thuoc nhiet o nh : s gian n
cua chat kh, long, ran, s truyen nhiet, o nong cua cac chat tinh khiet, va
s thay oi mau sac theo nhiet o . . . . Da vao nhng ac iem tren ma
ngi ta che tao ra cac loai cam bien nhiet o vi kha nang chuyen oi
nhiet o thanh cac gia tr ap, dong,ien tr, . . . va cung tuy theo cau tao
cua chung ma ta co cac loai cam bien nhiet o khac nhau.
3.2.1 Cac loai cam bien hien tai
Tuy theo lnh vc o va ieu kien thc te ma co the chon mot
trong bon loai cam bien : thermocouple, RTD, thermistor, va IC ban
dan. Moi loai co u iem va khuyet iem rieng cua no.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 38 SVTH: Nguyen Phng Thao
1.Cap nhiet ien:
Dong nhiet sinh ra v tr tiep xuc do s chenh lech nhiet o.
u iem
n gian.
Re tien.
ap ng nhanh.
Tam thay oi rong hn nhieu so vi nhiet ke ien tr.
La thanh phan tch cc, t cung cap cong suat.
Khong can dong ien chay qua do vay khong co hieu ng ot
nong.
Khuyet iem
Phi tuyen.
Thi gian on nh lau.
ien ap cung cap thap.
oi hoi ien ap tham chieu.
Kem on nh nhat.
Kem nhay nhat.
ng dung:
ng dung rong rai trong o nhiet o cua cac chat ran, long,
kh.
o nhiet o be mat cua vat.
2.RTD (resistance temperature detector)
o nhiet o theo s thay oi ien tr
u iem
On nh nhat.
Chnh xac nhat.
Tuyen tnh hn thermocouple.
Khuyet iem
Mac tien.
Can phai cung cap nguon dong.
Lng thay oi R nho.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 39 SVTH: Nguyen Phng Thao
ien tr tuyet oi thap.
T gia tang nhiet.
3.Thermistor
u iem
Ngo ra co gia tr ln.
Nhanh.
o hai day.
Khuyet iem
Phi tuyen.
Gii han tam o nhiet.
De v.
Can phai cung cap nguon dong.
T gia tang nhiet.
4.IC cam bien
u iem
Tuyen tnh nhat.
Ngo ra co gia tr cao nhat.
Re tien.
Khuyet iem
Nhiet o o di 200C.
Can cung cap nguon cho cam bien.
Do cam bien nhiet s dung trong luan van la cam bien nhiet
chuyen oi thanh tn hieu ien nen ta ch khao sat hai loai cam bien o
la cap nhiet ien va nhiet ien tr.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 40 SVTH: Nguyen Phng Thao
3.2.2 Cap nhiet ien
Cap nhiet ien la cam bien nhiet n gian c cau tao bi hai day
dan kim loai a, b khac nhau c noi vi nhau bi hai moi han co nhiet
o T1 , T2 .
Khi gia nhiet mot au noi th se co dong ien chay trong mach o.
Neu mach b h mot au th hieu ien the mach h (hieu ien the
Seebeck) la mot ham cua nhiet o moi noi va thanh phan cau thanh nen
hai kim loai.
Khi nhiet o thay oi mot lng nho th hieu ien the Seebeck cung
thay oi tuyen tnh theo :
eAB = T vi la he so Seebeck
Neu nhiet o moi noi T1 bang khong va nhiet o moi noi T2 bang T
th suat ien ong tao ra bi cap nhiet ien c tnh nh sau:
2 31 1
2 2E AT BT CT
Trong o: A, B, C la cac hang so phu thuoc vat lieu che tao.
Khi dung cap nhiet ien th gia tr hieu ien the thu c b anh
hng bi hai loai nhiet o : nhiet o can o va nhiet o tham chieu. Cach
gan 0C cho nhiet o tham chieu thng ch lam trong th nghiem e rut ra
cac gia tr cua thermocouple va a vao bang tra. Tuy nhien khi a vao
Kim loai B
Kim loai A Kim loai A
Kim loai B
Kim loai A
eAB
+
-
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 41 SVTH: Nguyen Phng Thao
s dung thc te th nhiet o tham chieu la nhiet o moi trng, mot ai
lng khong co nh, thay oi theo tng a iem va thi gian. Do o e
tang tnh chnh xac cua phep o ta phai bu nhiet cho au t do cua cap
nhiet ien.
Cac phng phap bo chnh nhiet:
- Nhung au t do vao nc a ang tan.
- Chon sau di at 1m en 2m la ni c xem nh co nhiet o on
nh.
- Dung mach bu nhiet.
- Dung day bu: dung mot oan day bu co vat lieu giong nh cap
nhiet ien, moi loai cap nhiet ien c trang b mot cap day dan
rieng biet. Nhiem vu cua day bu la ieu hoa cac ai lng dao
ong nhiet o tai iem o va gi cho au t do duy tr c nhiet
o quy nh.
Mat khac e am bao o on nh cua suat ien ong, phai an nh
nhiet o s dung cao nhat cho cap nhiet co tnh en cac ieu kien thc
te. Day cang nho th nhiet o cc ai cang thap.
Cac loai cap nhiet ien:
Tuy theo cau tao nen hai day dan ma ta co cac loai cap nhiet ien
sau:
- Loai J : ket hp gia sat vi constantan, trong o sat la cc dng
va constantan la cc am. He so Seebeck la 51V/C 20C.
- Loai T : ket hp gia ong vi constantan, trong o ong la cc
dng va constantan la cc am. He so Seebeck la 40V/C 20C.
- Loai K : ket hp gia chromel vi alumel, trong o chromel la cc
dng va alumel la cc am. He so Seebeck la 40V/C 20C.
- Loai E : ket hp gia chromel vi constantan, trong o chromel la
cc dng va constantan la cc am. He so Seebeck la 62V/C
20C.
- Loai S, R, B : dung hp kim gia platinum va rhodium, co 3 loai.
S): cc dng dung day 90% platinum va 10% rhodium, cc am la
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 42 SVTH: Nguyen Phng Thao
day thuan platinum. R): cc dng dung day 87% platinum va 13%
rhodium, cc am dung day thuan platinum. B): cc dng dung day
70% platinum va 30% rhodium, cc am dung day 94% platinum va
6% rhodium. He so Seebeck la 7V/C 20C.
