chuong2 giao trinh ndht

38
Chương 2: MÔ HÌNH HÓA Hunh Thái Hoàng – Bmôn Điu khin Tđộng 1 Chương 2 MÔ HÌNH HÓA Chương 2: MOÂ HÌNH HOÙA 2.1. Gii thieäu 2.2. Phaân tích chöùc naêng 2.3. Phaân tích vaät lyù 2.4. Phaân tích toaùn hoïc 2.5 Mt sthí dTham kho: [Smith, 1994], chương 2, 4. [Johansson, 1993], chương 7. 2.1 GIÔÙI THIEÄU Moâ hình hoùa laø phöông phaùp xaây döïng moâ hình toaùn cuûa heä thoáng baèng caùch phaân tích heä thoáng thaønh caùc khoái chöùc naêng, trong ñoù moâ hình toaùn cuûa caùc khoái chöùc năng ñaõ bieát hoaëc coù theå ruùt ra ñöôïc döïa vaøo caùc qui luaät vaät lyù, sau ñoù caùc khoái chöùc naêng ñöôïc keát noái toaùn hc ñeå ñöôïc moâ hình cuûa heä thoáng. Ba böôùc moâ hình hoùa: Phaân tích chöùc naêng Phaân tích vaät lyù Phaân tích toaùn hoïc

Upload: anative7395

Post on 24-Sep-2015

215 views

Category:

Documents


2 download

DESCRIPTION

Giáo trình Mô hình hóa và Nhận dạng hệ thống

TRANSCRIPT

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    1

    Chng 2

    M HNH HA Chng 2: MO HNH HOA 2.1. Gii thieu 2.2. Phan tch chc nang 2.3. Phan tch vat ly 2.4. Phan tch toan hoc 2.5 Mt s th d Tham kho: [Smith, 1994], chng 2, 4. [Johansson, 1993], chng 7. 2.1 GII THIEU Mo hnh hoa la phng phap xay dng mo hnh toan cua he thong bang cach phan tch he thong thanh cac khoi chc nang, trong o mo hnh toan cua cac khoi chc nng a biet hoac co the rut ra c da vao cac qui luat vat ly, sau o cac khoi chc nang c ket noi toan hc e c mo hnh cua he thong. Ba bc mo hnh hoa: Phan tch chc nang Phan tch vat ly Phan tch toan hoc

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    2

    2.2 PHAN TCH CHC NANG (tham khao chng 2, [Smith, 1994])

    2.2.1 Khai niem

    Phan tch chc nang la phan tch he thong can mo hnh hoa thanh nhieu he thong con, moi he thong con gom nhieu bo phan chc nang (functional component).

    Khi phan tch chc nang can e y lien ket vat ly (connectivity) va quan he nhan qua (causality) gia cac thanh phan ben trong he thong.

    Ba bc phan tch chc nang: Co lap he thong Phan tch he thong con Xac nh cac quan he nhan qua 2.2.2 Co lap he thong - Lien ket ngoai Xac nh gii han cua he thong can mo hnh hoa, cat ket noi gia he thong khao sat vi moi trng ngoai, moi ket noi b cat c thay the bang mot cong e mo ta s tng tac gia he thong va moi trng.

    Hnh 2.1: He thong co mot cong lien ket vi moi trng

    He thong Moi trng U

    Y

    bien cua he thong

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    3

    Cong (port) : la mot cap au cuoi ma qua o nang lng hoac cong suat vao hoac ra khoi he thong. Mot he thong co the co nhieu cong (multiport system). Bon loai cong thng gap: c kh (Structural), ien (Electrical), nhiet (thermal), lu chat (fluid) Loai cong

    Ten (Ky hieu) S o Co lap

    1. C

    K

    H

    a. Tnh tien (Structural Translation - ST)

    b. Quay (Structural Rotation - SR)

    c. Phc hp (Structural Complex - SC)

    3.

