Electro-Mechanical Friction Clutch (EMFC) Controller Development for Automotive Application

Transcription

1 , Jun 30 - July, 010, London, U.K. Elctro-Mchanical Friction Clutch (EMFC) Controllr Dlopmnt for Automoti Application Mohamd Hussin, Mmbr, IAENG, Mohd Salman Ch Kob, Mmbr, IAENG, Kamarul Baharin Tawi, Bambang Supriyo, Mmbr, IAENG, Sugng Ariyono Abstract Vhicl with adancd control tchnology in its powr-train systm offr many adantags in trms of prformanc, ful consumption and impromnt of driing comfort. This papr aims to proid a contribution in this dirction by proposing a PD controllr for an lctronically controlld dry friction clutch ngagmnt systm. Th ngagmnt procss for a nol Elctro-Mchanical Friction Clutch (EMFC) is bing studid and aluatd smi-mpirically which xploits static and dynamic modls for th systm. This EMFC will b intgratd with a nol Elctro-Mchanical Dual Acting Pully (EMDAP) continuously ariabl transmission (CVT) for th nxt gnration of an automoti transmission in th futur. Simplifid static and dynamic modls of th EMFC systm consisting of mchanical actuator, dry friction clutch, a DC motor systm and clutch linkags wr dlopd. Th DC motor systm is usd as an actuator to actuat powr scrw mchanism for ngaging and disngaging th clutch. Matlab/Simulink is usd to simulat th modl ngagmnt procss basd on th xprimntal alus of opn-loop clutch ngagmnt procss. Computr simulation rsults ar prsntd to dmonstrat th ffctinss of th proposd control schm for th closd loop systm. Indx Trms Elctro-Mchanical Friction Clutch, CVT, PD Controllr. I. INTRODUCTION Dri-by-wir will play important rol in futur automoti systms. In automoti powr-train systms, th main ida of dri-by-wir is to rplac purly mchanical transmission systms by mchatronic componnts. Diffrnt approachs, such as automatic transmission (AT), automatd manual transmission (AMT) and continuously ariabl transmission (CVT) ar xploiting th aailability of rliabl dri-by-wir tchnologis. Ths transmissions rprsnt th ky lmnts for th impromnt of hicl safty, comfort, rliability and driing prformancs as wll as th rduction of ful consumption and missions [1]. For Manuscript rcid April 14, 010. M. Hussin is with th Applid Mchanic Dpartmnt of Mchanical Enginring, Unirsiti Tknologi Malaysia, UTM Skudai, Johor, Malaysia (-mail: mohamd@fkm.utm.my). M. S. Ck Kob, K. B.Tawi and B. Supriyo ar with th Automoti Dpartmnt of Mchanical Enginring, Unirsiti Tknologi Malaysia, UTM Skudai, Johor, Malaysia (-mail: salman_qlt@yahoo.com.my; bsupriyo7763@yahoo.com; kamarul@fkm.utm.my). S.Ariyono was with th Dpartmnt of Mchanical Enginring, Politknik Ngri Smarang Jl. Prof.H. Sudarto, S.H. Tmbalang, Smarang 5039, Indonsia (-mail: s.ariyono@gmail.com). xampl, hicl with AMT is gnrally constitutd by a dry friction clutch-by-wir systm as man of asing th drir task and thus, nhancing his satisfaction about th car [6]. With rspct to manual transmission, th AMT allows to impro driing comfort and shift quality by controlling th dry clutch ngagmnt procss. Th ngagmnt of dry friction clutch is a ry important procss both to nsur small friction war and good powr-train prformanc []-[3]. Currntly, most of th clutchs usd in CVT applications ar basd on hydraulic actuators [4]. Som also usd lctro-magntic powdr clutchs [5]. Ths clutchs ar slctd bcaus thy can b controlld lctronically. Toward in this dirction, a nol Elctro-Mchanical Friction Clutch (EMFC) systm (patnt pnding) for a nol Elctro-Mchanical Dual Acting Pully (EMDAP) CVT (patntd) applications ha bn dlopd by Powr-Train Rsarch Group (PRG) in Unirsiti Tknologi Malaysia (UTM) as th nxt gnration transmission for th futur. Th EMFC consists of mchanical actuator, a typical dry friction