Study on Fuzzy Automatic Transmission Strategy of vehicles

Transcription

1 Study on Fuzzy Automatc Transmsson Strategy of vehcles ZhY Zhang BeHua Unversty Engneerng Tranng Center JLn Cty, P.R.Chna Dngxuan Zhao JLn Unversty College of Mechancal Scence and Engneerng ChangChun Cty, P.R.Chna Be Sun BeHua Unversty Mechancal Engneerng Insttute JLn Cty, P.R.Chna Abstract In ths study we dscussed automatc transmsson method of vehcles utlzng fuzzy technology and composed a control unt usng PLC(PLC: programmable logcal controller), and verfed the correctness of ths method on the automotve transmsson testng table. The result of the experment showed that, usng the fuzzy automatc transmsson strategy, dfferent shftng strateges would be used n dfferent workng condtons, wth effectvely avoded the problems occurred n crculated shftng and delay shftng. Ths control rule has enrched the operatonal theory of the vehcles and has produced a knd of practcal control method. Keywords vehcles, automatc transmsson, fuzzy control, PLC I. INTRODUCTION Most of the vehcles have bad operaton and workng envronment. The drver should operate the workng devces and at the same tme manually and frequently change the gears n order that the power performance of the vehcles can satsfy the workng performance[1]. The operators work wth great workng strength whle the economy performance of the vehcles can not be secured. The realzaton of the automatc transmsson of the vehcles wll be able to ncrease the transmsson effcency, the workng effcency, and at the same tme, decrease the laborng force. So t s practcal to realze automatc transmsson system of the vehcles. When the drver wants to shft, he can decde accordng to the surroundng condtons checked and the runnng condtons of the vehcles and the experence n drvng. Ths system utlzes the fuzzy controller to mtate human beng. Through the analyss on the samples of sgnals of engne rotaton speed, turbo output rotaton speed and the throttle degree and the analyss on the operaton status of the vehcles, the analyss results are delvered to the fuzzy reasonng unt to conduct nference. The result wll drve gear-shft(type s 4D180, XuGong Co.,Ltd, Chna) n automatc shftng, ths can ensure effcency of the torque converter s hgh. II. NOMENCLATURE η : Effcency of hydrodynamc torque converter (deal value,η 0.75) λ B γ:moment modulus of hydrodynamc torque converter K :Change torque modulus of hydrodynamc torque converter :Transmsson rato of hydrodynamc torque converter 1 : Settng Mn-transmsson rato 2 : Settng Max-transmsson rato n 1 : Engne Rev [r/mn] n 2 :Turbne Rev of hydrodynamc torque converter [r/mn] g : Shft poston T : Load torque [Nm] α : Throttle poston [ ] III. RULES OF FUZZY CONTROL A. Rules of fuzzfcaton In constructng the rules of shftng, all the operatonal parameters, such as engne rotaton speed, turbo output rotaton speed and throttle openng degree and other nformaton alke, shall be collected nto the controller n order to get the correspondng shftng rules wth fuzzy calculaton. The followng s the fuzzy shftng rules got from summarzng the operatonal experences of the drvers and accordng to the utlzaton characters of the vehcles. 1) In case of operaton n hgher shft, the economy performance shall be regarded as the rule of shftng. 2) In case of operaton n lower shft, the power /08 /$ IEEE CIS 2008

