sổ tay cdt chuong 21-dkhien cdt

8/6/2019 s tay cdt Chuong 21-dkhien CDT

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21Vai tr ca iu khin trong C in t

Job van AmerongenUniversity of Twente

21.1Gii thiu ..........................................................................1

21.2Cc phn t ch cht ca h C in t c iu khin ...... .3

21.3M hnh ha tch hp, thc hin thit k v iu khin ..... 3

21.4Cc v d h C in t hin i .......................................10

21.5Cc yu cu khc bit ca cc h C in t khc vi cc h c in v thitk iu khin ................................................................. ...12

21.1 Gii thiu

"Thit k C in t l thit k tch hp v ti u mt h thng c hc v h iu khin nhng ca n." nh ngha nyhm rng h c c m rng bng cc thnh phn in t t c hiu sut tt hn, h thng mm do hn, hocgim gi thnh h thng. Trong nhiu trng hp cc thnh phn in t c dng mt h (iu khin) nhng da trn mytnh. iu ny khng c ngha rng mi h c c iu khin u l h c in t bi v trong nhiu trng hp, phn iukhin ch n gin l c thm vo h c nh mt th tc thit k tip sau. Vic tip cn h c in t thc i hi s lachn ti u thc hin c cc c tnh thit k trong cc lnh vc khc nhau. Trong k thut iu khin, thit k mt h

iu khin ti u c nghin cu k v tn ti cc phng php chun cho cc h tuyn tnh. Vn ti u c phtbiu nh sau: cho mt qu trnh c iu khin, v cho mt tiu ch (v d hm gi), tm cc tham s iu khin ti u saocho hm gi l ti thiu. Vi mt b iu khin phn hi trng thi v mt hm gi bc hai, cc li gii cho bi ton ti u cth c tm thy bng phn mm thit k b iu khin chun nh Matlab1 (Hnh 21.1).

Tri li, thit k c in t i hi khng ch b iu khin l ti u. N i hi s ti u ca c h thng. Trong trnghp l tng, tt c cc thnh phn ca h thng: i tng, b iu khin, cng nh cc b cm bin v cc c cu chphnh phi ng thi ti u (Hnh 21.2).

Ni chung iu ny l khng kh thi. Vn t ra l khng chnh v phi tch thnh cc vn nh hn c th ti uha mt cch ring bit. Sau cc li gii ca tng phn li c kt hp li v vic thc hin ca ton b h thng phic nh gi. Vic iu chnh ln cui cng mt vi phn ca h thng s a ra mt gii php ti u thnh phn.

HNH 21.1 Ti u ha b iu khin

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S tay C in t

HNH 21.2 Ti u ha tt c cc thnh phn ca h thng mt cch ng b

Trong giai on thit k tng ban u, cn phi quyt nh u l vn phi c gii bng c hc u l vn phic gii bng in t. Trong bc ny, cc quyt nh v cc tnh cht c hc tri phi c thc hin v a ra mt mhnh n gin thit k b iu khin. C tng ban u v cc cm bin, cc b truyn ng v cc giao din cn phi ctrong giai on ny. Khi thit k cc phn khc nhau c vch ra tng i chi tit, thng tin v nhng thit k phic s dng nh gi c h thng v c tho lun nhn c thit k chi tit v thc t hn cho cc phn khc nhau.

Mc d thut ng c in t l mi nhng sn phm c in t c t lu. Thc t l tt c cc h thng c hc ciu khin bng in t u da trn tng ci tin sn phm bng cch thm cc tnh cht c thc hin trong cc lnhvc khc. Cc thit k c in t tt l da trn vic tip cn h thng thc. Nhng phn ln cc k s in t phi i mt

vi thit k m trong cc tham s chnh c c nh da trn nhng nh gi tnh hoc kinh t. iu cn tr s tiu ton b h thng, thm ch c khi iu khin ti u c p dng. Trong nhng ngy cui cng ca my quay a, ccthit k phc tp nht s dng phn hi tc kt hp vi mt gi quay quang in t c tc quay khng i.Nhng thit k thc s mi li l my chi a compact. Thay v phi gi s vng quay a khng i l gi tc u cdc theo rnh ca a khng i. iu ny c ngha l a phi quay chm hn khi rnh c bn knh ln hn c c. Ccbit c c t a CD c t trong b m in t gi cc thng tin ca n ti b bin i DA, c iu khin bimt tinh th thch anh. iu ny cho php thc hin tc c bit thc s khng i v loi tt c cc s thay i tc cth nghe c. Mt s thc hin nh vy khng th nhn c t mt thit b c hc thun tu, ngay c khi n c trang bmt h thng iu khin tt. Trong thc t, vng iu khin tc quay a khng cn c cc c tnh qu chnh xc. N chcn ngn chn trn trn hoc trn di b m. chnh xc cao nhn c trong ch vng h, c iu khin bi mttinh th thch anh (Hnh 21.3).