    IEN

    a. ien dan (Electrical Conduction EC)

    b. ien bc xa (Electrical Radiation ER)

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    4

    3. N

    HIE

    T

    a. Dan nhiet (Thermal Conduction TC)

    b. oi lu nhiet (Thermal Convention TV)

    c. Bc xa nhiet (Thermal Radiation TR)

    4. L

    U

    CH

    AT

    a. Lu chat trong (Fluid Internal FI)

    a. Lu chat ngoai(Fluid External FE)

    Th du 2.1: Co lap he canh tay may

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    5

    Hnh 2.2: S olien ket ngoai cua canh tay robot

    Th du 2.2: Co lap he thong lam mat

    (a)

    (b)

    Hnh 2.3: He thong lam mat (a) S o he thong (b) S o trao oi nhiet

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    6

    (a)

    (b)

    Hnh 2.4: He thong lam mat (a) S o a cong cua he thong

    (b) S o a cong cua bo trao oi nhiet

    Hnh 2.5: S o a cong lu chat long trong he thong lam mat

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    7

    2.2.3 Phan tch he thong con - Lien ket trong Phan tch he thong sau khi co lap thanh cac he thong con (subsystem), sau o tiep tuc phan tch cac he thong con chi tiet en cac bo phan (component), thay the lien ket gia cac bo phan bang cac cong.

    Th du 2.3: Phan tch lien ket trong he canh tay robot

    Hnh 2.6: S o khoi canh tay may chi tiet en cac he thong con

    Hnh 2.7: S o khoi canh tay may chi tiet en cac bo phan

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    8

    2.2.4 Quan he nhan qua - Cac bien cua he thong V cong la au cuoi ma qua o cong suat (nang lng) truyen vao ra he thong nen quan he nhan qua cua cong c xac nh bi cac bien nh ngha cong suat tai cong.

    Th du 2.4: Canh tay may

    Hnh 2.8: S o khoi hoan chnh cua canh tay may

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    9

    2.3 PHAN TCH VAT LY

    2.3.1 Phng phap phan tch vat ly

    2.3.1.1 Cac qui luat vat ly

    a. Quan h c bn gia lng, th v dng

    H thng vt l c th chia thnh 4 loi: in (Electrical) C (Machenical) Nhit (Thermal) Lu cht (Fluid)

    Mt h thng phc tp c th gm nhiu h thng con thuc 4 loi ni trn.

    Mi loi h thng c 3 phn t c bn (basis element): Tr (resistance) Dung (capacitance) Cm (inductance) hay qun tnh (inertia)

    Cc phn t c bn ny c nh ngha da trn 3 bin: Lng (quantity) Th (potential) Thi gian (time).

    Bng 2.1: Cc bin c s dng nh ngha cc yu t c bn ca cc loi h thng.

    Loi H thng

    Bin Lng Th Thi gian

    in in tch (Charge)

    in th (Voltage)

    Giy

    C kh Khong cch (Distance)

    Lc (Force)

    Giy

    Lu cht (lng)

    Th tch (Volume)

    p sut (Pressure)

    Giy

    Nhit Nhit nng (Heat energy)

    Nhit (Temperature)

    Giy

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    10

    Cc bin khc c nh ngha da trn 3 bin c bn trn. Cng dng l bin thin lng trong mt n v thi gian

    (hay cng dng l tc bin thin lng).

    lngdong o cng dtd (2.1) Cong suat

    dongocngthesuat cong

    nh ngha cc phn t c bn (Quan h gia lng, th v dng)

    Tr l s chng li s chuyn ng hay dng vt cht, nng lng. Tr c o bng th cn thit chuyn mt n v lng trong mt n v thi gian (giy).

    dong o cng

    thetr (2.2)

    Dung biu din mi quan h gia lng v th. Dung c o bng lng cn thit l cho th bin thin mt n v.

    the

    lngdung (2.3)

    (2.1) & (2.3) dt dong o cngdungthe 1 (2.4)

    Cm hay qun tnh l s chng li s thay i trng thi chuyn ng. Cm c o bng th cn thit lm tc bin thin ca lng thay i mt n v.

    dong o cngcamthedtd (2.5)

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    11

    * Cc phng trnh cn bng

    Cc nh lut bo ton khi lng, nng lng, v xung lng l cc nh lut c bn c s dng khi m hnh ha. Phng trnh cn bng c bn c dng tng qut nh sau: radongvaodongluytch dong (2.6) Nu h thng khng c cc phn t tch tr khi lng, nng lng v xung lng th phng trnh (2.6) tr thnh: radongvaodong 0 (2.7) Nu h thng c phn t tch tr khi lng, nng lng hay xung lng th s tch tr ny lm thay i trng thi ca h thng.

    ra dongvao dongthai trang bien dtd (2.8)

    Cc hin tng t nhin xy ra theo hng lm ti thiu nng

    lng, v nhiu bi ton m hnh ha m t iu kin cn bng lin quan n s ti thiu nng lng. 2.3.1.2 L tng ha cc phn t vt l Cc nguyn tc l tng ha:

    Nguyn tc thun ha: nhn ra nh hng vt l c bn chi phi hot ng ca i tng v dng cc phn t thun biu din.

