Cdng trinh Khoa hpc
ANH HironvG CUA DO CUKG BEN CUA L O P VA GIO NGANG DEN ON DINH CHUYfiN DONG CUA 6 TO
DAO MANH HUNG NGUYEN THANH CONG
Trudng Dgi hgc Giao thong Van tdi NGUYEN ANH TUAN
Trudng Cao ddng Ky thugt Ly Tu Trgng Thdnh phd Hd Chi Minh
Tdm tdt: On dinh Id mpl trong nhirng tinh chdt khai thdc quan trpng ciia d td. Bdi bdo nghien cuu dnh hudng cda dp cdng ben ctia lop vd gid ngang den sg dn dinh chuyin ddng ciia d td. Cdc tdc gid dd xdy dgng md hinh vgt ly. mo hinh todn hpc nghien cdu dn dfnh chuyen ddng cua d td, tir dd su dung phdn mim Matlab - Simulink di liin hdnh md phdng. Kit qud md phong cho Ihdy sg mat dn dinh chuyen ddng cua d td do su khong phu hpp giua do cirng cda Idp cdu tnrdc - cdu sau vd do tdc dung cua gid ngang.
Summary: Stability is one of the important utilizing characteristics of automobiles. In this paper, influence of lire cornering stiffness and side wind on automotive stability will be presented, reviewed and evaluated. The authors have established a physical model and a mathematical model to study the automotive stability, thereby using Matlab - Simulink software for simulation. The results show the unsuitahility of the tire cornering stiffnesses between front axle and rear axle and the side wind effects have resulted in the instability of automotive movements
I. DAT VAN DE
Tinh dn dinh la kha nang d td dam bao giii dugc quy dao chuyen ddng theo yeu cau tiong mgi dilu kien khai thdc khac nhau nhu khi quay vdng, khi phanh hoac khi chuyen ddng tien dudng ddc, chuyen dgng dudi tdc dung cua gid ngang . . . Day la mdt trong nhiing tinh chdt khai Ihdc quan trgng cua d td.
Khi d td chuyen dgng quay vdng, trong nhieu trudng hgp d td chuyen dgng khdng diing vdi quy dao nhu mong mudn ciia ngudi lai (hien tugng quay vdng thira, quay vdng thieu), gay ra hifin tirgng mil dn dinh hudng chuyen ddng. Bdi bdo nay cac lac gid tdp trung xem xet tinh dn dinh chuyen ddng ciia d td tiong hai trudng hgp quay vdng va chuyen ddng thdng chiu lac dgng gid ngang.
Tgp chi KHOA HQC GI AO THONG VAN TAI S6 dac biet - 1 1 / 2 0 1 5 1 1 7
n. XAY DUlSG MO HINH NGHIEN ClTU
2.1. Mo hinh dgng luc hgc 6 td chuyin dong trong m | t phdng
Md hinh d td hai vet banh xe nghien ciiu chuyin dgng cua d td tiong trudng hgp tdng qual khi chiu lac dung ciia phan lire dgc va ngang tii mat dudng len cdc banh xe, luc gid ngang Fwy va luc can khdng khi F^x vdi gia thiet tai trgng tinh phdn bd ddi xung Iheo phuang chuyen ddng ciia dtd (hinh 1) [1,3].
y
V,
F J f xi
Hinh 1. Mo hinh chuyin ddng cua d td trong mat phdng ngang
Sii dung nguyen ly D'Alembert ta thiet lap dugc cac phucmg trinh vi phan chuyen dgng ciia d td trong mat phang:
V = VV^ + - ( F X I C0S5, - F , i sin5, +F,2 cosS^ -F^^ s m 6 j +F,3 + E , , - F „ ) (1)
V=-"i"xC+—(FxiSm5,+F,,cos8,+F,2Sin82+FyjCOs5j+F,3+F,,+F^) (2)
V = — [ - ( F ^ I COS5, - F J , sin5,)b, + ( F J | sinS, +Fy, cos8,)a,
+(F,jCOs5j-Fj,2sin5j)b2+(F,jSin62+FyjCos5j)a, (3) + F - , l ' 2 - F , 3 a ; - F . , b , - F , A + F „ l „ J
Trong do F^i va Fy, - cac phan lire doc va phan luc ngang tu mat duong tic dung len binh xe. Cac luc nay duoc xac dinh theo mo hinh H. Pacejka [4] voi:
F„=f{Ci„>.„F„) F,=g(C„„u„F,)
(4) (5)
118 Tap chi KHOA HOC GIAO THONG V;4N TAI So dac bift - 11 /2015
Cdng trinh Khoa hpc Vdi X„ tti - tuang iing la he sd trugt dgc va gdc l?ch ben ciia Idp; Fzi - phan luc thang diing tir mgt dudng tac dung len cac banh xe; Cx,, Cai - tuang iing la do ciing dgc va do ciing ben ciia ldp.
