Study On Multiple Sliding Mode Control Method For DCT Dual Clutch Engagement With Dynamic Characteristics

In recent years, oil consumption, energy conservation and emissions reduction and environmental protection has become a hot topic in the automotive industry, fuel consumption regulations of our country is becoming more and more strict, which presents a severe challenge for the automotive industry. In order to compete in the future, the automobile enterprises must strive to make breakthroughs in the core technology. As the current leading-edge Transmission products of the dual Clutch automatic Transmission (Dual Clutch Transmission, DCT),the research on dual clutch control system has become one of the main ways to realize new the new fuel consumption regulations. It has important theoretical significance and application value for the accurate control of clutch and improve the fuel economy and power.At present, there is little research on the wet dual clutch hydraulic control system, which has not formed a mature theoretical system. For the study of the dual clutch control, it is mainly focused on the calculation of the clutch engagement trajectory according to the need of vehicle driving, and the lack of the research on how to perform the clutch engagement. Therefore, it is of great theoretical significance and engineering application value to control the clutch with multiple sliding mode adaptive control method.Based on the analysis and summary of the domestic and foreign wet clutch pressure control, clutch friction characteristics and starting control strategy, By means of theoretical analysis and numerical simulation, the tracking control method of engine rotation speed and clutch driven disk speed is studied in different conditions. To complete the main research work and achievements are as follows:1, A multiple sliding mode adaptive control method is proposed,which is based on the idea of Backstepping,and combines with the input/output feedback linearization method and adaptive control method. This method avoids the appearance of "calculating expansion", further simplifies the design process of the controller, improves the stability and dynamic response of the system,and the control accuracy and robustness of the controller are obtained.2, Based on the analysis of the composition and working principle of dual clutch hydraulic system, the nonlinear model of the proportional pressure solenoid valve and hydraulic actuators nonlinear model is established. According to the nonlinear characteristics of pressure control system, the SMAC clutch pressure control method is put forward. This method has the characteristics of fast response, by combining adaptive control method, the controller has good robustness to the uncertainties of system parameters and external disturbances.3, The mathematical model of the clutch torque transfer is established,and the mechanism of the self-excited vibration caused by the negative slope of the friction coefficient is found. Starting from the expression of system eigenvalue real part, the clutch engagement pressure, friction coefficient, slope and system damping changes impact on the stability of the system is analyzed, thus reduce the jitter of clutch engagement solutions are put forward. To reduce the jitter of clutch engagement process, one way is to through the adoption of paper-based friction material or adding proper additive in lubricating oil, to increase the friction coefficient of the slope; Second way is appropriate to improve the system damping coefficient. In view of the clutch engagement process jitter problem, FLSMC clutch engaging process control method is proposed. This method through the design of sliding mode, the system characteristic value is converted to a sliding mode control parameters,and can improve the stability of the system by increasing the control parameters kiand k2, so as to reduce the clutch torque chattering phenomenon in the process.4, Based on the dynamics model of the starting process, the clutch engagement process as well as the control target and evaluation standard are analyzed, and the starting control strategy is formulated to meet the three requirements. For starting control, a new method for control strategy of the partial constant engine speed is proposed. This method can predict the target speed of clutch driven plate by target jerk and engine target speed,which can improve the vehicle ride comfort.Through the sliding speed threshold value to reflect the driver’s intention, and simplify the design process of the control strategy.5,In this paper,a FLMSMAC control method for starting clutch is proposed. The method uses adaptive method to deal with the problem of parameter uncertainties and external disturbances, and improves the robustness of the system. At the same time, the feedback linearization method is used to transform the dynamic subsystem of the starting process to an equivalent linear system, which improves the system stability and control precision.So as to realize the engine speed and clutch platen speed precision tracking, ensure the accuracy of the start control strategy implementation in theory.