Optimization Of Gearshift MAP Based On DP For Automated Transmission

Optimization of gearshift schedule is a crucial problem in the control system of stepped automatic transmission,which can directly affect the dynamic performance and the overall efficiency of the vehicle.An accurate and reasonable shift schedule has significant theoretical and practical meaning for improving both dynamic and economic performance since it defines the control parameters used for gearshift decision making and shift timing.Therefore,many car manufacturers,colleges,universities and scientific research units have been putting attempt on optimization of gearshift schedule.Traditional methods usually only consider a certain unique performance index,such as power or economical performance,which can not improve the comprehensive performance of vehicle.On the basis of the previous research,based on the experimental platform of a certain type of AMT passenger vehicle with 5 gears assembled,the optimal shift schedule of fuel economy is designed by using Dynamic Programming theory under the dynamic constraints.By building the whole vehicle model,comparing and analysing with the other gearshift schedule in power performance and fuel economy,the gearshift schedule based on Dynamic Programming is optimized.Finally,the whole control scheme is downloaded to the dSPACE control system to verify its real-time effectiveness.The specific research contents are as follows:(1)This paper introduces several popular transmissions in the market and their respective characteristics,and emphatically analyzes the working principle of AMT.At the same time,the research progress of gearshift schedule optimization at home and abroad is summarized,and some related problems are put forward.(2)According to the known vehicle data,the AMEsim software is used to build the whole vehicle model,including engine module,transmission module,driver module,whole vehicle module and driving cycle mode module,and the shift logic controller model is built in the MATLAB/Simulink tool.The joint simulation and verification platform is formed together.(3)Based on the vehicle powertrain system model,using Dynamic Programming theory,taking the minimum fuel consumption as the optimization objective,the gear of the transmission as the state variable and the shift command as the control variable,theoptimal solutions of the gear sequence under three operating conditions,NEDC,UDDS and 1015,are solved.(4)The optimal solution of the gear sequence is introduced into the transmission module of the simulation model,and the gearshift schedule based on Dynamic Programming is worked out by simulation analysis.The gearshift schedule based on Dynamic Programming is introduced into the shift logic control module of the whole vehicle model for off-line simulation experiment,and the results are compared with the dynamic gearshift schedule and the economic gearshift schedule simulation experiment results based on the rules.Testing its power and fuel economy,and adjusting the gearshift schedule based on Dynamic Programming.The experimental results show that the adjusted gearshift schedule based on Dynamic Programming has achieved a good tradeoff between power performance and fuel economy.(5)In order to verify the real-time validity of the shift rule based on dynamic programming,the whole control scheme is downloaded to the dSPACE control system for rapid control prototype experiment.