    Hnh 2.9: Mo hnh tu ien gom cac phan t thuan nhat

    ien moi C R

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    12

    Nguyn tc tp trung ha: cc nh hng vt l thc lun phn b trong mt min hay khng gian nht nh (d nh). Cc nh hng phn b ny c th l tng ha bng cch m hnh ha tp trung.

    Hnh 2.10: Mo hnh van nhay

    Nguyn tc tuyn tnh ha: tt c cc h thng thc u l h

    phi tuyn l tng ha bng cch tuyn tnh ha.

    Hnh 2.11: ac tnhphi tuyen cua ien tr

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    13

    2.3.1.3 S tng ng ca cc quan h vt l

    Do cc hin tng vt l c s tng ng nn c th m hnh ha h c bng h in, h nhit bng h in,

    Hnh 2.12: S tng ng gia cc phn t c bn ca cc loi h thng vt l

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    14

    2.3.2 Phan tch vat ly he thong ien

    2.3.2.1 Cc phn t in

    Cc bin c bn trong h thng in: in lng: q [C] in th: u [V] Cng dng in: i [A]

    (2.1) dtdqi

    Cc phn t in c bn in tr: S

    lR [] (2.2)

    iuR

    in dung: d

    SC [F] (2.3)

    uqC

    (2.4) idtCu 1

    in cm: b

    NrL2 [H]

    (2.5) dtdiLu

    Ngun p l tng: Ngun dng l tng

    2.3.2.2 Phng trnh cn bng in nh lut Kirchoff v dng. nh lut Kirchoff v p.

    2.3.2.3 Phng php gii tch mch in Phng php dng vng Phng php th nh

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    15

    2.3.3 Phan tch vat ly he thong c 2.3.3.1 Cc phn t c Chuyn ng thng Cc bin:

    Khong cch: x [m] Lc: f [N] Tc : v [m/sec]

    (2.1) dtdxv

    Cc phn t: Tr: bRM

    b: h s ma st nht [N.sec/m]

    (2.2) vfb

    vfRM

    Dung: kCM /1

    k: cng l xo [N/m]

    (2.3) fx

    k1

    fxCM

    (2.4) kxvdtkf vdtCf M1

    x f

    b

    f

    x f

    k

    f

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    16

    Qun tnh c: m : khi lng [kg]

    (2.5) madtdvmf

    Chuyn ng quay Lc Moment Khong cch Gc quay Vn tc Vn tc gc Gia tc Gia tc gc Qun tnh Moment qun tnh 2.3.3.2 Phng trnh cn bng c Phng trnh cn bng lc. Phng trnh Euler Lagrange:

    qP

    qL

    qL

    dtd

    Trong : UTL U: th nng T: ng nng P: nng lng tiu hao q: ta tng qut : ngoi lc (hay moment)

    x f

    m

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    17

    2.3.3.3 S tng ong gia he thong c va he thong ien

    Hnh 2.13: S tng ong gia cac phan t

    Hnh 2.14: S tng ong gia cac nguon

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    18

    2.3.4 Phan tch vat ly he thong nhiet 2.3.4.1 Cac phan t nhiet Cac bien trong he thong nhiet :

    Nhit : [0C] Nhit nng: Q [J] Dng nhit: H [J/sec]

    (2.1) dtdQH

    Cac phan t nhiet: Nhit tr:

    Nhit tr dn nhit: Sk

    lRC

    T trong : kC: l h s dn nhit ca mi trng truyn nhit l: l chiu di ca mi trng truyn nhit S: l tit din ngang ca mi trng truyn nhit (2.2)

    HRT

    Nhit tr i lu + Bc x nhit: xem (Smith,1994)