2 performance shall be regarded as the rule of shftng. 3) In case that the hydrodynamc torque-converter does not work n the hgh effcency area, the shft shall be decreased or ncreased to make t work n the hgh effcency area 4) In case that the throttle openng degree s very large, the shft shall be ncreased n normal travel, or shall be decreased n workng condton. 5) In case that t s n travelng condton for a long perod, the economy shft shall be adopted and at the same tme, consderng the effcency of hydrodynamc torqueconverter. 6) In case of short perod travelng or to-and-fro travelng, the usage range of lower shft shall be ncreased. 7) In case that the engne wll be over the speed, the shft can not be ncreased. 10 λ γ K K η =0. 75 λ γ η η IV. STRATEGY OF FUZZY AUTOMATIC TRANSMISSION A. Structure of the controller of fuzzy Automatc transmsson Automatc transmsson controller s the core of the whole control system. Fgure 2 shows the structure of the controller for fuzzfcaton reasonng transmsson. It s decded by the controller through collectng the throttle degree, engne rotaton speed, hydrodynamc torque-converter output rotaton speed and analyzng the parameters, the workng condton of the system and accordng to the gear-shftng rules, thus guaranteeng the hghest transmsson effcency of the system and the best performance. Heren, the nput s engne rotaton speed n 1, turbo output rotaton speed n 2, the output s shft g. the throttle degree s α, t s the parameter for selectng the rules n database. n 1: Eng ne Rev n 2: Tur b ne Rev Fuzzfcaton Fuzzy nference Defuzzfcaton pos t on Fgure 1 orgnal characterstc for hydraulc torque converter B. Basc technology of fuzzy Automaton transmsson In ths system, the ncreasng and decreasng of the shft s accomplshed accordng to the effcency of the hydrodynamc torque-converter, see Fgure 1. Wheren, refers to the transmsson rato of the hydrodynamc torqueconverter.[2](general η < 0.7[1], n ths paper η mn =0.75) 1)When η>η mn, the workng pont of the hydrodynamc torque-converter s n the hgh effcency area, t s not necessary to change the speed of the gear-shftng, and at ths tme, we choose the orgnal shft of the gear-shftng. 2)When η<η mn, the workng pont of the hydrodynamc torque-converter s n the low effcency area, the gear-shftng shall be adjusted or the addtonal loadng moment shall be adjusted n order to ensure the torque-converter workng n the hgh effcency area. As there are two low effcency areas n the hydrodynamc torque-converter, we call the area wth torque-convert rato of K>1 as K1, and the area where K<1 s called K2[3]. If K>K1, the gear-shftng shall be decrease by one shft; If K<K2, the gear-shftng shall be ncreased by one shft. 3)If the gear-shftng s dfferent(form 1 to 4) n the Fgure 1, theηcurve wll change,so 1 and 2 wll change too( 1,2 =f (η)). We set four group data of 1 and 2 n the fuzzy controller. The shft wll be changed by the fuzzy controller accordng dfferent 1 and 2. α :Throttle poston Fgure 2 Fuzzy transmsson controller structure B. Rules of fuzzy gear-shftng 1)4 fuzzy sets are used to descrbe the engne rotaton speed n1: mn, small, large, max, marked as {VS, S, B, VB}; 5 fuzzy sets are used to descrbe the turbo output rotaton speed n2: mn., small, mddle, large, max., marked as {VS, S,M, B, VB}; 4 fuzzy sets are used to descrbe shft 1, 2, 3, 4, marked as {I, II, III, IV}. The true areas needed for samplng are respectvely converted nto nternal areas of the fuzzy controller: {0,1,2,3,4,5,6}, {0,1,2,3,4,5,6,7,8}, {0,1,2,3,4,5,6,7}, and ts 12 a + b y = [x ] (1) b a 2 mappng relaton s (x`s actual change range s [a,b],t wll change accurate varable of [a,b] nto y varable of {0,6}or {0,8}or {0,7}.If y s not a nteger, t wll be come down to a nteger that t s the nearest y[4]), then trangle-trapeza method are utlzed to establsh membershp functons for n1, n2, and g, the results are shown n Fgure 3. VS S α 1 Rul e base 1 α 2 Rul e base 2 VB (a) n1:member sh p f unct ons of eng ne r ev B Rul e base α 10 Rul e base10

3 VS S M B VB As Fgure 4 shows, hardware of the fuzzy controller s combned by PLC, HMI, nput sgnal, output drve, communcatons, computer program and confgure. n1: Eng ne Rev PC/PPI RS232 Per sonal Comput er (b) n2:member sh p f unct ons of turb ne rev n2: Turb ne Rev α :throttl e pos t on PLC Fuzzy Controller RS485 HMI D s pl ay n1, n2 D spl ay sh f t Set t ng par ameters Manual /Aut o swtch Ampl f er val ves Ⅰ Ⅱ Ⅲ Ⅳ Fgure 4 consttutes of fuzzy controller (c) g:member sh p f unct ons of sh f t pos t on Fgure 3 Membershp functons 2)To determne 20 reasonng prncples by summarzng the experences of the people. IF n1 IS VS AND n2 IS VS THEN g IS Ⅰ IF n1 IS VS AND n2 IS S THEN g IS Ⅱ The results from the fuzzy reasonng usng Mamdan algorthm consttute the fuzzy control nqurng lst for a certan degree of throttle[5]. Table 1 s the fuzzy control form of travelng wth accelerated speed. Table.1 Inqurng lst of fuzzy control n some throttle n n 1 2 g The target of the control system s to mantan the best effcency of the system. So fuzzy control makes also the best transmsson effcency as the gear-shftng prncple. Through large amount of experments, collectng the transmsson status wth throttle of dfferent degrees (engne rotaton speed, turbo output rotaton speed, shft poston), and make them as the specmen for makng the fuzzy lsts and generatng the fuzzy control form on off-lne. The fuzzy control basng on ths form can acheve the control target n steady status. Save the fuzzy nqurng forms under varous condtons nto the controller, then the controller wll control on the gear-shftng accordng to the real operatonal condtons nqurng data n the lst. C. Consttute of fuzzy controller In followng, we wll ntroduce each part purpose. PLC(Programmable Logcal Controller, S7-200 CPU214 transstor output, SIEMENS Co.,Ltd.): hardware of fuzzy controller; software nclude sample subprogram, man program, fuzzy reasonng program etc. When PLC fuzzy controller samples nput sgnals(engne Rev, turbne Rev, throttle poston), these sgnals wll be changed and fuzzfed and delvered to the fuzzy reasonng unt n PLC, the result wll drve shft valves. HMI(Human Machne Interface, PWS1700-TSN, Delta Co.,Ltd. ): settng and dsplay parameters. RS485: communcaton nterface connect PLC wth HMI. Amplfer: amplfy PLC output sgnal to drve shft valves. Personal computer: program and confgure to PLC and HMI, connect PLC wth PC/PPI cable, connect HMI wth RS232 nterface. Control procedure: f nstructon for forwardng s gven, t shall be gven to the frst forward shft, and then the controller wll gve the proper operatonal shft accordng to the samples nput sgnals and through fuzzy calculaton and reasonng. The followng regulatons are gven for the gear-shftng delay: the nterval of two shfts s allowed to be 2s (whch can be adjusted accordng to the practcal stuaton), that s, after one shft, the next s allowed after 2s. The followng regulatons are for ntervals of shfts: When shft s allowed, the tme taken for changng from one shft to another s s (whch can be adjusted accordng to the real stuaton). V. EXPERIMENT A. Automatc transmsson system test bed Fgure 5 shows the structure of the automatc transmsson system test bed. It s composed by desel engne, hydrodynamc torque-converter, gearng box, accelerator and electrc-eddy power measurng nstrument. Wheren, the engne s the orgn of the power. The gearng box s composed by 4 forward shfts and 4 backforward shfts, whch are controlled by 6 electro-magnetc valves. The electrc-eddy power measurng nstrument s a devce for addng load to the transmsson testng bed. The brakng load wll be adjusted by