clutch, clutch linkags and a DC motor. Th DC motor systm is usd as an actuator to actuat powr scrw mchanism for ngaging and disngaging th clutch. This nol EMFC nabls th clutch to b opratd lctronically so that a suitabl closd loop control stratgy can b applid in ordr to satisfy som objctis such as small friction losss, minimum tim ndd for th ngagmnt, and prsration of drir comfort []. In ordr to achi thos control objctis, many diffrnt approachs of control stratgis ha bn proposd in th litratur on dry friction clutch ngagmnt such as an optimal control in [] and [6], a proportional control in [7], also dcoupling control in [8] and [9], and a fuzzy control in [10]. This papr proposs a PD controllr for th clutch ngagmnt procss of EMFC systm which xploits static and dynamic modls for lctrical DC motor, mchanical actuator, clutch linkags and dry friction clutch. Modls of th systm ar dlopd and tund basd on xprimntal data. A simpl rlay fdback xprimnt is usd to obtain a critical priod and a critical gain in ordr to find th paramtrs of PD rgulator using Ziglr-Nichols typ of control dsign mthods. EMDAP CVT changs ratio continuously similar to othr CVT applications. During up or down changing ratio procss, it dos not nd clutch ngagmnt and disngagmnt procss inolmnt. Th clutch is rquird to b usd during th hicl standing start and stop

2 , Jun 30 - July, 010, London, U.K. scnarios. Particularly, th nrgy dissipatd in th dry clutch is maximal during standing start scnario [6]. Basd on this cas, th numrical simulation only considrs at th critical clutch ngagmnt procss which is during standing start only. A Matlab/Simulink simulation schm is usd to simulat th modl ngagmnt procss. Computr simulation rsults ar prsntd to dmonstrat th ffctinss of th proposd control schm for th closd loop systm. A. ngagd B. Disngagd T m : Motor Torqu [Nm] K T : Torqu Constant [Nm/A] T L : Load Torqu [Nm] J m : Motor Inrtia [Nm.sc ] B m : Viscous friction cofficint [Nm/rad/sc] B. Modlling of Gar Rducr and Powr Scrw Mchanism A gar rducr srs as a spd rducr and torqu multiplir. Th gar rducr has ratio 5:1 and it is coupld with th DC motor shaft. Th gar rducr output is connctd to th powr scrw mchanism to produc a linar momnt. Th linar momnt is thn transmittd to actuat th shift arm ithr to ngag or disngag th clutch systm. Th powr scrw mchanism is conrtd ry of rotation into millimtrs of linar momnt. Figur 1 Elctro-Mchanical Friction Clutch II. SYSTEM MODELLING This sction dscribs th mathmatical modls of th EMFC systm. Th modl cors a DC motor in conjunction with rduction garing systm, a powr scrw mchanism, clutch linkags and th typical dry friction clutch as shown in Figur. Figur 3 Forc diaphragms for th powr scrw to disngag (A) and ngag (B) th clutch Th torqu rquird to mo th powr scrw axially from ngagd to disngag is gin by: T lift dm l dm x xdx d l m (5) Figur Rprsntati Simplifid Modl of Dsignd EMFC A. Modlling of DC motor Th quations dscribing th dynamic bhaiour of th DC motor ar gin by th following quations: dia Va La Raia b (1) dt Tm KT ia (t) () d ( t) d(t) Tm - TL = J m + B m dt dt (3) d ( t) b b ( t) Kb dt (4) whr: V a : Motor Voltag [V] L a : Motor Inductanc [H] i a : Motor Currnt [A] R a : Motor Rsistanc [] K b : Back mf constant [mv/(rad/sc)] b : Back mf [mv] : Angular displacmnt [rad] Th torqu rquird to mo th powr scrw axially from disngagd to ngag is gin by: T lowr dm l dm x xdx d l m whr: T lift : Torqu for lifting load [Nm] T lowr : Torqu for lowring load [Nm] P R : Forc rquird to raising th load [N] P : Forc rquird to lowring th load [N] D x : Axial forc [N] N : Normal forc [N] fn : Friction forc [N] d m : Man diamtr of powr scrw [mm] l : Pitch of powr scrw [mm] μ : Friction of powr scrw surfac contact : Lad angl [rad] C. Modlling of Clutch Linkag It follows Figur that th clutch linkag quations of (6)