    Nhit dung: McCT . trong : c: l nhit dung ring ca mi trng truyn nhit M: l khi lng ca mi trng truyn nhit (2.3)

    QCT (2.4) HdtCT

    1

    Qun tnh nhit: TI (2.5)

    dtdHIT

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    19

    Hnh 2.15: Nhiet tr (a) Nhiet tr truyen nhiet (b) Nhiet tr oi lu (c) Nhiet tr bc xa

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    20

    Hnh 2.16: Nhiet dung

    2.3.4.2 Cac phng trnh can bang nhiet 2.3.5 Phan tch vat ly he lu chat long 2.3.5.1 Cac phan t lu chat Cac bien trong he lu chat :

    p sut: p [N/m2] Th tch: V [m3] Lu lng: q [m3/sec]

    (2.1) dtdVq

    Cac phan t lu chat: Lu tr:

    Lu tr ca ng ng: 4128dlRL [N.sec/m]

    (2.2) qpRL

    Cng thc trn ch ng trong trng hp lu cht chy tng (c hng), v ng ng dn lu cht di (l>20d) Lu tr ca van: phi tuyn

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    21

    Hnh 2.17: Lu tr

    Dung: g

    ACL [m5/N]

    (2.3) pVCL

    (2.4) qdtCp L1

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    22

    Hnh 2.18: Lu dung

    Qun tnh: alIL [Nsec2/m5]

    (2.5) dtdqIp L

    2.3.5.2 Cac phng trnh can bang trong h lu cht

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    23

    2.3.6 Mt s th d Th du 2.5: M hnh ha h thng sau: Cch 1: Dng nh lut Newton Chiu ln phng chuyn ng, p dng nh lut II Newton: sin)()( PtFtxm Cch 2: Dng cng thc EulerLagrange: ng nng: 2

    21 xmT

    Th nng: sinmgxU sin

    21 2 mgxxmUTL

    p dng cng thc EulerLagrange: F

    xL

    xL

    dtd

    Fmgxmdt

    d sin

    Fmgxm sin Th du 2.6: Mo hnh hoa he thong giam soc cua xe may (phuoc nhung)

    Cch 1: p dng nh lut Newton:

    )()()()( txbtkxtftxm

    )()()()( tftkxtxbtxm

    P

    N F

    x

    x

    f

    b k

    m

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    24

    Cch 2: p dng cng thc Euler-Lagrange: ng nng: 2

    21 xmT

    Th nng: 221 kxU

    2221

    21 kxxmUTL

    p dng cng thc EulerLagrange: xbf

    xL

    xL

    dtd

    xbfkxxmdtd

    )()()()( tftkxtxbtxm Cch 3: p dng s tng ng gia h thng in v h thng c: Th: Uf Lng: qx Dung: Ck /1 Tr: Rb Cm: Lm Quan h gia dng v p ca mch in tng trn l: )(1)( sULs

    CsRsI

    )(1)( 2 sULs

    CRs

    ssI

    )(1)( 2 sULsC

    RssQ

    )()(1)()( tutqC

    tqRtqL Do quan h gia cc i lng ca h c l:

    )()()( tfkxtxbtxm

    U R C L

    i

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    25

    Th du 2.7: Mo hnh hoa he con lac ngc

    Chu thch: M : trong lng xe [Kg] m : trong lng con lac [Kg] l : chieu dai con lac [m] u : lc tac ong vao xe [N] g : gia toc trong trng [m/s2] x : v tr xe [m] : goc gia con lac va phng thang ng [rad] Cach 1: Dung nh luat Newton Goi (xP, yP) la toa o cua vat nang m au con lac, ta co: sinlxxP (1) coslyP (2) Ap dung nh luat II Newton cho chuyen ong theo phng x, ta co:

    Fdt

    xdmdt

    xdM P 22

    2

    2

    (3)

    Thay xG bieu thc (1) vao bieu thc (3) suy ra:

    Flxdtdm

    dtxdM sin2

    2

    2

    2

    (4)

