Driving Cycle Construction and Gear-shifting Analysis of AMT Semi-trailer Tractor
In recent years,the market share of AMT heavy semi-trailer tractor(AMT tractor hereinafter)in China has expanded rapidly.However,research pertaining to this vehicle type has not progressed accordingly with this trend,and the vehicle performance can be further improved.Thus,typical driving cycles for AMT tractors in China should be established,shifting scenarios analyzed,and stylistic cycles constructed to facilitate the optimization of AMT shifting strategies.This will improve the power,economic,and environmental performances of the vehicle and allow the advantages of AMT tractors to be leveraged more effectively.Using measured data of the vehicle,the Douglas-Peucker algorithm was applied to disperse the speed and power indicators such that the difference and trend data of the two indicators can be obtained.Subsequently,four typical shifting scenarios,i.e.,acceleration,deceleration,starting,and parking,were efficiently constructed,and the shifting speeds,power-consumption fluctuation,number of shifts,and shifting load were counted and analyzed under different scenarios.Next,a non-freeway driving cycle was constructed using the improved short-trip method combined with the t-SNE and K-means algorithms,and a freeway driving cycle was constructed using the Markov chain method to compensate for the intrinsic defects of the short-trip method.Finally,based on the non-freeway driving cycle,an objective scoring method was used to distinguish between conservative and aggressive difference data,after which they were superimposed on the non-freeway cycle skeleton to construct style cycles more flexibly.The results are as follows:The shifting velocity of the AMT tractor is particularly evident in two intervals,i.e.,0-20 and 55-70 km·h-1,and the four typical shifting scenarios are different from each other.This implies that the dynamics and economic tendency of the shifting strategy should be dynamically adjusted depending on the scenario.The average relative error(MRE)of the indicators for the freeway and non-freeway driving cycles are 4.834％and 3.431％,respectively(while the latter reduced by 27.49％compared with the conventional method),and the MREs of the simulated fuel consumption are 6.68％and 3.97％,respectively,thus indicating that the two cycles are superior to the standard cycles of CHTC-TT and C-WTVC.The MREs of both the aggressive and conservative driving cycles are approximately 5.6％,which indicates that they can be used to evaluate the performance of the shifting strategy under different driving intensities.The MREs based on the conventional method and style cycles exceed 3.431％,which indicates that the driving behavior data must be separated during the construction of the driving cycle to mitigate the negative impact.
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