2.2. Mo hinh l6p o to a. Xdc dinh he sd truat dpc
Khi banh xe lan, do bien dang vdng cua cac phdn tu ldp tiong vung tilp xiic giiia banh xe vdi mat dudng, xudt hi?n su chenh l$ch gifta van tdc chuyin ddng linh tiln thirc tl ciia banh xe v, va van tdc vdng tuang duong rbco,, dugc dgc trung bang he sd trugt X,:
^=—V^
max(v,,r|,£»J
Hay A,, =-(v,-rj(D,)/v, khi phanh va X,, =-(v,-i^a),)/r^o)i khi tang tdc.
h. Xdc dinh gdc Igch ben cua lop
Gdc 16ch b8n cua Idp cd the xac dinh tir binh 2 theo cdng thiic sau:
a,=5,-p,, i={l, 2, 3, 4)
(6)
(7) Trong do: 5j - gdc quay cua bdnh xe. Pi - gdc l$ch gifta phuang van tdc v, cua cac banh xe va phuang chuySn dgng x ciia d Id, dugc xac dinh bdi:
B =arclan-^ (8)
Hinh 2. Cdc goc quay cua bdnh xe
Nhu vgy, ta se xdc dinh dugc cdc phan luc dgc va phan luc ngang tii mat dudng tac dung len banh xe theo md hinh Pacejka theo cdng thirc (4) va (5) [4], Phan luc dgc Fx, dugc xac dinh flieo cdng thuc (4) khi bilt dd cimg dgc ciia ldp C^i, he sd tiirgl dgc ciia ldp X, va phan luc thdng dung Fz,. Tuang tu, phan lgc ngang Fy, dugc xac dinh theo cdng thiic (5) khi biel do ciing ben cua ldp Ccu, gdc lech bfin ciia ldp a, va phdn luc thdng dung F;,. Tir dd ta cd the khao sat bai loan ddng luc hgc chuyin dgng quay vdng cua d td.
Tap chi K H O A H Q C GIAO THONG VAN TAI S6 d a c biet - 11 /2015 119
III. MO PHONG TREN MATLAB-SIMULINK 3.1. Khao s^t chuyin dgng ctia 3 to khi quay vdng
•? 0,05
..jzor
Z i j I
81 JZ
Hinh 3. Gdc quay bdnh xe ddn hudng 60
Hinh 4. Quy dgo chuyen dgng cua d td
0 20 40 x(m) Hinh 5. Quy dgo chuyin ddn^
Tren co sd cac phuang tiinh vi phan va cac thdng sd, md Mnh ddng lire hgc chuyen ddng ciia d td dugc md phdng tren phdn mem Matlab-Simulink. Cac dieu kien khao sat khi quay vdng bao gdm: ban ddu d Id chuyen ddng vdi van tdc 40 km/h, sau dd thuc hien quay vdng bdng cdch thay ddi gdc quay ciia cac banh xe ddn hudng nhu hinh 3. Tiln hanh khao sat tiong 2 trudng hgp: tirudng hgp 1, gia tn dd ciing ben/tai tigng cua ldp cdu trudc Id 4098 N/1077 N/dg va cua ldp cau sau la 3552 N/1077 N/dg, khi dd xay ra hien tugng quay vdng thieu, ket qua md phdng quy dgo chuyin dgng ciia d td Ihl hien tien hinh 4; trudng hgp 2, tang gia tri do ciing ben cua Idp trudc len 1877 N/dg, khi do xay ra hien tugng quay vdng thda, kit qua md phdng quy dao chuyen ddng ciia d Id tien hinh 5.
Tu hai tiirdng hgp da khao sat ta thdy, khi giu nguyen do ciing ben cua ldp cau sau (1077 N/dg) ddng thai lang do ciing ben cua ldp cau trudc tu 1077 N/dg len 1877 N/dg dii d td chuyin tii ti^g thai quay vdng thilu sang quay vdng thua.
Tu hinh 4 va hinh 5 ta thay, khi xay ra hien tugng quay vdng thieu vd quay vdng thua, quy dao chuyen ddng sai lech tuong ddi Idn so vdi mong mudn ciia ngudi lai. Neu ggi phdn tidm sai lech la ti sd gifta su sai lech vl Iga do tigng tam cua d td vd ban kinh quay vdng thi sg sai lech Idn nhat khi xay ra quay vdng thilu la 21,1% va su sai Igch Idn nhat khi xdy ra quay vdng thiia
120 Tap chi KHOA HQC GIAO THONG VAN TAI So d3c biet - 11/2015
Cdng trinh Khoa hpc la 12,6%. Nhu vay sy sai lech khi quay vdng thieu va quay vdng thira diu rdt ldn nhung sai lech khi quay vdng thieu ldn hon nhilu (gap gdn 2 lan). Tuy nhien sir sai lech khi quay vdng thua nguy hiem han do ban kinh giam cd thi lam tang dgt nggt lire ly tdm gay Idt xe.