    Khai trien cac ao ham bieu thc (4) va rut gon ta c: FmlmlxmM )(cos)(sin)( 2 (5)

    x

    x F M

    m

    l

    mg lcos

    lsin

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    26

    Mat khac, ap dung nh luat II Newton cho chuyen ong quay cua con lac quanh truc ta c:

    sinsincos 22

    2

    2

    mglldt

    ydmldt

    xdm PP (6) Thay (1) va (2) vao (6) suy ra:

    sinsin)cos(cos)sin( 22

    2

    2

    mgllldtdmllx

    dtdm

    (7)

    Khai trien cac ao ham bieu thc (7) va rut gon ta c: sincos mgmlxm (8) T (5) va (8), ta co the de dang tnh c:

    22

    )(cossincos)(sin

    mmMmgmlFx

    (9)

    lmMml

    mlgmMF)()(cos

    )sin(cos)(sin)(cos2

    2

    (10) Cach 2: Dung cong thc EulerLagrange: Goi (xP, yP) la toa o cua vat nang m au con lac, ta co: sinlxxP (1) coslyP (2) ong nang cua vat nang au con lac:

    2222 sin21cos

    21

    21

    21 lmlxmymxmT PPP

    22221cos

    21 mlxmlxmTP

    ong nang cua xe:

    221 xMTC

    ong nang cua he thong:

    22221cos

    21 mlxmlxmMTTT CP

    The nang cua he thong = the nang vat nang au con lac: cosmglU

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    27

    cos21cos

    21 222 mglmlxmlxmMUTL (3)

    Phng trnh Euler Lagrange:

    FxL

    xL

    dtd

    (4)

    0

    LL

    dtd

    (5) Thay (4) vao (3): FmlmlxmM 2)(sin)(cos 0sincos mgmlxm Suy ra:

    22

    )(cossincos)(sin

    mmMmgmlFx

    lmMml

    mlgmMF)()(cos

    )sin(cos)(sin)(cos2

    2

    Th du 2.8: Mo hnh he tay may hai bac t do

    l1, l2 : chieu dai cua 2 m1, m2 : khoi lng 1, 2 : goc quay cua cac khp canh tay 1, 2 : moment lam quay cac khp noi

    Toa o cua canh tay may trong he toa o De-cac la: 111 sinlx 111 cosly 22112 sinsin llx 22112 coscos lly

    1

    2

    l1

    l2

    m1

    m2

    y1

    y2

    x2 x1

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    28

    Van toc:

    111

    111

    1

    11 sin

    cos

    ll

    yx

    v

    222111

    222111

    2

    22 sinsin

    coscos

    llll

    yx

    v

    ong nang:

    )(21)(

    21 2

    2222

    21

    211 yxmyxmT

    222222121221211 21

    21

    21 lmlmlmT

    )sinsincos(cos 212121212 llm The nang: )coscos(cos 22112111 llgmglmU Do o:

    22222

    21

    212

    21

    211 2

    121

    21 lmlmlmUTL

    )sinsincos(cos 212121212 llm )coscos(cos 22112111 llgmglm (1) Phng trnh EulerLagrange:

    111

    LL

    dtd

    (2)

    222

    LL

    dtd

    (3)

    Thay (1) vao (2) va (3) ta c: 221212121

    2121 )sinsincos(cos)( llmlmm

    11121222121212 sin)()sincoscos(sin glmmllm (4)

    121212122

    222 )sinsincos(cos llmlm

    2222212121212 sin)sincoscos(sin glmllm (5)

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    29

    Th du 2.9: Mo hnh toan bon cha chat long (Single Tank) A: tiet dien ngang bon cha a: tiet dien van xa k: he so t le vi cong suat may bm

    Phng trnh can bang: )()()( tqtqtAhdtd

    outin Dong vao: )()( tkutqin Dong ra: )()/2()( 222 tpCatq Dout trong o: )()( tghtp : ap suat 6.0DC : he so xa

    Suy ra: )(2)(1)( tghaCtkuA

    th D Th du 2.10: He bon noi tiep (Cascade Tank)

    )(2)(21)(

    )(2)(1)(

    2221112

    2

    111111

    1

    tghCatghCaA

    th

    tghCatukA

    th

    DD

    D

    h(t) u(t)

    qin

    qout

    h1(t) u(t)

    qin1

    qout2 h2(t)

    qout1=qin2

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    30

    Th du 2.11: He bon lien ket (Coupled Tank) Mo hnh toan:

    )()(2)()(sgn)(2)(1)(

    )()(2)()(sgn)(2)(1)(

    21121212222222

    2

    21122112111111

    1

    ththgaththCtghCatukA

    th

    ththgaththCtghCatukA

    th

    DD

    DD

    Th du 2.12: S tng ong gia he lu chat va he thong ien:

    e 2 mo hnh tren tng ng ta can gia thiet bon cha rat ln, khi he thong van hanh o cao mc chat long trong bon cha thay oi khong ang ke.

