| In the automobile industry there has been a clear trend in recent yearstowards increased motoring comfort and towards making cars easier to drive.At the same time, driven by substantially the rising fuel price, stricteremissions regulations, continued pressure on operating costs, increasing trafficcongestion, and a shortage of skilled drivers, these changes will take place inthe engine, the exhaust gas treatment system, and the transmission oncommercial vehicles, especially middle-size and heavy-duty trucks. Thecharacteristics are more efficient, cleaner, easier to drive, lower costs andmaintains expense. So the development trend of commercial vehicles probablyis the utilization of several forms of hybridization, as engines move fromconventional diesel operation towards homogenous charge compressionignition (HCCI). Transmissions go toward to automated manual transmission(AMT), which is low produce cost, high efficient, can shift and operateclutches automatically.On commercial vehicles the AMT has already established itself well inWestern Europe and North America for several years. But it still is at thebeginning stage in China. According to the study of Global Insight, a industryforecasting firm, the demand for self-shifting transmission technology inmiddle-size and heavy-duty trucks will increase dramatically over the next 15years. So the market will be very large. Though the system-caused tractivepower interruption during shifting and the limited shifting comfort it causescompared to a powershift transmission is a disadvantage for commercialvehicles, this clearly takes a backseat to the advantages for them. When specialapplications are ignored, the AMT remains the first choice for the commercialvehicle sector in the long term.Till now, the domestic factories have no ability to industrialize theautomatic gearbox. In recent years, some manufacturers have been trying toseek automatic products, which suit our country situation and can bedeveloped independently. Due to its high efficiency, low cost, and easier tomanufacture, AMT is considered to be the right product, which is suitable forours most and has greatest potential in the development of industrialization.Combined with the collaborative project of AMT control strategydeveloping for truck, which is consigned by R&D FAW, this paper aims at thecontrol strategies of start and shifting processes. The purpose is to research theshifting behaviors of skilled drivers, to compare it with the control strategiesof present sample truck with AMT, to research the differences between manualand AMT manipulation, to analyze the comparability index, to optimize AMTcontrol strategies and to establish optimum control strategies through testingand model-based simulating. The paper addresses four areas:1. Reviewing the development stages of the AMT. Summarizing thestructure, the characteristic and the type of it. Introducing two AMT productsavailable in the commercial vehicle market. Analyzing the merits andshortcomings of the AMT equipped with commercial vehicles, and thepracticability of the AMT development on trucks.2. Analyzing the basic control strategies of AMT briefly. The closingconditions and process, the control requirements, the control mode andmethods of the clutch in the launch stage, including driveability, ride comfort,clutch protection. The control metrics of the clutch and the gearbox in therunning and stopping stage. The influence factors of shift quality. Introducingsome practical assistant control strategies of the AMT3. Analyzing the control strategies using simulation. A complete vehiclemodel of the CA1145P1K2L7 was built in CRUISE software,which is used toperform vehicle simulation and powertrain analyses designed by AVL LISTGMBH. A transmission control unit (TCU) model was established inMATLAB/SIMULINK software. Analyzing the characteristics of the startingand shifting combined with the two models. Analyzing the shifting MAPfeatures through comparing the performance and the Extra Urban DrivingCycle (EUDC) with the manual model of the truck.4. Analyzing the shift features of skilled drivers' manipulation based ontests. All tests were done on the CA1145P1K2L7 truck. Several skilled driversoperated the truck following their own habits to launch, shift gears, brake andhill start. The clutch position, velocity, engine speed and input speed of thegearbox were recorded. After analyzed the data, the shift behaviors and controlmetrics were found, as well as the shifting scheduling and the shifting MAP.In conclusion, the paper used different research methods to analyze theshift strategies of AMT. It will help firmly to support the AMT benchmarking.
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