Journal of South China University of Technology (Natural Science Edition) ›› 2016, Vol. 44 ›› Issue (3): 60-67.doi: 10.3969/j.issn.1000-565X.2016.03.009

• Automotive Engineering • Previous Articles     Next Articles

Control of Positive-Torque Downshifting Process of Automatic Transmission with State Variable Constraints

YE Jie1 HUANG Xiang-dong1 ZHAO Ke-gang1 HE Xiao-peng1 LIU Yan-wei2   

  1. 1.Guangdong Key Laboratory of Automotive Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China; 2.School of Electro-Mechanical Engineering,Guangdong University of Technology,Guangzhou 510006,Guangdong,China
  • Received:2015-07-10 Revised:2015-11-01 Online:2016-03-25 Published:2016-02-02
  • Contact: 赵克刚(1977-)，男，博士生，副教授，主要从事车辆传动与电动汽车理论研究． E-mail:kgzhao@scut.edu.cn
  • About author:叶杰(1991-)，男，博士生，主要从事车辆系统动力学和自动变速器理论研究． E-mail:452016239@ qq． com
  • Supported by:
    Supported by the National Natural Science Foundation of China(51575189)

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Abstract: By taking an automatic transmission that implements the power shifting only with a single friction clutch as the research objective,the dynamic process of positive-torque downshifting of automatic transmission is analyzed to establish a coordination control strategy for friction clutch and engine torque.By considering the jerk at the end of the inertia phase and the friction work as the comprehensive objective functional,the coordination control is ac- complished on the basis of minimum principle,which is used to optimize the inertia phase in downshifting process with torque constraints.Moreover,by taking the gradient of the power source torque and the friction clutch as two control variables and by applying the inequality constraints on control variables and state variables,the constrained Bolza problem is solved numerically and the optimal state variables’trajectory is obtained.Simulation and bench test results indicate that the proposed method effectively decreases the torque fluctuation of transmission output shaft,promotes the dynamic property and improves the shift quality.

Key words: automatic transmission, downshifting process, inequality constraint, minimum principle, coordination control strategy