Study On Shifting Of Automatic Transmission Of Off-road Vehicle Based On Fuzzy Control

Off-road vehicles is a special vehicle and its main job is to complete a particular job. The working environment of off-road vehicles is spanking harsh. In addition, external loads of off-road vehicles are often complicated. So, not only the need for frequent shifting, and the need to guarantee that the job of the off-road vehicles can have sufficient power. Jobs underpowered of off-road vehicles will reduce operating efficiency, increase working time, which leads to not only increasing costs, but also significantly increasing the driver’s working hours, so that make the driver fatigue.Therefore, to guarantee the optimum power of the off-road vehicles, the paper developed a best shift law, which makes off-road vehicles shift in the best shift point, on the basis of the automatic transmission system. In this regard, this paper mainly research on the following related content:(1)Analysising the powertrain characteristics of the off-road vehicles. Including off-road vehicles powertrain operating characteristics, driveline force, the engine operating characteristics together with the hydraulic torque converter, and finally putting forward the methods of matching the hydraulic torque converter and the engine of this proposed research project.(2) Studying the off-road vehicles best shift rule and control methods. This paper puts forward the engine throttle opening and the vehicle speed as the basic two parameters shift schedule, which making the engine and the torque converter as a whole to consider shifting control strategy. On this basis, to ensure that the off-road vehicles dynamics as the ultimate goal, and using the graphical method to calculate the best Shift rule curve of Off-road vehicles. Finally,the shifting process of fuzzy control system on the basis of the automatic transmission that this project is analyzed.(3) Based on Matlab/Simulink, the simulation analysis of double-parameter shift schedule of off-road vehicles automatic transmission system was completed. The simulation model of power transmission system of off-road vehicles was built including the engine the hydraulic torque converter model and so on. On the basis of the simulation results curves, the working characteristics of off-road vehicles was analyzed when the vehicle was under starting and acceleration condition, operation condition or climbing condition.(4) The four-parameter shift schedule based on rapid change of throttle opening was studied. Rapid change of throttle opening will lead shift circularly, so the reason is firstly researched by analyzing the power characteristic of off-road vehicles. Through researching the Stateflow tool of double fuzzy control and application, the four-parameter simulation model was built that considering the rapid change of throttle opening. The simulation verifies that four-parameter shift schedule can eliminate or reduce the cyclic shift phenomenon.