THROTTLE CONTROL STRATEGIES IN THE PROCESS OF INTEGRATED POWERTRAIN CONTROL

CHINESE JOURNAL OF MECHANICAL ENGINEERINGVol.18, No.3, 2005,429●Lei YulongTHROTTLE CONTROL STRATEGIESGao BingzhaoIN THE PROCESS OF INTEGRATEDTian HuaPOWERTRAIN CONTROL .*Ge AnlinCollege of Automotive Engineering,Abstract: Combining with the development of automated manual transmission (AMT), the variousJilin University,throttle control demands are analyzed under different working conditions of AMT such as trackingChangchun 130025, Chinaacceleration pedal, start, shift and so on. Based on simulation, the responding throttle control strategiesare proposed, and a simple but efective throtle control method is presented. The testing results haveYan Suproved that the strategies are effective for improving the pedal tracking precision and the qualities ofstart and shif.Department of Mechanical Engineering,Key words: Electronic throttle control Automated manual transmissionUniversity of Hawai,Integrated powertrain controlManoa Honolulu, HI 96826, USAthe gear position and so on, are fed to TCU. According to the➊INTRODUCTIONcontrol strategies, TCU generates and sends the commands toThe conventional way of controlling the throttle position iscontrol the throttle actuator, clutch actuator and shift actuator in aby stepping on the pedal, which is directly connected to the throt-timing way so that the automatic shift control is realized.tle. While using electronic throttle control (ETC), the driver con-trols the acceleration pedal, whose position information is sensedHandleand transferred to the electronic control unit (ECU). ECU com-DriverBrake pedalTCUbines this information with the vehicle working condition, makesthe proper decision according to the inference logic, and sends thecommand to control the throttle through the control device, whichThrottle Clutch. Shiftis either a DC servo motor or a step motorl"). The diagram of thisYYactuator actuator actuatorcontrol process is shown in Fig.I. In the scheme proposed, theAccelerate pedalETC is integrated into the transmission control unit (TCU).VehicleSenseEngineITransmissiog GearEvnironmentFTL Irput speePedal。Clutch positionsensorTransmissionEngine speedcontrol unitFig.2 Control pinciple of AMTAcelerator pedalThrottlePosition feedback1 ANALYSIS OF CONTROL STRATEGIESig.1 Throttle control process through ECUTo meet the software modularization requirement, AMT con-Electronie trotle is not only necessasry in realizing vehicle trol system is defined regarding. six working cases, specifiallycruise control, but also a key component in achieving the optimal stop, reverse, start, normal driving, shift and brake. The trans-match between the engine and the transmission in the process of forming processes among these cases are shown in Fig.3.the integrated powertrain control. Therefore it is important forimproving the driving performance of vehiclel!- Finish.Combining with the development of automated manualtransmission (AMT), the integrated powertain control process is,D>N-,D>N.analyzed systematically, the thottle control modes and their con-trol strategies are categorized, according to different driving cases,StartStopNormar~ ~N>D'and furthermore, a simple but efective reliable control algorithmBrakedownis proposed for fulling the control strategies. Finally the controlR>Nstrategies are verified in a testing truck with AMTB.FinishFinish ShiftThe basic control principle of AMT is shown in Fig.2. Thescheduledriver drives the car through operating the handle, the acceleration(ReverseShiftpedal and the braking pedal. Besides other positions, there arehree essential handle positions: D-driving forward, N-neutal( Brake_Brakeposition and R-driving backward. The signals reflecting the vehi--7wncle runing conditions such as the engine rotating speed, the input中国煤化工king cses of AMTshaft rotating speed, the vehicle speed, the throttle opening degree,the acceleration pedal opening degree, the brake pedal position,.MHCN M H Gnegies are used in tremodes, which are tracking acceleration pedal, start and shift.' This priee is sppored by Rovinial open Fondation ofKeyLlb for 1.1 Tracking aceleraion pedalAutomobile of Jiangsu, China (No.KJS02076) and 985 Project of AutomotiveThe electronic throttle works mostly