HNH 21.3 T hp ca iu khin kn v iu khin h trong mt my chi CD

HNH 21.4 H c in t

Tnh mm do nhn c bng s kt hp ca cc h c chnh xc v b iu khin in t cho php pht trin cc my

CD-ROM chy tc ln hn 50 ln so vi tc ca ca cc my chi CD m thanh lc u. Mt cch ngh mi l cnthit cho mt gii php mi nh vy. Mt khc my chi CD vn l mt vn phc tp ca c hc chnh xc. Khng mtthit b nh in t dng cng no c th cnh tranh mt cch kinh t vi kh nng lu tr quang c ca a CD v th h sau l DVD. Nhng iu ny c th thay i rt nhanh.

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Vai tr ca iu khin trong c in t

21.2 Cc phn t ch cht ca h C in t c iu khin

Mt h c in t bao gm phn c thc hin cc dch chuyn nht nh v phn in t (trong nhiu trng hp l mth my tnh nhng) mang li s thng minh cho h thng.

Trong phn c ca h thng, lc ng vai tr quan trng nht. Tri li, phn in t ca h thng, x l thng tin lnhim v chnh. Cc cm bin bin i cc dch chuyn c hc thnh cc tn hiu in m ch c ni dung thng tin lquan trng hoc thm ch thnh cc thng tin theo dng s (nu cn th qua mt b bin i AD). B khuych i cng sut

bin i cc tn hiu thnh nng lng c iu ch. Trong hu ht cc trng hp, ngun nng lng l in nhng ccngun khc nh thy lc, kh nn l cng c th. Mt h dch chuyn c c iu khin kiu nh vy bao gm mt cu trcc, mt hoc nhiu b truyn ng to ra cc dch chuyn mong mun, v mt b iu khin iu khin thun da trncc c cu chp hnh v iu khin phn hi da trn cm bin (Hnh 21.4).

21.3 M hnh ha tch hp, thc hin thit k v iu khin

M hnh ha

Trong khi thit k cc h c in t, iu quan trng l s thay i trong cu trc v b iu khin phi c nh ging thi. Mc d b iu khin thch hp cho php xy dng mt cu trc r hn, nhng mt h c thit k km s khngbao gi c th hot ng tt bng cch thm vo mt b iu khin phc tp. V vy, iu quan trng l trong giai on uca thit k, mt la chn thch hp cn c tin hnh i vi cc tnh cht c hc cn thit h c iu khin hot

ng tt. Mt khc, dng cc kh nng ca b iu khin b cho nhng khim khuyt v mt c hc c th cho php cutrc c hc c xy dng theo cch r hn. iu ny i hi trong giai on u ca thit k phi c mt m hnh n gin pht hin nhng yu t hn ch ca h thng. Lun lun c mt khong cch gia m hnh v phn mm m phng nh gi cc cu trc c v phn mm s dng cho vic thit k cc b iu khin. Cc k s c kh quen vi cc bchng trnh phn t hu hn nghin cu cc tnh cht ng lc ca cc cu trc c. Ch sau khi n gin xung cc mhnh bc thp (phn tch modal), th nhng m hnh ny mi c th s dng thit k cc b iu khin. Mt khc, phnmm k thut iu khin thng dng cha h tr trc tip qu trnh thit k c in t; trong qu trnh m hnh ha, cchm truyn v nhng m t khng gian trng thi thng dng thng nh mt mi quan h vi cc tham s vt l ca cutrc c. Cc cng c cn c cho php m hnh ha h thng c sao cho cc tham s vt l ni tri (nh l khi lng v cng tri) c bo ton trong m hnh v ng thi cung cp mt giao din cho vic thit k b iu khin v cc cng cm phng m cc k s iu khin quen bit (Coelingh [2]; Coelingh, De Vries, v Van Amerongen [3]).

M phng l mt cng c quan trng nh gi thit k ca cc h c in t. Hu ht cc chng trnh nh Simulink

[1] dng cc biu din di dng s khi v khng h tr m hnh vt l theo cch iu chnh trc tip cc tham s vt lca cu trc c v ca cc b iu khin m iu ny c th c i hi khi thit k cc h c in t. Gn y, c ccchng trnh cho php m hnh ha kiu vt l trong cc min vt l khc nhau. H s dng phng php hng i tng cho php m hnh ha theo th bc v cho php dng li cc m hnh. Bc tnh ton ch b c nh sau khi t hp cc hcon. V d: chng trnh 20-sim [4], c m t bi Broenink [5] nh CAMAS v Dymola [6]. Trong mc ny, m hnh hav chng trnh m phng 20-sim (pht m l Twente Sim) s c dng minh ha vic thit k ng thi cu trc v biu khin trong mt h c in t.20-sim h trvic m hnh ha hng i tng. Cng sut v cc cng tn hiu vo raxc nh mi mt i tng (Weustink, De Vries, and Breedveld [7]). Bn trong i tng c th c cc i tng khc hocmc thp nht l cc phng trnh. Cc thc hin (realizations) khc nhau ca mt i tng c th cha cc m t khchn nhau hoc chi tit hn min giao din (s lng v kiu ca cc cng) l ng nht. M hnh ha c th c bt ubng vic ni mt cch n gin cc m hnh con (rng). Sau chng c th c in cc m t thc vi phc tp khcnhau. De Vries [8]gi l m hnh ha kiu a hnh thi (polymorphic modeling). Cc m hnh con c th c xy dngt cc m hnh con khc theo cu trc th bc. M hnh vt l ng n t c bng cch kt hp cc m hnh con theo