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    31

    Th du 2.13: Mo hnh lo say )(tS : nhiet o nguon nhiet )(t : nhiet o lo say )(tH : dong nhiet Ta co:

    Dong nhiet: T

    S

    RtttH )()()(

    Phng trnh can bang: )()( tHdt

    tdCT trong o:

    AkdRT 2

    : nhiet tr d: chieu dai lo say A: tiet dien ngang k: he so dan nhiet TC cM : nhiet dung c: nhiet dung rieng cua moi trng truyen nhiet M: khoi lng moi trng truyen nhiet Suy ra mo hnh toan hoc cua lo say la:

    )()()( ttdt

    tdCR STT Trng hp lo say dai, co the mo hnh hoa bang cach chia lam nhieu ngan:

    (t) S(t) H(t)

    2(t) S(t) H1(t) 1(t)

    d/4 d/4 d/2

    H2(t)

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    32

    Dong nhiet:

    1

    11

    )()()(T

    S

    RtttH

    2

    212

    )()()(TR

    tttH Phng trnh can bang:

    )()()( 2111 tHtHdttdCT

    )()( 222 tHdttdCT

    Suy ra:

    2

    2122

    2

    21

    1

    111

    )()()(

    )()()()()(

    TT

    TT

    ST

    Rtt

    dttdC

    Rtt

    Rtt

    dttdC

    2.4 PHAN TCH TOAN HOC (tham khao chng 5 va chng 8, (Smith, 1994)) Phan tch toan hoc:

    Ket hp tat ca cac he phng trnh mo ta ac tnh ong cua cac bo phan chc nang e c he phng trnh mo ta he thong.

    Tuyen tnh hoa quan he phi tuyen e c mo ta toan hoc

    tuyen tnh Xet he phi tuyen bac n co p ngo vao, q ngo ra mo ta bi phng trnh trang thai.

    ))(),(()())(),(()(

    tttttt

    uxhyuxfx

    trong o nt )(x la vector trang thai, pt )(u la vector tn hieu vao, qt )(y la vector tn hieu r; n(.)f , q(.)h la vector ham mo ta ac tnh ong cua he phi tuyen.

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    33

    Khai trien Taylor xung quanh iem lam viec tnh ),( ux ta co the mo ta he thong bang phng trnh trang thai tuyen tnh:

    )(~)(~)(~)(~)(~)(~

    tttttt

    uDxCyuBxAx

    trong o: ),( ,)()(~

    )()(~)()(~

    uxhyyyyuuuxxx

    tttttt

    Cac ma tran trang thai cua he tuyen tnh gan ung c tnh nh sau:

    )(2

    2

    2

    2

    1

    2

    1

    2

    1

    1

    1

    )(

    u,x

    ,xxfA

    n

    nn

    n

    n

    n

    n

    u

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    )(21

    2

    2

    2

    1

    2

    1

    2

    1

    1

    1

    )(

    u,x

    u,xufB

    p

    nnn

    p

    p

    uf

    uf

    uf

    uf

    uf

    uf

    uf

    uf

    uf

    )(21

    2

    2

    2

    1

    2

    1

    2

    1

    1

    1

    )(

    u,x

    u,xxhC

    n

    qqq

    n

    n

    xh

    xh

    xh

    xh

    xh

    xh

    xh

    xh

    xh

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    34

    )(21

    2

    2

    2

    1

    2

    1

    2

    1

    1

    1

    )(

    u,x

    u,xuhD

    p

    qqq

    p

    p

    uh

    uh

    uh

    uh

    uh

    uh

    uh

    uh

    uh

    ai so s o khoi Phng phap s o dong tn hieu va cong

    thc Mason e tm ham truyen tng ng cua he tuyen tnh. anh gia s phu hp cua mo hnh Dung mo hnh e d bao ap ng cua he thong oi vi tn

    hieu vao cho trc.