3.2.3 Nhiet ien tr:
Nh a noi tren, khi nhiet o thay oi tac ong len ien tr se
lam thay oi gia tr cua ien tr. Li dung tnh chat nay ngi ta xac
nh thong so nhiet o thong qua gia tr ien tr o c.
Trong trng hp tong quat, gia tr cua mot ien tr phu thuoc
nhiet o nh sau:
0 0( ) ( )R T R F T T
vi R0 la ien tr o c nhiet o T0 va F la ham at trng bi
vat lieu.
Vi vat lieu la kim loai ta co ham sau:
2 3
0( ) (1 )R T R AT BT CT
trong o T o bang 0
C va T0 la nhiet o o 00
C.
Vi vat lieu la hon hp cua cac oxt ban dan (nhiet ien tr ) ta co ham sau:
0
0
1 1( ) .expR T R B
T T
trong o T o bang K (nhiet o tuyet oi ).
Khi nhiet o bien thien T nho ma cam bien co the nhan biet
c ta noi o la o nhay nhiet R .
1.
( )R
dR
R T dT
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 43 SVTH: Nguyen Phng Thao
o nhay cua nhiet ien tr rat cao, khoang 10 lan ln hn so vi
o nhay cua ien tr kim loai cho phep ng dung chung e phat hien
nhng bien thien rat nho cua nhiet o (t 10-4
en 10-3
K ). Mat khac
kch thc nhiet ien tr lai nho gon cho phep o nhiet o tng
iem,ong thi do nhiet dung nho nen toc o hoi ap ln.
3.3 Mach gia cong:
Mach gia cong can thc hien 3 chc nang sau: bu nhiet cho au t do,
khuech ai, va tao ien ap ra la 0V khi o 00
C. Xet mach sau:
U1, U2, U3 (dung OP07 cho offset thap) ong vai tro mot bo em
ien ap ly tng : co tr khang vao rat ln va tr khang ra rat nho,
khong e cac au vao anh hng lan nhau.
ien ap ra tren thermocouple :
V3 = S(Td Ta) = S.Td S.Ta
Vi : Td la nhiet o can o.
Ta la nhiet o moi trng.
S la o nhay cua thermocouple (40V/C).
Nh vay la gia tr ien ap ra tren cap nhiet ien ngoai nhiem vu
mang thong tin cua nhiet o can o con b anh hng bi nhiet o moi
trng.
e loai tr anh hng tren, ta can phai co mot khoi tao ra ien ap
theo nhiet o moi trng nhng co dau ngc lai dung IC cam bien
LM335A.
IC LM335A la loai cam bien nhiet o ban dan, co o nhay la
10mV/K. Ap tao ra do LM335A cam bien c la :
V2 = K.Ta [K] = K(273 + Ta) [C]
= K.273 + K.Ta = C + KTa (C = K.273)
vi K = 10mV/K; C = 2,73V
co the triet tieu anh hng cua Ta, nhng lai tao ra mot mc ien
ap la 2,73V 0C nen can phai co mot khoi e tr 2,73V nham tao ien
ap au ra la 0V 0C.
Bien tr R12 chnh la thanh phan bu tr ien ap 2,73V nh a noi
tren.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 44 SVTH: Nguyen Phng Thao
U4 (dung OP07) ong vai tro bo cong co khuech ai, ien ap ra cuoi
cung la :
2 3 3 24 44 1
1 2 3 1
2 34 41
1 2 3 1
1
2.731
out
d a a
R V RVR RV V
R R R R
R ST ST R KTR RV
R R R R
Khong b anh hng cua nhiet o moi trng :
2 3
2
3
0
10250
40
a aR ST R KT
R K mV
R S V
(1)
Triet tieu ien ap tnh (2,73V) :
3 341
1 2 3 2 3
311
4 2 3
2.73 2.73
2.73 1
R RRV
R R R R R
RRV
R R R
(2)
Sau khi a triet tieu nhiet o moi trng va ien ap tnh, khi o, ien ap ra
V4 la :
24
2 3
. 4(1 )
1
dout
R ST RV
R R R
Ta chon o tang cua 10
C la 10mV, th ng vi Td =1 , th V4out
se la 10mV. Hay o nhay cua mach se la 10mV/ 0
C.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 45 SVTH: Nguyen Phng Thao
2 44
2 3 1
2 4
2 3 1
2 4
3 1
. .11 10
1 250
250
out
R S RV mV K
R R R
K R R
S R R R
R R
R R
Neu ta chon:
3 1
2 4
100
250 100 25000 25
R R
R R K
(*)
th t (*) ta suy ra cach chnh V1 phng trnh (2) nh sau:
1
1 12.73 1 10.92
250 1 250V mV
Cac tu C14, C15, C16 chon gia tr 10F e chong nhieu.
Lu y :
1. Cac bien tr nen dung loai bien tr tinh chnh (hay bien tr o lng) co
cau tao gom nhieu vong day ien tr xoan ben trong (chnh nhieu vong
mi het gia tr), tranh dung bien tr thong thng rat kho chnh va khong
on nh (khi va cham nhe b thay oi gia tr).
2. Cac OPAMP dung loai OP07 hoac tng ng, co mc offset thap e
phu hp vi cac ai lng o co gia tr nho, cac chan 1 va 8 dung e chnh
offset khong dung trong thiet ke nay.
*Hoat ong cua OPAMP:
Op_amp ly tng co 3 at tnh can thiet c xem nh chuan e anh
gia hoat ong cua Op_Amp:
1.o li ap vong h A0L la xac nh am.
2.ien tr vao R
gia cong 1 va 2 la rat ln. Do o dong vao la zero.
3.ien tr ra R0 la zero. Thong thng hieu ien the ra phu thuoc vao tai.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 46 SVTH: Nguyen Phng Thao
Khuech ai OP_Amp chang qua la s la s khac biet 1 2dv v v gia
hai tn hieu vao. o li vong ap
0OL
L
vA
v
.
Cong 1 la cong vao ao vi hieu ien the v1.
