THIET KE BO DIEU KHIEN THONG MINH TREN NEN DSPIC33F
Phgm Xudn Khdnh ^"\ Nguyin Viet Hung, Phgm Tudn Anh ^'"
(a) Trudng CDN Cdng nghe cao Hd Ndi (b)Tru-ang Dgi hgc Bach khoa Hd Ngi
Tdm tdt:
Bdi bdo trinh bdy ve thiet ke hg dieu khien thdng minh tren nin dsPIC33F ciia Microchip.
Nhieu thugt todn dieu khien dua tren ly thuyet dieu khiin kinh diin vd hifn dgi duac cdi dgt Bo cue bdi bdo cd thi chia thdnh 3 phan. Phan I. Ca sa ly thuyet thiet ke bg diiu khiin, trinh bdy cu the ve cdc thugt todn dugc cdi ddt: PID, md ddng, PID-Fuzzy Interx'ention vd PID-
FUZZY Self- Tunning. Phdn 2: Ca sd thiet ke phdn cirng bg diiu khiin, dua ra nhung im diem cua ddng DSPIC33F vd cdc modules cdn thiet cho irng dgng cdng nghiep. Phdn 3: lfng dung bd dieu khien thiet ke cho ddi tirgnig thuc Id binh mire, tdt cd cdc thudt todn diu duac cdi dgt vd cd xet den dnh hudng ciia nhieu, qua dd thi hiin duac uu nhugrc diim cua timg thudt todn vd khd ndng irng dung da dgng ciia bd dieu khien. Tir thiet ki phdn cimg vd phdn mim cua bd dieu khien, vd nhung kit c^iid thuc nghiem dd chirng td khd ndng thay thi hiiu qua cua bo dieu khien ndy cho cdc bd diiu khiin chuyen dung dd cd trong cdng nghiep.
Chu viit tdt
I Integral PD Proportional - Derivative PI Proportional - Integral
PID Proportional - Integral - Derivative PWM Pulse Width Modulation
I. DAT V A N D E
Phuang phap dieu khien kinh dien PID Id phuang phdp dugc dp dyng phd bien nhdt trong cdc bd dieu khien cdng nghiep. Sy phd bien nay Id do tfnh dan gidn cua phuang phdp vd yeu cdu ve chdt lugng dieu khien khdng qud cao cua he thdng. Phuang phdp dieu khien thong minh, ma md la mgt dai dien tieu bieu dang dugc khai thdc va img dyn» bdi khd ndng hoat ddng mdt cdch dgc lap hodc ket hgp vdi thudt todn PID de dem lai chat lugng cao cho he thdng dieu khien Thiet ke mdt bd dieu khien thdng minh cd khd ndng thyc hien cdc thuat todn PID, Fuzzy dgng, PID-Fuzy Intervention, PID-Fuzzy Self-tunning Id mdt hudng di hiia hen trong tuong lai.
De xdy dung mdt bd dieu khien nhu vay, thiet ke phdn cung ddi hdi viec sir dyng ddng vi dieu khien cd dung lugng nhd Idn, tdn sd boat dgng cao vd cdc yeu cdu can thilt khdc ve ngoai vi. Ddng dsPIC33F mgt trong nhung ddng vi dilu khiln manh nhdt hien nay cua Microchip vdi nhieu tfnh ndng uu viet - Id sy lya chgn phii hgp, ddp ung dugc yeu cdu.
II. CO SO LY THUYET DIEU KHIEN 2.1 Thuat toan dieu khiln PID
Thudt todn PID[I,6] Id sy kit hgp ciia ba thdnh phdn: Khulch dai (P), vi phdn (I) va vi phan (D) ciia sai lech ddu vdo.
Uu diem Idn dem lai iing dyng rdng rai cho thudt todn nay Id tfnh don gidn ve cau triic vd nguyen ly lam viec. Vdi he thdng lam viec trong mdi tmdng ft bj dnh
<t)
o
Kp
Ki/s < > * •
Kd.5
Doitixcmg
y(t)
Hinh 1. He dieu khiln thirc hien thuat toan PID
hudng CLia nhieu, thdng sd ciia doi tugng chi thay doi nhd trong qua trinh Idm viec va yeu cdu ve do chfnh xac va on djnh khdng cao thi PID la mdt giai phap dieu khien hiru hieu.
2.2 Thuat toan dilu khiln md dong
Thudt toan md ddng[l,4] la thudt toan ket hgp giiia he kinh dien vd he md, cu the Id su kit hgp ciia thuat todn dilu khiln md co ban va cac thanh phdn P, I, D. Cac thdnh phdn P, D thudng Id cac thdnh phdn ciia sai lech dau vao, c6n I Id thanh phdn cua ddu ra bg dilu khiln mdcobdn.
