Research On Rollover Control System Of Semi-Trailer Train Based On Parameter Identification

Semi-trailer train is composed of tractor and semi-trailer. Comparing with the general truck, it has the advantages of large load capacity of carrying, high efficiency, low operation cost and the better effect of energy saving, so it has been widely used. But because of its high center of gravity, great weight, large volume and the coupling interaction between tractor and trailer, its rollover, folding and other major traffic accidents are easily to occur, resulting in heavy losses of life and property especially the rollover accident. Therefore, it is very necessary to control the rollover of semi-trailer train so as to improve its traveling stability.In order to improve the rollover stability of semi-trailer train, this paper focused on the study of vehicle rollover control system. It mainly researched on the model establishment of semi-trailer train, the model parameter identification and the rollover control system establishment:First of all, according to the need of the stability control of semi-trailer train, the dynamic model that involving the motion of yaw, lateral and rollover was established based on the vehicle dynamic theory.Secondly, aiming at the problem that the model parameters of semi trailer train were difficult to identify because of its complicated structure and much parameters, this paper relied on the simulation data under angular step condition in TruckSim, and then put forward a two-step identification method which combining the genetic algorithm and L-M optimization algorithm to identify the eight key parameters which were difficult to measured directly, such as tire cornering stiffness of the tractor front axle, tractor rear axle and trailer axle, the suspension roll stiffness and damping of the tractor and the trailer, and the roll stiffness of the 5th wheel, and then designed other five conditions to verify the correctness of the parameter identification. The results showed that this two-step identification method can get accurate parameter values of the model, So that the model can better describe the basic motion characteristics of real vehicle, and lay the foundation for research of vehicle rollover control system.Semi-trailer train rollover control strategy was studied. It took real vehicle movement state as close as possible to the ideal reference state as the control target, used LQR controller to determine the additional yaw moment required by the tractor and the trailer, and adopted differential braking mode to produce the corresponding yaw moment to avoid rollover. Among them, a method of combining lateral acceleration threshold with lateral load transfer rate was adopted to predict the potential risk of vehicle rollover, and a selection rule of the target wheel and a principle of the braking force distribution under the differential braking control strategy were formulated. Finally, The MATLAB/Simulink was used to build a vehicle rollover control system model, and combined with TruckSim software to carry out simulation test under the hook condition and high/low adhesion coefficient of double lane condition. The results showed that the established vehicle rollover control system can effectively control the rollover of sime-trailer train, avoid occurring rollover, yaw, folding and other dangerous accidents, and improve the driving stability and safety.