phng php dng nng lng (flow of energy), ch khng phi theo tn hiu nh l in p, dng in, lc v vn tc. Cchm hnh ha ny rt thch hp cho thit k h thng c in t. iu s c minh ha bng mt v d. Xt vic thit kmt h servo n gin, dng mt ngun in p, mt ng c mt chiu v mt ti c hc c iu khin qua mt b truynlc (Hnh 21.5). B truyn lc c b qua trong lc ny.Dy curoa c xt nh l cng hon ton v t s truyn nhnc bng cch thay i hng s ca ng c. Nu mt b khuych i cng sut c iu khin bi mt b pht tn hiu lngun in p, chng ta c th v s biu tng nh trn hnh 21.6. giai on ny, cc thnh phn khc nhau trong mhnh ny vn l rng. Nhng tt c cc thnh phn u c cc cng in t v/hoc c. Vi cc giao din (l cc cng) thchhp c xc nh, cc thnh phn c th c ni vi nhau.

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S tay C in t

HNH 21.5 H servo - DC n gin

HNH 21.6 S biu tng ca h servo n gin

HNH 21.7 Biu tng ca ng c c khai trin thnh cc thnh phn vt l l tng

bc tip theo chng ta c th chi tit ha vic m t ng c DC. Mt gii php c th c a ra trong hnh 21.7.ng c by gi c m t bng mt s cc phn t vt l l tng, mi phn t miu t mt mi quan h vt l c bn.ng c c mt cng in (EL) cng nh mt cng c (MECH).

Mi phn t trong hnh ny c th c m t nh l mt phn t vi mt cng in v/hoc mt cng c. Khi nimcng to ra s r rng hn trong cc biu quan h [9-12]. Vi cc phn t in, l s khc nhau v in p trn phn tv dng qua phn t. Cc phn t c, l m men v vn tc gc. Tch ca cc bin lin hp (P=ui orP=T) biu dincng sut.

Nu i thm mt bc trong s th bc, chng ta s ti mc phng trnh. V d mt in tr c th c m t bngphng trnh:

. .p u R p i= (21.1)

trong cc binp.u vp.i ch ra cc bin lin lin hp u v i ca cng inp. Ch rng l mt phng trnh ch khngphi mt lnh gn. N cng c th c vit dng:

. / .p i l R p u= (21.2)

Tng t, cun cm c th c m t bng cc phng trnh:

( ) ( ) ( )= = . . hoc . 1/ int . pu L ddt pi pi L pu (21.3)

trong ddt(pi) k hiu di/dtv int(pu) k hiu udt . Phn t R thch hp vi c hai dng m t. Vi phn tI, dng tchphn thch hp hn khi m phng. Chng trnh 20-sim xc nh dng nhn qu mong mun v dn ra cc phng trnh mtcch t ng. Dng nng lng hoc cng sut Pl tch ca hai tn hiu lin hp (two conjugated signals), c gi l effort(e) v flow (f):

=P ef (21.4)

Cc v d ca biu thc ny trong min c v in l

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= =hocP Fv P T (21.5)

=P ui (21.6)

trong Fl lc, v l vn tc, Tl m men, l vn tc gc, u l in p, v i l dng in.

HNH 21.8 M hnh y dng cc phn t vt l l tng

HNH 21.9 M hnh c trin khai vi b truyn lc

Khi khai trin ton b hnh 21.6 chng ta nhn c hnh 21.8. Khi m hnh ny c x l, mt thng bo xut hin ch ra rng qun tnh 2 c mt trng thi ph thuc. Hai qun tnh trong m hnh ny lun c cng tc v v vy chngph thuc ln nhau. Chng khng th c cc iu kin u c lp. Thng bo ch ra rng phn t ny ch c th c vittheo dng o hm:

= /T J d dt (21.7)

C mt vi cch gii quyt vn ny.

1. Hai inertia c th c t hp thnh mt (chng trnh s lm iu ny mt cch t ng). Mt thng bo xut hin ch

ra rng s ph thuc ca hai inertia c gii quyt mt cch tng trng.2. Gii quyt o hm nhn qu bng thut ton tch phn n.

3. B truyn lc c th c thm bng mt cht mm do cho dy curoa.

Nu s mm do l khng ng k, th li gii 1 dn ra m hnh n gin nht. Mt khc, cnh bo xut hin cu hi mm do ca dy curoa c th b qua c hay khng. Nu khng, m hnh phi c trin khai vi mt phn t l xo. Cnch rng iu c lm khng ch v l do s tr. Nu b truyn lc rt cng dn n vn ng lc hc tn s cao vm phng s chm khng cn thit. Mt khc nu mm do ln nh trong h ny th cnh bo s lm ngi thit k ch n vn rng m hnh c th b n gin qu. Trong hnh 21.9 b truyn lc bao gm mt phn t l xo c thm.Vic x l m hnh ny khng gy ra mt cnh bo no. V d ny minh ha cch mt phn mm hin i c th tr gip xy dng m hnh c phc tp cn thit cho mt vn c th. Cc m hnh vt l dng s biu tng da trn vicni cc phn t bng cc cng cng sut c th h tr qu trnh m hnh ha ny. Ngi dng c th chn cch nhn thchhp, mt s quan h, mt s biu tng vi cc phn t vt l l tng hoc mt cch nhn s dng cc m hnh con

mc cao nh trong hnh 21.6. Trong mc tip theo s ch ra cch dng m hnh ny thit k cc b iu khin.