0 0
Mgt sd cdu true he thyc hien thudt toan md dgng:
Thuat toan md dgng PI Thuat toan md dgng PD
m
e— •
•'^',- .«;:, - • d
dt >
Bo dii$u
kluennw
CO b i n
<0
• Doi tK«\g
y(t) Kt)
1—
1 - '
— * •
d dt
- •
B 6 d i « u kltiSnircr
ccrbin u(t)
E>oifcron< y(0
Hinli 3. He dieu kliicn tliuc hien tliudt toan md PI Thuat toan md dgng I
Hinh 2. Hf dieu khien th^rc hifn thuat toan mcr PD
Hinh 4. He dieu khien thuc hien thuat toan md I 2.3 Thuat toan dilu khiln PID-Fuzzy Intervention
Sa dd tdng qudt mdt be thyc hien thudt todn PID-Fuzzy Intervention [5]:
:1V>|
PID
FiizzN' ^
Doi tinrng
>tt)
Hinh 5. He dieu khiln thirc hien thuat toan PID-Fuzzy Intervention
hda va tiep tyc tang do tdc ddng cua khau tfch phdn, dilu ndy tiim tang khd ndng gdy qud dilu chinh Idn vd tang thdi gian qua dg. Bd md bii windup cd tdc dung gidm thieu dnh hudng ciia hien tugng ndy. Khi xdy ra windup, sai lech giira tin hieu ra bd dieu khiln PID va gid trj bao hda se dugc dua vdo bg md bu, bd md bii dua ra tin hieu bii den ddu ra bd PID, tdc ddng ndy Idm cdi thien dang ke chdt lugng dieu khien.
2.4 Thuat toan dieu khiln PID-Fuzzy Self- tunnlng[3]
Dya tren so dd tdng qudt ndy, cd nhieu thuat todn khdc nhau cd the hinh thdnh. Nhdm tdc gid bdi bdo tap tmng vdo thudt todn trong dd he md cho phep cdi thien chat lugng dieu khien khi hien tugng Windup xdy ra:
Khi xdy ra hien tugng windup, tfn hieu ra bd dilu khiln PID cd gid trj Idn hon gid tri bao
1(0 -^
PID
o
Bo 1110 bu will dii|)
+ '
"V,
i<k
i)oi tttoiis vm
Hinh 6. He dieu khiln thyc hien thuat toan PID-Fuzzy Intervention bu windup
E)INH MO
T l — I
Day la thuat loan mii d do tham s6 bg PID trong qua irinh dilu khiln dugc chinh dinh bang he md. Thual loan dem lai chai Iirgng clieu khien lol, trong ca trirdng hgp cd nhieu dang ke tac dong len he Ihong
Sa do ting quat he ihong dilu khien trong do cac tham so PID dugc chinh dinh bfing he md:
Phuang phap chinh dinh dugc nhom tac gia thuc hien la phuang phap chinh dinh md ciia Zhao, Tomizuka va Isaka:
Vdi gia thilt cac tham sl Kp, Kd bi chan, tire:
KpG [Kp_Min,Kp_Max] ; Kde [Kd_Min, Kd.Max]
Cac tham sd nay dugc chudn hoa theo cdng thirc:
Kp- Kp _ Min
THli'T B|
nilNII PI.MI
T
Hinh 7. Hf dieu khien chinh dinh tham so PID bdng he md
kp = kd =
Kp _ Max - Kp _ Min Kd-Kd _ Min Kd Max - Kcl Min
kp&[0.\]
kde[Q,{]
•Bg chinh dinh cd hai dau vao la e(t) vd de(t)/dt vd ba ddu ra la kp, kd vd a trong dd
a = Kp- :^ Ki = Kp'
Ki.Kd a.Kd
Ben trong bg chinh djnh md theo phuang phdp Zhao, Tomizuka, vd Isaka:
Ludt dilu khien dk chinh djnh dugc thyc hien
dya tren phan tfch dap ung budc tieu bieu cua qud trinh Khi bat ddu khdi ddng, d khodng thdi gian
a, liic ndy cdn tfn hieu dieu khien Idn de tfn hieu ra tdng nhanh, suy ra liic ndy Kp Idn, KD nhd, vd KI Idn (a Idn). Xung quanh khodng thdi gian b ta mudn tfn hieu dieu khien nhd de khdng qua dieu chinh, nghTa Id Kp nhd, KD Idn cdn K| Idn (a ldn).Cdc tdc ddng dieu khien xung quanh khoang thdi gian c vd d tuong ty nhu d a vd b.