3.2. Khao sat chuyen dgng cda o td khi chuyen tan
x(in) x(m) Hinh 7. Quy dgo chuyen dpng cua d to Hinh 8. Quy dgo chuyen ddng cua d td
Cac diSu kien khao sat khi d Id chuyen Ian bao gdm: d td chgy vdi van Idc 40 km/h, sau do thuc hien chuyen lan bdng each thay ddi gdc quay ciia cac bdnh xe ddn hudng nhu hinh 6. Ta se khao sat quj dao chuyen dgng ciia d td tiong 2 trudng hgp gidng nhu khi quay vdng.
Ket qua md phdng tren hmh 7 va hinh 8 cho thdy, Irong ca hai trudng hgp, do su khdng phu hgp giua do ciing ben cua ldp cau trudc va cau sau, quy dao chuyen ddng ciia d td bi lech so vdi mong mudn ciia ngudi lai.
3.3. Khao sdt chuyen dgng cua 6 to khi chuyen d$ng trong gid ngang
Cac dieu kien de tien hanh khao sat bao gdm: ban ddu xe chuyen ddng thang vdi van tdc 40 km/h. Sau dd bat ddu chiu tac dung cua luc gid ngang nhu hinh 9, gdc quay vanh lai dugc gift bdng 0, khao sat trong khoang thdi gian ngdn 20s, ta thu dugc dd thi quy dao chuyin dgng nhu hmh 10.
Tap chi KHOA HQC GIAO THONG VAN TAI S6 dac biet - 11 /2015 121
soo
400 g 300
^ 2 0 0 100
5 10
1(8)
15 20
Hinh 9. Luc gio ngang Hinh 10. Quy dgo chuyen ddng ciia d Id Tu kit qua md phdng tren hinh 10 ta thdy, dudi tac dgng cua luc gid ngang, d td chuyin ddng lech khdi quy dao mong mudn. Vdi thdi gian md phdng la 20s, su sai lech quy dao chuyin ddng ldn nhat la 4m. Sir sai lech nay la khd ldn va rat nguy hiem khi d td chuyin ddng tien dudng. Ngoai ra, tiong thuc tl phdn ldn xay ra sir tang ISn ddt nggt cua lire gid ngang, do dd su sai lech cda quj dgo cd the ldn hon nhieu so vdi gia thiSl sii diong de md phdng.
IV. KET LUAN
Bai bao d3 tiln hanh xdy dung md hinh vat ly, md hmh loan hgc de nghien ciiu dgng luc hgc chuyen dgng cua d Id khi quay vdng va khi chuySn ddng trong gid ngang, tii dd tien hanh rad phdng chuyen ddng ciia d td su dung phan mem Matlab-Simulink. Ket qua md phdng eho thay su mat dn dinh chuyen ddng ciia d td khi quay vdng do su khdng phii hgp ciia dg ciing b6n ciia cac banh xe cau trudc va cdu sau. Khi gift nguySn tdi tigng tren cdc ldp xe va dg ciing ben ciia ldp cau sau, neu tang do ciing bSn cua ldp cdu Irudc thi se lam giam ban kinh quay vong.
Ngoai ra, sir mat dn dinh chuyin ddng cdn xay ra khi d td chuyen dgng dudi tac dung ciia gio ngang. Ket qua ciia bai bao ndy la nen tang cho cac nghien ciiu tiep theo nhu nghiSn cihi on dinh quy dgo chuyen ddng cua d td su dimg he thdng lai tich cue.
Ngay nhan bdi lan dau: 24/9/2015 Ngdy nhSn bdi sira: 4/10/2015 Ngay ch4p nh^n dSng bai: 1/10/2015
Tai lieu tham khao
[1]. Nguyen Khdc Trai, "Tfnh dieu khien va quy dao chuyin dgng cua 6 to", Nha xudt bdn Giao th6ng Van tai, 1997.
[2]. Cao Trpng Hiin vd Ddo Mgnh Hiing, "Ly thuylt 6 to", NXB Giao thong Van tai. Ha Ngi, 2010.
[3]. Tao Sun, Hao Guo, Jian-young Cao, Ling-Jiang Chai vd Yue-dong Sun, "Study on Integrated control of active front steering and direct yaw moment based on vehicle lateral velocity estimation", Hindawi publishing corporation, mathematical problems in engineering, volume 2013.
[4]. H. Pacejka, E Bakker, L. Nyborg, Tyre modelling frir use in vehicle dynamics studies. SAEPaper No.
870421 •
Phan bien: Tr4n Van Nhir, Dinh Thi Tbanb Huyin
122 Tgp chi KHOA H Q C GIAO T H O N G VAN TAI So d a c bi§t - 1 1 / 2 0 1 5