Cc phng php lun thit k h iu khin

Nhiu qu trnh c th c iu khin mt cch hp l bng cc b iu khin PID. l do cc qu trnh c th cm t chnh xc hoc km chnh xc hn bng m hnh bc hai. Cc quy tc iu chnh nh nhng quy tc ca ZieglerNichols, cho php nhng ngi t kinh nghim iu chnh cc b iu khin ny. Cc m hnh tng i n gin cng cth m t nhiu h c in t. Mt h c in t thng bao gm mt b truyn ng, mt vi dng ca b truyn lc v mtti. Mt m hnh bc bn c th m t ng mt h nh vy. H s gii hn thc hin trong cc h ny l tn s cng hng.Mt s phi hp gia phn hi v tr v phn tc (v c bn l b iu khin PD) c th c dng tt y. Nhng dovic chn cc im cc cng hng thch hp ca cc tn hiu dng trong phn hi l cn thit nn cc c gng cto ra (Groenhuis [13]; Coelingh [2]; Coelingh, De Vries, and Van Amerongen [3]) nhn c cc phng php iuchnh cc h nh vy, ngoi ra cn chn cc tn hiu phn hi thch hp. My tnh cung cp cc cng c cn thit cho php

ngi thit k t kinh nghim s dng cc phng php ny (Van Amerongen, Coelingh, v De Vries[14]). Coelingh[2] vCoelingh, De Vries, v Van Amerongen [3]) m t mt phng php thit k cu trc cho cc h c in t. Phng php btu bng vic rt gn thit k tng ti m hnh bc bn biu din cc tnh cht tri ca h thng theo khi lng tng cndi chuyn v cng tri. M hnh ny vn c cc tham s vt l quan trng. Trong m hnh ny, cc cm bin thch hp

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S tay C in t

cng nh b pht dn c chn. Trong giai on thit k tng, mt b iu khin n gin c pht trin v cc tnhcht c c thay i nu cn. Tip theo l giai on thit k chi tit hn m thiu tin cy ca cc tham s cng ctnh n.

Thit k h servo

y chng ta s xem xt mt vi kha cnh n gin ca thit k h servo minh ha li th ca vic dng cc mhnh vt l v minh ha s cn thit ca mt phng php thit k tch hp. Chng ta xt m hnh c bn n trn,

Mt ti c iu khin bi mt ng c in qua mt b truyn lc mm. S biu tng ca m hnh ny c a ratrong hnh 21.9. Trong v d ny, mt b khuych i dng c thay th b khuych i p cho php b i in tr vin cm. Trong cc p ng bc hnh 21.10, cng hng do b truyn lc mm c th thy r.

T cc phng trnh dng m phng, 20-sim c th t ng a ra mt m hnh theo dng thch hp cho vic thit kb iu khin, nh m t khng gian-trng thi, hm truyn, hoc cc im cc v cc im khng. Mt giao din cung cpcc tin ch ca Matlab1, v d dng cc thut ton ca Matlab tnh h s khuych i ca cc b iu khin tin tin nhb iu khin LQR (phn hi trng thi ti u) hoc b iu khin LQG (vi mt b lc Kalman c tnh trng thi vphn hi trng thi ti u). S qu trnh cng b iu khin LQG c a ra trong hnh 21.11 v mt vi p ng tronghnh 21.12.

Mt b iu khin P(I)D c thit k thch hp c th thc hin hu nh tng t, c bit l khi lng nhiu l nh.Th nghim u tin c th s dng ch o gc ca ti v tc ca ti.

HNH 21.10 Cc p ng vng h

HNH 21.11 Thc hin vi b lc Kalman v phn hi trng thi

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HNH 21.12 p ng ca h iu khin LQG

Php th ny b li bi v phn hi tc ti hu nh ngay lp tc lm h mt n nh nh c th thy t im gc chocc thay i khc nhau ca phn hi vn tc. T cc p ng hnh 21.10, 20-sim c th d dng xc nh hm truyn giadng ca ng c v tc ti v v im gc (Hnh 21.13).

Hnh 21.14 ch r rng ngay c mt lng nh phn hi vn tc cng dn n mt h mt n nh. Bit rng, phn hi tc ng c l mt gii php tt hn. Vic dng li m hnh hnh 21.9 v 21.10 xc nh hm truyn t dng in vo titc ng c cho ra im gc hnh 21.15.

