| In order to improve the performances of heavy off-road vehicle equipped withautomated manual transmission (AMT) during travelling, the powertrain of AMT system isanalyzed and modeled. Based on the control parameter analysis, the multi-dimension shiftschedule is developed. Then, the recursive least square (RLS) method with forgettingfactors is applied to estimate generalized road resistance coefficient β which is one ofinputs of shift time and gear decision-making. Finally, an overall shift sequenceoptimization is realized by dynamic programming (DP) on the premise of knowngeneralized road resistance coefficient. The main study points are as follows:(1) Mathematic modelling of AMT powertrain in static and dynamic conditions,including the torque map and fuel consumption characteristics, clutch, transmission, etc.(2) Determine the control parameters of shift schedule, and calculate the shift pointswith deactivated throttle, velocity and generalized road resistance coefficient β.(3) Use RLS method to estimate vehicle mass and β based on dynamics analysis andestimate the sine value of road slope based on kinematics, then to obtain β in complicatedconditions. On the basis of β estimation, the repeated gear position decison-making isdeveloped and simulation shows it is important to improve vehicular dynamic performance.(4) With known generalized road resistance coefficient, DP method is applied tooptimize the shift sequence. The optimization model is built and calculating instruments areprogrammed considering the power interruption during shifts. Simulation shows theoptimal shift sequence can satisfy the need of comprehensive performance. |
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