in the tracking accelera-Engineering Innovation Platform of Jilin University, China. Rceived January30, 2004; received in revised form March 20, 2005; accepted April 7, 2005 tion pedal mode. This mode covers the conditions of the normal●430●Lei Yulong, et al: Throttle control strategies in the process of integrated powertrain controldriving, stop, brake and so on, where the electronic throtle isHere 0w. is the error between actual engine speed ore and therequired to follow the driver's intention by responding to thetarget speed Wormovement of the acceleration pedal rapidly and accurately. In thismode, the throttle opening is determined by the acceleration pedalS@. =0。-0a .1)positionl".The throttle target position can be assigned according to theHowever, tracking delay is inevitable because of the phaserelationship chart shown in Fig.5.delay of the control system and the mecbanical hysteresis, there-fore the tracking accuracy depends on the responding speed.13 ShiftMoreover, the vehicle vibration due to the road surface uneven-In the shifing process, in order to reduce the impact andness will wobble the driver's foot and therefore generate the un-noise, and elongate the service life of the clutch, it is necessary towanted wobbling noise to the throttle command. To avoid this, weharmonize the actions of the engine, the clutch and the transmis-use an error filter to filter out the wobbling noise, in which a con-sion. This is called the integrated powertrain control process astrol error range is defined providing that the control accuracy isshown in Fig.6.still met. The pedal opening will not change when the pedalopening varies in this scope.Disengag1.2 StartThe sketch map of the starting process is shown in Fig.4.L DisengageTouch points EngageA EngeTime tTime I(aa)Pedal .Dowm .5g富Trotlelp_b)(b)Fig.6 Shiting poces of AMTisThe shifting process is divided into two phases. The firstphase is the duration from the clutch disengaging to the instantwhen the new. gear has been engaged,, within which the engineload is suddenly reduced due to clutch disengagement. This re-sults in the engine power interruption. To avoid the excessiveTime 1noise and fuel waste that is generated by the sharp rising of thec)engine speed, the throtte opening should be reduced significantly.Fig.4 Starting process of AMTIn this process, the engine speed is the main control parameter asWhen the driver pushes the brake pedal down, the clutch isshown in Fig.5.quickly engaged to the touch point. Then, when the brake pedal isSuppose that the vehicle speed is constant during shifting, thereleased and the acelerate pedal is pushed over a pre-set target engine speed can be calculated using the fllowing equationvalue (an) , the starting mode of the control program is triggered.0。=@In this mode, the main control parameter is also the accelerationpedal position, which reflects the driver's starting intention.In order to reduce the engine power loss and noise, our strat-where Oom is the engine speed before shifting, igny is the gear ratioegy here is to keep the engine speed constant at the target speedbefore shifting, ig(n+t) is the gear ratio after shifting, ign+1) is the(0). The engine speed is the secondary parameter in the throtteshifing-up ratio and ig(m .1) is the shifting-down ratio.control. Their relationship is shown in Fig.5.The second phase begins after the clutch engages to the touchpoint. In this phase, with the re-engagement of the clutch the en-gine torque will be resumed. The shifting quality is determined bythe cooperation between the thottle opening and the clutch en-gagemere powertrain, as shownin Eg.(3)中国煤化工-analyze the contollingrelationsleEngine speed rror Ao。MYHCNMHGr.-Te-T=J.“3)e dtengine speed in the starting processg andT.-Tn=JOdt4)CHINESE JOURNAL OF MECHANICAL ENGINEERING●431●where T。is the engine torque; Ter is the resistant torque due to the target speed. From these results we can conclude that in order toengine friction. Tc is the torque due to the clutch friction. In Eq.(3)，keep the lowest speed difference and to reduce clutch slipping,T。is the load of engine and T。≤Tvf; In Eq.(4), T。is the driving first we should control the engine speed close to the target speed,torque and T≤T。