Research On Optimal Control Method Of Gear Shifting For Heavy Mining Vehicles

Shift quality control is one of the most important technologies in shift process control.It is not only related to the comfort of passengers,but also has an important influence on the sevice life of components,fuel economy and emissions.Based on a hydraulic mechanical automatic transmission of heavy mining vehicles,a new phased optimal control strategy of gear shift quality was presented according to different control objectives of different stages of shifting.The proposed method was verified in hardware in the loop simulation(HILS).Firstly,the powertrain system models including engine,torque converter,transmission and load were built according to the test and survey data.The flow,pressure and dynamic characteristics of electronic-hydraulic system were studied before setting up the simulation modules.Then the P-I curve of proportional pressure control solenoid and the In-Out pressure curve of pressure regulation spool valve were obtained based on bench test,which calibrated the simulation models and laid the foundation for the study of gear shift quality control strategy and hardware in-loop test.Then,the shift quality requirements of heavy mining vehicles were presented according to applied characteristics.The kinematic and dynamic relationships of shift process were analyzed by using the planetary gear train equation and the Lagrange equation and the expressions of jerk of torque phase and inertial phase were obtained.Then the quantitative relationship of torque of cluches under the ideal alternating sequence conditions were proposed.Afterwards,the control objectives of torque phase and inertial phase were proposed respectively according to the analysis above.Taking jerk and slipping loss into comprehensive consideration,the phased optimal control strategy of gear shift quality based on different shifting stages was developed according to LQR optimal control theory.The torque tracking control method of torque phase and the state regulation control method of intertial phase were respectively studied and simulated.In order to solve the problem of how to choose parameter values of performance functional weight matrix Q?R,the genetic algorithm is used to optimize the calculation,which reduced the number of manual attempts and ensured the optimal control performance of the selected weight matrix.In the end,combining with the existing electro-hydraulic two-stage voltage regulator test bench,the control strategy was validated by using dSPACE real-time simulation system and RapidECU rapid control prototype,the hardware-in-the-loop simulation test platform was set up and the influence of vehicle quality or mine ramps on shift quality was studied.The results showed that the optimal control strategy can achieve good shift quality.