Study On The Key Drive And Control Problems In The Design Of Automated Mechanical Transmission

The automatic shift control is not only an important technique used in modem vehicles, but also one of the basic functions in coming intelligent vehicles. Due to its high transfer efficiency, low price and easiness to manufacture, It is an automatic transmission which fits the reality of development of automobile industry in China and has broad prospects of manufacture and wide applications. Although a good deal of study has been done on AMT there are still many problems due to the characteristic of AMT and complexity of technology, such as automatic adaptive faculty to complicated and volatile environment and different driving intent during startup and shift. To achieve higher performances and more flexible strategies, the key drive and control problems in the design of automated mechanical transmission of commercial vehicle were studied in depth both in theory and experiment with intelligent control theory and methods.Aiming at many such problems as drive's complex structure, high precision in manufacture and high cost in the used fluid actuator, DC motor were used to substitute the fluid cylinder to reduce system cost and improve reliability of the system. The control strategies of the DC-motor-driven clutch, step motor-driven transmission and step motor-driven oil valve were studied. To solve system control complexities, a hierarchical control strategy was proposed, which includes a decision-making controller and a driving controller. With intelligent control theory and methods, the decision-making controller is responsible to provide a real-time instruction signal based upon differentiating and analysing driver's intent, the vehicle conditions and environments.While the driving controller is controllable to process specified signals and drive certain motor motions rapidly and precisely.The control of clutch engagement is one of the most important and difficult point for AMT control. The control demands and targets were analyzed during startup. According to driver's startup intent, the maximum of longitudinal jerk degree and plane slippage power were confirmed. To achive higher startup quality, different control parameters and strategies were used to cooperae the control between the clutch and the engine with intelligent control theory and methods. The half joint of clutch will be changed due to abrasion, different load or different road. This will depress startup and shift quality. A half joint fuzzy observer was proposed to follow the varieties of clutch half joint to improve system robustness.Another key technique in the AMT system is how to ascertain the optimum shift schedule. Main modifying factors of shift quality are found out through analyzing the shift quality criterion and shift process. The control methods to improve shift quality were studied. The methods to differential and analyse driver's intent, the vehicle conditions, environments and vehicle load were proposed. An idea of shift gene was put forward to improve adaptability. This method is different from modifying shif- schedule straightway, but same goal may be achived through weighting vehicle speed and oil opening.Shift, startup and ride performance will be improved and clutch life will be prolonged if engine speed is well controlled according to control strategy and vehicle dynamics. Engine speed can be well controlled during startup and shift by controlling oil opening drived by step motor. The system performance will be improved.Development of AMT system was carried out. Actuators of automatic electric clutch, shift and transmission were developed. These actuators are simple in construction, low in cost and reliable in working. Its performance achieves the anticipated result. TCU control unit of AMT was developed, test bench of AMT system is built up and test vehicle of AMT was also developed. Testing under different work conditions has been done both on bench and vehicle. The results indicate that this AMT and its control system have a good performance. The driver-vehicle-road intelligent control theory is verified in practice.