3 , Jun 30 - July, 010, London, U.K. S1 X1, S1 S, S / R, 3, S3 3xR3, (7) S3 S4, 4 S4 / R4, 4 5, S5 5xR5 whr: X 1 : Numbr of rolution of outr powr scrw S 1 : Displacmnt of innr powr scrw S : Angular Displacmnt of clutch fork arm (xtrnal) : Angl of Displacmnt of clutch fork (xtrnal) S 3 : Angular Displacmnt of clutch fork arm (intrnal) 3 : Angl of Displacmnt of clutch fork (intrnal) S 4 : Angular Displacmnt of diaphragm spring A 4 : Angl of Displacmnt of diaphragm spring A S 5 : Angular Displacmnt of diaphragm spring B 5 : Angl of Displacmnt of diaphragm spring B D. Modlling of Dry Friction Clutch Litraturs on mathmatical modls of dry friction clutch ngagmnt ha bn proposd in many diffrnt approachs in [1]-[3] and [6]-[11]. Th EMFC uss of a typical dry friction clutch systm. This clutch consists of thr basic parts. Ths ar th ngin flywhl, a dry friction disc and a prssur plat. Th flywhl and prssur plat ar th driing mmbrs. Thy attach to and rotat with th ngin crankshaft. Th dry friction disc is th drin mmbr. In ordr to instigat th systm and to dsign a controllr through analytical procdurs, a simplifid mathmatical modl of th typical dry friction clutch which can b thought as a systm consisting of two spinning disc modls wr dlopd basd on papr [] and [11]. Whn th clutch is slipping, th diffrntial quations of th clutch ngagmnt systm can b xprssd as: T cl R N.. Fa. R sign ( ) 3 3 o o r r r r 3 i i (10) whr: r o : Outr radius of friction plat r i : Innr radius of friction plat μ : Th friction cofficint of th clutch surfac matrial N : Th numbr of friction plat surfac F a : Normal forc applid to th friction clutch R : Equialnt disk ratio Whn th clutch is ngagd, th angular locity of th ngin and th transmission input shafts ar th sam. Whr ω= ω = ω and th diffrntial quations (8) and (9) bcom I I Tin b b Tl (11) Actually, th normal forc is nonlinar function of th clutch mchanical prformanc. In Figur 4, th load-dflction cur for th diaphragm spring of th EMFC is plottd basd on th xprimntal data. For numrical application, this nonlinar function was approximatd by a 4 th ordr polynomial [1] and xprssd in trms of th displacmnt as x F a (x) = -4E10x 4 + 1E9x 3-3E7x x (1) I T b T (8) in cl cl I T b T (9) l whr I : Engin inrtia, ω : Th crankshaft rotor spd T in : Th ngin torqu b : Th crankshaft friction cofficint T cl : Th torqu transmittd by th clutch, I : Th quialnt hicl momnt of inrtia (it taks into account th prsnc of th clutch, th mainshaft, th powrtrain and th hicl) - which will also dpnd on th gar ratio ω : Th clutch disk rotor spd b : Th corrsponding friction cofficint and : Th quialnt load torqu T l Equation (8) modls th rotation of th driing mmbrs, whras (9) modls th rotation of th drin mmbr. Th rmaining parts of th powr-train systm ar simply modlld through th quialnt hicl inrtia I and th load torqu T l as usd in []. Basd on th clutch gomtry and friction charactristics, th clutch torqu T cl is calculatd as follows: Figur 4 Loads (kn)-dflction (mm) Cur for Diaphragm Spring III. MODEL VALIDATION AND EXPERIMENTAL RESULTS Firstly, dynamical proprtis of EMFC systm ar instigatd on a laboratory tst-bnch. Thn, th orall simplifid modls of th EMFC ngagmnt procss during standing start ar analyzd. Matlab/Simulink simulation schm is usd to simulat th ngagmnt bhaiour of th proposd modls with rspct to xprimntal alus. Figur 7 shows th ngagmnt bhaiour of EMFC tst-bnch systm. Paramtrs of th dry friction clutch modl ha bn idntifid from [] and th othr parts of EMFC ha bn rcognizd from data shts on th basis of thortical and physical laws. From th prious sction, load-dflction cur for diaphragm spring has bn approximatd by a 4 th