Cong 2 la cong vao khong ao vi hieu ien the v2.
Mach khuech ai khong ao:
Tn hieu vao tai cong khong ao. Khi v2 dng, v0 dng va dong
dng. Hieu ien the v1=iR1 uc cung cap cho cong ao nh hoi tiep hieu
Rd
+
+
+
+
+
+VCC
-VCC
vd
v1
v0
v2
0V
S o cau tao cua Op_Amp
+VCC
-VCC
Rd
+
+ +
+
+ vd
v1
v0
v2
0V
R2
R1 i
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 47 SVTH: Nguyen Phng Thao
ien the am. khuech ai khong ao nay dong vao cong khong ao la
zero, do o 1 20;dv v v .o li ien ap la: v0/v2 . Vi dong vao
Op_Amp la zero, nen dong qua R2, R1 phai giong nhau. Ta co:
0 1 2
2 1
0 0 2
2 1 1
1
v v v
R v
v v RAv
v v R
Chu y: Neu Op_Amp khong ly tng, ien tr vao Op_Amp c tnh
nh sau:
2 22
1 1
(1 )in d OLv R
Z R R Av R
ien tr nay rat ln co the len en 1210 .
Khuech ai vi he so bang 1:
Bo khuech ai mot tang n khong ao pha vi he so khuech ai
bang 1. Co ien tr vao rat ln va ien tr ra rat nho, ap vao va ap ra
c xem nh khong oi. Dung mach nay lam au vao cua mach phoi hp
tr khang se lam giam anh hng nhieu.
+VCC
-VCC
Rd
+
+ +
+
+ vd
v1
v0
v2
0V
i
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 49 SVTH: Nguyen Phng Thao
CHNG 4: BO IEU KHIEN M
IEU KHIEN NHIET O C BAN
4.1 Bo ieu khien m c ban:
Cac thanh phan c ban cua bo ieu khien m bao gom khau m hoa,
thiet b thc hien luat hp thanh va khau giai m. Mot bo ieu khien m
ch gom ba thanh phan nh vay co ten goi la bo ieu khien m c ban.
- Khau m hoa co nhiem vu chuyen oi mot gia tr ro au vao x0
thanh mot vecto gom cac o phu thuoc cua gia tr ro o theo cac
tap m a nh ngha trc.
- Khau x ly m x ly vecto va cho ra tap m B' cua bien ra.
- Khau giai m co nhiem vu chuyen oi tap m B' thanh mot gia
tr ro y' ac trng cho thong tin cha trong tap m o.
Do he m c ban ch co kha nang x ly cac gia tr tn hieu hien thi
nen no thuoc nhom cac bo ieu khien tnh. Tuy vay vi viec ghep them
cac khau ong hoc can thiet nh vi phan, tch phan, ta se co c mot bo ieu khien m co kha nang x ly cac bai toan ong.
y'(t)
X LY
M
GIAI
M
M
HOA
x1
xn
B' y'
Bo ieu khien m c ban
HE M C BAN
Vi phan
x(t)
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 50 SVTH: Nguyen Phng Thao
4.2 Nguyen ly ieu khien m:
Nguyen tac tong hp bo ieu khien m hoan toan da vao nhng
phng phap toan hoc tren c s nh ngha cac bien ngon ng vao/ra va
s la chon nhng luat ieu khien. Do cac bo ieu khien m co kha nang
x ly cac gia tr vao/ra bieu dien di dang dau phay ong vi o chnh
xac cao nen chung hoan toan ap ng c cac yeu cau cua mot bai toan
ieu khien ro rang va chnh xac.
Bo ieu khien m hoat ong chu yeu da vao kinh nghiem e thiet
ke cac luat ieu khien, trien khai cac menh e hp thanh xay dng mo
hnh luat hp thanh .
4.3 Cac bc xay dng mot he m c ban :
Xac nh cac bien vao va ra.
nh ngha cac tap m cho cac bien vao va ra.
Xay dng cac luat ieu khien (cac menh e m).
Chon luat hp thanh.
Chon phng phap giai m.
Toi u he thong.
1. nh ngha cac bien vao/ra:
Cac bien vao la cac bien ieu khien cac qua trnh ben trong cua
bo ieu khien m, cac bien ra dung e ieu khien oi tng .
Sau khi xac cac bien vao/ra ta can phai xac nh mien gia tr cho
tng bien cung nh n v cua tng bien.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 51 SVTH: Nguyen Phng Thao
2. nh ngha cac tap m cho cac bien :
Do cac tap m chnh la oi tng thao tac cua cac luat ieu
khien nen ta phai nh ngha cac tap m trc khi xay dng cac luat
ieu khien. Mat khac do dang tap m phan anh moi lien he gia gia
tr cac d kien va y ngha cua chung -> khau quan trong trong viec
tong hp bo ieu khien m.
e xac nh tap m can:
Mien gia tr vat ly cho cac bien ngon ng vao/ra.
So lng tap m(gia tr ngon ng).
Xac nh ham lien thuoc:
Cach thc hien la bat au bang cac dang ham lien thuoc a biet
trc va mo hnh hoa no cho en khi nhan c bo ieu khien m
lam viec nh mong muon.
Trong nhieu trng hp dang ham lien thuoc hnh tam giac cho
ket qua khong kem g dang ham lien thuoc phc tap hn la dang hnh
chuong, do bo ieu khien m t khi nhay vi s thay oi hnh dang
tap m. ieu nay lam cho he m kha ben vng va de thch nghi, o
la mot thuoc tnh quan trong khi mo hnh lan au c khao sat.
3. Xay dng cac luat ieu khien :
ay la bc tong hp cac hieu biet cung nh chien lc ieu
khien oi tng di dang mot tap cac luat ieu khien.Va cung la
bc kho khan nhat do hoat ong cua bo ieu khien hoan toan da
tren cac luat ieu khien. Cac luat ieu khien c thiet lap da tren
cac menh e hp thanh.