4 adjustng the wndng current, thus mtatng the operatonal condtons of the vehcles. The accelerator s manly used to match the central dstance between the two transmsson shafts. The fuzzy controller s made of PLC, whch set up and dsplay the parameters usng HMI, and change the shft by controllng the electrc-magnetc valves accordng to the fuzzy gear shftng rules through samplng of the engne rotaton speed, turbo output rotaton speed and throttle openng degree. D esel eng ne Tr ansm- ss on val ves Hydr aul c torque convert er Ra se transmss on El ect r c eddy power - measur ng nstrument Throttle Engne rev PLC f uzzy control l er Turbne rev Powermetry controller Fgure 5 consttutes of automatc transmsson system test bed B. Analyss on the testng results Frstly we shall calculate the loadng torque needed n varous workng condtons, then load t through adjustng the electrc-eddy power measurng nstrument so to mtate the gear-shftng process of the vehcles under varous workng condtons. Fgure 6 shows the curves of the gear-shfts that s changng wth the tme n the stuaton of accelerate runnng and of load condtons. The runnng process of the vehcle wthout load s: start, accelerate, steady runnng process. The change of the shft, see left of Fgure 6a, the vehcle start from the frst shft and change t contnuously to the fourth shft and keep t at ths shft durng runnng, no crculaton shftng process. When t s n load condton(fgure 6c), the change of the shft,see rght of Fgure 6a. wth the workng shft strategy, though ncrease load of the power measurng nstrument, Fg 6b shows effcency curve changed form four shft hgh effcency area nto one hgh effcency area. It satsfy the condton of η mn >0.75. Accordng to the performance curve (Fgure 1) of hydrodynamc torque-converter, the effcency of hydrodynamc torque-converter s changng wth ts transmsson rato, that s, η=f(). The transmsson rato wll come through the engne rotaton speed n1 and hydrodynamc torque-converter n2 and the effcency curve η wll come nto beng through the effcency curve. If η>0.75, the hydrodynamc torque-converter wll work n the hgh effcency area and t need not to change the shft; f η<0.75, the hydrodynamc torque-converter wll work n the low effcency area and t need to change the shft (ncrease or decrease shft). Fgure 6 change rule of automatc transmsson test bed

5 VI. CONCLUSION The results show correctness of the automatc transmsson and the effcency of hydrodynamc torque-converter s hgh(η>0.75). Shft s steady and smooth and very lttle mpact. The control system s workng relably from testng, the fuzzy control strategy can determne the runnng status of the vehcle, thus realzng the change of shfts correctly. Due to the hgh relablty of PLC, the perod of development s very short, PLC can consttute the controller used for test, and t s also can be used n real vehcles. From the above, the fuzzy control strategy s sutable for automatc transmsson n vehcles, and t has a hgh steadness and excellent performance. REFERENCES [1] Zhao Dngxuan, Ma Zhu, Yang Lfu. Analyss of Dynamc Performance of Hydraulc and Mechancal Transmsson System of Engneerng Vehcles. Chna Mechancal Engneerng, (8): [2] Zhu Jngchang. Desgn and Calculaton of Torque Converter. Naton Defense Industry Press, Bejng,1991. [3] Gong Je etc. Study on Shft Schedule and Auto-Controllng Smulaton of automatc Transmsson. Journal of X An JaoTong Unversty,2001.9(9): [4] Y JKa, Hou YuanBn. Intellgent control. BeJng Industry Unversty press,1999. [5] Zhu Jng.Theory and Applcaton of fuzzy Control. Mechancal ndustry Press,1995.