By gi cc im_khng phc lun i cng vi cc im-cc phc v bi v chng gn nhau nn nh hng ca chngln p ng hu nh khng ng k. Nhnh ca qu o nghim trn trc thc by gi ch ra ng x mong mun: chuynim cc tri sang pha tri ca mt phng s. T hp phn hi tc ca ng c vi phn hi gc ca ti cho ra cu trc biu khin PD hnh 21.15 v cc p ng hnh 21.16. Ngoi nhiu ra, khng c s khc nhau nhiu so vi p ng ca hc b lc Kalman, mc d h iu khin PD n gin hn. Cc nhn xt a ra y c th p dng mt cch tng qut. Mth vi hai im cc (phc) cng hng v khng c im khng nh trong hnh 21.13 l kh iu khin bng mt b iukhin n gin. Nu cc im khng phc cng vi cc im cc cng hng vi phn o nh hn phn o ca cc, th iukhin n nh l dng t c. Trong min tn s, iu ny c thy nh mt phn cng hng, tip theo l mt cnghng (kiuAR). Ngc li mt h kiuRA m tn s cng hng thp hn tn s phn cng hng (phn o ca im

cc nh hn phn o ca cc im khng) th kh iu khin nh trng hp ch c mt im cc cng hng. S tn ti vv tr ca cc im khng cng hng c xc nh hon ton bi (mt cch hnh hc) v tr ca cc b cm bin trong hc. S la chn cn thn cc v tr ca b cm bin l rt cn thit ng dng thnh cng mt b iu khin. Cn ch rngvic dng cc b pht t im c thit k thch hp c th cn tr cng hng nh thy trong hnh 21.10. B pht tim c th khng kch hot cc tn s cng hng, v d nh vic s dng b lc thng thp vi gii thng thp hn cc tns cng hng. Tuy nhin, b pht t im nh vy khng gii quyt vn n nh nu ra trn.

HNH 21.13 im gc cho phn hi vn tc ca trc ti

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Hnh 21.14 im gc cho cho phn hi vn tc ca trc ng c

HNH 21.15 H servo vi b iu khin PD

HNH 21.16 Cc p ng ca h trong hnh 21.16

HNH 21.17 Cc biu Bode ca cc h kiuRA v kiuAR

Thit k mt robot di ngMt v d in hnh v th tc thit k giai on u l thit k tng ca mt robot lp rp di ng. Ngay trong giai

on u ca vic thit k, cc mu thun phi c gii quyt. Mt robot nh vy cn phi c kh nng thu thp cc b

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phn xung quanh v lp rp trong lc vn hnh. V chnh xc cao c yu cu gia u kp ca robot v b mt ni mcc b phn c t, nn iu quan trng l phi lm sao cho khng u ca mt sn v cc mod dao ng ca cu trckhng ngn cn vic lp rp chnh xc. Mt khc b iu khin dn, mt phn da trn s xc nh v tr ca robot bng labn (c ngha l s o vn tc v hng ca bnh), yu cu cc bnh l rt cng. gim chn phi c thc hin bng ccb gim xc khc. iu ny dn ti tng khung trn v khung di ni vi nhau bi cc l xo (Hnh 21.18).

HNH 21.18 Thit k tng ca robot di ng

HNH 21.19 M hnh n gin vi cc phn t vt l l tng tnh sai s etip.

Robot c th c gn khung trn v c th c phm vi lm vic sai s v tr ( etip=ztip-zupper frame) gia ukp ca robot (ztip) v khung trn (zupper frame) l nh.

Bc tip theo l a ra mt m hnh n gin, c mt vi tham s cho vic phn b trng lng v cng v gim chn ca cc l xo. Trong m hnh hnh 21.22, robot phi ng u vi s va chm mnh vi nn tc 1 m/s.

Da trn ti - ch yu l trng lng ca cc pin - khi lng tng ca xe c tnh 500 kg. cng v gim chn cacc bnh xe c a ra t cc yu cu ca chnh xc ca vic c tnh v tr. Khi lng v phm vi lm vic ca tay

my c iu khin l bit t cc nghin cu khc, cho php xc nh cng hiu dng v gim chn ca u robot.Khi cng v gim chn ca cc l xo gia khung trn v khung di c c tnh th ch mt tham s b thay i lphn b trng lng gia khung trn v khung di. Bng cch dng c tnh ti u ha ca chng trnh 20-sim, th vicphn b trng lng ti u c th d dng tm thy. ti thiu ha sai s gia u robot v khung trn (Hnh 21.19), thtrng lng phi c t nhiu nh c th khung trn (Hnh 21.20). V d ny minh ha cch xc nh mt cu hnh chc thng qua cc yu cu v iu khin dn tt v iu khin chnh xc cc nhim v lp rp.

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S tay C in t

HNH 21.20 Cc sai s ca u robot trc v sau ti u ha phn b trng lng gia khung trn v khungdi

HNH 21.21 Robot di ng (MART) sau khi hon thin

Bc tip theo c th l ti u ha cc tnh cht ca h thng gim xc gia khung trn v khung di. iu ny s ci

thin chnh xc. Quyt nh ny c thc hin ngay trong giai on u ca thit k nh hng cc quyt nh thitk khc. Sau khi hon thnh d n dng nh cc tham s khc nhau ca cu trc cui cng gn vi cc thng s cc tnh trc (hnh 21.21).