Je is the total moment of inertia of all the rotat- then control the engine torque to track the clutch friction torque.ing parts from the active plate of the clutch to the engine. Tvt is theSince when the engine speed is constant, the torque is a functionequivalent value of all the resisting torque to vehicle. J, is the of the throttle opening, the friction torque of clutch is a functionequivalent value of the total moment of inertia of all the rotating of the clutch engagement, we get the telationship diagram be-parts from the passive plate of the clutch to the whcels and the tween the clutch engagement and the thotle opening as in Fig8.vehicle mass. 0e is the rotating speed of the engine and the active Considering driving safety, the thotte canot be higber thanplate. a is the rotating speed of the passive plate. According to pedal position'sEq(3) and Eq.(4) the dynamics model is established and simu-lated using Simulink.Pedal openTo make the analysis of the relationship between the enginetorque and the clutch torque easier and more straightforward, inthe simulation all the resisting torques are regarded as constants.The research uses the rotational speed difference between theactive plate and the passive plate to control the engine torque, anda PI controller is designed as the controller. All the parametersused in simulation are shown in Table. Where, K is the integralcoefficient and Kp is the proportion coefficient. The simulationEngageTouch pointDisengageresults are shown in Fig.7.Clutch position 1cFig.8 Control relation of trotte and clutch in shift processTable Sinulation parametersParameterValue2 CONTROL METHODT。/(N●川)100J/(kg●mTel/(N●m) .J(kg" m2)The throttle is actuated by a stepper motor, which is con-TIr/(N.m)90山e/(r●min )300trolled by a special driver with two output ports. One is the pulse_K4060port, through which the pulse signals are sent out, in each pulsethe motor will run one step at a certain angle. If this port is set at aconstant level then the motor will be held. The other is the direc-tion port. If a high level is sent to this port, the motor will move in1201the direction of increasing the throttle opening, and vice versa.The load of the motor is the force of the throttle retracting spring.ERR 80-Even though the stepper motor can achieve accurate pos itioning0fTwhen open-loop, considering the significance of throttle controland its tough environment, here we use it in the closed-loop way.Furthermore, the throttle speed-tracking is also required besidesthe position-tracking. Therefore, regarding that under each pulse0.20.40.60.8.0the motor will move the same angle, a PI contoller is designed, inTime 1/swhich the input is the error between the target position and the(a) Rigial engine speed is higher than target speedactual position, and the output is the pulse period (t), i.e, toachieve speed-tracking by adjusting the pulse period. Fig.9 shows旨男E 120the control diagram, where tpmnx is the upper limit of period that isdetermined by the acceptable error.g 80~I String” 4CTof_A些Calculate targepositionlalposition (Q) position (a)O.0.0.81.0Time /sCalculate error (Aa)(b) Riginal engine speed is equal to target speedAa= a-aβad≤daNo_200-Yesy20-Set high level厂Calculateto impulse | periodic timeportPrinSpS YesNoTe↓.↓11 Send immilce Il Set high level Set low level0.4 0.61.0中国煤化工- direction to directionTime t/s= port(c) Riginal engine speed is lower than target speedMHCNMH(Fig.7 Simulation resuts of torque control for dfferent OoeDelay to theperiotic timeIn Fig.7a the original engine speed is higher than the targetspeed, in Fig.7b the original engine speed is equal to the targetFig.9 Control metbodspeed, and in Fig.7c the original engine speed is lower than the.●432●Lei Yulong, et al: Throttle control strategies in the process of integrated powertrain control3 TESTING3.3 ShiftIn the shifting process the integrated powertrain controlAll the strategies and method are verified on a testing truck quality will be exhibited fully. The results of up-shifing andwith AMT. The step angle of the motor is 1.6 rad, gear down ratiodown- shiting are shown in Fig.13 and Fig.14, respectively.is 3.0, controlling accuracy is set to be 5%, minimum pulse periodHere the engine speed is controlled at target speed successfully,tpmin and maximum pulse periods tpmaxa are set as 3 ms and 15 ms, and the clutch slipping reduction is achieved too. After shifing,respectively.to fulfll the driver's intention, the throtte tracks pedal as soonas possible.3.1 Tracking acceleration pedalFig. 