4. Chon thiet b hp thanh :
Thiet b thc hien luat hp thanh trong bo ieu khien m la thiet
b hp thanh. Co the chon thiet b hp thanh theo nguyen tac
Max_Min, Max_Prod e trien khai phep hoac khi thiet lap luat hp
thanh chung:
R=R1or R2 or Rn
5. Chon nguyen ly giai m:
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 52 SVTH: Nguyen Phng Thao
Giai m hay ro hoa, tuy theo cach chon la phng phap giai
m ma o phc tap va trang thai lam viec cua ca he thong cung b
anh hng .
4.4 Thiet ke:
Thiet ke bo ieu khien m co mo hnh nh sau:
Nguyen tac tong hp mot bo ieu khien m hoan toan da vao nhng
phng phap toan hoc tren c s nh ngha cac bien ngon ng vao/ra va
s la chon nhng luat ieu khien. Do o e thiet ke bo ieu khien m
trc tien ta se nh ngha cac bien ngon ng vao/ra.
Cac bien ngon ng vao/ra va tap m:
ai lng vao cua bo ieu khien m chnh la sai lech nhiet o va
toc o tang giam nhiet.
1. Sai lech nhiet o:
c nh ngha nh la o sai khac gia nhiet o at va nhiet
o hien tai o c, ky hieu la ET.
ET = nhiet o at nhiet o o [C]
ET
DET
Thiet b hp thanh M hoa Giai m
y
Cau truc bo m ieu khien nhiet o
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 53 SVTH: Nguyen Phng Thao
Mong muon cua chung ta la ieu khien en 128C nen mien
xac nh cua bien se la khoang [-128C,+128C].
Trong mien xac nh o, ta nh ngha 7 tap m :
ET = {am nhieu, am va, am t, bang khong, dng t, dng va,
dng nhieu}
hay ET = {NB, NM, NS, ZE, PS, PM, PB}
Tuy nhien, e tap trung hn trong khoang sai lech nho, ta
khong phan bo eu 7 tap m nay tren khoang [-128C,+128C]
ma ch phan bo eu trong khoang [-12C, +12C].
2. Toc o tang giam nhiet o:
La gia tr tang hay giam cua nhiet o hien tai so vi nhiet o
trc o trong khoang thi gian lay mau, ky hieu la DET.
DET=(nhiet o hien tai nhiet o trc)/thi gian lay mau[C/s]
oi tng ieu khien la mot lo nng dan dung co o quan
tnh tng oi ln, trong khoang thi gian lay mau la 3 giay ch
tang hay giam toi a 1,3C nen ta nh ngha DET vi mien xac
nh la [-2,+2].
Cung nh ngha cho bien DET co 7 tap m vi ten goi nh
tren, nh ngha trong khoang [-2;+2].
0 3 6 9 128 -3 -6 -9 -128 [C]
ZE PS PM PB NS NM NB
12 -12
Cac tap m cua bien ET
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 54 SVTH: Nguyen Phng Thao
ai lng ra cua bo ieu khien m chnh la phan tram cong suat
kch cho lo nhiet ( %P ).
- Bien OUT vi 7 tap m dang singleton.
%P = {V1, V2, V3, V4, V5, V6, V7}
- Bien OUT vi 7 tap m dang tam giac.
%P = {V1, V2, V3, V4, V5, V6, V7}
0 0,5 1.0 1.5 2 -0.5 -1 -1.5 -2 [C]/T[s]
ZE PS PM PB NS NM NB
Cac tap m cua bien DET
60 80 40 20 10 0 %P
V1 V2 V3 V4 V5 V6 V7
100
Cac tap m bien ra P
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 55 SVTH: Nguyen Phng Thao
Thiet ke he luat:
Gom 7x7 = 49 luat s khi ban au da tren nhng nhan nh ve
oi tng.
DET
NB NM NS ZE PS PM PB
ET
NB V1 V1 V1 V1 V1 V1 V1
NM V1 V1 V1 V1 V1 V1 V1
NS V1 V1 V1 V1 V1 V1 V1
ZE V1 V1 V1 V1 V1 V1 V1
PS V2 V2 V2 V3 V3 V4 V4
PM V3 V4 V4 V5 V5 V6 V7
PB V6 V6 V7 V7 V7 V7 V7
60 80 100 40 20 10 0 %P
V5 V6 V7 V1 V4 V3 V2
Cac tap m cua bien ra P
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 56 SVTH: Nguyen Phng Thao
4.5 Giai thuat ieu khien:
Sai
Sai
Sai
ung
Nhap Tat
Bat au
ETcu:=Tat 280C
To:=nhiet o hien
tai
ETmi:=Tat - To
DET:=ETmi - ETcu
ETmi = 12
?
X ly m
%P:=0
%P:=100
0 < %P < 100
Ton:=%P*T
Toff:=T Ton
Etcu:=ETmi
Dng?
Ket thuc
ung
ung
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 57 SVTH: Nguyen Phng Thao
Tnh o phu thuoc Bj(DET)
Luat hp thanh
MaxMin : R = min[Ai(ET); Bj(DET)]
MaxProd : R = Ai(ET)* Bj(DET)
Tm luat ieu khien
Cap nhat mien m bien ra
Het luat ?
ung
Sai
Tnh o phu thuoc Ai(ET)
X ly m
Giai m
Luat ieu khien
ke tiep
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 58 SVTH: Nguyen Phng Thao
CHNG 5:
5.1 Qua Trnh Phat Trien:
Mang neuron c xem nh mot mo hnh toan hoc n gian cua bo
nao con ngi, co chc nang x ly song song. Trai vi may tnh hoat ong
da tren chng trnh do con ngi viet san, mang neuron hoat ong da
tren nhng g con ngi day no trc o.
Mang neuron co the hoc cac ket hp mi, cac chc nang mi hay
nhan biet cac mau mi. Mac du may tnh co the thc hien nhng viec hien
tai vi o chnh xac va toc o cao, nhng mang neuron ha hen mot the
mi trong lnh vc x ly thong tin.
5.2 Mang Neuron La G ?
Mang Neuron, mot he thong x ly thong tin ay ha hen, chng minh
kha nang hoc, truy cap thong tin trong bo lu tr va tong quat hoa t viec
huan luyen mo hnh hay d lieu.
La mang c xay dng bang cach sao chep lai cac nguyen ly to
chc cua he neuron con ngi. Bo oc con ngi la mot he neuron gom co
1010
en 1012
neuron c to chc co cau truc vao khoang 200 mo hnh
khac nhau di dang nhieu lp.