    Th du 2.14: Mo hnh toan he con lac ngc truyen ong dung ong c DC, xet anh hng cua ma sat: * ac tnh ong cua he xecon lac co xet en anh hng cua ma sat: Tng t nh th du 2.7, tuy nhien lc tac ong phai ke them lc ma sat: CfFmlmlxmM )(cos)(sin)( 2 (1) Pfmgmlxm sincos (2) trong o: Cf lc ma sat tac ong len xe Pf lc ma sat tac ong len con lac

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    35

    * ac tnh ma sat: Gia thiet co ca ma sat tnh va ma sat nht tac ong lam can tr chuyen ong cua xe va con lac. Cac lc ma sat nay co the mo ta bang cac phng trnh sau: xBeAxf x

    xCxC

    x )sgn( (3) BeAf CP )sgn( (4) trong o xA , xB , xC , A , B , 0C . * ac tnh ong c: baaaaa EIRVIL (5) bb KE mlmm BTTJ (6) agim IKKT FrTl rxKg / aL : ien cam phan ng aR : ien tr phan ng aI : dong ien phan ng aV : ien ap phan ng mT : moment ong c lT : moment tai : toc o quay ong c r : ban knh pu-li mJ : moment quan tnh ong c mB : he so ma sat nht iK : he so moment iK : he so moment gK : he so giam toc bE : sc phan ien F : lc tac ong vao xe ac tnh ong c co the bieu dien theo aI , x va F nh sau:

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    36

    abg

    aaaa VxrKK

    IRIL (7)

    FIrKK

    xrBK

    xr

    JKa

    gimgmg 22 (8)

    Do o mo hnh toan hoc cua he xe con lac vi tn hieu vao la ien ap cap cho ong c nh sau:

    abg

    aaaa

    P

    Caigmgmg

    VxrKK

    IRIL

    fmgmlxm

    fIrKK

    xrBK

    mlmlxr

    JKmM

    sincos

    )(cos)(sin)( 22

    2

    Th du 2.15: Mo hnh tuyen tnh cua he con lac ngc xung quanh v tr thang ng. He phng trnh mo ta ac tnh ong phi tuyen cua he con lac ngc (xem th du 7):

    22

    )(cossincos)(sin

    mmMmgmlux

    (1)

    lmMml

    mlgmMu)()(cos

    )sin(cos)(sin)(cos2

    2

    (2) at Txxt ],,,[)( x : vector trang thai, ta c:

    (.))(cos

    sincos)(sin)(

    )()(cos)sin(cos)(sin)(cos

    )(

    )()()()(

    21

    11221

    4

    21

    221111

    2

    4

    3

    2

    1

    fx

    xmmMxxmgxxmlu

    txlmMxml

    xxxmlxgmMxutx

    txtxtxtx

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    37

    (.))()(

    )()(

    )(3

    1

    h

    txtx

    txt

    ty

    iem can bang v tr thang ng: )0,(),( 0ux Tuyen tnh hoa xung quanh iem can bang:

    )(~)(~)(~)(~)(~)(~

    tttttt

    uDxCyuBxAx

    trong o:

    0001000

    000)(0010

    )0(4

    4

    3

    4

    2

    4

    1

    4

    4

    3

    3

    3

    2

    3

    1

    3

    4

    2

    3

    2

    2

    2

    1

    2

    4

    1

    3

    1

    2

    1

    1

    1

    )(

    gMm

    gMl

    mM

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    xf

    u

    ,

    ,xxfA

    0

    M

    Ml

    ufufufuf

    u u 10

    10

    )0(

    4

    3

    2

    1

    )(

    ,

    ,x

    fB

    0

    01000001

    )(4

    2

    3

    2

    2

    2

    1

    2

    4

    1

    3

    1

    2

    1

    1

    1

    )(

    u,x

    ,xxhC

    xh

    xh

    xh

    xh

    xh

    xh

    xh

    xh

    u

    00

    )(

    2

    1

    )(

    u,x

    ,x

    hD

    uhuh

    u u

  • Chng 2: M HNH HA

    Hunh Thi Hong B mn iu khin T ng

    38