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PHNG PHP IU KHIN TI U TRONG H THNG TREO CH NG T

Nguyn c Ngc Deng Zhaoxiang The College of Mechanical Engineering of Chongqing University, China 400030.

Tm tt: Thng qua vic thit lp xy dng m hnh tng th h thng treo t vi by bc t

do, ng dng l thuyt phng php iu khin ti u thit k b iu khin tuyn tnh kim sot hot ng h thng treo ca xe. S dng phn mm Matlab xy dng m hnh m phng iu khin h thng treo. Kt qu m phng so snh vi h thng treo b ng, cho thy vic kim sot h thng treo ch ng vi b iu khin tuyn tnh ci thin ng k hiu sut ca h thng treo, lm cho ngui ngi trn xe cm thy thoi mi hn.

1. t vn i vi mt chic xe t, h thng treo l

mt trong nhng b phn phc tp v rc ri nht trn xe. H thng treo ng mt vai tr thit yu trong vic gi n nh xe v gip ngi s dng cm thy thoi mi. H thng treo ch ng l mt trong nhng b phn quan trng nht trn t hin i. u im h thng treo ch ng: C kh nng t ng iu chnh cng v c ch hot ng ca h thng treo p ng vi nghing khung xe khi vo cua, nhp nh ca mt ng, gi thng bng khi phanh v khi tng tc t ngt, c kh nng t ng thch nghi vi ti trng ca xe v thay i cao gm xe cho ph hp vi iu kin hnh trnh. Mc ch em li cho xe c mt h thng treo thch hp v hiu qu nht.

H thng treo ch ng ca t l mt h thng ng lc hc rung ng phc tp, phn tch nghin cu n ta cn n gin ha m hnh, cc m hnh thng c s dng nghin cu l: M hnh 1/4 h thng treo vi hai bc t do, vi m hnh n gin, ch c th m t s bin ha ca vn tc v gia tc rung ng ca thn xe theo chiu thng. M hnh mt na h thng treo vi bn bc t do, la chn mt na thn xe theo ng i xng xy dng m hnh nghin cu, n phn nh c rung ng thng ng v gc nghing theo mt phng ca thn xe. M hnh tng th h thng treo vi by bc t do (hnh1), vi m hnh ny n phn nh ton b h thng rung ng ca thn xe v gc nghing ca thn xe theo ba phng, th hin tng th rung ng ca thn xe nh vi thc t.

Trong h thng treo ch ng, phng php iu khin h thng ng vai tr rt quan trng, ngy nay vi s pht trin khng ngng ca ngnh ton tin, hin c rt nhiu phng php iu khin nh: phng php iu khin ti u ha, phng php iu khin t thch ng, phng php iu khin fuzzy logic, phng php iu khin mng thn kinh,vv.

Bi vit nghin cu tng th h thng treo ch ng ca t vi by bc t do, s dng phng php iu khin ti u ha iu khin, y l phng php iu khin c s dng rng ri. Mc ch nghin cu l m phng hot ng ca h thng treo ch ng cho kt qu v dao ng gi treo, bin dng lp, gia tc dao ng v lc tc ng ln tng gi treo ca h thng treo ging vi thc t vn hnh xe trn ng. T kt qu l thng s phc v vic thit k ch to gi treo, thit b sinh lc v iu khin h thng treo ch ng cho t.

2. Xy dng m hnh rung ng tng th h thng treo t

2.1 Thit lp m hnh by bc t do ca h thng treo b ng v ch ng

Theo tnh ton cc thng s k thut c bn xy dng m hnh rung ng xe t: Khi lng thn xe trn gi treo ms=1170 kg; Khi lng gi treo ca mt bnh trc mu1=31 kg; Khi lng gi treo ca mt bnh sau mu2=28 kg; M men qun tnh theo trc Iy=2350 kg.m2; M men qun tnh theo trc Ix=1100 kg.m2; Khong cch t trng tm ti trc bnh trc L1= 1,305m; Khong cch t trng tm ti trc bnh sau L2=1,140 m; Chiu rng vt bnh xe

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w=1,405m; cng gi treo trc ks1=30000N/m; cng gi treo sau ks2=31500N/m; cng ca lp kt=181000N/m; H s gim chn h thng treo b ng Cs=30000 Ns/m.

