| The liquid-filled tractor-semitrailer is widely used in the transportation of liquid chemical products.It not only has the common characteristics of semi-trailers,but also has the coupling effect between the liquid sloshing and the vehicle movement,especially in the process of emergency avoidance or high-speed steering.So it's necessary to carry out anti-rollover control strategy to improve the stability of liquid-filled tractor-semitrailers,in this way,the casualties,environmental pollution and other serious consequences will be reduced.In the process of building vehicle anti-rollover control strategy,some vehicle motion state variables need to be known.While these variables can't be measured directly or cost a lot,so it's necessary to estimate the motion state of the liquid-filled tractor-semitrailer.The estimation of motion states is based on the vehicle dynamic model.The parameters of the model generally change as the actual operating conditions change.so it is necessary to identify vehicle key parameters.This paper is supported by the National Natural Science Foundation project which is Research on mechanism of fluid-structure interaction and anti-rollover control strategy of liquid-filled tractor-semitrailers,Jilin Provincial Science and Technology Development Project which is Heavy Duty Vehicle Electronic Pneumatic Brake System Development and Matching,Jilin Provincial Science and Technology Development Project which is Stability control for Heavy Duty Vehicle based on Electronic Pneumatic Brake System.Based on the present research of liquid sloshing methods,vehicle parameters identification and motion states estimation,the liquid sloshing model is built and verified by real vehicle test,the estimation algorithm of key parameters and motion state are proposed and verified by simulation,the anti-rollover control strategy is built and verified by simulation.The main work of this paper is as follows:(1)The mathematical model of the liquid-filled tractor semitrailer is established.Firstly,the pendulum model is established to describe the sloshing rule of the liquid in the tank.The numerical model of liquid sloshing is established by FLUENT,which provides the lateral forceand roll moment for the parameter identification of the pendulum model.In order to ensure the effectiveness of the parameter identification,the correction of the numerical model of liquid sloshing is verified by real vehicle test based on the similarity principle of fluid mechanics.The validity of the pendulum model is verified by comparing the calculation results of the pendulum model and the numerical model.The dynamic model of liquid-filled tractor-semitrailer is established based on the pendulum model.(2)The mass of the liquid-filled tractor-semitrailer is estimated by recursive least squares algorithm based on the longitudinal dynamic model.The centroid height of the liquid-filled tractor-semitrailer is identified by the recursive least square algorithm based on the dynamic model of liquid-filled tractor-semitrailer.The equivalent lateral stiffness of the axles and the roll stiffness of the vehicle are identified by genetic algorithm based on the dynamic model of liquid-filled tractor-semitrailer.The key motion state of the dynamic model of liquid-filled tractor-semitrailer is estimated by Kalman filtering algorithm based on the dynamic model of liquid-filled tractor-semitrailer,the validity of estimation algorithm is verified by TruckSim-Simulink co-simulation.(3)The anti-rollover control strategy which is based on differential braking is established.Firstly,the reference model of the liquid-filled tractor-semitrailer is established.Secondly,the optimal additional yaw moment is calculated by using the LQR algorithm.Thirdly,the braking wheels are selected based on the yaw rate,the wheel braking moment is calculated by the additional yaw moment.The effectiveness of the anti-rollover control strategy is verified by TruckSim-Simulink co-simulation. |
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