e cle (It
Bu cliinh ctiiili iiio 1
Bo cliiiili (tiiili nio 1
B o cliinh (tinh luo 1
kp ' •
kd w
a
•
Hinh 8. Ben trong bg chinh djnh mii
Hinh 9. Ddp irng budc tieu bieu ciia qua trinh
HI. CAU TRIJC P H A N ClTNG
3.1 Gidi thieu vi dieu khiln dsPIC33F[7]
Microchip Id mgt trong nhirng hang sdn xudt vi dieu khien Idn nhat the gidi hien nay, ddng DSC(Digital signal controllers) 16 bits Id sdn phdm mdi nhdt vd thu hiit dugc nhieu su quan tdm ciia cdc nhd phdt trien. Nhu ten ggi cua nd, theo mdt cdch hiiu nao dd, ddng nay la san phdm ket hgp giira vi xir ly tfn hieu sd DSP vd vi dilu khien. dsPIC33F, mdt trong nhiing ddng DSC manh nhat ciia Microchip, sd hiiu rat nhieu ddc tfnh uu viet phu hgp cho iing dung xay dvrng bd dilu khiln:
Nguon
~220V
• Tieu thy nang lugng thdp: dien ap nguIn cap cd 3.0-3.6V
• CPU tfnh nang DSC cho phep thuc hien cdc phep tfnh todn phuc tap mot each nhanh chdns
• Cd ddy dii cac ngoai vi cdn thiet nhu nhirng ddng vi dieu khien khac: Cdng va/ra so, bd djnh thdi, ADC, PWM, UART..., ddc biet cd hi trg 8 kenh DMA phdn cirng.
• Bd nhd chuong trinh 256Kbytes va bd nhd dii lieu 30Kbytes dugc tfch hgp ngay tren chip.
• HO trg tfnh ndng In-circuit Debug and Programming dem din sy tien dyng to Idn cho cdc nhd phdt trien he thong.
• Cd nhilu cdng cy hd trg lap trinh bdng ngdn ngir C vdi thu vien phong phd vd dl sir dyng
3.2 Bo dicu khien
• Khdi xir ly trung tam Id vi dilu khien dsPIC33F
« 0
• Ddu vao sd: Digital & Counter
• Ddu vdo tuong ty: 0-20mA, 4- 20mA,0-5V,0-10V
• Ddu ra sd: Digital & PWM
• Ddu ra tuong ty: 0-20mA, 4- 20mA, 0-5V, 0-IOV
• Ban phfm cho phep nhdp cdc tham . sd, che do dieu khien tryc tiep ngay tren bd dieu khien
• LCD cho phep hien thj cdc tham so chi'nh trong qud trinh thiet lap budc ddu vd cdc bien qud trinh
0 \
• Giao tiep RS232 cho phep bd dieu khien ket ndi vdi mdy tfnh, truyen
0 0 \
nhdn cdc tham sd, che do dieu khien vd hien thj qud trinh dieu khien Nhd thilt kl da dang ddu vdo vd ra theo cac chudn cdng nghiep nhu tren, bd dieu khien cd khd ndng giao tiep vdi nhieu loai thiet bj cdm bien vd chdp hdnh khdc nhau.
Chuang trinh vi dilu khien dugc viet bdng phdn mem MPLAB 8.0, C30 (Microchip).
. Phdn giao dien ngudi diing dugc viet bdng phdn mim Visual C+-H 6.0 (Microsoft). Hinh ve sau minh hga cua sd giao dien chi'nh:
€>iu vao si Dau v4o ti/omgnr
Khoi XU' ly trung tam
Oiu ra $0
&lura ti.roiigM
Biiphim
T ' ' T
LCD CSflg
RS232
Hinh 10. Sa do cau true bo dieu khien
•XZJ
I ^ ^ L M ^
^Tnvjrrr.Mf :»e«;^£aURiiKv' •#t»ig^rffJMw.w. ^wy•li^Ll'..^n^^'!.^^o;YW^gwft«;w?ytHBffn].^^»gtf.y»;?gy*
Hinh 11. Ciia so giao dien chinh ciia chuong trinh giao difn nguoi dung
IV. HE THONG DIEU KHIEN MLIC NU'6C Ddi tugng dilu khiln mire nhu Hinh 12
Thilt bi do mire la cam bien dp sudt ddt tai day ciia binh, ddu ra cdm biln dudi dang^chudn ddng cdng nghiep: 4-20mA, Adapter biln ddi tuyin tfnh tfn hieu ndy thdnh tfn hi?u di?n dp dugc dua vao ADC cua dsPIC33F.
Co cdu chdp hdnh Id van ti I? dugc dilu khien theo phuang phdp PWM.