4 , Jun 30 - July, 010, London, U.K. ordr polynomial for numrical application basd on xprimntal data. Th laboratory tst-bnch of EMFC is shown in Figur 5 and Figur 6. Th laboratory tst-bnch consists of dry friction clutch and lctro-mchanical clutch actuator, ngin as powr sourc, watr-brak dynamomtr as a ariabl load, torqu spd snsors for masuring ngin and output spds and torqus, and data loggr systms for rcording th data during xprimnts. simpl rlay fdback xprimnt and to us Ziglr-Nichols mthod typ of control dsign mthod to dtrmin th suitabl alu of thr paramtrs namly, K p, K i, and K d to satisfy crtain control spcifications. Th block diagram of th proposd controllr schm is gin in Figur 8. Figur 8 Block diagram of th PD controllr for DC motor systm Figur 5 Exprimntal Bnch-Tsts Figur 6 Data loggr systm A. Paramtr tuning for PD controllr Th transfr function of a PD controllr is gin by: Figur 7 Exprimntal ngagmnt bhaiour of opn loop EMFC systm IV. PROPOSED CONTROLLER Adancd control stratgis in many diffrnt tchniqus ha bn proposd in th litratur during standing start to control th dry clutch ngagmnt procss, th main objcti of thos dsign controllrs is to nsur that two fundamntal conditions; no-kill conditions and no-lurch conditions ha to b satisfid [8] and [9]. Th no-kill condition stats that th ngin stall must b aoidd, whras th no-lurch condition assums that th unwantd oscillations inducd in th powr-train should b rducd in ordr to prsr th drir comfort. Howr ths rquirmnts ar conflictd with a minimum duration of th ngagmnt tim lik an oscillations inducd in th powr-train systm du to th suddn chang of torqu within limitd of tim during th clutch ngagmnt procss. Also for an ngin could b stalld if an xcssily fast ngagmnt procss is occurrd. In ordr to satisfy th diffrnt rquirmnts and dsir ngagmnt tim, this papr proposs a PD controllr to control th clutch systm for th ngagmnt procss bcaus PD controllr is quit asy to b achid and can mak th systm ha xcllnt prformancs through optimizing th P and D paramtrs [13]. Significant fforts ha bn dotd to proiding tuning of PD controllr paramtrs. A mthod for automatic tuning of simpl rgulators was introducd in Astrom and Hagglund [14]. Th ida was to dtrmin th critical priod of waform oscillation (T c ) and th critical gain (K c ) from a GPD = K p + K d s (13) Th paralll form of th PD controllr has transfr function: GPD = K p 1+Td s (14) Th alus of critical priod of waform oscillation (T c ) and critical gain (K c ) is dtrmind using Astrom-Hagglund mthod and will b usd in Tabl 1 in ordr to obtain th initial paramtrs of PID controllr. Rlay fdback is utilizd as a controllr to th closd loop control systm of th DC motor as shown in Figur 9. Th priod of oscillation attaind from a proportional fdback is approximatly th critical priod. Basd on this critical priod (Figur 9, [15] and [16]) th critical gain can b drid as follow: 4d K c = (15) a Figur 9 Th rlay fdback controllr

5 , Jun 30 - July, 010, London, U.K. Onc T c and K c alus ar obtaind, th PID paramtrs (K p, T i, and T d ) can b spcifid using Ziglr-Nichols formula (Tabl 1). Tabl 1 Ziglr Nichols paramtr tuning. K p T i T d P 0.50 K c PI 0.45 K c 0.85 T c PI D 0.60 K c 0.50 T c 0.15 T c using quation (15), th critical gain (K c ) was found to b Thn, by applying th Ziglr-Nichols formula (Tabl 1) th alus of K p, T d, and T i can b obtaind. Finally, th thr paramtr gains of PID can b spcifid as follows: K p = 59.7, K i = , and K d = 3.7. From this data, it can b sn that th alu of th intgral gain (K i ) is much biggr compar to othr gains. Basd on th systm bhaiour