10 shows the tracking performance of the throttle to theacceleration pedal. It shows that the cortolling error is 5%, theresponse time from 0% to 100% or from 100% to 0% is 450 ms,the average delay time is 120 ms. The delay is determined notonly by the actuator parameters, but also by the values of thepre-set control accuracy and the minimun control period. For thegεClutchInput shaft speedsystem, the higher the accuracy and the shorter the minimum con-爱家琴trol period, the shorter the delay time. The response of the throttleto the pedal jarring is shown in Fig.11. It can be seen that whenthe pedal wobbles are in the range of - 5% to 5%, the throttle does20212232425 26Timet/snot change, in this way the engine could work in a smooth way,and therefore elongate its life and improve emission quality.(a)Throttle open100r5880-Pedal openControl error 5%区60-60r Hystercal timne 0.12s” 40-Throtle open20-20-本之一24 25 261717sTime 1/s(b)Fig.10 Throule response in the tracking aceleration pedal mnoedFig:13 Result of up shifig test58 80-Clutch positionEnine speed155156157158159160161162163Time t/s/Input shaft speedFig.11 Thotle response to the pedal jaring257258259260261- 262 263Time i/sa)3.2 StartThe result of the starting test is shown in Fig.12. It can beseen from Fig.12 that, while tracking the pedal position, the har-mony among the throttle, the clutch and the engine achieves theEy 100psteady speed running of the engine, and reduces the clutch slip-ping.医60Throttle open/更20-257 258 259 260 261 262 263Engine speedb)Fig.14 Result of down- shifing testInput shaft speed -89919293 942号出E4 CONCLUSIONSThe parameters for controlling the engine speed and theengine torque include the throttle angle, the oil injection, theignition advance and so on. Aiming at finding out what aree 60Pedalrequiredhe engine torque inthe proc| 中国煤化工: control, the researchtakes AMYHthe throttle controlThrotlestrategieCNM H Chis rserch will notonly make a great sense for improving the controlling qualityof AMT, but also provide a valuable reference to other re-searches considering the matching issue between the transmis-(bsion and engine.Fig.12 Result of the sarting testCHINESE JOURNAL OF MECHANICAL ENGINEERING●433●automatic control theory of vehicle, powertrain integration control, develop-Referencesmentotautonantes Toanataniassto etei,Tel: +86-431-5095198; E-mail: leiyl@jl.edu.cnDaniel M, Gary N, Bart S. Delphi electronic throtule control systems forGao Bingzhao is a PhD candidate in College of Automotive Engineering, Jilinmodel Year 2000; Driver features, system secunity, and OEM benefits. ETCUniversity, China. His research interests include driveline automatic controlfor the mass market. SAE Technical Paper No.2000-01-0556theory of vehicle.! Peter J M. A production wide-range AFR control algorithm for direct injec-Tel: +86-431-5095198; E-mail: gaobz@jlu edu.cntion gasoline application. SAE Technical Paper Series, 2001-01 -02603 Lei Y L. Study on auto-shifting technology for bus based on advancedTian Hua is a PhD candidate in College of Automotive Enginering, Jilin Uni-public transport system: [Postdoctoral Report]. Jilin: Jilin University,versity, China.，Streib H M, Bischof H. Electronic throtle control (ETC): A cost effectiveTel: +86-431-5095198; E mail: huacage@163.comsysterm for improved erisions, fiucl economy, and driveability. SAE Tech-Ge Anlin is a professor in College of Automotive Engineering, Jilin University,Stanton N, Marsden P. Drive-by-wire systems: Some reflections on theTel: +86-431-5095198; E mail: gebjl@jlu edu.cntrend to automnatethe driver role. SAE Technical Paper No.18-211-D4-267Yan Su is curently a PhD candidate in Departmeat of Mecbanical Engineering,Biographical notesUniversity of Hawai, Manoa, USA. Her research interests are optimization andLei Yulong is currently an associate professor in Collcge of Automotive Engi- control of inelligent composite structures, active vibraion sppression andsity of Technology, Cbina, in 1999. His research interests include driveline中国煤化工MYHCNMHG