Bo oc con ngi, mot bo may phc tap va het sc tinh vi vi kha
nang x ly mot cach nhp nhang, ong bo co s lien ket chat che vi cac
phan t x ly ma khong mot he thong nao b kp. Mo hnh mang neuron a
c thuc ay bang s nhan nh la tr oc con ngi tnh toan theo cach
khac han so vi may tnh. T o con ngi a ra mang neuron nham hieu
nhng li giai cua tr oc ve cac lnh vc nh nhan dang hnh anh, tieng noi
va ap dung nhng lnh vc o vao may tnh. Sau nhieu nghien cu, ngi
ta a ra nhan xet sau :
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 59 SVTH: Nguyen Phng Thao
ieu quan trong chnh la cach x ly song song ch khong phai toc o
tnh toan cua bo nao.
Mac du cha hieu cach mo ta cac y tng cua bo nao nen cha the bat
chc hoan toan, nhng ta co the thay rang bo nao s dung nhng phan
t tnh toan co toc o cham nhng c lien ket vi nhau.
Hoat ong cua he than kinh c chia thanh 3 giai oan :
Con ngi nhan c kch thch t ben ngoai thong qua cac giac quan.
S kch thch nay c chuyen oi thanh xung ien va c chuyen
en nao.
Bo nao lien tuc thu nhan thong tin, x ly, anh gia va so sanh chung
vi nhng thong tin ang lu tr e a ra cac quyet nh thch hp.
Nhng menh lenh a ra sau khi bo nao x ly c truyen en cac bo
phan chap hanh nh tay chan cho hanh ong hay li cho tieng noi di dang xung ien. Bo phan thi hanh bien oi xung ien a en
thanh hanh ong.
Mac du cac neuron co hnh dang va kch thc khac nhau nhng ve can
ban, co the chia thanh 3 phan :
Synapse kch thch
Synapse han che
Dendrite
soma
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 60 SVTH: Nguyen Phng Thao
au vao dendrities: co nhiem vu nhan tat ca thong tin t ben
ngoai.
Than neuron: la phan t x ly co chc nang thu thap tat ca thong
tin en t cac au vao dentries, tnh toan va a ra quyet nh ngo
ra axon.
au ra axon: Axon la mot thiet b phi tuyen tao ra xung ien ap
c goi la the nang kch hoat, ton tai trong khoang 10-3
giay co tac
dung gi tn hieu i.
Moi neuron co mot mc kch hoat, nam trong tam gia gia tr ln
nhat va gia tr nho nhat. Viec gia tang hay giam mc kch hoat cua neuron
nay oi vi neuron khac c thc hien thong qua cac synapse bam tren
dendrite. Gia tr cua cng o synapse c goi la he so trong lng. Neu
la synapse kch thch, mc kch hoat t neron gi lam gia tang mc kch
hoat cua neuron nhan. Con neu la synapse han che th mc kch hoat t
neuron gi se lam giam mc kch hoat cua neuron nhan. Mc kch hoat tai
neuron nhan at en mot gia tr ngng nao o se kch thch au ra,
truyen tren axon en cac neuron khac, cuoi axon co khoang 10000
synapse. Cac synapse khong ch khac nhau tac dung kch thch hay han
che ma con khac nhau mc kch hoat.
Trong thi gian he tiep xuc mot vai oi tng, mot so phan t cam
bien b tac ong, cng o ket noi cua mot so neuron thch hp trong he
se c gia tang nham cung cap toan bo thong tin ve oi tng ma he
ang tiep xuc va sau o a ra mot so quyet nh lp neuron au ra e
ieu khien mot vai phan t c. Qua trnh tiep xuc oi tng, a ra quyet
nh va ieu khien phan t c c goi la qua trnh hoc va cng o ket
noi cua mot so neuron thch hp c gia tang trong thi gian he tiep xuc
oi tng c goi la luat hoc. Trong mot vai trng hp, he co chuan
oan sai, he co the ieu chnh e co mot chuan oan ung bang cach he
co the cap nhat he so trong lng ket noi gia cac neuron thch hp sao
cho he co mot chuan oan ung.
Cong viec c ban cua mot neuron nhan tao la cong cac mc kch hoat
au vao roi tao mot mc tac ong au ra neu tong cac mc kch hoat
au vao ln hn mot gia tr ngng nao o.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 61 SVTH: Nguyen Phng Thao
Co kha nhieu mo hnh toan hoc cho neuron. ay trnh bay mo hnh
thong dung nhat, dung mot ham truyen ket noi cac au vao e tao au ra:
- Phng tien ket noi la tong co trong so, trong o trong so ai dien
cho o manh yeu cua synapse.
- Synapse kch thch co trong so dng va synapse han che co trong
so am.
- Gia tr ngng c them vao e bieu dien mc o kch hoat cua
neuron.
- Dong tn hieu t au vao xi c xem nh dong mot chieu c
bieu dien bi mui ten. Tn hieu ra c cho theo quan he :
n
i
ii
T xwfxwfxwfy1
,
vi w = (w1, w2, , wn)T
Rn la vector trong so. Ham f(wTx) c
goi la ham kch hoat hay ham truyen.
Trong bieu thc co e cap en gia tr ngng nh la mot gia tr
anh gia s ket hp cua cac mc kch hoat au vao. Hoan toan co the
chuyen gia tr ngng vao tch vo hng wx bang cach xem no nh mot
au vao co trong so bang 1.
au vao
au ra
Ham truyen
n
i
ii xwf0
Ham tac ong
f
Y
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 62 SVTH: Nguyen Phng Thao
w1x1 + . . . + wnxn > w1x1 + . . . + wnxn + (-1). > 0
o la ly do tai sao thng ngi ta cho gia tr ngng bang 0 trong bieu
thc.
5.3 Cac Thanh Phan C Ban Cua Mang Neuron Nhan Tao Gom:
Phan t x ly, mo hnh ket noi va viec huan luyen mang.