prformd during rlay fdback xprimnt, a small tolrabl stady stat rror has occurrd; thrfor th intgral gain was not usd for controlling this kind of systm bcaus th us of big intgral gain will mak th systm unstabl. Th tuning algorithm proposd in this papr only tuns th proportional gain (K p ) and driati gain (K d ) of th PID controllr. Th intgration gain (K i ) in this mthod was not usd. Thr ar thr rasons why th intgration gain was not usd [13]. Firstly, it is hard for th intgration gain to kp stabl th plant haing a dad zon which is usually xistd in an lctrical actuator systm. Onc th systm works in th dad zon, th control signal will b zro. But th intgration function maks it impossibl, bcaus it will sum up th small rror of th dad zon, and gi out a control signal. Th scond rason is th rror of this PD control systm is not ry big bcaus a strong K p and it is tolratd for an lctric actuator usd in th EMFC systm. For th last on is th PD controllr is asy to b ralizd, and th rliability of th systm is much bttr. V. SIMULATION AND PERFORMANCE EVALUATION Matlab/Simulink is usd to simulat th mathmatical modls of th EMFC basd on th xprimntal alus as rportd in Figur 7. A part of this simulation schm for EMFC which is th dry friction clutch systm usd in this work is an olution that on prsntd in [11]. In ordr to aoid th ngin stall during standing start scnario, th ngagmnt procsss at constant alus of th ngin spd (at 500 and 3000 rpm) ha bn considrd [9]. Th diffrnt ngagmnt bhaiours ar dtrmind by 10 Nm of th load torqu for ach constant ngin spds. Th simulation will us paramtrs of th dry friction clutch systm basd on mdium siz car prsntd in []. Th DC motor systm and th othr parts of EMFC modls ha bn both idntifid from data shts on th basis of thortical and physical laws and rcognizd xprimntally. All rlatd paramtrs ha bn chosn and shown in appndix (Tabl ). Simulation studis of th proposd PD controllr ar carrid out in ordr to instigat its ffctinss in this position control. Control prformanc is dtrmind basd on prcnt orshoot (POS), sttling tim t s, and stady stat rror ss of th systm. A closd loop control application incorporating Astrom-Hagglund mthod basd on a rlay fdback controllr was carrid out to attain th critical priod of waform oscillation (T c ) and th critical gain (K c ) which ar thn usd as initial paramtr gains for th PID controllr. Th amplitud of th rlay controllr is st to 48 sinc th input oltag is in th rang of -4 to +4 olts. From th simulation rsults, th following paramtrs T c, a and d wr found to b s, and 48 rspctily (Figur 9). By Figur 10 Output rspons whn th powr scrw mchanism nd to mo axially for ngagmnt procss Figur 10 shows th output rsponss of th controllr systm. It can b obsrd that th prcnt orshoot of th manual tuning of PD controllr (about 0.15%) is smallr than that of Ziglr-Nichols auto tuning mthod (about.05%). Thus, PD controllr with manual tuning gis bttr rsult with good minimum (tolrabl) rror. Howr, PD controllr with Ziglr-Nichols tuning gis a guidanc to attain th initial paramtrs of PID controllr. In trms of prcnt orshoot and stady stat rror, both PD controllrs with diffrnt tunings ha good prformanc. Figur 11 Engagmnt spd profils of EMFC for diffrnt alus of ngin spd By prforming a closd loop control application, th smoothr ngagmnt procss has bn achid, whr th tim driatis of ώ and ώ ar almost qual to zro and at th momnt of slipping phas of ngagmnt procss as shown in Figur 11. Furthrmor, th PD closd loop controllr dos slightly rduc th unwantd oscillations inducd in th powr-train during slipping phas of th

