Simulating Study On Vehicle Hill-start Control Of Dual Clutch Transmission

With the development of the automobile automatic operation, automatic transmission has a booming trend and wide use because there are many advantages such as easing the drivers'labor intensity, increasing the life of the engine and power train, improving the economy and emission performance and so on. Dual Clutch Transmission(DCT)is a new automatic transmission system build on the parallel shaft transmission . It maintains the advantages of the Manual Transmission such as simple structure, low cost and high efficiency. At the same time, it can change the ratio with the power on so that the shift time will be shortened and shift quality can be increased. Dual clutch transmission has excellent capability and wide foreground.The dissertation is about how to develop the dual clutch transmission control system. Based on the abroad achievements in this field, the following issues are discussed: modeling of dual clutch transmission control system, analysis of the effect of hill-start, the design of control logic. There are seven chapters in the dissertation.In Chapter One, the function and the construction of dual clutch transmission system are introduced. The research history and present status of the automatic transmission control are discussed. Meanwhile, the contents of the dissertation are put forward.Chapter Two is a review of automatic transmission control technology. In this chapter, the author elucidated the development of automatic transmission control technology and provided references for independent development of automatic transmission control system.Chapter Three is about modeling of vehicle system. In this chapter, the vehicle with dual clutch transmission is analyzed by modeling. Dual clutch transmission is the researching object of this study. Dual clutch transmission dynamic model was constructed in this study. Dual clutch component is the key part of dual clutch transmission, a clutch model fit for researching of dual clutch transmission control and a engine model for researching of dual clutch transmission control was constructed in this study。Tire has large effects on running status of vehicle and the force of tire is one of the main factors for vehicle movement. Therefore, the tire model is significant in the dynamic simulation of vehicle. In this dissertation, the"UNITIRE MODEL"introduced by Prof. GUO KONG HUI was used, which can be used in simulation of vehicle launching and stopping and ramp holding. The model of vehicle for hill-start control can meet the requirement of research. Chapter Four is about the hydraulic system of dual clutch transmission. The main function of automatic transmission hydraulic system is to produce pressure so that all kinds of operation such as clutch control in gear shifting can be accomplished. The hydraulic system is composed of oil supply system and actuators, the former including oil pump and main pressure adjuster and the latter including clutch component and shifting mechanism. In gear shifting, the hydraulic system has to accomplish shifting as while as ensure the quality of shifting. In this study, the main parts of dual clutch transmission hydraulic system are modeled and validated by contrasting with experiment data.In Chapter Five, the author introduced a recognition algorithm about mass of vehicle and slope of ramp. This recognition algorithm has datasheets and simple model as references which were built according to the relation between the change volume of the speed in certain time range with mass of vehicle and slope of ramp. Through theoretical analysis and simulation analysis using commercial dynamical simulation analysis software CARSIM, we can work out the influence of mass and slope on vehicle speed variation which can be the basis of the algorithm。In Chapter Six is about study on vehicle hill-start control of dual clutch transmission. Utilizing the recognition algorithm of mass and slope mentioned in chapter five, the author introduced a control algorithm of hill-start which was fit for various mass and slope. In this chapter, the author also provided an overall analysis on hill-start process. According to the simulation verification in different conditions, the adaptive control algorithm which is introduced in this dissertation can be proved having good practicality.Chapter Seven is the summary and conclusion of the dissertation.The following conclusions can be derived from the theoretical analysis and simulating study on dual clutch transmission control:(1) Transmission model and vehicle model were constructed for study on dual clutch transmission control. Meanwhile, a hydraulic system model of dual clutch transmission was constructed.(2) Through theoretical analysis, this study has worked out the influence of mass and slope on vehicle speed variation. The results of theoretical analysis have been tested by simulation test. According to the analysis results, this study has put forward the on-line recognition algorithm of mass and slope.(3) Utilizing the recognition to the mass of vehicle and slope of ramp, this study put forward an adaptive control algorithm which can be fit for various mass and slope. This method can prevent slipping backward during hill-starting in all kinds of conditions so that the aim of smooth launching can be achieved. The practicality of this method made it can be used conveniently in practical control system.The dissertation has following creative works:(1) Through deeply theoretical analysis, this study has worked out the influence of mass and slope on vehicle speed variation. According to the practical results of simulation test analysis, the on-line recognition algorithm on mass of vehicle and slope of ramp has been put forward.(2) Through deeply analysis to start control in particular working situation, this study has put forward a method of combined control logic of brake control system and transmission control system to accomplish the aim of preventing slipping backward. (3) This study put forward an adaptive control logic based on the on-line recognition algorithm on mass of vehicle and slope of ramp. Through simulation in different conditions, this adaptive control logic has been tested.