21.4 Cc v d h C in t hin i

Mt vi v d c xem xt trong cc mc trc. Trong mc ny s a ra hai v d na.

S n nh bnh li ca cc tu thy

Ngy nay, cc tu thy dng mt my li t ng iu khin u tu. Bnh li l c cu chp hnh thng dng nht.Mt vi tu nh cc ph v cc tu hi qun cng cn n nh bnh li. iu ny c th thc hin mt cch b ng bngcch ni cc thng y nc to ra cc lc n nh ngc pha vi cc lc ca sng. to ra h thng ph hp vi cc

tn s khc nhau ca cc sng, dng nc gia hai thng cha cn phi c iu khin. Cho cc tu nhanh, thng s dngcc vy n nh. Chng l mt loi cnh c iu khin mt cch tch cc to ra mmen cn thit chng li mmenca sng. Cc vy khng ch nh hng ti dch chuyn ca li m cn nh hng ti c u tu. Mt khc, bnh li khngch nh hng ti u tu m cn tc ng c ti li. Trong k thut iu khin, iu ny dn n mt h a bin i himt thit k b iu khin a bin thc hin ti u. Trong thc t, mt h a bin nh vy him khi thy v hai h iukhin ring bit thng c s dng.

Mt phng php khc l ch dng mt trong cc b truyn ng (bnh li hoc vy). V cc tn s ca chuyn ng quayl nm ngoi di thng ca h thng iu khin hnh trnh nn iu ny l c th. Bnh li l ph hp nht vi b truynng. Ngoi ra, mt thun li cho tu hi qun l b cc vy s gim n di nc.

Thit k li cc b iu khin hnh trnh n nh li cng chng minh tnh kh thi ca phng php ny, nhng cnglm sng t rng qu trnh tu thy cn phi c sa i. S sa i quan trng nht l cn cho my li. Tc ti aca my li a ra l h s gii hn cho mt h nh vy (n phi c tng t cc gi tr thng dng t 37/s ti 20

25/s). Bng cch m phng ng lc, cc thng s cho my li c th c xc nh theo tc cc i ca my li v thigian cc i cho php t c tc ny. iu ny i hi thit k li my li thy lc. Bc xa hn cng c th l xt ccthay i hnh dng ca tu ti u cc tham s xc nh hiu qu ca h thng n nh bnh li.

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khng nh gii php mi ny l tt hn hay khng, cn phi nh gi my li c thit k li l t t tin hn ccc cu chp hnh ca bnh li v vy hay khng. Cc vn ny phi c gii quyt ngay trong giai on u ca qu trnhthit k. S n nh bnh li c p dng thnh cng trn cc tu hi qun cng nh cc thng thuyn ln (VanAmerongen, Van der Klugt, and Van Nauta Lemke [15]).

B cc hiu ng phi tuyn trong cc ng c tuyn tnh

Nhiu h c mt cht lng do cc hiu ng phi tuyn lm hn ch chnh xc m n c th t c. Ma st v s n

khp l hai v d. Mt b iu khin phn hi c th gim nh hng ca cc tnh cht phi tuyn, nhng b hon ton l kh.Vi cc h thc hin cc dch chuyn lp i lp li, th mt b iu khin tuyn tnh lp c th gip ci thin hn cc thchin (Arimoto [16]; De Vries, Velthuis, and Van Amerongen [17]). tng c cabr c gii thch trong hnh 21.22. tng c bn c gii thch trong hnh 21.22.

Ch khi c vng phn hi v vi gi thit rng khng c s nhiu lon, th cc tn hiu li v v vy tn hiu ca b iukhin UCs l ging nhau trong mi dch chuyn lp li. Hin nhin rng, chnh xc c th c ci thin khi m trongdch chuyn tip theo, tn hiu ca b iu khin t chu k trc c dng nh tn hiu cp, UF. Phn hi s to ra mt tnhiu b li cn li bng cch cp nht tn hiu cp UFtheo cng thc:

k 1 k

kU U LE+ = + (21.8)

HNH 21.22 Nguyn tc ca iu khin t hc tng tc

HNH 21.23 B iu khin thun t hc cho cc dch chuyn lp

Trong L l hm truyn ca b lc t hc. Ch s kk hiu dch chuyn lp th k. Tn hiu UFcn phi hi t ti tn hiucp b tt c cc sai s lp. Mt v d v tnh hung m cc li nh vy tn ti l my chi CD c b lch tmca a.