5.3.1 Phan t x ly:
Mot mang neuron nhan tao c ket noi bang nhieu than neuron, moi
ket noi cua chung la mot thanh phan t x ly. Moi phan t x ly nay co
nhieu au vao va mot au ra. e ket hp vi cac au vao cua moi phan t
x ly th i o la mot ham tong hp fi co chc nang tong hp tat ca thong
tin ben ngoai hoac t nhieu phan t x ly khac gi en va e ket hp vi
au ra cua moi phan t x ly th i o la mot ham tac ong hay con goi la
ham truyen a(fi ).
Ham tong hp: Ket hp tat ca thong tin t au vao cua phan t x ly
th i, vi xj la au vao t moi trng hoac au ra cua phan t x ly th
j, wij la he so trong lng ket noi gia xj va phan t x ly th i, i la
gia tr ngng cua phan t x ly th i. Ham tong hp c nh ngha
mot trong cac dang sau:
+Ham tong hp tuyen tnh :
1
m
i ij j i
j
f w x
+Ham tong hp phi tuyen bac 2:
y
w1 wn
x1 xn
0
y
w1 wn
x1 xn
-1
. . . . . .
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 63 SVTH: Nguyen Phng Thao
2
1
m
ji ij i
j
f w x
+Ham hnh cau:
2 2
1
( )m
i j ij i
j
f x w
vi p va wij la ban kn va tam cua hnh cau.
Ham tac ong: ket hp au ra cua phan t x ly th i, con goi la ham
truyen at .
+Ham bac thang n v:
1, 0( )
0, 0
fa f
f
+Ham ngng hay con goi la ham doc:
1, 0( ) sgn( )
1, 0
fa f f
f
+Ham Ramp:
1, 1
( ) ,0 1
0, 0
f
a f f f
f
+Ham Unipolar sigmoid:
1( )
1 fa f
e
+Ham Bipolar sigmoid:
2( ) 1
1 fa f
e
vi >0 c s dung e xac nh bc lien tuc cua ham tac
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 64 SVTH: Nguyen Phng Thao
ong khi ma ham tong hp fi tien gan en zero.
5.3.2 Mo hnh ket noi cua mang neuron nhan tao:
Mo hnh ket noi cua mang neuron nhan tao c chia lam 2 loai:
Mang nuoi tien (FeedForward network): au ra cua lp neuron trc
chnh la au vao cua lp neuron sau.
Mang nuoi lui (FeedBack neywork): au ra c nh hng lui ve
lam au vao cho cac neuron cung lp hoac lp trc o.
Mo hnh mang neuron nuoi tien mot lp gom: m au vao, n au
ra, va khong co lp neuron an.
Mo hnh mang nuoi tien nhieu lp gom: m au vao, n au ra, va
cac lp neuron an.
x1
xm yn
y2
y1
x2
x1
x2
xm
y1
y2
yn
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 65 SVTH: Nguyen Phng Thao
Mo hnh mang neuron nuoi lui mot lp gom: lp neuron au
vao, lp neuron au ra, khong co lp neuron an.
Lp neuron au vao ban au c nhan t moi trng, sau o
th c nhan t s hoi tiep cua lp neuron au ra.
Mo hnh mang nuoi lui nhieu lp gom: lp neuron au vao, t
nhat 1 lp neuron an, lp neuron au ra.
x1
x2
xm
y1
y2
yn
x1
x2
xm
y1
y2
yn
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 66 SVTH: Nguyen Phng Thao
Ban au mang nhan cac au vao t moi trng va thong qua
viec huan luyen mang lp neuron au ra chnh la lp neuron
au vao mang.
5.3.3 Luat Hoc Thong So Tong Quat Cho Cac Mang Neuron
Nhan Tao:
Viec huan luyen mang e co c au ra mong muon da tren hai
cach hoc sau:
Hoc thong so: la phng phap hoc bang cach cap nhat cac he so trong
lng ket noi.
Hoc cau truc: la phng phap hoc bang cach thay oi ben trong cau
truc mang gom cac phan t x ly, va mo hnh ket noi.
Phng phap hoc thong so: Co 3 che o hoc:
Hoc giam sat: Chu yeu tm c ma tran he so trong lng e
au ra cua mang xap x au ra mong muon vi mot sai so chap
nhan c. Noi cach khac mang c cung cap au vao, ra mong
muon. Mang huan luyen khi nhan thong so au vao, cho ket qua
au ra cua mang c so sanh vi au ra mong muon----->phat
sinh sai so. Sai so nay c dung e ieu chnh lai he so trong
lng cua mang.
X( au vao) Y (au ra thc s )
d (au ra
Tn hieu mong muon
sai so c )
Hoc cung co: La hoc giam sat thieu thong tin chi tiet san co ve
au ra cho moi au vao. cach hoc nay thong tin hoi tiep ch cho
biet au ra trang thai tot hay xau t o a ra cach ieu chnh
Mang
neuron
W
Khau phat sinh
tn hieu sai so
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 67 SVTH: Nguyen Phng Thao
he so trong lng cho thch hp vi mong muon au ra lan ke
tiep se tot hn.
X( au vao) Y (au ra thc s )
Tn hieu Tn hieu
nhan nh cu cung co
Hoc khong giam sat: Khong co bat ky mot thong tin nao t moi
trng giup cho viec nhan nh au ra cua mang la ung hay sai.
Do o mang se t ieu chnh bang cach hoi tiep t au ra thc s
cua mang.
X( au vao) Y (au ra thc s )
Qua tham khao ba che o hoc c ban tren, ta xem xet mot cau truc
huan luyen tong quat cho phan t x ly th i trong mot mang neuron nhan
tao c mo ta hnh sau:
Mang
neuron
W
Mang
neuron
W
Khau phat sinh
tn hieu nhan nh
Learning
Signal
Generator
x2
xj
xm-1 xm-1
xm=-1
wi1
wi2
wij
wim-1
wim=
wi
X
i th neuron
di
yi
r
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 68 SVTH: Nguyen Phng Thao
Vi xj , j = 1,2,...m la cac au vao, la gia tr ngng c a vao
trong viec hoc bang cach xem no nh la he so trong lng cua au
vao xm = -1.