T xy dng m hnh gi treo ng lc hc rung ng cho tng th xe vi by bc t do, c th hin trn (hnh 1). Trong m hnh: Hnh trnh dao ng ca gi treo bnh trc bn tri l (Zs1l Zr1l), ca gi treo bnh trc bn

phi l (Zs1r Zr1r), ca gi treo bnh sau bn tri l (Zs2l Zr2l), v ca gi treo bnh sau bn phi l (Zs2r Zr2r).

2.2 Thit lp h phng trnh vi phn chuyn ng ca h thng treo

Theo phn tch ng lc hc rung ng ca m hnh ta thit lp c cc phng trinh vi phn nh sau:

Phng trnh vi phn ca trng tm thn xe theo phng thng ng:

DCBA

s2ru2rs2rs2ru2rs2rs2lu2ls2ls2lu2ls2l

s1ru1rs1rs1ru1rs1rs1lu1ls1ls1lu1ls1l

UUUU )zz(K)zz(C)zz(Kzz(C

)zz(K)zz(C)zz(K)zz(C

zms

(2.1)

Phng trnh vi phn chuyn ng ca cc gc nghing thn xe: 2DCs2ru2rs2rs2ru2rs2rs2lu2ls2ls2lu2ls2l

1BAs1ru1rs1rs1ru1rs1rs1lu1ls1ls1lu1ls1l

LUU)zz(K)zz(C)zz(Kzz(C

LUU)zz(K)zz(C)zz(K)zz(C

yI (2.2)

2wUU)zz(K)zz(C)zz(Kzz(C

2wUU)zz(K)zz(C)zz(K)zz(C

DCs2ru2rs2rs2ru2rs2rs2lu2ls2ls2lu2ls2l

BAs1ru1rs1rs1ru1rs1rs1lu1ls1ls1lu1ls1l

xI (2.3)

Trong : ms khi lng thn xe trn gi treo, tng

ng vi z l dao ng ca trng tm thn xe theo phng thng ng; Cs1l, Cs1r, Cs2l v Cs2r l h s gim chn gm bnh trc bn tri v bn phi, bnh sau bn tri v bn phi ca h thng treo b ng; Ks1l, Ks1r,Ks2l v Ks2r l h s

cng ca gi treo bnh trc bn tri, bn phi, bnh sau bn tri v bn phi; UA, UB, UC v UD l lc tng tc cn thit ln gi treo trc bn tri, bn phi, bnh sau bn tri v bn phi ca h thng treo ch ng. Ix l m men qun tnh tng ng vi gc nghing ; Iy m men qun tnh tng ng vi gc nghing .

Hnh 1: M hnh tng th h thng gi treo rung ng ca t

Phng trnh vi phn chuyn ng thng ng ca bn gi treo bnh xe: Au1ls1ls1lu1ls1ls1lu1lr1lt1l1lA U)zz(C)zz(K)zz(K uzm (2.4)

Bu1rs1rs1ru1rs1rs1ru1rr1rt1r1rB U)zz(C)zz(K)zz(K uzm (2.5)

Cu2ls2ls2lu2ls2ls2lu2lr2lt2l2lC U)zz(C)zz(K)zz(K uzm (2.6)

Du2rs2rs2ru2rs2rs2ru2rr2rt2r2rD U)zz(C)zz(K)zz(K uzm (2.7)

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Trong : mA, mB, mC v mD l khi lng gi treo tng ng bnh trc bn tri, bn phi, bnh sau bn tri v bn phi; Kt1l, Kt1r, Kt2l v Kt2r cng ca lp tng ng vi bnh trc bn tri, bn phi, bnh sau bn tri v bn phi.

thit k h thng iu khin da trn c

s tiu chun tch phn ti u tuyn tnh, cc tham s ca khu iu khin c chn xut pht t n lc tm cc tiu cho mt hm cht lng. Cc tham s , , , ,z ,z ,z ,z ,z ,z ,z,z ,z z, u2ru2ru2lu2lu1ru1ru1lu1l

Ta c: Vector Tu2ru2ru2lu2lu1ru1ru1lu1l , , , ,z ,z ,z ,z ,z ,z ,z,z ,z z,X (2.8) Tu2ru2ru2lu2lu1ru1ru1lu1l , , , ,z ,z ,z ,z ,z ,z ,z,z ,z ,zX (2.9)