Mt phng n ca tng ny v thm ch trc tip hn l vic ci t b iu khin thun t hc trn hnh 21.23. Khitn hiu cp l hon ho th tn hiu ra ca b iu khin c th s l khng. iu ny c ngha rng tn hiu ra c th cdng nh l tn hiu hun luyn cho mt mng n ron. Mt mng ni suy trn thch ng (B-spline) cho php hc cc tnhcht phi tuyn phc tp. C cc my h tr vc t cng c dng thc hin vic hc cp (De Kruif and De Vries [18]).Tn hiu vo ca mng B-spline l tn hiu thi gian t. N c t li khi mt dch chuyn mi c bt u. iu ny cgi l mt b iu khin thun t hc LFFC c ch s thi gian. Thay th cho thi gian, tn hiu lin quan v cc o hm can - nhn c t mt b pht dn c th c dng nh ch s ca mng (LFFC c ch s dn). Thun li ca cu trc nyl sau vic hun luyn thch hp, LFFC cng c th c dng thnh cng cho cc dch chuyn khng lp. Velthuis19 ara phn tch n nh cho cc b iu khin LFFC ch s thi gian cng nh LFFC ch s dn. Phn tch n nh l tng id cho trng hp ch s thi gian. Vi trng hp ch s dn, th phc tp hn v mt vi phng php gii quyt vn bng nh gi kinh nghim c i hi m bo h thng n nh. Vn chnh l s cc B-spline cn phi khng cqu ln. Mt khc, Mt s phn b B-spline thch ng c mong mun cho mt xp x chnh xc ca qu trnh phi tuyn.LFFC c p dng thnh cng b s n khp trong mt ng c tuyn tnh cng nghip (Otten et al. [20]) v b mast (Coulomb) ca mt ng c tuyn tnh c dng trong m phng bay (Velthuis [19]). N cng c p dng iukhin t chnh ca robot di ng c m t trong mc Thit k robot di ng (Starrenburg et al. [21]).

ng dng b n khp ca ng c tuyn tnh s c m t trong mt on nh chi tit hn. Mt ng c nh vy lmt phn t thng dng trong cc my lp rp. Thm ch vi cc nam chm tt nht v lp rp chnh xc th sai s khngth nh hn 100, vi mt b iu khin PID phi hp vi iu khin thun khng t hc. ch ca thit k l ci thin chnh xc c th t c c ti a t 100 ti nh hn 10 . Hnh 21.24 ch ra nh ca mt ng c tuyn tnh.

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Theo cu trc trn hnh 21.23, ng c tuyn tnh c iu khin bng mt b iu khin PID, trong khi mt mng nron B-spline c mt hc m hnh ng c o chiu, bao gm thnh phn phi tuyn do n khp. n khp xy ra trong ccng c DC vi cc nam chm vnh cu. N gy ra cc lc dng sin ln hoc nh ph thuc vo v tr ca b chuyn i sovi stator. Nu cc lc thc s c dng sin th chng c th d dng c b bng mt b b cp. Tuy nhin iu ny ihi cc nam chm c cc tnh cht t ging nhau hon ton v khong cch ca cc nam chm rt chnh xc. Mt s la chnl thit k mt b iu khin hc cc kiu nhiu v b n bng mt b b cp t hc. Ngoi ra, mt u im na l mt hnh vy cng c th c dng b cho cc hiu ng phi tuyn khc nh ma st. iu ny cng c minh ha trongmt phn ca b m phng bay (cn iu khin) cc lc ma st lm hng cm gic ca s m phng thc, c bit tc gn nh khng. Hnh 21.25 ch ra rng vic hc gn nh c hon thnh sau su chu k hun luyn.

iu khin thun t hc l mt phng php hp dn b cho cc s phi tuyn tn ti trong cc h c in t, nh s nkhp v ma st. Vic dng mng n ron B-spline s dn n hi t nhanh, tnh ton tng i t, v kh nng khi qut hatt. Bi v gn y nhn c cc kt qu i vi n nh ca cc h thng nh vy, nn cc h iu khin tt c thc thit k.

HNH 21.24 ng c tuyn tnh. Cc nam chm gy ra s n khp c th thy r

HNH 21.25 Tn hiu v tr v tn hiu sai s trong khi hc

Trn quan im c in t, vn thit k ny s ny sinh ra cu hi c th dng chnh phng php ny xy dngmt ng c tuyn tnh r hn khng, khi chnh xc ti a khng phi l mc tiu chnh ca vic thit k. c chngminh rng mt ng c c xy dng vi cc thnh phn t t tin v cc c tnh lp rp t kht khe nhng vi B iukhin LFFC c th cnh tranh tt vi cc cu trc t tin hn. chnh xc c th c ci thin thng thng vi h s 10.

21.5 Cc yu cu khc bit ca cc h C in t khc vi cc h c in v thit k iukhin

S khc nhau chnh gia "thit k b iu khin thng thng" v thit k h c in t l thit k c in t nh l mtkhi thng nht. Phng php ny c th c xem xt nh vic ti u ha tt c cc thnh phn ca h thng mt cch ng

b, mc d khng c thut ton lm iu ny mt cch t ng. Trong thc t, vn ny thng c tch thnh cc vn nh hn c th ti u ha. Sau vic tch hp tt c cc gii php thnh phn, mt h ti u con t c c th ctip tc ti u hn bng cch iu chnh li cc phn khc nhau, ch n nhng thit k trung gian sn c ca ton b hthng. t c s ti u ca ton b h thng, i hi phn c m lc ng vai tr quan trng v phn x l thng

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tin (b iu khin) phi c m phng v hiu chnh ng thi. iu ny i hi cc tham s c nh khi lng v ccthng s khc c th dng c trong m phng cc h iu khin. Cc v d c a ra v m hnh ha v m phngbng 20-sim chng t 20-sim cho php thc hin nh vy.

