Research On Shift Quality Control For Automatic Transmission

Gearshift control is a key point in automatic transmission control, which not onlyconcerns about the comfort in gear shifting but also plays an important role in the lifetimeof a clutch, so the research of shift quality control has great theoretical significance andhigh value in engineering.Based on a hydraulic mechanical automatic transmission with wet clutches, the dis-sertation is dedicated to study the closed-loop gearshift control. Under the in?uence of thewear of clutch materials, the oxidation of automatic transmission ?uid (ATF) and variationof temperature, clutch friction characteristics change during the usage, therefore, how toovercome and suppress its in?uence on the shift quality is the major concern in the study.After that, in order to further enhance the shift quality, the power-train integrated gearshiftcontrol is studied as well.Firstly, in order to study and analyze the gearshift control, power-train model andthe simulation environment are built. In this dissertation, from the perspective of gearshiftcontrol, combing with the professional engine simulation software enDYNA, the simula-tion platform is set up in the MATLAB/Simulink environment for the sake of analysis, inwhich the model of engine, automatic transmission, as well as axle shaft and vehicle loadare involved. With different axle shaft, two control-oriented gearshift models with stiff,torsional axle shaft are given and verified in the simulation environment.Secondly, gearshift controller design with stiff axle shaft is studied on the basis of theturbine speed regulation. When the clutch slip control is controlled effectively by turbinespeed regulation, the lifetime of the clutch can be guaranteed during gear shifting. Atwo-degree-of-freedom PID (2DOF PID) gearshift controller is designed by static outputfeedback control theory. On the one hand, feedforward channel is applied in this controllerto suppress the in?uence of changed turbine torque on turbine speed regulation; on theother hand, for the varies of clutch friction characteristics and parameter uncertainties ofhydraulic control system, robust control is discussed in the feedback channel design.Moreover, anti-shudder gearshift controller design with torsional axle shaft is pro-posed in the following. For torque converter plays an important role in the suppressionof output shaft torque oscillation, it is involved as the controlled plant in this study, and clutch pressure controller is designed on the basis of the sliding mode output feedbackcontrol technique, the in?uence of variable clutch friction characteristics on the outputshaft torque oscillation and the system stability is overcome. By clutch pressure con-trol, the proposed approach combines with the measurement information of the chassiscontrol system and gearbox, achieves turbine speed regulation and suppression of outputshaft torque oscillation at the same time.Lastly, based on anti-shudder gearshift controller, which overcomes the in?uence ofclutch friction characteristics on gearshift control and suppress the output shaft torquesoscillation, a discussion of the power-train integrated gearshift control is further presentedto enhance shift quality. The control strategy takes electro-hydraulic system inputs, enginethrottle opening and efficiency correction factor of spark angle as control inputs, and thepowertrain integrated gearshift controller is designed by applying backstepping techniqueand control allocation. By the proposed controller, not only turbine speed is controlledproperly, but also the shift quality is improved as well by further smoothing output shafttorque.