Research On The Construction And Evaluation Method Of Driving Cycle Of City Mixed Road

Driving cycle test,which is conducted to detect the emission level,energy consumption and powertrain matching,is a core technology of automobile development.At present,the Chinese regulation system employs the European "ECE+EUDC" cycle for vehicle test,but the traffic environment and urban road conditions of China are actually very different from that of Europe.Therefore,it is unreasonable to apply the European cycle to testing the Chinese vehicles,and it is of practical significance to establish a driving cycle typically for China.Two key factors for setting up such a cycle test include fast and accurate construction of the driving cycles,and a series of feasible appraisement indices.In this research,a data acquisition and analysis platform of vehicle driving cycle was set up based on the data obtained from the No.503 bus of the Tianjin Binhai bus system.In order to acquire real and full vehicle driving data,which is the fundamental of driving cycle synthesis,vehicle running data of 1400 laps and over 100 thousand kilometers were collected.These data cover the operations at different conditions,concerning the roads,seasons,time periods of a day,driving manners of drivers and applications of accessories(including air conditioning).A combined distribution test and clustering analysis method was proposed to overcome the problem of large amount of computation for the WLTC method.In this method,the entire route was divided into three typical sub-sections according to the geographical conditions,and for each of the sub-section,short strip and idle segment database were constructed respectively.The combination and selection method of driving cycle segments was optimized,after which an alternative typical driving cycle of the route was obtained.Compared with the WLTC synthesis,this method avoids the random sampling procedure,and thus reduces the intensity of computation and the time consumption by synthesis.Results show that compared with the WLTC method,the proposed method consumes only 1/(3.32 * 1012)of the computing resources when dealing with the same problem.An effective evaluation method based on the fuel consumption characteristics of a driving cycle is proposed.A series of comprehensive evaluation indices for alternative operating conditions was constructed on the basis of 10 alternative operating conditions selected by the Euclidean distance method and via the analysis of the correlation between the fuel consumption and the characteristics of the working conditions.By using the indices,optimum operating conditions can be selected in atypical driving cycle,and the problem of low resolution and single index of the Euclidean distance method can be solved.The proposed GT-model-based evaluation method,together with the characteristic parameter test method and the velocity acceleration joint distribution test method,was verified against the data obtained from the No.503 bus.Results show that,in contrast to the average relative error of 4.72% and 6.06% of the latter two methods respectively,an error of 0.03% can be achieved by using the GT-model based model,indicating that effective and reliable driving cycles and appraisement indices can be accomplished in this research.