Neu wi (t) la vector he so trong lng, X(t) la vector cac mau au
vao, va r la tn hieu hoc tai bc hoc th t, va la mot so dng c goi
la hang so hoc c dung e xac nh toc o hoc th luat hoc he so trong
lng tong quat trong cac mang neuron nhan tao c nh ngha nh
sau:
wi(t) = r X(t)
Vi wi(t) = wi(t+1) wi(t): s gia tang cua vector he so trong lng Do vay ta co the cap nhat he so trong lng cho bc ke tiep nh sau:
wi(t+1) = wi (t) + r X(t)
oi vi 3 che o hoc ta co cac cach xac nh tn hieu hoc r khac nhau.
Hoc giam sat: do a biet c au ra mong muon, ta co the tnh sai so
gia au ra mong muon va au ra thc s cua mang. Tn hieu sai so
nay dung e xac nh tn hieu hoc cua mang
r = fr (wi ,X,di ) = Tn hieu sai lech = di yi
==>wij = (di yi )xj vi i=1,2,...n; j=1,2,...m
Hoc cung co: do co tn hieu cung co di , nen tn hieu hoc cua mang:
r = fr (wi ,X,di ) = Tn hieu cung co = di
==>wij = di xj vi i=1,2,...n; j=1,2,...m
Hoc khong giam sat: do khong co tn hieu au ra mong muon, nen
au ra thc s cua mang c dung e xac nh tn hieu hoc:
r = fr (wi ,X ) = Tn hieu ra thc s cua mang = yi
==>wij = yi xj vi i=1,2,...n; j=1,2,...m (luat hoc Hebbian)
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 69 SVTH: Nguyen Phng Thao
Neu hoc trong thi gian lien tuc, th s dung phng trnh sau e
cai tien vector he so trong lng tai thi iem ( t+1 ):
( )( )i
dw trX t
dt
5.4 Mot So Luat Hoc Va Giai Thuat Hoc BP:
5.4.1 Luat hoc perceptron:
Luat hoc perceptron, chu yeu da tren mo hnh perceptron ch gom
mot neuron duy nhat, dung ham ngng tuyen tnh lam ham truyen nen
c dung cho viec nhan dang va phan oi tng thanh hai loai ma thoi
c xem nh tieu bieu cho nguyen ly sa sai theo giai thuat lan truyen
ngc sai lech.
Mo ta giai thuat:
Luat hoc chu yeu c s dung trong giai thuat nay chnh la cach
hoc giam sat. Vi cach hoc nay mang neuron nhan tao c cung cap
vi mot day au vao, au ra mong muon: (x(k)
, d(k)
).
Tap au vao: ( ) ( ) ( ) ( )
1 2, ,...,T
k k k k
mx x x x ,m so au vao.
Tap mau au ra mong muon: ( ) ( ) ( ) ( )
1 2, ,...,T
k k k k
nd d d d , n so au
ra.
Chung ta mong muon au ra thc s cua mang sau khi c hoc xong
se can bang vi mau au ra mong muon:
( ) ( ) ( ) ( )1
mk T k k k
i i ij j i
j
y a w x a w x d
Va 1 2, ,...,TT
i i i imw w w w la vector he so trong lng c s dung
cho viec huan luyen mang.
au ra mong
muon
au ra thc
s
w11
w21 d1
y1
e1
x1
x2
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 70 SVTH: Nguyen Phng Thao
Mau Perceptron n gian co ham tac ong chnh la ham dau, va gia tr
au ra mong muon ch co 2 gia tr la +1, -1 ma thoi.
Qua trnh truyen tien: ( ) ( )sgn( )k T ki iy w x .
Sau o he se cap nhat lai he so trong lng thong qua sai so gia au ra
mong muon va au ra thc s:
2 ,
sgn0,
i j i iT
ij i i j
i i
d x y dw d w x x
y d
vi 0, la he so hoc.
T phng trnh nay ta thay rang gia tr ra cua mang neuron bang
gia tr ra mong muon, di = yi , khi w khong thay oi. Khi o qua trnh
hoc ket thuc.
5.4.2 Giai thuat hoc delta:
Luat hoc delta da tren tnh chat cua ao ham ma nen tang la
phng thc giam nen co the dung cho ham truyen bat ky (tuyen tnh
hay ban tuyen tnh).
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 71 SVTH: Nguyen Phng Thao
1. ao ham:
nh ngha : ao ham cua
ham so f tai mot iem x thuoc
mien xac nh, ky hieu la
)(xf , c cho bi :
n
n
xx xx
xfxfxf
n
)()(lim)(
Neu )(xf > 0 th ta noi rang f tang tai x, neu )(xf < 0 th ta noi
rang f giam tai x, con neu )(xf = 0 th ham f co mot cc tr tai x.
Phng trnh ng thang d i qua iem (x0
,f(x0
)) c cho bi :
)()( 0
0
0
xfxx
xfy
)()()( 000 xfxxxfy
goi x1 la giao iem cua d va truc hoanh, the th x
1 la nghiem
phng trnh :
0)()()( 000 xfxxxf
suy ra
)(
)(0
001
xf
xfxx
Tong quat, ta co :
)(
)(1n
nnn
xf
xfxx
Qua trnh tren c goi la phng thc giam. Ap dung ieu nay cho
trong so w, ta thay vong lap ke wn+1
phai thoa tnh chat :
Hng giam
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 72 SVTH: Nguyen Phng Thao
f(wn+1
) < f(wn)
tc la gia tr cua f tai wn+1
nho hn gia tr trc o tai wn
.
Trong luat hoc sa sai, moi phep lap theo phng thc giam se tm
hng giam tai wn
e vi mot > 0 nho bat ky sao cho :
)())(( nnn wfwfwf
at wn+1
la vector
)(1 nnn wfww
at f : Rn
R la mot ham thc va at e Rn vi 1e la mot hng
cho trc. ao ham cua f theo hng e tai w c nh ngha nh sau :
t
wftewfwf
te
)()(lim)(
0
Neu
T
ithu
e )0..,.1.,..0(
tc e la mot hng c s trong khong gian vector th thay v )(wfe , ta
viet ) (w f i , c nh ngha bi :
t
wwwfwtwwfwf nini
ti
),...,,...,(),...,,...,(lim)( 11
0
gradient cua f tai w, ky hieu la )(wf , c nh ngha :
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 73 SVTH: Nguyen Phng Thao
T
n wfwfwf ))(),...,(()( 1
2. Mo ta luat hoc delta:
Xet mot neuron s dung au ra la ham tuyen tnh, the th vector
trong so tm c trong giai thuat hoc se la mot ng thang (trng
hp khong gian hai chieu). ieu nay co ngha la luat hoc cho ham
truyen tuyen tnh ch co the xap x mot ham tuyen tnh ma thoi.