Vector iu khin: TDCBA U U UUU (2.10) Tn hiu nhiu mt ng: Tr2rr2lr1rr1lryrx z z z z z zW (2.11)

t gia tc dao ng ca gi treo, hnh trnh ng ca gi treo, bin dng ca lp l cc gi

tr bin i, ta c Vector (2.12)

Trrrulrlurrrulrlu

rurlulrurlu

zzzzzzzzzzzzzzzzzY

],,,

,,,,,,,[

22221111

2s22s21s11s1l

(2.12)

T thit lp c m hnh phng trnh trng thi EWU BAXX (2.13) v

FWU DCXY (2.14). Mc ch ca phng php iu khin ti u h thng treo ch ng, l nng cao tnh nng iu khin v tnh n

nh ca t, khi xe vn hnh cc tn hiu nhiu ca mt ng tc ng ln gi treo. H thng treo ch ng c tc dng lm gim bt dao ng v s bin dng ca lp, khng ch lc l ca gi treo, t ta c hm s mc tiu:

dtUrUrUrUrzzq

zzqzzqzzqzzq

zzqzzqzzqqqzq21J

2D4

2C3

2B2

2A1

2r2ru2r11

2r2lu2l10

2r1lu1r9

2r1lu1l8

2u2rs2r7

0

2u2ls2l6

2u1rs1r5

2u1ls1l432s1

(2.15)

dtRuUQYY21J

0

TT

(2.16)

Trong : ijqQ , ij qij=0 ; R = r. T m hnh lin tc, ta s dng khu phn hi trng thi:

PxB-RKxu T-1 (2.17) Trong K l ma trn phn hi, c thit

k sao cho hm cht lng mc tiu l cc tiu. P thng s tha mn phng trnh:

0QBPPBRPAPA 1T (2.18) ng dng Matlab tm ma trn phn hi K

theo tiu chun tch phn ti u tuyn tnh: [K,S,e]=lqry(sys,Q,R[,N]) (2.19) S dng lnh trn trong Matlab ta xc nh

c kt qu ma trn phn hi K. T cc thng s gi treo, v la chn cc thng s q1=100q2=1q3=80q4=q5=q6= q7=20q8=q9=q10=q11=1000; r1=r2=r3=r4=0,00035.

3. Xy dng m hnh m phng iu khin h thng treo ch ng

3.1 Thit k m hnh iu khin ti u h thng treo ch ng t:

Khi xy dng m hnh cn phi xc nh c xe ang hot ng trn mi trng mt ng nh th no, ph hp vi iu kin giao thng thc t ta xy dng m phng tn hiu mt ng vi iu kin mt ng cp C c h s khng bng phng Gq(no)=256x10-6m3, vn tc xe V=20m/s, m hnh trn (Hnh 2), tn hiu mt ng tc ng ln bn bnh xe, c th hin trn (Hnh 3).

ng dng d liu m hnh SIMULINK trong phn mm MATLAB thit k m hnh m phng to thnh mt s iu khin, cn c theo m hnh ti u ca bi ton iu khin h

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thng treo ch ng v b ng ca t, xy dng m hnh iu khin ti u h thng treo ch ng ca t s (Hnh 4) v h thng treo b ng ca t s (Hnh 5).

3.2 Kt qu m phng iu khin ti u gi treo ch ng v b ng ca t

T m hnh iu khin tin hnh vn hnh m phng vn hnh h thng iu khin cho ta kt qu th hin trn (Hnh 6 13). Vi h thng

treo ch ng ch cn tc ng mt lc ln nht 1285N vi gi treo bnh trc v 570N vi gi treo bnh sau, lm cho gia tc dao ng ca thn xe gim xung ch cn thay i trong phm vi t 0,0461m/s2 n 5,7611m/s2, ng thi cc kt qu v gia tc gc nghing, bin dng lp ca h thng treo ch ng cng nh hn nhiu so vi h thng treo b ng.