Nhng ngi thit k c in t cn phi lun nhn thc c vn l cc gii php c th c tm thy cc lnh vckhc nhau. Khng phi mi s thiu hiu qu ca phn c u c th gii quyt d dng bng iu khin. Mt thit k c ttc th thc hin d dng hn v r hn. Mt khc, mt b iu khin tt c th t c cc thc hin mong mun r hn vd hn nhng cu trc c phc tp. Trong mt s trng hp, s phi hp c th t c s thc hin m khng bao gi c

th c nu thiu thit k c in t.iu cng xy ra cho vic thit k cc b cm bin. Mi b cm bin c th c lp mt b lc loi nhiu khi cc

php o. Nhng nu vi b cm bin c t hp th t hp ca cc cm bin theo thut ton lc Kalman s c hiu qu vid liu th.

Vic truyn thng gia tt c nhng ngi thit k lin quan v s r rng ca cc quyt nh thit k trong cc lnh vckhc nhau l cn thit cho s thnh cng ca mt thit k c in t

Ti liu tham kho

[1] Matworks (2001). The Mathworks: Developers of Matlab and Simulink, www.mathworks.com

[2] Coelingh, H.J., Design Support for Motion Control Systems, Ph.D. thesis, University of Twente, 2000, alsowww.rt.el.utwente.nl/clh/

[3] Coelingh, H.J., de Vries, T.J.A., van Amerongen, J., Design support for motion control systemsapplication to thePhilips fast component mounter, in Mechatronics Forum 7th Int. Conf., Mechatronics 2000, Atlanta, Ga, USA.

[4] Controllab Products, 20-sim, www.20sim.com

[5] Broenink, J.F., Computer-Aided Physical-Systems Modeling and Simulation: a Bond-Graph Approach, Ph.D. thesis,University of Twente, 1990.

[6] Dynasim,Dymola, www.dynasim.se/

[7] Weustink, P.B.T., de Vries, T.J.A., Breedveld, P.C., Object Oriented Modeling and Simulation of MechatronicSystems with 20-sim 3.0, in Mechatronics 98, J. Adolfson and J. Karlsn (Eds.), Elsevier Science, 1998.

[8] De Vries, T.J.A., Conceptual Design of Controlled Electro-Mechanical Systems, Ph.D. thesis, University of Twente,1994.

[9] Breedveld, P.C., Fundamentals of bond graphs, in IMACS Annals of Computing and Applied Mathematics, Vol. 3:Modelling and Simulation of Systems, Basel, 1989, pp. 714.

[10] Cellier, F.E., Elmqvist, H., Otter, M., Modeling from physical principles, in The Control Handbook, W.S. Levine(Ed.), CRC Press, pp. 99108, 1996.

[11] Gawthrop, P., Lorcan Smith, L., Metamodelling: Bond Graphs and Dynamic Systems, Prentice-Hall, NJ, 1996.

[12] Van Amerongen, J., Modelling, simulation and controller design for mechatronic systems with 20-sim 3.0, inProc.1st IFAC Conf. on Mechatronic Systems, Darmstadt, Germany, September 2000, pp. 831836.

[13] Groenhuis, H.,A Design Tool for Electromechanical Servo Systems, Ph.D. thesis, University of Twente, 1991.

[14] Van Amerongen, J., Coelingh, H.J., de Vries, T.J.A., Computer support for mechatronic control system design,Robotics and Autonomous Systems, vol. 30, no. 3, pp. 249260, PII: SO921-8890 (99)00090-1, 2000.

[15] Van Amerongen, J., van der Klugt, P.G.M., van Nauta Lemke, H.R., Rudder roll stabilization for ships, Automatica,vol. 26, no. 4, pp. 679690.

[16] Arimoto, S., A brief history of iterative learning control, inIterative Learning Control: Analysis, Design, Integrationand Applications, Kluwer Academic Publishers, pp. 37, 1988.

[17] De Vries, T.J.A., Velthuis, W.J.R., van Amerongen, J., Learning feed-forward control: a survey and historical note, in1st IFAC Conf. on Mechatronic Systems, Darmstadt, Germany, September 2000, pp. 949954.

[18] De Kruif, Bas J., de Vries, T.J.A., On using a support vector machine in learning feed-forward control, inProc. 2001IEEE/ASME Int. Conf. on Advanced Intelligent Mechatronics, Como, Italy, 812 July, 2001.

[19] Velthuis, W.J.R., Learning Feed-Forward ControlTheory, Design and Applications, Ph.D. thesis, University ofTwente, 2000, also http://www.rt.el.utwente.nl/vts/

[20] Otten, G., de Vries, T.J.A., van Amerongen, J., Rankers, A.M., Gaal, E., Linear motor motion control using a learningfeedforward controller,IEEE/ASME Transactions on Mechatronics, vol. 2, no. 3, ISSN

[21] 1083-4435, pp. 179187, 1997.

[22] Starrenburg, J.G., van Luenen, W.T.C., Oelen, W., van Amerongen, J., Learning feed-forward controller for a mobile

robot vehicle, Control Engineering Practice, vol. 4, no. 9, pp. 12211230, 1996.

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sổ tay cdt chuong 21-dkhien cdt

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