Study On Control Strategy Of Automated Mechanical Transmission

The conventional manual transmission has high efficiency, simple structure and low cost. They are also used extensively. Automated mechanical transmission(AMT) holds the merits of the conventional manual transmission, and can be manipulated simpler and easier by the driver. The driveline life is extended by the electronic control. Therefore the AMT plays an important role in automated transmissions. Having high ratio of the performance to cost, it is suitable for the situation of our country.The AMT can be actuated by electrical-hydraulic, electrical-pneumatic or electrical way. The electrical-hydraulic way is the most. It's principle was described, and it was operated automatically by electronic equipments. The function of control system of the AMT was designed to meet the need of manipulation, safety and service, which is equipped in a Santana 2000 car, developed by the author. These functions include the constitution of ECU hardware, the program flowchart of ECU software and the principle of the hydraulic system.The control performance of the AMT has relations to the characteristics and parameters of the engine, the clutch and the transmission in the driveline. For the reasons that the output torque of the engine is nonlinear to the engine speed and the throttle angle, the friction torque of the dry clutch is nonlinear to the clutch position, the gear position of the transmission is changeable in terms of the vehicle condition and the road condition, the driver's intention and the road condition are different, variational and random, the control problem of the AMT is the nodus. The nonlinear characteristics of the engine and the clutch is analysed and studied. The load characteristics of the driveline is analysed. The force applied to the wheel in the starting-up and gearshifting process is analysed from the point of view of kinematics, which makes the mastery of mostly external factors influencing he starting-up and gearshifting process. From the above discussion, the control strategy can be established reasonedly and availably.During the starting-up process, there are demands that the driver's intention is satisfied, the engine stall is avoided, the vehicle runs backward a little on the slope, the clutch wears out a little, the jerk grade is small. This leads to the results that it is difficult to control the starting-up process to the extent of satisfaction and practicality. Thus the starting-up control is important and difficult. The throttle angle controlling the engine usually tracks the accelerator pedal position, the transmission is in a given gearposition, how to control the clutch engagement process to meet the driver's intention, the vehicle condition and the road condition is crucial. The starting-up process is analysed from the point of view of dynamics, the influencing factors is analysed sufficiently, and then a MAP control strategy is proposed, in which the clutch permissible position is decided by the accelerator pedal position and the engine speed, the clutch engagement velocity is decided by the accelerator pedal position, the engine speed and the engine change-in-speed. The control strategy is used in Santana 2000 sample pattern. That gains good results.The clutch position is controlled by the hydraulic actuator. It will be relatively difficult to control the position accurately, for the reasons that high speed on-off valve has dead zone and nonlinearity, the power supply voltage fluctuates, the hydraulic pressure undulates, the oil viscosity changes with its temperature. A multi-mode control algorithm is proposed, in which the maximum control is applied to eliminate the error rapidly in big error range, the fuzzy control is used to improve the robustness in medium error range, the PI regulator is used to eliminate the steady error. It has been proved that the clutch position control can meets the need of application.For the purpose of the starting-up performance improved further, several control schemes are simulated, analysed and compared on the basis of the seventh order dyna...