0 1 2 3 4 5 6 7 8 9 10

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25The C level road spectrum

Road

spe

ctru

m (m

)

Time S

Hnh 2: S m phng tn hiu mt ng Hnh 3: Tn hiu mt ng

Hnh 4: M hnh iu khin h thng treo ch ng Hnh 5: M hnh iu khin h thng treo b ng

Hnh 6: Kt qu gia tc dao ng thng ng ca h thng treo ch ng v b ng

Hnh 7: Kt qu gia tc gc nghing ca h thng treo ch ng v b ng

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Hnh 8: Kt qu hnh trnh dao ng gi treo

bnh sau bn tri ca h thng treo Hnh 9: Kt qu bin dng lp bnh trc

bn tri ca h thng treo

Hnh 10: Kt qu hnh trnh dao ng ca gc thn xe bnh trc bn tri

Hnh 11: Kt qu hnh trnh dao ng ca gc thn xe bnh sau bn tri

Hnh 12: Kt qu lc tc ng ln hai

gi treo bnh trc h thng treo ch ng Hnh 13: Kt qu lc tc ng ln hai gi treo

bnh sau h thng treo ch ng 4. Kt lun: Kt qu ng dng phng php iu khin

ti u h thng treo ch ng trn cho thy, vic ng dng h thng treo ch ng trn t em li nhng li ch tt hn nhiu so vi h thng treo b ng, vi h thng treo ch ng ch cn iu khin lc tc ng ch yu trong phm vi 1300N, n lm cho h thng treo ch ng n nh hn, v bin dng ca lp nh hn so vi h thng treo b ng.

T kt qu m phng cho bit lc tc ng cn thit trn tng gi treo, hnh trnh, vn tc v gia tc dao ng ca gi treo ch ng, t l c s tin hnh nghin cu thit k ch to

cc h thng gi treo ch ng c cu to khc nhau, vi mc ch em li s an ton v thoi mi cho ngui vn hnh, nh h thng treo ch ng kh nn, h thng treo ch ng in thy lc, h thng treo ch ng in t, ...

Vi ng dng MATLAB/SIMULINK trong vic iu khin ti u, y l mt phng php iu khin c ng dng rng ri trong cc lnh vc iu khin t ng, thit ngh vi kt qu nghin cu ban u ny, c vn dng v pht trin trong vic nghin cu cc vn lin quan c nhng kt qu khoa hc tt hn, s em li nhng li ch to ln cho cng cuc pht trin t nc.

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Ti liu tham kho: [1] Semiha Turkay and Huseyin Akcay, Aspects of achievable performance for quarter-car

active suspensions, Journal of Sound and Vibration 311 (2008) 440460. [2] Huseyin Akcay and Semiha Turkay, Influence of tire damping on mixed H2/H synthesis

of half-car active suspensions, Journal of Soundand Vibration 322 (2009) 1528. [3] Yuping He and John McPhee, Multidisciplinary design optimization of mechatronic

vehicles with active suspensions, Journal of Sound and Vibration 283 (2005) 217241. [4] Y. He, J. McPhee, Design optimization of rail vehicles with passive and active

suspensions: a combined approach using genetic algorithms and multibody dynamics, Vehicle System Dynamics 37 (Suppl.) (2002) 397408.

[5] J. Sobieski, J. Kodiyalam, R. Yang, Optimization of car body for noise, vibration and harshness and crash, in: Proceedings of the 41st AIAA/ASME/AHS/ASC, Structures, Structural Dynamics, and Materials, Number AIAA- 2001-1273, Atlanta, 2000.

[6] Qin Zhu, Mitsuaki Ishitobi, Chaotic vibration of a nonlinear full-vehicle model, International Journal of Solids and Structures 43 (2006) 747759.

[7] Hyo-Jun Kim, Hyun Seok Yang, Improving the vehicle performance with active suspension using road-sensing algorithm, Computers and Structures 80 (2002) 15691577.

Abstract:

OPTIMAL CONTROL OF FULL VEHICLE ACTIVE SUSPENSION SYSTEM

Through the establishment of full vehicle model with seven degrees of freedom and the application of optimal control theory, a Linear Quadratic Gaussian (LQG) controller of full vehicle active suspension was designed. The system simulation model based on Matlab environment were built and used for simulation. Simulation results were compared with passive suspension. The simulation results demonstrated that the active suspension with a LQG controller could improve automobile riding comfort performance enormously.