V. KE:T QUA T H ^ C NGHIEM
Nhdm tac gid tiln hdnh thf nghiem tr6n ca sd khdo sat dap img cua he thing vdi cdc thuat todn dilu khiln khdc nhau khi thay dii gid trj ddt dhng thdi cd xem \6t din dnh hudng ciia nhilu:
5.1 Ket qud
Hinh 12. Dii tugng dieu khien mire nud^c
Hinh 13. Thuat toan PID va Fuzzy d$ng Setpoint=80mm, khong nhieu
Hinh 14. Thufit to^n PID, Fuzy d$ng Setpoint=120nun, khong nhiSu
» i
K
»
C
/ "
/
m
mmt W«-*l
/ ' • ' * ' v . ^
120 kMHI
m
K>
sm X B
Hinh 15. Thuat toan PID va PID-FUZZY Intervention; Setpoint=:120mm, khong nhieu
Hinh 16. Thudt toan PID, Fuzy dong va PID- FUZZY Self-Tunning Setpoint=100mm,
nhieu hang tac dgng tVong thoi gian 5s bat dau tir thoi dilm t=180s
5.2 Nhan xet
Thuat toan PE) c6 chdt lugng dilu khiln phy thugc vdo gia tri ddt, nhu tren cac hinh ve H.13, H.14, H.15, H. 16, khi thay dii gia trj dat, chat lugng dilu khiln kem ddn khi gia tri dat tang ddn, ddng thdi chju dnh hudng kha rd ciia nhilu
Thudt todn Fuzzy dgng dem lai chdt lugng dilu khiln tit ca khi gid trj ddt thay dii, ddng thdi khi khdng cd anh hudng cua nhieu thi thudt toan ndy la thudt todn hieu qud nhdt: gan nhu triet tieu qud dieu chinh va gidm thdi gian qua dg. Tuy nhien thudt todn khdng dem lai chdt lugng tot khi nhieu tac dgng
Thudt toan PID-Fuzzy Intervention cdi thi^n ddng kl chat lugng dilu khiln trong tmdng hgp xay ra hien tugng Windup, dan din qud dilu chinh Idn trong lie thong (H. 16).
Thudt todn PID-FUZZY Self-Tunning cd khd nang dem lai chdt lugng dilu khiln khd tdt khi khong cd dnh hudng ciia nhilu, mat khdc thi hien dugc uu dilm so vdi cdc thudt todn khdc trong tmdng hgp he thdng cd nhieu tdc ddng (H. 17, dudng net dirt).
VI. KET LUAN
Bd dilu khiln dugc thilt kl dya tren ddng vi dilu khiln DSC dsPIC33F cho phep tang hi?u qud tfnh todn, mat khdc lai cd khd ndng kit nli vdo ra theo cdc chudn cdng nghiep phd biln, qua do gdp phdn dem lai khd nang dilu khiln da dang cdc doi tugng cdng nghiep cd chu ky dieu khien Idn nhd khdc nhau,,
Bd dilu khien thdng minh (thyc hien cdc thudt todn PID, Fuzzy ddng, PID-Fuzzy Intervention, PID-Fuzzy Self-tunning) cd khd ndng img dyng linh boat, cho chdt lugng dilu khiln tdt khi thay ddi gid tn ddt vd ngay cd khi he thing chju dnh hudng ciia nhieu. Dilu nay khdc phyc ban chl ciia bd dilu khien PID kinh diln, thudng khdng dem lai chdt lugng mong mudn khi he thdng cd gid trj ddt thay ddi trong khodng rdng hoac cd nhilu tdc ddng.
Phuang phdp dilu khien md ddc lap hodc kit hgp vdi phuang phdp dilu khiln PID kinh dien dya tren nen vi dieu khien manh, nhu dsPIC33F hira hen khd nang xdy dyng bd dilu khien cdng nghiep trong tuong lai.
TAI LIEU THAM K H A O
1. Phan Xudn Minh, Nguyen Doan Phuac; Ly thuylt dilu khiln md; NXB KHKT, 2004 2. Nguyin Dodn Phuac; Ly thuylt dilu khiln tuyin tfnh; NXB KHKT, 2002
3. L X. Wang; A course in Fuzzy Systems and Control; Prentice Hall Intemational, Inc 4. K. M. Passino, Stephen Yurkovich; Fuzzy Control; Addison Wesley
5. E. Chakir El Alaoui, H. Ayad and S. Doubabi; Fuzzy Anti-Windup Schemes for PID Controllers; ISSN 0973-4562 Volume 1 Number 3 (2006) pp. 295-306 Intemational. Journal of Applied Engineering Research
6. Aidan O'Dwyer; Handbook of PI and PID Controller Tuning Rules; Imperial College Press, 2003
7. Microchip Technology Incorporated; dsPIC33F Family Data Sheet; DS70165A, 2005.