6 , Jun 30 - July, 010, London, U.K. ngagmnt procss and considrably rduc ngagmnt tim. VI. CONCLUSION Simplifid static and dynamic modls of a nol Elctro-Mchanical Friction Clutch (EMFC) ha bn dlopd and prsntd. Th ngagmnt procss during standing start scnario for th EMFC has bn considrd. A Matlab/Simulink simulation schm has bn built and a control schms ha bn implmntd and tstd within th simulation nironmnt of th EMFC systm. Som numrical rsults of th control ngagmnt procss ha bn aluatd in trms of position control application and its shown impromnt achiabl by mans of th proposd controllr. Furthr optimizd by dsigning and tuning th proposd controllr will soon b tstd on an EMFC bnch-tst. APPENDIX Tabl Modl paramtrs Dry Friction Clutch Paramtrs Valu Unit I 0.45 kg m I kg m b 0.03 Nm s b 0.03 Nm s μ d R m Powr Scrw Mchanism d m 0.04 m μ m l 0.00 m DC Motor V a 4 V L a H R a B m x 10-3 Nm/rad/s K T 0.07 Nm/A T L Nm J m 9.00 x 10-4 Nm.s K b x 10-3 mv/(rad/s) REFERENCES [1] Lucnt, G., M. Montanari, t al. "Modlling of an automatd manual transmission systm", Mchatronics 17(-3): 73-91, 006. [] L. Glilmo and F. Vasca, Optimal control of dry clutch ngagmnt, SAE Transactions, Journal of Passngr Cars, Mchanical Systms, ol. 6, no , 000. [3] B. K. Powll, K. E. Baily, S. R. Cikank, Dynamic modlling and control of hybrid lctric hicl powrtrain systms, IEEE Control Systms Magazin, p , [4] Yamamoto, M, Wakahara, T. Okahora, H. and Oshita, H, Hydraulic systm, shift and lockup controls dlopd for a larg torqu capacity CVT, Intrnational Continuously Variabl Transmission and Hybrid Transmission Congrss, Sptmbr 3-5. [5] Kasai, Y. and Marimoto, Y., Elctronically controlld continuously ariabl transmission (ECVT-II), Intrnational Congrss on Transportation Elctronics, 1988, pp [6] P. Dolcini, C. Canudas d Wit, and H. Bchart, Improd optimal control of dry clutch ngagmnt, Proc. of th 16th IFAC World Congrss, 005. [7] Chiw Y. S., M. Z. Md Zain, K. B. Tawi, S. Ariyono, B. Supriyo and Ng. W. S., Prformanc of proportional control in CVT lctro mchanical clutch, CIM-07, 007, Johor Bahru. [8] A. Srrarns, M. Dassn, and M. Stinbuch, Simulation and control of an automoti dry clutch, Proc. of th Amrican Control Confrnc on Boston, Massachustts, p ol.5, 004. [9] F. Garofalo, L. Glilmo, L. Iannlli and F. Vasca, Smooth ngagmnt of automoti dry clutch, Proc. of th 40 th IEEE CDC, pp , 001. [10] Shuiwn, S., G. Anlin, L.Bangji, Z. Tianyi and F. Juxin, Th Fuzzy control of a clutch of an lctronically controlld automatic mchanical transmission, JSAE Tchnical Papr Sris, [11] Using simulink and statflow in automoti applications, Th Mathworks Inc., [1] L. Fn, L. Yuxuan, Z. Jianwu and H. Hongchng, Robust control for automatd clutch of AMT hicl, SAE Tchnical Papr, no , 00. [13] J. Chng, X. Yao, Control of lctric actuator using brushlss DC motors and its prformanc aluation, ICICTA'09 Scond Intrnational Confrnc Intllignt Computation Tchnology and Automation, Vol. 3, Oct. 009, pp [14] Åström, K. J. and T. Hägglund, Automatic tuning of simpl rgulators with spcifications on phas and amplitud margins, Automatica 0(5): , [15] Hyung-Soo Hwang, Jng Na Choi, Won Hyok L, Jin-Kwon Kim, A Tuning for Th PID Controllr Utilizing Fuzzy Thory, IJCNN 99 Intrnational Joint Confrnc on Nural Ntwork,1999 Vol. 4,10-16 July 1999, pp [16] B. Supriyo, K. B. Tawi, H. Jamaluddin, and S. Ariyono, DC Motor Position Control for Pully Axial Momnt of an Elctromchanical Dual Acting Pully (EMDAP) CVT Systm, 1st Rgional Confrnc on Vhicl Enginring & Tchnology, 3-5 July 006. ACKNOWLEDGEMENT Th authors would lik to thank th Malaysian Ministry of Scinc, Tchnology and Innoation (MOSTI) and Unirsiti Tknologi Malaysia (UTM) for thir continuous support in th rsarch work. This work was financial supportd in part by th Malaysia Scincs Fund undr Grant numbr Vot