Tuy nhien, neu ham truyen la phi tuyen th kho co the co mot xap x
tot. o la ly do tai sao ngi ta dung ham kch hoat ban tuyen tnh.
au ra cua neuron :
o() = f(wT
x)
Cung nh luat hoc perceptron, luat hoc delta can mot tap d lieu mau
cho qua trnh
He lay xk
lam au vao, tao ra ket qua ok
cua rieng no roi so sanh vi
ket qua mong muon yk
. Sai lech cua mau th k c tnh theo :
22 ))((2
1)(
2
1xwfyoyE Tkkkk
Sai lech cua tat cac cac mau :
K
K
k
k EEEEE
...211
Luat hoc se thay oi w theo hng lam cc tieu hoa sai lech bang cach
s dung phep lap :
)(wEww k
vi
)())(())((2
1)( 2 xwfxwfyxwfy
dw
dwE TTkTkk
3. Mot so ham truyen va ao ham cua no:
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 74 SVTH: Nguyen Phng Thao
Bieu thc tren cho thay trong luat hoc delta, ta can phai tnh ao
ham cua ham truyen. Sau ay la mot so ham truyen hay dung va ao
ham cua no :
Ham dang ch S lng cc :
))(1(2
1
))exp(1(
)exp(2)(1
)exp(1
2)( 2
2tf
t
ttf
ttf
Ham dang ch S n cc :
))(1)(())exp(1(
)exp()(
)exp(1
1)(
2tftf
t
ttf
ttf
4. Tom tat giai thuat:
Cho trc K mau d lieu :
1 1{( , ),..., ( , )}k kx d x d
vi ),...,( 1k
n
kk xxx va dk R, k = 1,,K.
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 75 SVTH: Nguyen Phng Thao
Do tnh chat khong tuyen tnh cua ham truyen ma giai thuat kho co
the dng ung ngha (gia tr tao ra bi mang neuron bang ung gia tr
mong muon hay sai lech = 0). Do o ngi ta thiet lap tieu chuan dng
theo mot gia tr sai lech Emax cho phep nao o : khi sai lech E nho hn
hoac bang Emax th dng.
Trong thc te ngi ta con co mot tieu chuan dng theo so lan lap:
khi at en mot so lan lap xac nh th dng.
Bc 1 : chon trc gia tr > 0 va Emax > 0.
Bc 2 : khi tao ngau nhien w, bat au vi mau th nhat k = 1 va
gan sai lech E = 0.
Bc 3 : bat au qua trnh hoc, gan x = xk, y = dk. au ra cua mang
neuron tnh theo :
= o() = f(wTx)
Bc 4 : cap nhat trong so
)(wEww k
Bc 5 : tnh sai lech bang cach cong them sai lech hien tai
2)(
2
1oyEE
Bc 6 : neu k < K th k = k + 1 va tr lai Bc 3. Neu khong th qua
Bc 7.
Bc 7 : ket thuc chu ky hoc. Neu E Emax th ket thuc qua trnh hoc.
Con neu E > Emax th gan E = 0 va bat au mot chu ky hoc mi bang
cach tr lai Bc 3.
5.4.3 Giai thuat hoc truyen lui BP:
Giai thuat truyen lui (Back propagation Alogorithm ) hay con goi
la giai thuat hoc BP la mot trong cac giai thuat quan trong nhat trong
lch s phat trien cua cac mang neuron nhan tao. Giai thuat c s
dung e huan luyen cac mang nuoi tien nhieu lp vi cac phan t x ly
trong mang co ham tac ong la ham phi tuyen. Mang nuoi tien nhieu
lp c ket hp vi giai thuat truyen lui con c goi la mang truyen
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 76 SVTH: Nguyen Phng Thao
lui. Giai thuat van hanh theo hai luong d lieu sau: hng truyen tien
dung cac mau huan luyen truyen t lp neuron au vao en lp neuron
au ra va cho ket qua thc s Ok (hoac Y
k
) cua lp neuron au ra, sau
o hng truyen lui se s dung sai lech gia au ra mong muon vi au
ra thc s cua mang lam tn hieu vao i ngc t lp neuron au ra en
lp neuron au vao e cap nhat he so trong lng ket noi trong mang.
Ham tong hp cho moi phan t x ly th q cua lp neuron an la:
1
m
q qj j
j
net v x
va au ra cua no: q qz a net Ham tong hp cho moi phan t x ly th i cua lp neuron au ra la:
1
m
i iq q
j
net w z
va au ra cua no: i iy a net
o sai lech gia gia tr tao ra cua mang neuron vi gia tr mong muon
cho mot mau d lieu hoc c cho bi :
x1
x2
xm
vqj wiq
y1
y2
yn
xj (j=1,..,m) , vqj zq (q=1,..,l) , wiq yi (i=1,..,n)
LVTN: ieu Khien Nhiet o Dung M Thch Nghi
GVHD: Ts Nguyen Thien Thanh 77 SVTH: Nguyen Phng Thao
21( ) ( )2
i i iE w d y
o sai lech tong the c tnh bang cach lay tong cua cac o sai lech :
1
( ) ( )K
i
k
E w E w
V the he so trong lng gia lp neuron au ra va lp neuron an co the
c cap nhat bang mot lng :
/iq iqw E w
S dung luat chain cho ( / iqE w ), ta co:
/ / /iq i i i i iw E y y net net wq
trong o:
/
/ ( )
/
i i i
i i i
i iq q
E y d y
y net a net
net w z
Do o ta co the viet lai:
iq i i i q oi qw d y a net z z
Trong o: oi la tn hieu sai lech cua neuron th I trong lp neuron au
ra cua mang.
Tn hieu sai lech